Im in SM but of course this applies to ASP as well. Here's a vid of the tire flex on a 285 A6 mounted on a 10" wheel.


I get a fair amount of rubbing on things that statically don't touch and that prompted me to see how much things are actually moving. Am I right in thinking a wider wheel will not only give more contact patch but also reduce this roll significantly?

I would also like to point out another thing here. If you watch right when the wheel lifts off the ground you'll see a bit of slow extension. This is where the tender spring is extending. My early thoughts were that the tender should help keep the wheel in contact with the ground longer and possibly help overcome the sway bar partially but because its far to over-damped it seems to just react way to slow. This video alone might be enough in my eyes to tip my hat to Marshals view of tenders are unnecessary.

At a minimum I'm going to be pulling the fronts for extra tire clearance and less front weight.

 

Tender spring at spring rates of around 10 lb per square inch (if so) have no effect to your ride. They are there just to keep your main spring in the same location so it doesn't clunk around when you go to the full extension. Typical race spring is around 8" of length and damper should be able to extend further than that at full extension and that is where the helper spring helps.

Your main spring was extending your shock and rebound inside was fighting it back. The more spring is compressed more force it creates. Once it fully extends there is nothing there to push it down beside the weight of the wheel itself and pressure inside the damper.

I would not remove those helpers from the front (or rear for that matter) unless you have an obvious issue with them being there!

 

You're backwards on the Tender vs Helper. Helpers are around 10lb/in. Eibach calls its tender, Swift calls it Assist, but med rate springs that compress flat are what Im talking about.

I have 5kg/mm (280lb/in) assist springs all around right now.

 

Interesting! I had no idea people would do that for the race setups. I guess, using it for streat would make the whole thing work like a progressive spring (having 280 lb and another that is 600 lb for example) and make it a bit more comfortable. But I would never do that for my car that I use for racing and want every single bit out of it in every corner. Than again, I have been wrong before...

Btw, how long each of your springs are? Tender and main one that is?

 

What tire pressure were you running? I used to run about 38 psi hot when I had that same 285 on 18x10 setup.

 

The idea started back when I was running 900lb springs and had about 1" of suspension compression from static. The rates we run for tenders had them fully compressed at static ride so nothing changes as a corner is loaded.

We though it would help in two ways. 1) Help push the wheel down a bit harder when leaned over. Turns out this just happens to slow to really happen since by that point its over dampened, at least from the looks of it in the video.

2) Soften the "landing" when the wheel comes down. In this respect, it does seem to really help the ride quality going over bumps and lets the wheels drop further.

Up front it takes up an extra inch of space. If I remove it then we would have the spring perch completely above the tire and could fit a little extra wheel, less offset, or more camber at the hub.

 

We run way less pressure. We're at 30psi front 28 psi rear. That was set with a temp probe on a skid pad with the old setup about 2 years ago. We tried just a little more pressure and seemed to both slow down (co-driver and myself).

 

That seems abnormally low for A6's. I would expect pretty high sustained g's. But lack of transitional stability and premature shoulder cording.

 

Would be interesting to see what others are running then. Higher pressure just felt slower. My last set were flipped at 40 runs and dead at 80 runs. The edges were beat but still had rubber. The tires themselves just fell off a cliff and street tires were faster at that point.

Conversely, the BFG R1-S ran 32-30 with raising the rear pressures if I needed more rotation. They lasted 150+ runs with a flip around 100. The didnt feel amazing at the end but were still faster than the street tires. Edges were fine.

I'm definitely not saying you're wrong or I'm right. I'll have to test the tires up higher to see if I like it better. We have the Packwood prosolo next weekend and I might use the first set of runs to test 38psi and see how it feels then drop to 30 for the other 2 unless its magical.

 

yes 30/28psi is too low for an evo on A6's. you may have found the optimum pressure for a non optimum suspension setup. increasing pressure from where you are should increase grip and probably lead you in a different direction with your setup (camber and/or springs/bars). It is plausible that simply increasing pressures from where you are at now will slow the car down but it doesn't mean you're at a global optimum.

and yes, tender/helper/assist springs suck for race cars. all they do is slow the car down.

 

Haha, Good to know. Ill definitely try out 38psi as suggested then.

I have a lot of adjustability in the bars right now so if I do have some weird balance change I should be able to get things back to a happy place. Camber should be solid at -4.2deg with significantly more caster than ASP can run.

 

Just to add another data point, I ran my Hoosiers at 32/33 2-3 years ago and they felt ok to me at the time. I went up to 38-39/40 last year based on suggestions from other people and the car felt much crisper. Turn in was definitely improved because I wasn't dealing with sloppy sidewalls anymore. This was on a 11"/10" wheel setup.

 

Do you run any split front/rear? I was thinking of just starting 38/38. Hard to tell which way to go from there since roll isn't too useful with more than 4deg of camber and temp probing is hard without a skid pad to pull right off of.

 

I ran the rear around 40-41 and the front around 38-39 usually.

 

As Marshall said, you may be compensating for the suspension by running a soft tire. Increased air pressure should really "sharpen" the feel of the tires. It may also cause you to exceed the max grip of the tire too quickly, especially if your suspension is overly stiff/tuned for the soft tire. You will probably see overall cooler tire temps, once you stop working the tire and using it as the main system damper.

Just because a setup feels good, it doesn't mean it is the best. Speaking of which, I'm about due for some sort of drastic suspension change, lol. You can always go back to the old setup (assuming you keep good notes) if you don't like the new one!