daaa nope

No worries and it's actually a valid point to cover, because you are right: the driver and pace makes a big difference on tire wear. I've had the (mis)fortune of overhearing lots of different conversations at events (autocross, DE, even W2W racing) about car setup, driving tips, etc. from folks that really probably shouldn't be giving it.... and I know that's 10-fold on an internet forum

Yeah I definitely make the rears do more work with this setup - I'm able to get on the power much harder and much sooner this way, than I did before I made the bar change.... and I have a lot less cockpit-karate going on because the rear end tends to stay put despite an aggressive right foot. Based on wear, I'm likely just getting a lot of squat in the rear from mid-corner to corner exit and the camber change is eating up the outside edge.

This is further exacerbated by the fact that (as I've since relocated 800 miles) the new lot I've been running in is fairly slippery with not a ton of grip (hot black asphalt with a lot of sealer). I've found that leaving the shocks in the soft mode nets me a lot more grip (tho I do get some extra heave in transitions). This extra body roll is also likely contributing to the outer shoulder wear since I'm getting more camber gain with the squat.

Overall - I am just hoping against hope that I might be able to get a tiny bit more camber in the rear. Maybe I'll pony up and take the car to Goldcrest and have them do an alignment and center the subframes. I can otherwise align and corner balance the car myself but I don't want to mess with the subframes.

lovetoturn

"I run the bars at full hard front, middle setting in the rear. It makes the car a little pushy on the way in, but it puts the power down much better on exit. I can trail brake it in to dig the nose in."

Very good point for the mild push on entry. This is not a bad thing, cause the minute you start to trail brake you are inducing oversteer to balance the corner entry understeer and end up neutral. You can finish the trail with a touch more steering angle and induce a mild kick of over steer to add that final bit of rotation as you transition to gas. Then when you are powering out of the corner and are inducing a bit of throttle oversteer, you can use more of the gas pedal sooner if you have that inherent bit of stablizing understeer. So when you are poking around the track warming up or cooling off the tires, a well set up car may have a hint of understeer. But when you are up to full speed and on the limits of adhesion, then the car is perfectly balanced for that type of driving.

So daaa nope, unless your car is spot on for you, maybe going to a HM setting on the front bar might help reduce the understeer just a bit to even better balance your car. It would appear that the MM / MM setting wasn't working for you since you are at HH / MM now. Just a thought.

TRZ06

You make a good point on softer = more grip. Since having my MCS 2 -way remote dampers and trying a BUNCH of settings, I find that I have the most grip when the car is set up a little on the softer side. There is some additional vertical movements at higher speeds and when encountering dips and bumps in the road, but I have the most lateral grip.

As I tighten the car up, it gets more edgy and has a quicker break away, and the ultimate amount of grip decreases a little. The steering also gets lighter in general and more responsive, sometimes too responsive as things are tightened up.

sgreer78

I ran middle front stiff rear. 28/32 pressures on BFG Rival 1.5’s. Great wear, well over 200 runs and managed to win the Peru Tour in ‘20 on those.

what’s your rear toe?

jreifler

R7 295/35 are pretty “tall” compared to other brands. I made a chart once with relative diameters and widths, but can’t find it at the moment.

The rubbing is super marginal. Certainly not noticeable while driving, and it’s towards the front of the inner rear wheel well - at the very front edge of the rear tire.

It’s a track-only setup, so I have pretty much max camber dialed in front and rear (2.5 and 1 degree toe in at rear to stabilize under braking). Tarrett cup control arms front and rear, and Tarrett links as well. I genuinely think the cause is just that the R7s are beefy, so under heavy load, they ever so slightly rub. It’s not even noticeable on the tire itself.

StormRune

I assume you mean 1mm toe each side, not 1 degree.

jreifler

Correct. Sorry.

Edit - The stiffer Tarrett springs made a noticeable difference in stability under braking.

daaa nope

3mm total rear toe

aarodynamics

I've found Caymans need a minimum of 5mm total rear toe with TPC offset toe links and 6mm total rear toe with any other toe links.

aarodynamics

Are you running a 295/35-19?
What is the wheel size and offset you're running?

Westcoast

Does this cause increased wear on the street?

Inrev

Not just on street. I had to decrease toe to 1mm each side to reduce rear tire wear, the insides were wearing crazy fast at 3mm toe in. No wiggle under braking at 2mm total either.

Westcoast

I will have to look up what the rear toe is set to on mine, but given the amount of track time I get, I won't be making a change here, the wear is nominal on the street, and I can live with wiggle on the track.

lovetoturn

I went from 11-12 minutes to 14-15 minutes on the rear for my last alignment along with the stiffer swift front springs. Car is much more stable under braking now and even better in the high speed sweepers too. That equates to about 2mm going to 2.5mm. I think either number can work for those who frequent the track. Most of my driving is to the track or on it, so tire wear is not an issue. They wear out before there is any serious unevenness. I do have TPC toe links as well. For reference, I believe the GT4 Clubsport cars run about 15-17 minutes of toe in for the rear axle.

Maybe 3 mm (18 minutes) is too much for most as mentioned above, but it should be at least 1-2 mm (6-12 minutes) of toe in for the rear depending on your driving preferences.

All numbers mentioned here are per wheel, so you can double any of the numbers to get the total toe. There are of course 60 minutes in 1 degree, so for the example above, 12 minutes equals 12/60 or .2 degrees. It just amazes me how much difference there is between .1 and .2 degrees of toe-in on the rear end of the car when driven at the limits. Again we are talking about tenths of a degree, but when you are going 100+ mph it doesn't take much.

TRZ06

When talking about toe settings, it would be helpful to keep the unit of measure consistent. You talk about MM, then move to minutes. I think it would be helpful for those who are not well versed on how alignment measurements works to stay with a common denominator.

I still get lost when converting MM to minutes, to degrees, to inches.