1937-1957 Buick Oldsmobile Pontiac suspension upgrade
| Line 55: | Line 55: | ||
dictates the path you follow in later steps. | dictates the path you follow in later steps. | ||
[[image:41 frame bump good pic.jpeg]] | [[image:41 frame bump good pic.jpeg]] | ||
| + | The brakes on these cars definitely need improvement. | ||
| + | [The information listed here is general in nature and varies from model to model and year to year.] I’m diverting to a brake discussion here, because a decision on brakes determines the spindles you need, and you must have your spindles before you can design your suspension. | ||
| + | Earliest models had 1 ¾ by 11 inch brakes with 1 inch wheel cylinders. | ||
| + | Post war they were 2 ¼ by 12 with 1 1/8 wheel cylinders. The most basic upgrade would be to the later, larger, components. Control arms and spindles are unchanged for 20 years, so this is a basic bolt on. Even the shop manuals refer to this upgrade. | ||
| + | The single system master cylinder is located under the floor and bolted to the frame. | ||
| + | A new split system master cylinder and power booster will be an amazing transformation of your stopping ability. Several aftermarket MC’s and 7 inch boosters, with universal pedal mounts are available. (With a V8 engine swap a 7 inch booster seems to be the max you can squeeze under the hood). I like the Geo Metro hanging pedal and 7 inch booster, but the MC is small. Didn’t chase down a match, but the center hole and bolt pattern appear to be typical GM. Be sure to get one designed for a booster application, and pay attention to the pushrod length. (Pulling the old pedals out was twice the work of putting the new one in). I located the unit just outboard of the steering column to clear the engine. Under the dash I had to bend the hanging pedal slightly to the center to get a good pedal position. I also welded on a new larger pedal pad that seems more appropriate to a large car and automatic transmission. | ||
| + | If you elect to do a power only upgrade and keep 4 wheel drums, be aware most MC’s are designed for a disc/drum setup and you will have to add 10# residual valves to the front lines. | ||
| + | At this point I would like to comment on the cost of doing a brake job on the original brake setup. The front drums and hubs come together, at about $130 each. Wheel cylinders are $32 each, Shoes are $25 plus cores, hardware is $15, flex hoses are $25 each and the above mentioned wheel bearings are $200. So, a complete brake job will run $600 just for the 2 front wheels, without the MC or booster. | ||
| + | |||
| + | So let’s consider the next option, front disc brakes. There are several ways to go here, but personally, I like the Scarebird* setup. Basically they supply the brackets for the calipers and the correct spacers for the spindles/rotors, and a tech list of parts to finish the job. | ||
| + | For clarification purposes only, here is an example. On a 58 Pontiac they supply the brackets and spacers - From any source, new or used, you need a pair of 77 Bonneville 12 inch hubs/rotors, a pair of 88-91 GM truck calipers, and 2 choices of flex hoses depending on whether you want them 12 or 15 inches long. | ||
| + | Note: From CPP (Classic Performance Parts) you can get a tapered bearing conversion kit. | ||
| + | Bottom line, if you are using all new parts, you can have disc brakes cheaper than rebuilding the original drum setup. Before you rush out and order parts, finish the tutorial. We will be discussing suspension upgrades that include changing spindles, which will change the Scarebird setup you need. | ||
| + | |||
| + | Footnotes; | ||
| + | Your original drum setup used ¼ inch brake lines. 3/16 is recommended for disc brakes. | ||
| + | Many aftermarket MC’s have Metric fittings. You may find yourself putting different fittings on each end of your new lines to convert from Metric to Standard. There is a direct metric match to the American 3/16 line size, so that is not a problem. | ||
| + | Master cylinder size is important, but slightly flexible. I like the corvette style MC, with ports out each side. Makes installation easier, and they are pretty cheap. The 1 inch bore will do the job, but expect the pedal travel to be a bit long. On the other hand, a 1 ¼ or larger MC will move the fluid faster (shorter stroke) but the small 7 inch booster will not be up to the job. Your original MC 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. (Any change from the original setup – front or rear weight change, tire sizes, line sizes, rake or tail drag, disc conversion, etc. 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. | ||
| + | |||
| + | *I have no personal connection, or interest in, Scarebird Classic Brakes, in fact I didn’t even use them on my car, but that’s a whole different story we’ll get into in the next chapter. I recommend them because others have been very impressed with the product and they make a setup for Buick, Olds, Pontiac, Corvair, Dodge, Plymouth, Cadillac, Ford, Mustang, MGB, you name it. Plus I like the idea of knowing exactly what over the counter, inexpensive, parts will be needed later when you do a brake job. | ||
| + | |||
| + | Update. I ended up with a corvette 1 inch master cylinder and a 7 in single stage booster. | ||
| + | My opinion is: close enough. The brakes are a vast improvement over manual drums, but not perfect. Stopping power is great to about the last 20% of pedal travel. I made several panic stops to test the system. At the very bottom, you just can’t push hard enough to lock them up. Simply put, the system needs a 9 or 10 inch booster to be perfect. The tech man I spoke with at CPP felt the 7 inch dual diaphragm would have been better, but not much. There simply isn’t enough power in a 7in booster to lock up a set of 215x75 15s on a 3500 pound car, on dry pavement. The reason I say close enough; this would only be an issue in a total panic situation, to a full stop, on dry pavement. In that situation, do you want them to lock up? | ||
| + | |||
| + | Front Suspension | ||
| + | Here is where the fun starts. The original idea came from a magazine article that showed an 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 | ||
| + | With some research we figured this would work on all 37-57 BOP’s cause they all had the same basic set up. What we learned was, 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 BOP’s went to a completely different control arm mount. 58 Buick lowers are not symmetrical, so they won’t work. (waiting for someone to confirm that 37-57 Buicks are the same as BOP’s, right now it is unconfirmed) | ||
| + | Also we do not have a 58 Olds to check those lower control arms. What we do know is 57 is king pins, 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. Make a note that several uppers will work. Looks like 58 to 60 BOP’s 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 pics, the 58 control arms are more substantial than the 41. But all dimensions are the same. | ||
Your Privacy Choices