1937-1957 Buick Oldsmobile Pontiac suspension upgrade
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===Notes=== | ===Notes=== | ||
| − | *Your original drum setup used | + | *Your original drum setup used 1/4" brake lines. 3/16" is recommended for disc brakes. |
| − | *Many aftermarket master cylinders have metric fittings. You may find yourself putting different fittings on each end of your new lines to convert from metric to | + | *Many aftermarket master cylinders have metric fittings. You may find yourself putting different fittings on each end of your new lines to convert from metric to inch. There is a direct metric match to the 3/16" line size, so that is not a problem. |
| − | *Master cylinder size is important, but slightly flexible. One option is the Corvette-style master cylinder, with ports | + | *Master cylinder size is important, but slightly flexible. One option is the Corvette-style master cylinder, with ports located on either side. This makes installation easier, and they're fairly cheap. |
| − | *The 1 | + | *The 1" bore will do the job, but expect the pedal travel to be a bit long. On the other hand, a 1-1/4" or larger master cylinder will move the fluid faster (shorter stroke), but the small 7-inch booster might not be up to the job, the result being a too-hard pedal effort. Your original master cylinder may push the discs fine as far as volume goes, but pressure could be another matter. |
| − | *Virtually all cars will need an adjustable proportioning valve. | + | *Virtually all cars will need an adjustable proportioning valve. Any change from the original setup – front or rear weight change, tire sizes, line sizes, rake or tail drag, disc conversion, etc., has the potential to throw your brake system out of balance. |
*Most disc conversions will require at least 15 inch wheels; check it out before you order. | *Most disc conversions will require at least 15 inch wheels; check it out before you order. | ||
| − | *The project in this tutorial used a Corvette 1 | + | *The project in this tutorial used a Corvette 1" ID master cylinder, and a 7" single stage booster. This combination turned out to be "close enough". The brakes are a vast improvement over manual drums, but not perfect. Stopping power is great, until about the last 20% of pedal travel, as several test panic stops revealed. At the very bottom, you just can’t push hard enough to lock them up. The system probably needs a 9 or 10 inch booster to be perfect. There simply isn't enough power in a 7 inch booster to lock up a set of 215/75x15 tires on a 3500 pound car, on dry pavement. |
| − | + | ====IUmprovements two years later==== | |
| + | Never really happy with the 7 inch booster. Moved some things under the hood to get more room and installed a 9 inch dual diaphragm booster from a mid 1990s Camaro. Now it stops like a new car. I'll never use a 7 inch booster again. | ||
==Front suspension== | ==Front suspension== | ||
| − | The original idea came from an article in Rodder's Digest magazine that showed a suspension upgrade for a '55 Pontiac. Reading this article, which has some decent pictures, will get you thinking in the right direction: [http://www.pontiacsafari.com/L1Garage/BallJointConversion.pdf Project Strat-O-Streak]. | + | The original idea came from an article in ''Rodder's Digest'' magazine that showed a suspension upgrade for a '55 Pontiac. Reading this article, which has some decent pictures, will get you thinking in the right direction: [http://www.pontiacsafari.com/L1Garage/BallJointConversion.pdf Project Strat-O-Streak]. |
| − | The upgrade discussed in the article will work on all 1937- | + | The upgrade discussed in the article will work on all 1937-'57 BOPs, because they all have the same basic setup. The '58 Pontiac lower control arms are the key. They are a direct bolt in, exactly the same as the originals, but with ball joints instead of king pins. '59 and later BOPs went to a completely different control arm mount. '58 Buick lower control arms are not symmetrical, so they won’t work. |
| − | Also, we do not have a '58 Olds to check | + | New info indicates the ‘41 Buick lower control arm is 20 inches long, rather than 18 inches like the Pont/Olds. Other measurements are the same, so upgrade should still work, with redrilled mounting holes. |
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| + | Also, we do not have a '58 Olds available to check/measure the lower control arms. What we DO know is '57 is king pin, and '59 is all-new. So ‘58 is it. We used the '58 Pontiac upper control arms simply because we got the whole front end. Several uppers will work, as it looks like '58 to '60 BOPs all had the same basic dimensions on their upper control arms. In fact, the '58 Buick uppers we used on one conversion had some built-in twist that allowed us to add more anti-dive than we could get with the Pontiac uppers. | ||
As you can see in the photos, the '58 control arms are more substantial than the '41. However, all the dimensions are the same. | As you can see in the photos, the '58 control arms are more substantial than the '41. However, all the dimensions are the same. | ||
| − | [[image:58 pontiac 41 pontiac lower control arm s.jpg|frame|none|The '58 Pontiac control arms are more substantial than the ' | + | [[image:58 pontiac 41 pontiac lower control arm s.jpg|frame|none|The '58 Pontiac control arms are more substantial than the '41s, but dimensions are the same.]] |
| − | The upper control arm mount is a fairly simple fabrication. If you have a post | + | The upper control arm mount is a fairly simple fabrication. If you have a post 50s car, the upper mount will differ from this article. The pre-‘50s had the lever action shock, therefore no upper shock mount. On both of our tested conversions ('41 Pontiac and '49 Olds) we fabricated the mounts out of angle iron. We used 1/4" 3x3 inch angle iron on the Pontiac, and added two gussets. On the Olds, we had some 3/8" 4x6 inch angle iron, so only added one gusset. |
| − | [[image:49_olds_upper_mount_1.jpg|frame|none|49 Olds | + | [[image:49_olds_upper_mount_1.jpg|frame|none|49 Olds]] |
| − | Note in the pictures how the front mount is higher than the rear mount. This sets up the anti-dive angle. Up to 10 degrees is fine, as long as the upper ball joint is not in a bind. Be sure the frame is level side-to-side, and has the correct front-to-rear angle that you want. | + | Note in the pictures how the front mount is higher than the rear mount. This sets up the anti-dive angle. Up to 10 degrees is fine, as long as the upper ball joint is not in a bind. Be sure the frame is level side-to-side, and has the correct front-to-rear angle that you want. With 15 inch wheels, the spindle center was 12.5 inches off the ground. The frame was blocked, so that when the lower A-arm was level, the spindle was 12.5 inches up. |
| − | Even a small error here will be costly. It takes | + | Even a small error here will be costly. It takes 1/2" of shims to adjust just 1 degree of camber. If you need to put additional shims on the rear of the bracket to increase caster, and can't take enough out of the front to keep the camber static, you will have to cut it loose and start over. Unfortunately, you can't do a full alignment until it is totally basically finished and drivable. So, get this part right. If you have any doubts, shade towards the ''positive'' camber side, as you can add more shims later to move it towards negative. Likewise, move the upper mount to a position about 3/4" behind the plumb line for the spindle, to set up at least 5 degrees of caster in the neutral position (neutral being the static position as mocked up, before final alignment). |
If you intend to add power steering, shoot for 6 degrees in the neutral position, but don't get the uppers so far behind the lowers that you put the ball joints in a bind. In this situation, holes were drilled in the bottom plate of the angle iron, and, when it was mocked up, the frame was drilled and bolted up with 3/8 inch bolts. This was strong enough to allow for assembly of the entire front end, with springs, putting the wheels and tires on it, and setting it on the ground. Everything was double-checked, then torn down and welded in place. | If you intend to add power steering, shoot for 6 degrees in the neutral position, but don't get the uppers so far behind the lowers that you put the ball joints in a bind. In this situation, holes were drilled in the bottom plate of the angle iron, and, when it was mocked up, the frame was drilled and bolted up with 3/8 inch bolts. This was strong enough to allow for assembly of the entire front end, with springs, putting the wheels and tires on it, and setting it on the ground. Everything was double-checked, then torn down and welded in place. | ||
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