Editing TH700R4 through 4L70E tips and tricks

{{Youcanedit}} ==Summary== This section will contain some rebuild tips and tricks on the 700r4 - 4L70E transmissions. *These transmissions are all METRIC bolts, nuts and threads. ==Rebuild manual== There are several manuals, DVD and videos found online to aid the DIY person with the rebuild process for these transmissions. [http://www.atsgmiami.com/ '''ATSG''' manuals] are suggested as a reference material for a proper rebuild. They contain specs, photos, and a few upgrades for a basic non-high performance rebuild. ==Performance section== *Kits for performance modifications. '''TransGo''' seems to lead the market in quality kits. '''Superior Transmission''' brand products offer quality too. *3-4 clutch pack. The 3-4 clutch pack in these transmissions have been a problem area since production release in 1981. Various 3-4 clutch pack kits are offered. '''Z-Pak''' from '''Raybestos''' is a high energy material single sided friction plates , '''ALTO''' offers a kit with single sided red friction material friction plates. Also available are "Commercial Duty" 3-4 clutch packs that allows up to 9 friction clutches and steels for the 3-4 clutch pack. These 3-4 clutch upgrades are considered a heavy duty upgrade and will save the transmission in the event of the governor sticking in 3rd gear. Clearance on the 3-4 clutch pack frictions should be in the area of .050 to .070 . This can be adjusted via thin or thicker friction plates or steel plates *Boost valves; In a 700r4 - 4L60 non electronic trans, you will want a .470 to .500 main boost valve. The low-reverse boost valve a .282 or .296 works well. On the low-reverse boost valve measure the long valve land for size. In a pre-1987 700r4 - 4L60 trans a larger low-reverse boost valve will hold off the auto upshift to 2nd gear while the shifter is in manual 1st gear *External Cooler; The key to longevity in any automatic transmission is to keep the fluid cool; therefore installing an external bypass cooler is recommended. The Factory Transmission coolers are an integral part of the radiator and will only cool the fluid in accordance with the engine temperature. transmission fluid life decreases as temperatures rise above 160(f) an external transmission cooler will help to prevent trans fluid breakdown and Torque converter " Ballooning" or expansion which will cause the (catastrophic) pump bushing failure. Use the largest external cooler that will fit and not block radiator airflow. == Pump modifications == ===Drain back hole behind front seal=== Drain back holes from behind the converter hub seal at the bushing should be enlarged in some pumps. This is year dependent since GM did enlarge this hole in the late 1980's. [[image:Drillhole2.jpg]] The matching hole on the pump cover stator support (shown in yellow circle) should be enlarged too. [[image:Drain_back_hole.jpg]] ===3-4 clutch oil passage=== Early 700r4-4L60 pump covers (stator support) have an extra bleed hole in the 3-4 clutch circuit that can be plugged off. Modification for better 3-4 clutch pack apply on early pumps. The circled hole can be tapped and plugged with a 5/16 inch set screw. GM deleted this hole in later pumps [[Image:3-4_hole.jpg]] ===Stake the pump bushing=== Drill bit location to stake bushing. Pump bushing is removed for this operation. 1/4 inch drill bit works well here [[Image:Stakebush3.jpg]] This photo shows the small spot make with drill bit to stake the pump bushing in place. Does not need to be very deep. [[Image:Stakebush4.jpg]] This photo shows the pump bushing edge dimpled into the location created with a drill bit. Use the side of a screw driver and hit it with a hammer to bend the bushing edge into the recess area [[Image:Stakebush.jpg]] ===Pump rotor clearance check=== Photo shows the depth micrometer at .0015 showing clearance on the rotor. This is very desirable clearance. Set it at .001 to .002 for good pump performance. [[File:700r4_rotor_clearance.jpg]] A wide view photo of the depth micrometer in use. [[file:700r4_rotor_clearance01.jpg]] == Reference and reading material == A great place to read up on articles that have been written already and multiply this information in your recent re-build. === Links === *[http://purplesagetradingpost.com/sumner/techinfo/700R4p1.html 700R4 Info] *[http://www.hotrodders.com/articles/TH-700R4_basics.html TH-700R4 Basic Information] [[Category:Transmission]] [[Category:Good articles]]

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