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For anyone out there willing to help with some guidance!
In order to change to the new setup, I have some questions, as to the sequence and the best way.

This will involve the scaling of the car, increasing the front camber and the front positive caster. Normally this was not a problem, as I had to make minor changes. However now, I am now increasing the front camber and caster by much more than what I am use to doing. The front caster adjustment concerns me the most, going from a + 2 to a +6.

Here are my questions:

What is the best way and sequence? Do I first scale the car and get the proper corner weights? If so, do I next change the camber and finally the caster or do I do the caster and then the camber?

From what I remember increasing the positive caster is made by increasing the length of the caster rod clevis. Will this be enough for this major change or do I have to reduce the length of the forward control arm also? Not sure that would be a good idea.

While on the subject, I believe the thread rules for the rod ends do not apply to the clevis. What is a safe adjustment length for the clevis? I hope I have my terminology right.

So in summation, what is the proper sequence for scaling, camber and caster settings?
and what is the best and perhaps the only way of adjusting the caster along with the safe visual length of the clevis?

Thanks in advance for your suggestions

Pat

Pat,

We have never really worried about caster to much, and never ran 5 much less 6 degrees over all the different tires and setups, but the smaller front tires may be the reason you need more to load the inside tire.

We had outlined the setup procedures on our website a few decades ago, but still should be good. Look under "Secrets of the Brotherhood" and then hit "Chassis Setup Procedure".

Do you camber, then caster,bump if you do that. Ride height and last tow. Then scale last always. No bar connected,shocks full off rebound,set tire pressure to hot run pressure. Yes when you adjust it will change ride height a little but that is ok. corner weights are more important. I think that all of it. Tony Southeast Spec Racer

tonyrn99 wrote:Do you camber, then caster,bump if you do that. Ride height and last tow. Then scale last always. No bar connected,shocks full off rebound,set tire pressure to hot run pressure. Yes when you adjust it will change ride height a little but that is ok. corner weights are more important. I think that all of it. Tony Southeast Spec Racer

This sounds like the way I've always approached it.

One thing to remember is that more positive caster will result in increasing cross corner weighting as the steering wheel is turned off dead center. This is a good thing, as counter-steering in a slide "jacks" the corner weight to the wheels that need it most; it's kind of a "self correcting" effect. I once asked my friend, the late Joe Stimola, how much front positive caster is too much. His answer, "As much positive as the driver can stand."

With these new radials being more sensitive at the limit than our bias-ply Goodyears were, I like having that extra caster cranked in to make it easier to catch and correct the oversteer.

That said, when doing corner weights be sure to lock off the steering wheel at top dead center, straight ahead, just as you would with a toe adjustment.

Last summer when we were doing the corner weights on my car, for awhile we couldn't figure why the corner weight numbers weren't staying consistent after adjustments. Then I noticed the steering wheel was turned to about 11:00 off TDC to the left. We straightened and locked off the steering wheel at TDC and all was made right with our world.

Be careful to stay within the legal limit on the helm joint threads (note the 2016 spec has increased slightly from 9/16" to maximum of .570" from first thread to a standard sized nut.) Ended up pulling out the suspension pieces completely and adjusting both ends to allow more range (some were too short to meet minimums and some were too long for maximum.) Give yourself some adjustment room outside of the recommended settings if possible as we're still learning and I'm seeing differences between tracks to maintain optimum longevity.

The caster change was the most significant on my car so I ended up doing this first as I needed to lengthen pretty much all the lower suspension points anyway to keep them within the legal limit and offer some safety factor for further adjustment. In the end, expect to "rinse-repeat" if you want to get it really close (and as Bob D. noted, adding this much caster makes centering the steering very critical and easy to mess up pushing the car on-off the scales after each adjustment.)

I took one of my clevis' out and measured 2" of threaded stud. The Aurora Bearing website says that the minimum thread engagement for a spherical rod end is 1.5 times the major diameter. The clevis is not a rod end, but I think it would be safe to use the same rule; therefore, you'd need 3/4" of threads buried which would leave 1 1/4" of threads exposed. (Disclaimer: I am not a mechanical engineer and I did not stay at a Holiday Inn Express last night.)

I also had to take my front suspension completely out. Oddly, I found that my caster rods were two different lengths. One was 12 1/2" long (excluding rod ends and jam nuts) and the other was 12" long. I asked my CSR about it, and he told me that the new ones he had were 12" long. Too bad; the 12 1/2" rod made it easier to get to the recommended camber and caster settings while easily complying with the 0.570" rule on the inside spherical joint. The 12 1/2" long rod had the remnants of an SCCA Enterprises label on it and no apparent signs of modification, so I believe it's legit.

Ed, you're correct that there are two different sizes, with newer ones "downsized" to 12". I believe this was a change due to the significant reduction in camber with the Goodyears (though never published, to my knowledge.) Had a "new" one on one corner which was limiting camber adjustment to less than 4 degrees when I know we ran well over that when we were pushing 5 degrees in the past. Hold onto those old ones!

breton wrote:Ed, you're correct...

First time for everything!

breton wrote:Ed, you're correct that there are two different sizes, with newer ones "downsized" to 12". I believe this was a change due to the significant reduction in camber with the Goodyears (though never published, to my knowledge.) Had a "new" one on one corner which was limiting camber adjustment to less than 4 degrees when I know we ran well over that when we were pushing 5 degrees in the past. Hold onto those old ones!

Yeah. We also found this out the hard way when doing the setup last weekend. Had to call Mike Davies to find out the history of the front rod sizes, and why we had so much thread showing.

Kurt,

I am waiting as to what Mike told you!
I prefer not to call him and waste his time.
P l e a s e