SCCA Solo D Street discussion

[AustinTX]

I finally was able to try out a bigger rear bar on my 15 BRZ. RPF1's with RE71R's, camber bolts, stock shocks, stock front bar, Whiteline 16mm rear bar set on soft. The factory endlinks do work, though they are stretched a bit to get to the soft setting. I'll replace them if/when they break.

I got the chance to run both of my cars in the same event, so an interesting comparison of competitiveness. I took top PAX in the STU STI, and the BRZ was would be around 4th in PAX if double runs counted, 0.9 PAX seconds back. The rear bar didn't upset the BRZ or make it drive weird. Just slightly more rotation. I thought about going to the middle setting, but it's already really easy to maintain neutral balance right now.
PAX Result: https://axwaresystems.com/axorm/file...un2017_pax.htm
STI vid:

BRZ vid:

[blkwrxwag]

Debut for my FRS this weekend at El Toro Marine base. My codriver is four time BS National Champion, Jason Isley. The car has Koni shocks on it, and I set it to full stiff up front, and a turn from full stiff the the rear. I liked that setting a lot, but Jason thought it was crazy loose. He preferred full soft in the rear.

I ended up taking the win over Jason by 0.007 on my last run. Pretty exciting stuff and I really enjoyed driving the car on Nexen tires.

Me:

Jason :

[VVT4ME]

Help! I have graining issues on my RE71Rs. The first two photos we taken of the passenger side front tire after about 15 runs on a counterclockwise course about 3 weeks ago. I rotated the fronts to the rear before yesterdays event, and after 6 runs in the dry on a course with clockwise sweepers and 5 runs before that in the wet this weekend, the drivers side front tire looked like this. I ran them at 27 psi the first time i noticed this a few weeks ago, and this weekend i started at 30psi and my last couple runs i ran the fronts at 35 psi. I have factory crash bolts with roughly 1.6-1.7 negative camber, Hotchkis 25.4mm frony sway bar. Otherwise stock. Looks like the higher prssure alone didnt help very much. Could my big front bar be contribiting to it? Or am i likely just overdriving? Besides flipping the tires soon. I dont see much else i can do to preserve these tires except a drivers school to correct my poor tire preservarion skills......if that is even the problem. Any thoughts? Its only graining like that on the center rib.


facebook photos hosting

[Shneegle]

Originally Posted by VVT4ME

Help! I have graining issues on my RE71Rs. The first two photos we taken of the passenger side front tire after about 15 runs on a counterclockwise course about 3 weeks ago. I rotated the fronts to the rear before yesterdays event, and after 6 runs in the dry on a course with clockwise sweepers and 5 runs before that in the wet this weekend, the drivers side front tire looked like this. I ran them at 27 psi the first time i noticed this a few weeks ago, and this weekend i started at 30psi and my last couple runs i ran the fronts at 35 psi. I have factory crash bolts with roughly 1.6-1.7 negative camber, Hotchkis 25.4mm frony sway bar. Otherwise stock. Looks like the higher prssure alone didnt help very much. Could my big front bar be contribiting to it? Or am i likely just overdriving? Besides flipping the tires soon. I dont see much else i can do to preserve these tires except a drivers school to correct my poor tire preservarion skills......if that is even the problem. Any thoughts? Its only graining like that on the center rib.

This looks like normal tire wear for an autox tire. The RE71R's are really soft and are not really a 200TW tire like Bridgestone says they are. Which is why its considered a cheater tire for track events.

Graining happens usually due to the tire not being warmed up when you push it hard. Since your not allowed to warm tires in autox this is normal with soft rubber.

[justinco]

Yea, that looks mostly normal. That center rib wears so fast. I have a few hundred autox runs on multiple sets of RE71R's, on multiple cars, they all did that (not quite as much graining though).

[TrqlessWonder]

I also consider that to be non-alarming. Consider this a breaking-in wear pattern. That actually should clear up. Should also point out that sticker bridgestones are widely considered to need an event or two before they'll start really gripping at full capacity. The amount of runs you have on them suggest you might not be all the way there.

That said:
Since I've been on bridgestones, I've never run a pressure at any position on the car above 31 psi. So, stick with the lower pressures. It's a stock car. It's gonna chew up the shoulders. 30-31 psi should be all you need to keep the rollover from being too bad. Too high a pressure is actually a great way to specifically grind away the center rib of the tire and nothing else. It's a heavily reinforced balloon, but it's still a balloon. More air pressure makes the cylindrical tire much more sphere-shaped.

Sway bar gigante? I do think that's too much bar for a stock car. Most folks are sticking in the 19-22mm range.

Are you overdriving? Don't know. We'd need something to observe to comment on that. But significantly over-pressure tires, and a bar much bigger than most use will make it easier to push the front end and give you the same results as overdriving.

If you are overdriving, you don't need a full school to correct that, and I don't believe Evo schools even touch that topic in phase 1 or 2. Find a fast local instructor and ask them to help you at your next event. If you don't seem to be "getting it" from the first instructor, find another one to try and explain it to you. Not everyone learns or teaches the same way.

[VVT4ME]

Maybe i did run the presure up too high. Though this happenedat first after i ran 15 runs at 27psi. I driver in our region i hugely respect (Ryan Otis) suggested i bump the tires up a couple pounds....but that would be 29-30. Since i saw new graining after a couple runs at 30psi thats when decided to go even higher. At the least before i r7n again i will flip them.

[Locust]

Originally Posted by VVT4ME

Maybe i did run the presure up too high. Though this happenedat first after i ran 15 runs at 27psi. I driver in our region i hugely respect (Ryan Otis) suggested i bump the tires up a couple pounds....but that would be 29-30. Since i saw new graining after a couple runs at 30psi thats when decided to go even higher. At the least before i r7n again i will flip them.

Middle bar after 20 runs looks like it's going to disappear in a week. It stops wearing that fast after that and the tires settle in really well. What you see is perfectly normal and nothing to be alarmed over. When I first saw the wear on mine after 20 runs I thought I'd be buying a new set after 2 more events.

[TrqlessWonder]

Originally Posted by VVT4ME

Maybe i did run the presure up too high. Though this happenedat first after i ran 15 runs at 27psi. I driver in our region i hugely respect (Ryan Otis) suggested i bump the tires up a couple pounds....but that would be 29-30. Since i saw new graining after a couple runs at 30psi thats when decided to go even higher. At the least before i r7n again i will flip them.

Keep calm, and carry on. The only thing flipping at such a low run count is going to do for you is take $80 out of your pocket and destroy the opposite side shoulders.

The early indications of wear is not a condition to be prevented, it is a brief period to work through.

See if you can entice Ryan into co-driving with you.

[renfield90]

Originally Posted by VVT4ME

Maybe i did run the presure up too high. Though this happenedat first after i ran 15 runs at 27psi. I driver in our region i hugely respect (Ryan Otis) suggested i bump the tires up a couple pounds....but that would be 29-30. Since i saw new graining after a couple runs at 30psi thats when decided to go even higher. At the least before i r7n again i will flip them.

Did you used to have a Celica? Feel like I've seen your screen name elsewhere.

Anyways, Tire Rack heat cycling did wonders for the graining issues I've had on the Rival S. Current gen 200tw compounds will experience graining even at their optimal temperature, a very intense heat cycle helps the rubber form better bonds. Given the climate in OR you may have trouble reaching those temps; like others have said, there's nothing really wrong here, just keep going and eventually the graining will resolve or you'll find the cords.

I do recommend flipping at 50-60 runs, just be mindful that the tire wear is going to be beveled in Street trim and you'll have a less than optimal contact patch for a bit after flipping. If you wait too long, this beveling gets too severe and (in my experience) the car will drive like crap. You could flip earlier but then you will need to flip the tire more than once to get your money's worth.

[Roadphantom]

What kind of pressure do you recommend in the rain on 225/45/17 RE71R? Is it based on feel?

[TrqlessWonder]

Generally. I typically start out dropping everything by a pound, and then maybe keep dropping the rears a pound at a time on subsequent runs, based on how many hands the prior one required me to have.

[SlowCarFast]

Going to be going to my first event with the BRZ this weekend. Saw that there were a couple of ecoboost mustangs registered. Anyone noticed how they have been running compared to the twins?

[blkwrxwag]

Originally Posted by SlowCarFast

Going to be going to my first event with the BRZ this weekend. Saw that there were a couple of ecoboost mustangs registered. Anyone noticed how they have been running compared to the twins?

Depends on the drivers. They can certainly do very well.