1937-1957 Buick Oldsmobile Pontiac suspension upgrade
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| − | + | As with all custom modifications, there are lots of variables and side issues with doing a suspension and disc brake upgrade on a '37 - '57 Buick, Olds, Pontiac. In addition, there is little information on the topic, and few aftermarket parts available. | |
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| − | As with all custom modifications, there are lots of variables and side issues. | + | |
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| − | + | With minor variation between models and years, all Buicks, Oldsmobiles, and Pontiacs (BOP) share a common frame and front suspension. Chevrolet did not share this setup, but General Motors's "3 Ugly Stepsisters" did. | |
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| − | + | ==General summary== | |
| − | a | + | *The front suspension is made up of unequal length upper and lower control arms and coil springs. |
| − | + | *The coils sit in a spring pocket on the lower control arm, and a spring perch built into the frame design on the upper end. | |
| + | *Steering is thru a kingpin steering knuckle. Alignment is accomplished with an inner and outer concentric screw adjustment in the upper steering knuckle mount (accessible by removing the grease fitting and inserting | ||
| + | an allen wrench into the hole). | ||
| + | *There are two types of shock arrangements. Roughly '37 – '49 (not all 3 changed the same year) have a lever action shock that is built into the upper control arm and serves as the upper control arm mount. 50’s models went to a separate tube type shock. Some internal to the spring, some external. The upper control arm is still a fixed frame mount, with caster/camber adjustment in the concentric sleeves. | ||
| − | + | ==Key shortcomings of the original suspension== | |
| − | + | These cars actually drive reasonably well, and this basic technology was a mainstay for 50 years. However, it does have certain shortcomings: | |
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| − | These cars actually drive reasonably well, and this basic technology was a mainstay for 50 years. | + | |
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| − | First, these cars came with zero to ½ negative caster. | + | First, these cars came with zero to ½ 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 1940's and 50's. |
| − | Negative caster makes the car easier to turn and gives greater control in | + | |
| − | + | 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, | + | 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 2 ½ to 3 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 | + | |
| − | On the pre | + | 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. |
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| − | have shortcomings. | + | On the pre-50's 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 a stock only application. Raising or lowering the vehicle puts them out of their designed operating range. Increasing or decreasing weight with engine and tranmission swaps alters their effectiveness. |
| − | designed operating range. Increasing or decreasing weight with engine | + | |
| − | + | The hubs/drums run on ball bearings. While serviceable 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 | |
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bearings will run about $25). | bearings will run about $25). | ||
| − | + | The brakes are, obviously, inadequate: non-power 4 wheel drums with a single reservoir hydraulic system. | |
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| − | With this basic understanding of the issues, we can start to discuss solutions. | + | With this basic understanding of the issues, we can start to discuss solutions. |
Most attempts to gather advice will result in 2 stock answers, Mustang II or GM sub frame. | Most attempts to gather advice will result in 2 stock answers, Mustang II or GM sub frame. | ||
Personally I think the MII is a totally misguided answer. It may work well on Chevy’s, but they have a straight frame rail, | Personally I think the MII is a totally misguided answer. It may work well on Chevy’s, but they have a straight frame rail, | ||
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