John Parson's II MUCH Suspension Thread Hijack

[preston]

I just came back to this thread a couple notes -



CCW built my front wheels 10.5" wide with 9" backspacing although he did say that was the limit. Backspacing and packaging is the key to scrub radius. For my track wheels I'm planning on 12" with 10" backspacing so we'll see if he can do that.

Katz I no longer agree with Bruce on that statement concerning SAI. I ended up at 12 degrees and if I did it again I would drop down to 5 like you did, even taking the hit in scrub radius (I'm only at 0.4", so I don't think it would be a big deal). I find if I dial in more than 5 deg caster it starts feeling weird, and my intuition says its the combo of sai and caster. I agree that he was probably just saying that to justify the high SAI that he had to have in his early mustang design because of the SN95 spindle and adapter packaging and the limitations of the pickup points etc. Also that SN95 spindle has a very lower pin in my eyes (too close to the lower BJ) which would also contribute to difficulty getting the scrub right.

As far as the spindles, they seem as custom as you want. I had Coleman raise the pin 1.5" fro mtheir standard design, the upper bj mount determines the SAI and they could set it up at whatever angle (and offset) you wanted, its welded on custom. They made a set of custom "stepped" steering arms for me that I didn't end up using (went with their standard bolt on arms with a bit of ackermann). Even the spindle pin was competely custom machined to match my '70 Ford intermediate spindle based Baer hubs (a mistake I would correct next time around and just use a stand stock car hub, I think the problem was finding a 5*4.5 bolt pattern at the time).

And they were still only $300 apiece, although the custom hats they made were $550 d'oh !!! Using the stock car hub would also have allowed using a bolt on rotor plate, completely eliminating the hat.
I sent them my caliper and they welded on the mounts and everything.

So I guess I'm having a hard time imagining a spindle they couldn't make fairly cheaply. The only "constraints" were I stuck to the standard Chrysler (772 ?) ball joint on the lower and the standard 4029 ?? upper 4 bolt GM ball joint, but this was fine as I used circle track parts to fab the control arms anyway so that was perfect.

BUt as I said I had two big advantages - a pretty wide track (60" center to center) and a huge engine setback that avoided any rack packaging problems. I don't know how much you paid but my custom BRT rack was $700 but those guys have also been great and they changed out the center "rack gear" for a custom length when I built a 2nd car for only lik $150, and setup the servo with a real light assist for me real cheaply as well when the initial steering was too heavy.

Without bragging too much, I think mine is the real driveway suspension considering I didn't have any engineers help me (well I'm a EE but I didn't use any engineering other than using a suspension program) and I ACTUALLY BUILT IT IN MY DRIVEWAY !! In fact I didn't even have a carport the first two years, just a tarp shelter. But then it takes a lot of work to write and photograph an article and get it published, not taking anything away from II MUCH. (I'm still trying to get Hot Rod to feature the car. Had some promises but no appointment. A few more months of track season and it won't be presentable enough for a photo shoot.)

I've had the car at 3 autoxes and 2 track days and am very happy with it. I'm no expert driver, but I have been on track for several years and raced shifter karts for 3 seasons so I have some idea where it should go. It certainly drives better than any version of the hot rodded stock '67 Mustang suspension ever did. Not only does it perform nicely on track, but it satisfies my number one design goal of being stable and easy to drive even on rutted freeways. That doesn't mean there isn't plenty of chassis tuning to be done but in the ballpark is a good place to start.

Now if I could just tone down some of the NVH.....