Rear tire wear/anti-roll bars?

[texevora]

I get significantly higher wear on the outer edge of my rear tires (outer edge is rounded, and will get to the cords first) whereas the inner edge wears to a much "squarer" shape and look fine when I have to toss the tires due to the outer edge cording, even with -2.4 degrees camber. When checking tire temps with a pyrometer however, the inner edge is consistently about 15-25 degrees hotter, which makes me think that the chassis/body is rolling quite considerably in the twisties and accelerating wear on the outside edge quite considerably. My tire pressures are 18f/18r cold, and typically 21-22f/23-24r hot, for what it's worth.

I'm far from a suspension guru, but would anti-roll bars on the rear help combat this weird tire wear? If so, has anyone developed them for the SRA?

If not, i'd be curious how involved it would be to have someone fabricate a set. If i can get the tire wear to even out considerably, i bet i could double the number of cycles I'm getting out of my A7s.

[cvjoint]

I've run 225, 245, 295, and 355 section rears. I never got any unusual wear. Last set I ran to the cords did 55 heat cycles, and it was bare fairly evenly. Ran anywhere from 1.5 to 3 degrees of camber and temps from 16psi to 25psi cold.

I never heard of outer shoulder wear being caused by lack of sway bars. See base C7 Corvette owner feedback as well. Those cars come without sway bars.

My guess is you bent something and it's hard to see.

[argonaut]

I don't see outer edge wear on my SRA either. Thats with A7 - 225/15 front, 245/16 rear. I can't imagine sway bars are the answer here. Maybe need a full alignment, seems something is out of wack.

[texevora]

My settings have been fairly consistent:

-1/16" front toe
+1/8" rear toe

5.4deg caster front left & right

-2.1 deg front camber
-2.4 deg rear camber

I'll try to crank up rear pressures a bit (at 18f/18r cold, ~21f/~23r hot).

[cvjoint]

If anything the camber and toe should eat the inner block first.

[argonaut]

I wonder what spring rates you have. As far as I know, mine are:
Stock Springs:

• Front: 400 lbs/in
• Rear: 300 lbs/in
• hypercoil 8 in long, 2.25 inside diam

To me the car is very stiff and has little sway (thus the reason I can't imagine needing a sway bar).

[cvjoint]

I wonder what spring rates you have. As far as I know, mine are:
Stock Springs:

• Front: 400 lbs/in
• Rear: 300 lbs/in
• hypercoil 8 in long, 2.25 inside diam

To me the car is very stiff and has little sway (thus the reason I can imagine needing a sway bar).

That should be it for all SRAs with QA1 as far as I know.

[texevora]

@argonaut, same on mine, however I swapped the springs front/rear so my 300s are in the front, and 400s are in the rear.

I upped my tire pressure from 18f/18r (21f/24r hot) cold to 18f/20r cold (21f/26r hot), and car seems to feel a lot better in the rear. I think i've been rolling the rears due to too low tire pressure, causing the outside shoulder wear (just a theory).

[cvjoint]

The guys in Europe run insanely low pressures, as low as 12psi cold. Too risky for my book, but I don't think they reported any unusual wear. It could also be that your theory is right, but ran with something like high toe in can be compensating so the net effect is even wear.

How is that spring swap working out? I think it's a good idea, just too lazy to do it.

[texevora]

Don't have much in the way of spring swap feedback pre/post, I basically just copied the setup of a Sector111 post from years ago. And it seemed to make intuitive sense given the weight distribution front/rear of our Atoms.

As for tire pressures, here is a pic of my Atom at CotA from 2 weekends ago running 18f/18r cold under heavy lateral load.2020-06-20_EA_COTA_RP_11183.jpg

I have since upped the rears to 20psi cold, which seems to have helped the rollover effect, though time will tell when i see the wear.