1937-1957 Buick Oldsmobile Pontiac suspension upgrade
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| − | + | ==Overview== | |
| − | A suspension and disc brake upgrade on a 1937- | + | A suspension and disc brake upgrade on a 1937-'57 Buick, Olds, or Pontiac (BOP) is complicated by many variables and side issues. In addition, there is little information on the topic, and few aftermarket parts are available. |
With minor variation between models and years, Buicks, Oldsmobiles, and Pontiacs share a common frame and front suspension. Chevrolet did not have this setup. | With minor variation between models and years, Buicks, Oldsmobiles, and Pontiacs share a common frame and front suspension. Chevrolet did not have this setup. | ||
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These cars actually drive reasonably well, and this basic suspension technology was a mainstay for 50 years. However, it does have certain shortcomings: | These cars actually drive reasonably well, and this basic suspension technology was a mainstay for 50 years. However, it does have certain shortcomings: | ||
| − | *These cars came with zero to | + | *These cars came with zero to 1/2 degree of negative caster. When they were originally engineered, this was a reasonable setup. Negative caster makes the car easier to turn, and gives greater control in muddy ruts and other bad road conditions that were prevalent in the 1940s and 1950s. However, modern roads and increased speed limits favor positive caster, as it allows the car to stay centered and stable at today's highway speeds. High positive caster became more common as power steering became common. Conversely, manual steering is fine at higher speeds, but requires greater effort in low speed situations, especially parking lots. Manual steering works best at about 1-½ to 2 degrees of caster, which is a compromise between high speed stability and slow speed turning effort. |
*Due to the up and down-only rotation of the control arms, and cross-rotation of the king pins, any attempt to add more caster is fraught with problems. Anti-dive geometry is impossible in this setup. | *Due to the up and down-only rotation of the control arms, and cross-rotation of the king pins, any attempt to add more caster is fraught with problems. Anti-dive geometry is impossible in this setup. | ||
| − | *On the pre- | + | *On the pre-1950s models, the lever action shocks also present problems. They're hard to find, expensive (about $200 each plus $100 core charge if yours aren't rebuildable), and even in perfect working order, they have their shortcomings. The shocks are basically only good for a stock-only application. Raising or lowering the vehicle puts them out of their designed operating range. Increasing or decreasing weight with engine and transmission swaps alters their effectiveness. |
| − | *The hubs/drums run on ball bearings. While | + | *The hubs/drums run on ball bearings. While reasonably durable if properly maintained, tapered roller bearings are generally thought to be stronger, more stable, and better able to withstand continuous high-speed driving. Ball bearings are now hard to find and cost about $200 for the full set. By comparison, a full set of tapered bearings will run about $25. |
| − | *The brakes are, obviously, inadequate: non-power 4 wheel drums with a single reservoir hydraulic system. | + | *The brakes are, obviously, inadequate: non-power assisted 4 wheel drums with a single reservoir hydraulic system. |
==Solutions== | ==Solutions== | ||
| − | Most attempts to gather advice will result in one of two stock answers: Mustang II or GM subframe. | + | Most attempts to gather advice will result in one of two stock answers: Mustang II or some type of GM subframe. |
| − | In this application, the standard Mustang II recommendation may be misguided. It can work well on Chevys, however, their straight frame rail makes installation | + | In this application, the standard Mustang II recommendation may be misguided. It can work well on Chevys, however, their straight frame rail makes installation straightforward, and the weight is within specifications. For BOPs the frame rails are neither flat nor straight. There is also a built-in spring pocket, which requires modification of the frame rails. And, there may be a weight issue. |
| − | The GM subframe approach is definitely viable, and some would say | + | The GM subframe approach is definitely viable, and some would say the best possible solution. If you have the tools, welding and fabrication skills, and your car is stripped to the frame, it might indeed be your best option. |
| − | + | But if your car is assembled with the engine in and fenders on, or your fabrication skills are minimal, or you just don't like the idea of hacking your frame, the information in this article may be useful to you. | |
[[image:41 frame bump good pic.jpeg|frame|none|Built in spring pocket on the frame.]] | [[image:41 frame bump good pic.jpeg|frame|none|Built in spring pocket on the frame.]] | ||
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For this project, the tie rods only needed to be shortened less than an inch, rather than the 3 inches in the article. This was done by trimming a little off both the inner and outer tie rod threads and the sleeve. No cutting and welding. | For this project, the tie rods only needed to be shortened less than an inch, rather than the 3 inches in the article. This was done by trimming a little off both the inner and outer tie rod threads and the sleeve. No cutting and welding. | ||
| − | + | Incidentally, It looks like the tie rod ends in this project are closer to the Ackerman line than the '55 conversion in the article. The taper in the Chevy arms was a bit small for the Pontiac tie rods, so they had to be reamed a touch. | |
The CPP drop spindle/disc brake kit uses Chevelle 11 inch rotors and Chevy S-10 calipers. In this case, it was cheaper to order the entire kit, then getting the individual pieces. And with the kit, you get a matched set: spindles, rotors/hubs, bearings, brackets, calipers, pads, flex hoses, nuts, washers, and even cotter pins, all for about $500. | The CPP drop spindle/disc brake kit uses Chevelle 11 inch rotors and Chevy S-10 calipers. In this case, it was cheaper to order the entire kit, then getting the individual pieces. And with the kit, you get a matched set: spindles, rotors/hubs, bearings, brackets, calipers, pads, flex hoses, nuts, washers, and even cotter pins, all for about $500. | ||
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For the more adventuresome, and fabrication minded, there is another approach. | For the more adventuresome, and fabrication minded, there is another approach. | ||
| − | The only real issue with the stock lower control arms is the king pin mounts. My buddy with the ‘49 Olds has a junkyard, but no ‘58 Pontiacs. He | + | The only real issue with the stock lower control arms is the king pin mounts. My buddy with the ‘49 Olds has a junkyard, but no ‘58 Pontiacs. He didn't want to wait for one to come in, so we cut the outer end from his lower control arms and welded on a 3/8" plate for a ball joint mount. He did have a '58 Buick, so those were the uppers we used. He had already pulled a complete spindle/disc brake setup off an early 70's Chevy, so we knew going in that the 45 degree angle on the spindle was going to be a problem. As it turns out, the narrower end on the original lower control arms is a blessing. A Chevy spindle can be made to work, but the Ford Courier had a ball joint with a 3-point “crowsfoot” design -- it is very narrow at the outer end, and the Chevy spindle cleared with no problems. There must be several ball joint mounts that could be adapted to the original arms. Just remember, the ball joints point down. |
[[image:49_olds_lower_with_for_ball_joint.jpg|frame|none|Ford Courier ball joint mounted on a ‘49 Olds lower control arm.]] | [[image:49_olds_lower_with_for_ball_joint.jpg|frame|none|Ford Courier ball joint mounted on a ‘49 Olds lower control arm.]] | ||
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