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Thread: '63 Tempest project
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10-19-2012 #1Registered User
- Join Date
- Aug 2004
- Location
- Maine
- Posts
- 594
'63 Tempest project
Hi all,
After a few years out of the hobby due to being just too darned busy, I'm jumping back in with a new project - a '63 Pontiac Tempest. Ever since I first saw one, I've thought the '63 Tempest just has great lines. They didn't make a whole lot of them (only about 15,000 coupes), but I was lucky enough to find one only about 30 miles from the house last summer! While the car was a basket case, it was rust free and had a fairly straight body (aside from the crunched lower rear pan) and so I brought it home.
The car started life with an inline 4 cylinder engine and rear-mounted powerglide transaxle with IRS. From the factory, these cars weighed about 2800 pounds! The transaxle and rear suspension was long gone and the previous owner had welded an axle under the back end to allow the car to be rolled. Up front, he had installed a Heidt's universal Mustang II suspension. The car was completely disassembled, with about a dozen boxes of parts and a bunch of spare sheetmetal. I began by taking inventory of what I had and starting the build plan for the car.
My plan for the Tempest is to make it generally appear to the casual observer to be something that could have come off of the factory floor and that was mildly modified in the early 60s - a "sleeper car," so to speak. I don't care if a real afficionado can spot that the car has a different "stock appearing" engine from the same general period. Nor do I care if someone realizes the car is modified when they stick their head under the car to look at the undercarriage. What I want is a car that has an engine bay, body and interior that don't scream "highly modified." I plan for this car to be primarily a street car that will see some dragstrip action and which I also want to handle well on the windy country roads.
After developing the concept for the car, my next step was to turn to the chassis and suspension.
I took measurements of the Heidt's IFS system and plugged them into Suspension Analyzer to see how the numbers looked. Overall, the results looked generally OK, and I was satisfied feeling that I would not have to change things up front. As FYI, the front RCH is just under 3'' and follows suspension travel very closely. The roll center is also very stable left-to-right. FVSAL is about 155'' at static ride height. There is about 30% anti-dive. Camber gain goes in the right direction and bump steer is pretty minimal.
Then, I turned my attention to the rear suspension... since the car has none at present! Rather than trying to resurrect the rear transaxle and IFS, I decided to go with a Satchell link. To get started with the design, I began taking measurements of the underside of the car to determine the constraints with which I would be working. Given that I wanted to retain the rear bench seat to maintain a generally stock appearance, I didn’t want to design a suspension that would frustrate that purpose. Fortunately, one benefit of the Satchell link is that it generally packages very well. After taking my measurements, it appeared that a 15’’ long upper arm would be about as long as I could go without getting into the floor pan. For the lower (angled) arms, the floor of the car would be high enough to provide no real fore/aft constraint. So, my measuring concerns for the lower arms would focus primarily on where to locate the attachment points side-to-side to avoid wheel interference on the axle end and driveshaft interference on the frame end. With general measurements in hand, I began plugging specifics into Suspension Analyzer.
Ultimately, I came up with a design that gave me an 8.5'' RCH with 60% static anti-squat and minimal roll understeer. SVSAL is nice and long at almost 160''. I am making the frame mounts for the links adjustable so that I can fine tune it. With the front suspension, this gives a pretty close to neutral steer scenario. To get to a little understeer, I'll incorporate a small sway bar up front.
With design in hand, I began work on the rear end. I got a Ford 9'' housing and fabricated and welded-on the various brackets and mounts. The guts of the rear include a TrueTrac differential with 3.90 gears in a Strange Pro case, and Strange 31 spline axles.
I then began work on the upper frame mounts. This consisted of a crossmember welded between the car's existing framerails. The trailing arm mounts attach to that crossmember and are slotted for adjustability to tune understeer and to allow for changing the car's ride height if I ever decide to do so. As of right now I'm planning to run a 28'' rear tire. Here is a picture with the upper crossmember tacked-in.
As I began working on the design of the frame mount for the lower trailing arms, I realized that I didn't have an appropriate frame point for attachment. The early Tempest is a unibody design and the only "frame" structure (other than the rocker) under the main passenger compartment is a very small 1'' high x 2'' wide U-channel that is tack-welded to the floor, tying the front and rear subframes together. So, I decided it was time to hop from suspension to subframe connectors...
To build the connectors, I decided to follow the contour of the U-channel. I cut away the floor sheetmetal above the channel and formed some 2x2x.120 tubing to fit in the channel. The ends of the connector slip inside the front and rear frame rails. I then welded these connectors all along the length of the U-channel and around their perimeter (to the frame rail) at each end. These will give me an anchor for my lower link mount supports.
Floor cut open for rails to drop in:
Rail welded in:
So, that is where I am at for now. Next steps include finishing the frame mounts for the Satchell link suspension, fabbing motor and transmission mounts, and trying to stiffen up the frame a bit more.
My schedule is still a bit crazy, so my progress has been on-again off-again over the past few weeks, but hopefully I'll be able to post more updates every week or two.
Thanks for looking! It feels great to be back out in the garage!!!
PS - my signature is majorly out-dated... I need to fix it.John
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10-19-2012 #2Banned
- Join Date
- Aug 2012
- Posts
- 82