TH350 rebuild tech
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*This wiki is not intended to be a replacement for an ATSG or factory tech manual. First time builders will likely need a tech manual. Recommended is Ron Sessions' book, [http://www.amazon.com/Turbo-Hydra-Matic-350-Handbook-Sessions/dp/0895860511 '''''Turbo Hydra-Matic 350 Handbook'''''] in the HP book series. It has good pictures, a lot of good info, but has some outdated info. Outstanding value for the money. | *This wiki is not intended to be a replacement for an ATSG or factory tech manual. First time builders will likely need a tech manual. Recommended is Ron Sessions' book, [http://www.amazon.com/Turbo-Hydra-Matic-350-Handbook-Sessions/dp/0895860511 '''''Turbo Hydra-Matic 350 Handbook'''''] in the HP book series. It has good pictures, a lot of good info, but has some outdated info. Outstanding value for the money. | ||
*This is not a step-by step tutorial. That said, the following should help give a better understanding of the TH350 and possibly help when a question arises. | *This is not a step-by step tutorial. That said, the following should help give a better understanding of the TH350 and possibly help when a question arises. | ||
| − | *The following | + | *The following page was inspired by an original Hotrodders forum thread by jakeshoe, titled [http://www.hotrodders.com/forum/th350-rebuild-tech-145361.html ''TH350 Rebuild Tech'']. |
==Variations of the TH350 family== | ==Variations of the TH350 family== | ||
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===Bushings and thrust washers=== | ===Bushings and thrust washers=== | ||
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A TH350 is known to be rough on bushings. Bushings are critical in that they allow the rotating parts to ride true on center, and for the lube to make it to the rear of the trans. | A TH350 is known to be rough on bushings. Bushings are critical in that they allow the rotating parts to ride true on center, and for the lube to make it to the rear of the trans. | ||
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{| | {| | ||
| − | |[[File:T-350_bushings.jpg|thumb|300px|left| | + | |[[File:T-350_bushings.jpg|thumb|300px|left|TH350 bushings]] |
| − | |[[File:T-350_thrust_washers.jpg|thumb|300px|left| | + | |[[File:T-350_thrust_washers.jpg|thumb|300px|left|TH350 thrust washer kit]] |
|} | |} | ||
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===1-2 accumulator=== | ===1-2 accumulator=== | ||
| − | Photo shows accumulator cover, spring and piston (snap ring not shown). This is located on right side of | + | Photo shows accumulator cover, spring and piston (snap ring not shown). This is located on right side of transmission case. Check the bore in the case for scratches or other damage if the spring was found broken. |
| − | [[File:T-350_acumilator01.jpg|thumb|300px|left| | + | [[File:T-350_acumilator01.jpg|thumb|300px|left|TH350 Accumulator cover, spring and piston with sealing rings]] <br style="clear:both"/> |
Right side of TH350 case. Pressure ports are circled. | Right side of TH350 case. Pressure ports are circled. | ||
| − | *Rear port (yellow) is main line pressure. You will see pressure here in all gears for most valve body configurations. Some race-only valve bodies may not have pressure at this port or the others | + | *Rear port (yellow) is main line pressure. You will see pressure here in all gears for most valve body configurations. Some race-only valve bodies may not have pressure at this port or the others |
| − | *Middle port (red) is 2nd gear pressure | + | *Middle port (red) is 2nd gear pressure |
| − | *Front port (blue) is third gear pressure | + | *Front port (blue) is third gear pressure |
| − | [[File:T-350_acumilator02.jpg|thumb|300px|left|TH350 | + | [[File:T-350_acumilator02.jpg|thumb|300px|left|TH350 pressure ports circled]] <br style="clear:both"/> |
=Transmission reassembly= | =Transmission reassembly= | ||
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The first item to go in the case will be the low/reverse apply piston. Its function is for oil to force it towards the front or bellhousing side of the trans, applying the low/reverse clutches. This allows reverse when applied simultaneously with the direct (high gear) clutches, and allows manual low gear when applied with the forward clutches. Manual low gear creates engine braking on deceleration. The low/reverse clutches do not apply in automatic range 1st gear. The low sprag (low roller clutch actually) causes first gear when only the forward clutches are applied. | The first item to go in the case will be the low/reverse apply piston. Its function is for oil to force it towards the front or bellhousing side of the trans, applying the low/reverse clutches. This allows reverse when applied simultaneously with the direct (high gear) clutches, and allows manual low gear when applied with the forward clutches. Manual low gear creates engine braking on deceleration. The low/reverse clutches do not apply in automatic range 1st gear. The low sprag (low roller clutch actually) causes first gear when only the forward clutches are applied. | ||
| − | In the rare application that does not need reverse or low gear engine braking the low piston and low clutches can be deleted | + | In the rare application that does not need reverse or low gear engine braking, the low piston and low clutches can be deleted and the feed holes in the case blocked. |
Install new seals on the low piston, these are square cut seals, not lip seals. | Install new seals on the low piston, these are square cut seals, not lip seals. | ||
| − | [[File:T-350_low_piston.jpg|thumb|300px|left| | + | [[File:T-350_low_piston.jpg|thumb|300px|left|TH350 low-reverse piston has three seals on it, creating two separate sections]] <br style="clear:both"/> |
Then push it into the rear of the case evenly by hand, aligning it properly so it will seat (there is a "tang"). Look at the park pawl notch to help index it. | Then push it into the rear of the case evenly by hand, aligning it properly so it will seat (there is a "tang"). Look at the park pawl notch to help index it. | ||
| − | [[File:T-350caselowpiston.jpg|thumb|300px|left| | + | [[File:T-350caselowpiston.jpg|thumb|300px|left|TH350 low-reverse piston installed into case]] <br style="clear:both"/> |
Then install the return spring and retainer using the tool pictured. | Then install the return spring and retainer using the tool pictured. | ||
| − | [[File:T-350_low_pist_springtool.jpg|thumb|300px|left|Tool used to compress the springs | + | [[File:T-350_low_pist_springtool.jpg|thumb|300px|left|Tool used to compress the springs and retainer to install the retaining snap ring]] <br style="clear:both"/> |
==Output shaft install== | ==Output shaft install== | ||
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Next you install the output shaft. | Next you install the output shaft. | ||
| − | + | [[File:T-350_output_bearing.jpg|thumb|300px|left|TH350 output shaft with bearing that fits between case and ring gear]] <br style="clear:both"/> | |
| − | [[File:T-350_output_bearing.jpg|thumb|300px|left| | + | |
Be sure you have the output ring gear to case bearing in the case. | Be sure you have the output ring gear to case bearing in the case. | ||
| − | Also be sure on dis-assembly you inspected and replaced as necessary the input shaft to output bushing shown here | + | Also be sure on dis-assembly you inspected and replaced as necessary the input shaft to output bushing shown here(red arrow). |
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| − | [[File:T-350_pilot_bushing.jpg|thumb|300px|left|Check this bushing for wear, replace with new metal bushing or slip-in plastic insert | + | [[File:T-350_pilot_bushing.jpg|thumb|300px|left|Check this bushing for wear, replace with new metal bushing or slip-in plastic insert]] <br style="clear:both"/> |
==Rear planetary unit install== | ==Rear planetary unit install== | ||
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Next goes in the output planetary to output ring gear bearing or thrust washer (depending on year). | Next goes in the output planetary to output ring gear bearing or thrust washer (depending on year). | ||
| − | Then the planetary unit. Replace the bushing in this planet.Check planet pinion gears for side to side movement. Clearance of .030 to 0.050 is common. If the pinion gears wiggle like the bearings and pin are worn, replace the planet with a rebuild or good used. | + | Then the planetary unit. Replace the bushing in this planet.Check planet pinion gears for side to side movement. Clearance of 0.030" to 0.050" is common. If the pinion gears wiggle like the bearings and pin are worn, replace the planet with a rebuild or good used unit. |
| − | + | [[File:T-350_rear_planet.jpg|thumb|300px|left|TH350 rear planetary unit with fresh busing installed]] <br style="clear:both"/> | |
| − | [[File:T-350_rear_planet.jpg|thumb|300px|left| | + | |
Now you can install the low/reverse clutches, beginning with a steel, then a friction, alternating, ending with a friction. | Now you can install the low/reverse clutches, beginning with a steel, then a friction, alternating, ending with a friction. | ||
| + | [[File:T-350_low_clutch_install.jpg|thumb|300px|left|TH350 low-reverse frictions and steels installed with planetary and output shaft]] <br style="clear:both"/> | ||
| − | + | {{Note1}}If you have a light duty core with low count low pack, unless it is a transbrake application or will be manually shifted into low for engine braking often, fewer clutches is OK. In some cases where you are after every last bit of ET, using fewer clutches can cause less frictional loss in 2nd and high gear. "Turbulator" steel plates from a 4L60E will also help and are a direct drop-in. | |
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| − | If you have a light duty core with low count low pack, unless it is a transbrake application or will be manually shifted into low for engine braking often, fewer clutches is OK. In some cases where you are after every last bit of ET, using fewer clutches can cause less frictional loss in 2nd and high gear. "Turbulator" steel plates from a 4L60E will also help and are a direct drop-in. | + | |
There are Alto red frictions in this unit, however a stock tan clutch ( like Borg Warner brand) is more than adequate for even very high HP cars. A Hi-Energy Borg from a 4L60E is also a good choice. | There are Alto red frictions in this unit, however a stock tan clutch ( like Borg Warner brand) is more than adequate for even very high HP cars. A Hi-Energy Borg from a 4L60E is also a good choice. | ||
| + | Once the low clutches are installed, you can install the anti-clunk spring (or case-saver). Hold in place with assembly gel or vaseline and then install the low-reverse support. | ||
| − | + | [[File:T-350_anti-rattle_spring.jpg|thumb|300px|left|Anti rattle (clunk) spring shown in correct location; use assembly grease to hold in place]] <br style="clear:both"/> | |
Be sure the low sprag inner race is not brinelled or has any unusual wear. | Be sure the low sprag inner race is not brinelled or has any unusual wear. | ||
| − | + | [[File:T-350_center_suport_sprag.jpg|thumb|300px|left|Photo shows center support with sprag (roller clutch) and inner race]] <br style="clear:both"/> | |
| − | [[File:T-350_center_suport_sprag.jpg|thumb|300px|left|Photo shows center support with sprag(roller clutch) and inner race | + | |
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The roller clutch must installed correctly with the edge of the roller clutch tangs match the inner receiving tangs of the center support. Install snap ring. There is a snap ring on both sides of the roller clutch. | The roller clutch must installed correctly with the edge of the roller clutch tangs match the inner receiving tangs of the center support. Install snap ring. There is a snap ring on both sides of the roller clutch. | ||
| − | [[File:T-350_assembled_low_support.jpg|thumb|300px|left|Installed sprag (roller clutch), watch orientation of tangs into the center support housing | + | [[File:T-350_assembled_low_support.jpg|thumb|300px|left|Installed sprag (roller clutch), watch orientation of tangs into the center support housing]] <br style="clear:both"/> |
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Now is the time to air check the low clutches. You do so by applying pressurized air to the passage at the rear pan area of the worm casting in the case. | Now is the time to air check the low clutches. You do so by applying pressurized air to the passage at the rear pan area of the worm casting in the case. | ||
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Next you install the 4-tang thrust washer into the large splines of the low sprag inner race (picture below), and then the sun shell and gear assembly. | Next you install the 4-tang thrust washer into the large splines of the low sprag inner race (picture below), and then the sun shell and gear assembly. | ||
| − | [[File:T-350_center_support.jpg|thumb|300px|left|Center support, inner race, thrust washer shown | + | [[File:T-350_center_support.jpg|thumb|300px|left|Center support, inner race, thrust washer shown]] <br style="clear:both"/> |
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| + | Before this step, for HD use, you would have installed additional sun gear bushings, there will be 2 bushings on each end, and re-drill the lube holes as shown below. | ||
[[File:T-350_sun_gear_bush.jpg|thumb|300px|left|Double bushings installed. You MUST drill oil holes in bushings]] <br style="clear:both"/> | [[File:T-350_sun_gear_bush.jpg|thumb|300px|left|Double bushings installed. You MUST drill oil holes in bushings]] <br style="clear:both"/> | ||
==Install drive shell and front planetary unit== | ==Install drive shell and front planetary unit== | ||
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Drop the sun shell/gear in, spinning in the output carrier until it falls in place. | Drop the sun shell/gear in, spinning in the output carrier until it falls in place. | ||
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[[File:T-350_front_planet_with_bearing.jpg|thumb|300px|left|This shows drive shell installed with planet and thrust washer in place]] <br style="clear:both"/> | [[File:T-350_front_planet_with_bearing.jpg|thumb|300px|left|This shows drive shell installed with planet and thrust washer in place]] <br style="clear:both"/> | ||
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Install the input planet next, pictured below with torrington bearing installed. The design of the OE planet determines bearing or thrust washer use. A bearing will not fit a thrust washer design planetary unit with out machine work. | Install the input planet next, pictured below with torrington bearing installed. The design of the OE planet determines bearing or thrust washer use. A bearing will not fit a thrust washer design planetary unit with out machine work. | ||
| + | [[File:T-350_front_planet.jpg|thumb|300px|left|Front planet with torrington bearing in place]] <br style="clear:both"/> | ||
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| + | To prevent excessive end play, a pump thrust washer can be installed on top of the input planet, then the regular thrust washer. Then install the small outside snap ring to hold it all in place. | ||
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Check the output shaft for proper rotation, there will be some drag, especially in one direction. | Check the output shaft for proper rotation, there will be some drag, especially in one direction. | ||
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Check for excessive output end play. If end play is excessive, it can be tightened up by dis-assembling and shimming up the output ring gear bearing from the case. | Check for excessive output end play. If end play is excessive, it can be tightened up by dis-assembling and shimming up the output ring gear bearing from the case. | ||
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Then install the 3-tang thrust washer onto the top ring gear. | Then install the 3-tang thrust washer onto the top ring gear. | ||
| + | [[File:3_tang_whr_t-350.jpg|thumb|300px|left|Front ring gear with 3-tang thrust washer in place]] <br style="clear:both"/> | ||
| − | + | Next photo shows the ring gear with washer installed onto the planet in the case. | |
| − | + | [[File:T-350_ring_gear_with_washer.jpg|thumb|300px|left|Front ring gear with 3-tang thrust washer in place installed into case on front planet]] <br style="clear:both"/> | |
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| − | [[File:T-350_ring_gear_with_washer.jpg|thumb|300px|left|Front ring gear with 3 tang thrust washer in place installed into case on front planet | + | |
==Direct drum assembly== | ==Direct drum assembly== | ||
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For racing and heavy towing use, you will want to machine the direct clutch piston down approximately 0.160" to allow for one extra friction and steel plate for a total of 5 frictions, and 5 steels in the directs. This can be accomplished on a brake lathe. | For racing and heavy towing use, you will want to machine the direct clutch piston down approximately 0.160" to allow for one extra friction and steel plate for a total of 5 frictions, and 5 steels in the directs. This can be accomplished on a brake lathe. | ||
| − | Stock measurement is 0.835", machine the piston to 0.700". Ideally you would pre-assemble, and check clearance using a 4 clutch pack. Measure the additional thickness of the extra friction and steel, then cut the exact amount needed to leave you the exact clearance you desire. Rule of thumb | + | Stock measurement is 0.835", machine the piston to 0.700". Ideally you would pre-assemble, and check clearance using a 4 clutch pack. Measure the additional thickness of the extra friction and steel, then cut the exact amount needed to leave you the exact clearance you desire. Rule of thumb for most auto transmission clutch pack clearance is 0.010" clearance per friction. So a 5 friction direct setup would work well with 0.050" to 0.070" clearance. It will work with less, but no less than 0.040", and will work with quite a bit more, but excessive clearance can result in delayed engagement, busted lip seals, and unsatisfactory shift quality. |
If the piston is too low, the bottom flat steel plate can drop below the grooves in the drum and bind up the piston. You can leave out center cushion seal if dual feed is used. | If the piston is too low, the bottom flat steel plate can drop below the grooves in the drum and bind up the piston. You can leave out center cushion seal if dual feed is used. | ||
| − | + | [[File:T-350_direct_piston.jpg|thumb|300px|left|TH350 direct clutch drum pistons, piston on left cut for 5 friction use]] <br style="clear:both"/> | |
| − | [[File:T-350_direct_piston.jpg|thumb|300px|left| | + | |
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| − | + | Heavy duty applications should also get a heat treated intermediate sprag race. It is darker colored than a stock piece. The intermediate sprag race and intermediate sprag (actually roller clutch) take a brutal amount of force on a 1-2 shift at high rpm. Even more so with harsher shift calibrations. It is the single weakest part of a TH350. This is not to say a TH350 is not tough; they can reliably handle in the 600 HP or lb/ft range if properly assembled using the right parts. | |
[[file:TH350intspragraces.jpg]] | [[file:TH350intspragraces.jpg]] | ||
| − | An even heavier duty direct drum/sprag assembly is available. It uses a 36 element sprag and a machined drum, it will withstand more torque than a stock unit or one | + | An even heavier duty direct drum/sprag assembly is available. It uses a 36 element sprag and a machined drum, it will withstand more torque than a stock unit or one with just a hardened race. These units can cost $300.00 or more. Several companies offer these HD direct drums. |
| − | [[File:T-350_HD_drum_sprag.jpg|thumb|300px|left| | + | [[File:T-350_HD_drum_sprag.jpg|thumb|300px|left|TH350 direct clutch drum with 36 element sprag]] <br style="clear:both"/> |
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The parts go on the direct drum. | The parts go on the direct drum. | ||
| − | [[File:T-350 drum sprag race.jpg|thumb|300px|left| | + | [[File:T-350 drum sprag race.jpg|thumb|300px|left|TH350 direct clutch drum with sprag, race, retainer]] <br style="clear:both"/> |
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Assembled direct drum sprag and race with retainer. | Assembled direct drum sprag and race with retainer. | ||
| − | + | [[File:T-350_drum_sprag_assembled.jpg|thumb|300px|left|TH350 direct clutch drum with assembled sprag, race, retainer]] <br style="clear:both"/> | |
| − | [[File:T-350_drum_sprag_assembled.jpg|thumb|300px|left| | + | |
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The direct drum should use a wider bushing even on stock rebuilds. Stock is 0.500" a wider 0.750" is available in some bushing kits. Most bushing kits include the wide one. There is a lot of load on this bushing, and it should ALWAYS be replaced on overhaul. | The direct drum should use a wider bushing even on stock rebuilds. Stock is 0.500" a wider 0.750" is available in some bushing kits. Most bushing kits include the wide one. There is a lot of load on this bushing, and it should ALWAYS be replaced on overhaul. | ||
| − | [[File:TH350directbushings1.jpg|thumb|300px|left|The direct drum should use a wider bushing even on stock rebuilds | + | [[File:TH350directbushings1.jpg|thumb|300px|left|The direct drum should use a wider bushing even on stock rebuilds]] <br style="clear:both"/> |
| − | Also check the inside bore of the drum for wear from the sealing rings. A small amount of wear can be honed out. Visual shiny spots with no detectable wear are | + | Also check the inside bore of the drum for wear from the sealing rings. A small amount of wear can be honed out. Visual shiny spots with no detectable wear are acceptable. |
| − | [[File:T-350_direct_drum_bushing.jpg|thumb|300px|left|Direct drum with wide bushing, piston , springs | + | [[File:T-350_direct_drum_bushing.jpg|thumb|300px|left|Direct drum with wide bushing, piston, springs and retainer installed]] <br style="clear:both"/> |
Next you will install the direct piston lip seals, and install the piston in the drum. Take note of the orientation of the seals, the lip will face towards the "oil" side of the piston, not the clutch side. | Next you will install the direct piston lip seals, and install the piston in the drum. Take note of the orientation of the seals, the lip will face towards the "oil" side of the piston, not the clutch side. | ||
| − | + | Below is a high performance TH350 and no lip seal in the drum that would separate the two halves of the direct piston. | |
[[File:TH350directpistonseals1.jpg|thumb|300px|left|Direct piston with lip seals installed]] <br style="clear:both"/> | [[File:TH350directpistonseals1.jpg|thumb|300px|left|Direct piston with lip seals installed]] <br style="clear:both"/> | ||
==Dual feeding== | ==Dual feeding== | ||
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This is part of the process of "dual-feeding" the direct clutches. On a stock rebuild you would normally install this lip seal. | This is part of the process of "dual-feeding" the direct clutches. On a stock rebuild you would normally install this lip seal. | ||
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===Dual Feed direct drum=== | ===Dual Feed direct drum=== | ||
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Dual feeding doubles the area of the piston that has pressurized fluid on it in 3rd gear, more than doubling the capacity of the clutch. It is accomplished by most valve body kits without doing so internally but requires a "transfer" plate and gasket to be added under the support plate in front of the valve body. | Dual feeding doubles the area of the piston that has pressurized fluid on it in 3rd gear, more than doubling the capacity of the clutch. It is accomplished by most valve body kits without doing so internally but requires a "transfer" plate and gasket to be added under the support plate in front of the valve body. | ||
Internally dual feeding is preferred because it leaves out the additional gasket and eliminates that one extra possibility for a pressure loss resulting in burnt 3rd gear clutches. | Internally dual feeding is preferred because it leaves out the additional gasket and eliminates that one extra possibility for a pressure loss resulting in burnt 3rd gear clutches. | ||
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| − | + | All transbrake applications will require dual feed of the direct clutch, possibly as well as manual valve bodies. | |
| − | Don't thread the passage completely to bottom | + | Shown below is the passage that must be blocked. One method is to tap this hole with a 3/8" tap, and cut off the end of a 3/8" bolt. The head of the bolt can be slotted so a screwdrive can be used. |
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| + | Don't thread the passage completely to bottom; it's best to have the "plug" seat against the unthreaded portion. | ||
This passage may also be plugged by using a roller from a direct drum or sprag to drive into the passage, but this will be a more or less permanent modification due to the difficulty in removing the roller. | This passage may also be plugged by using a roller from a direct drum or sprag to drive into the passage, but this will be a more or less permanent modification due to the difficulty in removing the roller. | ||
| − | [[File:T-350_dual_feed02.jpg|thumb|300px|left|Plug the hole indicated for dual feed on | + | [[File:T-350_dual_feed02.jpg|thumb|300px|left|Plug the hole indicated for dual feed on TH350]] <br style="clear:both"/> |
| + | {{Note1}}Don't assume you need to plug this hole. Only plug this hole if you plan on doing the dual feed modification yourself. | ||
| − | + | You can omit the center seal, plug this passage, enlarge the 2nd and 3rd feed holes in the stock separator plate and you will have greatly increased the torque capacity of a stock TH350 as well as gained a firmer shift. | |
| − | + | Almost all aftermarket kits use a feed plate between the support plate in front of the valve body and the separator plate. This feed plate 'dual feeds' the directs, so plugging this hole is unnecessary. Also most manual valve bodies, trans-brakes, etc. will call for omitting the direct drum center seal and the sealing ring on the stator, but plugging this hole is also unnecessary due to the design of the separator plate. | |
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Even firmer shifts can be accomplished with check ball removal and modifications to the accumulators. It is recommend to NOT modify the 1-2 accumulator. Retain the cushion spring and do not block the circuit. The 2-3 accumulator can be blocked by several methods. | Even firmer shifts can be accomplished with check ball removal and modifications to the accumulators. It is recommend to NOT modify the 1-2 accumulator. Retain the cushion spring and do not block the circuit. The 2-3 accumulator can be blocked by several methods. | ||
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Removing the 2-3 accumulator spring and using a spacer (nut, washers, cut down section of tubing) between the piston and the E-clip is the "shade tree" method. You can also block the feed in the valve body to the 2-3 accumulator. | Removing the 2-3 accumulator spring and using a spacer (nut, washers, cut down section of tubing) between the piston and the E-clip is the "shade tree" method. You can also block the feed in the valve body to the 2-3 accumulator. | ||
| − | Installing the direct piston will require some patience, a lip seal installed or 0.010" feeler gauge, and a trick to use is a section of plastic cut from a 3 liter soda bottle to use as an outside installer tool. Set it in the drum, and it will force the lip seal into the drum without using a tool around the entire circumference. You may | + | Installing the direct piston will require some patience, a lip seal installed or 0.010" feeler gauge, and a trick to use is a section of plastic cut from a 3 liter soda bottle to use as an outside installer tool. Set it in the drum, and it will force the lip seal into the drum without using a tool around the entire circumference. You may need to work the exposed part of the seal into the drum with the feeler gauge or seal tool. |
| − | Use care using the lip seal tool | + | Use care using the lip seal tool. Use a push-in technique more than a work-around-the-drum technique. If you slide around the drum, and it catches the seal, it will cut it and then you must get a new lip seal and start again. Good lighting, patience, and technique are key here, and a be sure to verify using an air check. |
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| + | Once you have the piston seated in the drum you can install the return springs and retainer. You can buy or make a tool similar to the one pictured below, or use several 5" or larger C-clamps. | ||
[[File:T-350_direct_sprng_compress.jpg|thumb|300px|left|One method to compress springs to install the snap ring]] <br style="clear:both"/> | [[File:T-350_direct_sprng_compress.jpg|thumb|300px|left|One method to compress springs to install the snap ring]] <br style="clear:both"/> | ||
===Forward drum inspection=== | ===Forward drum inspection=== | ||
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Forward drum procedures are almost identical. No center seal to worry about on a TH350, it typically already has a 5 clutch pack, except light duty applications. Same 0.700" thickness piston for 5 frictions and steels. Removing the wave plate will cause harsh forward engagement. Reduce clearance of the stack to 0.040". | Forward drum procedures are almost identical. No center seal to worry about on a TH350, it typically already has a 5 clutch pack, except light duty applications. Same 0.700" thickness piston for 5 frictions and steels. Removing the wave plate will cause harsh forward engagement. Reduce clearance of the stack to 0.040". | ||
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Pay attention to this polished stub of the input shaft, it goes into the bushing that is in the end of the output shaft. It is a high wear area. Be sure it is smooth. Minor scoring can be smoothed down. May consider use of teflon bushing, only a lubrication passage, no pressure, no lateral loading. | Pay attention to this polished stub of the input shaft, it goes into the bushing that is in the end of the output shaft. It is a high wear area. Be sure it is smooth. Minor scoring can be smoothed down. May consider use of teflon bushing, only a lubrication passage, no pressure, no lateral loading. | ||
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[[File:T-350_fwd_drum.jpg|thumb|300px|left|Check forward drum for wear.]]<br style="clear:both"/> | [[File:T-350_fwd_drum.jpg|thumb|300px|left|Check forward drum for wear.]]<br style="clear:both"/> | ||
===Pump assembly=== | ===Pump assembly=== | ||
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'''Notice''' the scraped and split low reverse friction in the intermediate piston cavity. This slightly tightens the intermediate clutch clearance to achieve cleaner 1-2 shift. | '''Notice''' the scraped and split low reverse friction in the intermediate piston cavity. This slightly tightens the intermediate clutch clearance to achieve cleaner 1-2 shift. | ||
| − | [[File:T-350_intmed_piston_spacer.jpg|thumb|300px|left|Scraped and split low reverse friction in the intermediate piston cavity | + | [[File:T-350_intmed_piston_spacer.jpg|thumb|300px|left|Scraped and split low reverse friction in the intermediate piston cavity]]<br style="clear:both"/> |
Intermediate piston installed. | Intermediate piston installed. | ||
| − | [[File:T-350_pump_n_piston.jpg|thumb|300px|left| | + | [[File:T-350_pump_n_piston.jpg|thumb|300px|left|TH350 pump with intermediate piston installed]]<br style="clear:both"/> |
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| + | Sealing rings on the pump stator. Remove the second ring from the bottom if dual feeding. | ||
| − | [[File:T-350_stator_rings.jpg|thumb|300px|left| | + | [[File:T-350_stator_rings.jpg|thumb|300px|left|Sealing rings on pump]] <br style="clear:both"/> |
| − | Pump gear install. Note the orientation of the tangs on the inner gear. They are offset. They should face away from the seal. | + | Pump gear install. Note the orientation of the tangs on the inner gear. They are offset. They should face away from the seal. Incorrect installation will result in pump failure and converter damage. |
| − | + | [[File:T-350_pump_half.jpg|thumb|300px|left|Notice inner pump gear tangs, they must be '''up''' as seen here]] <br style="clear:both"/> | |
| − | [[File:T-350_pump_half.jpg|thumb|300px|left|Notice inner pump gear tangs, they must be up as | + | |
Notice the dowel pins threaded into the case, you use these and the case to align the pump halves. | Notice the dowel pins threaded into the case, you use these and the case to align the pump halves. | ||
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[[File:T-350_pump_alignment.jpg|thumb|300px|left|One method to align the pump halves shown]] <br style="clear:both"/> | [[File:T-350_pump_alignment.jpg|thumb|300px|left|One method to align the pump halves shown]] <br style="clear:both"/> | ||
| Line 306: | Line 272: | ||
Use a rubber tipped air nozzle to apply air to the passages around the pump circumference. As you apply air to the correct passages, you will see and hear the drums apply the clutches. Be sure there are no leaks from the lip seals. There will usually be some minor leakage at the sealing rings. Iron rings air check better than teflon on the bench. | Use a rubber tipped air nozzle to apply air to the passages around the pump circumference. As you apply air to the correct passages, you will see and hear the drums apply the clutches. Be sure there are no leaks from the lip seals. There will usually be some minor leakage at the sealing rings. Iron rings air check better than teflon on the bench. | ||
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[[File:T-350_air_check_pump.jpg|thumb|300px|left|One method to air check clutch drums in the pump shown. Refer to build manual for locations]] <br style="clear:both"/> | [[File:T-350_air_check_pump.jpg|thumb|300px|left|One method to air check clutch drums in the pump shown. Refer to build manual for locations]] <br style="clear:both"/> | ||
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Drums installed in the transmission case. Ready for intermediate pressure plate install. Ensure the lugs of the direct drum are engaged with the sun shell. They should be slightly below the top edge of the sun shell. If you do not get complete engagement, the input shaft will not turn when you install the pump and begin to tighten it. You can also see the braking band installed. | Drums installed in the transmission case. Ready for intermediate pressure plate install. Ensure the lugs of the direct drum are engaged with the sun shell. They should be slightly below the top edge of the sun shell. If you do not get complete engagement, the input shaft will not turn when you install the pump and begin to tighten it. You can also see the braking band installed. | ||
| − | + | [[File:T-350_coast_band01.jpg|thumb|300px|left|Both clutch drums installed with braking band shown]] <br style="clear:both"/> | |
| − | [[File:T-350_coast_band01.jpg|thumb|300px|left|Both clutch drums installed with braking band shown | + | |
===Braking band=== | ===Braking band=== | ||
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Install coasting band aka braking band. This band provides engine braking in manual 2nd gear.This slides in the case around the direct drum. Check band for wear at the struts. The servo pin can wear a hole through the strut. | Install coasting band aka braking band. This band provides engine braking in manual 2nd gear.This slides in the case around the direct drum. Check band for wear at the struts. The servo pin can wear a hole through the strut. | ||
| − | + | [[File:T-350_coasting_band.jpg|thumb|300px|left|Check band for wear in the area the servo pin rides]]<br style="clear:both"/> | |
| − | [[File:T-350_coasting_band.jpg|thumb|300px|left|Check band for wear in the area the servo pin rides | + | |
There are HD versions of this braking band. These HD bands should have welded reinforced band struts as show in photo. | There are HD versions of this braking band. These HD bands should have welded reinforced band struts as show in photo. | ||
| − | [[File:T-350_HD__braking_band.jpg|thumb|300px|left| | + | [[File:T-350_HD__braking_band.jpg|thumb|300px|left|Heavy duty brake band should have weld reinforced struts]]<br style="clear:both"/> |
=Intermediate clutch clearance= | =Intermediate clutch clearance= | ||
| + | After the pump is set into place to test end play clearance, you can also check the clutch clearance on the intermediate clutch pack. Clearance of 0.050" to 0.070" will work well. There are thicker steel plates available if need to tighten up the clutch pack clearance. | ||
| − | + | [[File:T-350_intermed_clearance_ck.jpg|thumb|300px|left|TH350 intermediate clutch pack clearance can be checked through this hole]] <br style="clear:both"/> | |
| − | + | ||
| − | + | ||
| − | [[File:T-350_intermed_clearance_ck.jpg|thumb|300px|left| | + | |
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| Line 346: | Line 303: | ||
| − | This gasket on a | + | This gasket on a TH350 sits against the valve body. Notice the open line in the gasket that will parallel the support plate that bolts on at front of the valve body. |
| − | [[file:T-350_v-body_gasket02.jpg|frame|none|Notice the open line in the gasket, this gasket installs against valve body, not the case | + | [[file:T-350_v-body_gasket02.jpg|frame|none|Notice the open line in the gasket, this gasket installs against valve body, not the case]] |
| Line 355: | Line 312: | ||
==Separator plate== | ==Separator plate== | ||
| − | + | Below is a picture of the feed holes. These regulate the amount of fluid, or how fast it can apply the clutches. Drilling them bigger allows a faster apply. However, bigger is not always better. | |
[[file:TH350feedholes.jpg]] | [[file:TH350feedholes.jpg]] | ||
| − | Remember that as the load increases on the trans, so does the pressure. The increase in pressure will cause the | + | Remember that as the load increases on the trans, so does the pressure. The increase in pressure will cause the fluid to move faster and shifts to be firmer. If you drill the holes ''too'' big the shifts become too harsh at light throttle openings. This causes undue wear on the internal transmission parts, rear differential and axles, drive line and u-joints. |
| − | The ideal situation is a shift that gets progressively | + | The ideal situation is a shift that gets progressively firmer as the throttle opening increases. Drilling the 2nd feed hole to 0.125" and the 3rd feed hole to 0.125"-0.140" works well for many applications. |
| − | Also note above the 2-3 accumulator hole marked in the upper portion. This hole can be blocked but it is easier to block the passage in the | + | Also note above the 2-3 accumulator hole marked in the upper portion. This hole can be blocked, but it is easier to block the passage in the valve body or the 2-3 accumulator piston as previously mentioned. |
===Shift kits=== | ===Shift kits=== | ||
| − | Often shift improver kits are installed at the time of the tranny rebuild. Various manufacturers make shift improver kits, | + | Often shift improver kits are installed at the time of the tranny rebuild. Various manufacturers make shift improver kits, TransGo has a good reputation. |
==Racing valve body== | ==Racing valve body== | ||
| Line 374: | Line 331: | ||
=Governor= | =Governor= | ||
| − | Image below of an OEM | + | Image below of an OEM TH350 governor and cover. |
[[file:T-350_governor.jpg|thumb|left|300px|Note the direction of the plastic drive gear teeth. If the plastic gear breaks or wears out, there will be no upshifts since the governor is not rotating.]]<br style="clear:both"/> | [[file:T-350_governor.jpg|thumb|left|300px|Note the direction of the plastic drive gear teeth. If the plastic gear breaks or wears out, there will be no upshifts since the governor is not rotating.]]<br style="clear:both"/> | ||
| Line 381: | Line 338: | ||
===Governor adjustment=== | ===Governor adjustment=== | ||
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Shift point changes made via the governor weights and springs. Stronger springs and heavier weights will bring earlier shift points. Lighter springs and weights have the opposite affect. | Shift point changes made via the governor weights and springs. Stronger springs and heavier weights will bring earlier shift points. Lighter springs and weights have the opposite affect. | ||
The springs have a greater affect on shift points at light throttle. After about 5/8 throttle the weights have more affect on shift points. Gear ratio and tire size will also play apart of the shift points and changes made. | The springs have a greater affect on shift points at light throttle. After about 5/8 throttle the weights have more affect on shift points. Gear ratio and tire size will also play apart of the shift points and changes made. | ||
| − | [[File:Bm goc recal kit.jpg|thumb|300px|left| | + | [[File:Bm goc recal kit.jpg|thumb|300px|left|Governor recalibration kit]] <br style="clear:both"/> |
=Filter= | =Filter= | ||
| − | Brass screened filter allows for more flow. Avoid the cloth looking material filters for the | + | Brass screened filter allows for more flow. Avoid the cloth looking material filters for the TH350 |
[[file:TH350HPfilter.jpg]] | [[file:TH350HPfilter.jpg]] | ||
=Vacuum modulator= | =Vacuum modulator= | ||
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The vacuum modulator senses vacuum in the intake manifold as an indicator of engine load. As the throttle is opened, vacuum decreases. The modulator on the transmission will raise the main line pressure in the transmission | The vacuum modulator senses vacuum in the intake manifold as an indicator of engine load. As the throttle is opened, vacuum decreases. The modulator on the transmission will raise the main line pressure in the transmission | ||
| − | + | [[File:T-350_modulators.jpg|thumb|300px|left|Two types of modulators shown. Low vacuum design on left, ID by the black and red strips. It has a larger diameter, too.]] <br style="clear:both"/> | |
| − | [[File:T-350_modulators.jpg|thumb|300px|left|Two types of modulators shown. Low vacuum design on left, ID by the black and red strips. It | + | |
=Fastener size and torque values= | =Fastener size and torque values= | ||
| − | + | *Pump cover to pump body- (5/16-18) 15 ft/lb | |
| − | *Pump | + | |
*Pump assembly to case- (5/16-18) 15 ft/lb | *Pump assembly to case- (5/16-18) 15 ft/lb | ||
*Valve body and support plate- (5/16-18) 10 ft/lb | *Valve body and support plate- (5/16-18) 10 ft/lb | ||
| Line 411: | Line 364: | ||
*Extension housing to case- (3/8-16) 35 ft/lb | *Extension housing to case- (3/8-16) 35 ft/lb | ||
*Modulator retainer to case- (5/16-18) 12 ft/lb | *Modulator retainer to case- (5/16-18) 12 ft/lb | ||
| − | *Inner | + | *Inner selector lever to shaft- (M10-1.5) 27 Nm (20 ft/lb) |
*External test plugs to case- (1/8-27) 8 ft/lb | *External test plugs to case- (1/8-27) 8 ft/lb | ||
*Transmission mount to transmission (M10-1.5) 48 Nm (35 ft/lb) | *Transmission mount to transmission (M10-1.5) 48 Nm (35 ft/lb) | ||
| − | * | + | *Speedometer sleeve retainer on extension housing- (M6.3-1.0) 17 Nm (150 in/lb) |
*Detent cable to case- (M6.3-1.0) 8.5 Nm (75 in/lb) | *Detent cable to case- (M6.3-1.0) 8.5 Nm (75 in/lb) | ||
*Nut on outer end of shift selector shaft- (M10-1.5) 27 Nm (20 ft/lb) | *Nut on outer end of shift selector shaft- (M10-1.5) 27 Nm (20 ft/lb) | ||
| − | *Converter to | + | *Converter to flexplate bolts- 35 ft/lb |
*Torque converter dust cover pan to transmission case- 110 in/lb | *Torque converter dust cover pan to transmission case- 110 in/lb | ||
| − | *Transmission | + | *Transmission case to engine- 35 ft/lb |
====Oil cooler line connectors to transmission case==== | ====Oil cooler line connectors to transmission case==== | ||
| − | |||
*Straight pipe fitting- 20 ft/lb | *Straight pipe fitting- 20 ft/lb | ||
*Tapered pipe fitting- 15 ft/lb | *Tapered pipe fitting- 15 ft/lb | ||
| Line 428: | Line 380: | ||
====Other torque values==== | ====Other torque values==== | ||
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*Gearshift bracket to frame- 15 ft/lb | *Gearshift bracket to frame- 15 ft/lb | ||
*Gearshift Shaft to Swivel- 20 ft/lb | *Gearshift Shaft to Swivel- 20 ft/lb | ||
| Line 435: | Line 386: | ||
*Intermediate Band Adjust Nut- 15 ft/lb | *Intermediate Band Adjust Nut- 15 ft/lb | ||
| − | = | + | =TH350 dimensions and tailshaft housing (or ''extension'' housing) lengths= |
[[File:TH350 dimensions.jpg|thumb|left|400px|]]<br style="clear:both"/> | [[File:TH350 dimensions.jpg|thumb|left|400px|]]<br style="clear:both"/> | ||
| − | You will find the | + | You will find the TH350 with 6", 9" and 12" tail housings. |
| − | There is also two 4WD output | + | There is also two 4WD output shaft lengths, the shortest and more common is seen below. A longer 4x4 output shaft was used for around 1.5 years. It is a 2WD shaft of 6 inch length that is cut off about 1.250 inches. Used on 208 transfer case with adapter. |
[[File:3504WD output.jpg]] | [[File:3504WD output.jpg]] | ||
=Gear ratios= | =Gear ratios= | ||
| − | + | Ratios of the TH350 were consistent throughout its production: | |
| − | Ratios of the | + | |
*First gear- 2.52:1 | *First gear- 2.52:1 | ||
| Line 455: | Line 405: | ||
=Aftermarket parts= | =Aftermarket parts= | ||
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*An aftermarket low-gear planetary is available that will lower the first gear ratio to 2.75:1. | *An aftermarket low-gear planetary is available that will lower the first gear ratio to 2.75:1. | ||
| − | |||
=Reference material= | =Reference material= | ||
[[File:Sessions- ATSG-Haynes manuals.jpg|thumb|600px|left|Left to right: [http://www.amazon.com/Turbo-Hydra-Matic-350-Handbook-Sessions/dp/0895860511 Turbo Hydra-Matic 350 Handbook] by Ron Sessions; [http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=786 ATSG manual] p/n 44400; Haynes [http://www.amazon.com/gp/product/1563924234/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0895860511&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0J4A1QHT1Y8B032P3Z6P GM Automatic Transmission Overhaul] manual, p/n 10360.]] <br style="clear:both"/> | [[File:Sessions- ATSG-Haynes manuals.jpg|thumb|600px|left|Left to right: [http://www.amazon.com/Turbo-Hydra-Matic-350-Handbook-Sessions/dp/0895860511 Turbo Hydra-Matic 350 Handbook] by Ron Sessions; [http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=786 ATSG manual] p/n 44400; Haynes [http://www.amazon.com/gp/product/1563924234/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0895860511&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0J4A1QHT1Y8B032P3Z6P GM Automatic Transmission Overhaul] manual, p/n 10360.]] <br style="clear:both"/> | ||
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[[Category:Transmission]] | [[Category:Transmission]] | ||
[[Category:Good articles]] | [[Category:Good articles]] | ||
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