SCCA Solo C Street Discussion

[Biggins]

Originally Posted by DaWorstPlaya

Seems like the new 86 armed with TRD parts, with extra torque and wider TRD wheels (=wider tires) might be able to give the ND Miata a run for it's money this year. CS is getting interesting.

Agreed, but I'm still being delusional that I have a chance with a 2013.

I want to see someone in a fully prepped and well driven 124 Abarth and/or 986 Boxster s. I think those cars could pose a threat more than a 2017 86. The local Fiat dealer only had a base version in automatic a couple weeks ago, not that I'm going to make a switch.

[DaWorstPlaya]

Agreed, the later Boxster might be a challenger in CS. The specs on it look very decent.

[JermMX5]

So I was in the D Street thread and saw that people there were running pressures as low as 26 up front.

I can't run below 37 up front without rolling over and I have the crash bolts installed. Do shocks/springs gain you any camber up front? Or am I having an issue with understeering because my pressures are too high and that's causing more rollover?

I'm running the 235/45/17 Re-71r on 17x7.5s.

[Biggins]

Originally Posted by JermMX5

So I was in the D Street thread and saw that people there were running pressures as low as 26 up front.

I can't run below 37 up front without rolling over and I have the crash bolts installed. Do shocks/springs gain you any camber up front? Or am I having an issue with understeering because my pressures are too high and that's causing more rollover?

I'm running the 235/45/17 Re-71r on 17x7.5s.

There are lots of variables, so there's no easy answer. It be driving style, event temperature, alignment, etc.

I would guess your pressures are still too high at 37f. On my 225 Bridgestones, I would run ~31f, 26-29r with 17x7 rims. I ran higher (32-34) when I used 235/45 Hankooks and I run low-mid 20s on 225 Kumhos. Pressures are tire dependent as what works for Bridgestones is not the same as BFG, Nexen, Kumho, Hankook, etc. and also not the same size-to-size and would also adjust depending on temperature.

The camber bolts get you the extra camber, and the best I could do was -1.5L and -1.1R up front with the bolts. I think the best I've heard on a legal CS/DS car is -1.7 in camber up front. The springs/shocks won't get you any or much more negative camber.

[strat61caster]

Originally Posted by JermMX5

I can't run below 37 up front without rolling over and I have the crash bolts installed.

How are you measuring 'rollover' with chalk? Looking at scuff marks?

Chalk lead me to a similar place on RE71R's (totally different size and chassis, but still relevent imo) and I ran 40 psi once, I've also run as high as 38 psi on my STX car. While that leads to good chalk wear and a tire that feels impervious and composed (and a bit fun to dance on), you're sacrificing a ton of grip and they're happier down lower.

Ditch the chalk, go by feel, drop 2 psi every run, all the way down to 26 (or hell, lower) and see what feels best and fastest bump back up to wherever it was. I've made the mistake of not doing that too many times but it's the only way imo you'll find a happy spot on a tire.

[Locust]

Originally Posted by JermMX5

So I was in the D Street thread and saw that people there were running pressures as low as 26 up front.

I can't run below 37 up front without rolling over and I have the crash bolts installed. Do shocks/springs gain you any camber up front? Or am I having an issue with understeering because my pressures are too high and that's causing more rollover?

I'm running the 235/45/17 Re-71r on 17x7.5s.

37 is insanely high if you're on Bridgestones. The OEM tires are set to 35psi purely for MPG reasons and otherwise would be set lower. I can't imagine any way that a non-oem tire would ever be higher than the oem ones. Are you absolutely certain you've been rolling onto the sidewalls on your tires? Did you use the chalk method and find that it was rubbing off the sidewalls?

When I was in CS spec last year I ran 29 front and 27 rear on Bridgestones. In DS spec this year I run 31 front and 29 rear on Rivals. I got to those by measuring temperatures for dozens of runs on multiple surfaces across the inside, center, and outside of the tires. When you are trying to dial in your pressures it's important to remember that every setup is different (like Biggins said) and that any recommendation you get from people is just a starting point. You absolutely have to adjust your settings and find your own.

Originally Posted by Biggins

The camber bolts get you the extra camber, and the best I could do was -1.5L and -1.1R up front with the bolts. I think the best I've heard on a legal CS/DS car is -1.7 in camber up front. The springs/shocks won't get you any or much more negative camber.

Guess I got lucky with my current FR-S. -1.7 on both fronts but only -0.9 on both rears. Koni Yellows w/ centering washers + crash bolts.

[Shark_Bait88]

Originally Posted by Locust

Guess I got lucky with my current FR-S. -1.7 on both fronts but only -0.9 on both rears. Koni Yellows w/ centering washers + crash bolts.

I reckon I hit the jackpot with -1.9/-1.8 in the front and -1/-1.1 in the rear. Also Koni Yellows w/ centering washers + crash bolts. When I first saw the alignment sheet I was worried that I must've installed the centering washer incorrectly to have achieved that much camber. Went outside and checked it, installed properly! #stancelyfe

[dutchman1]

Has anyone ever run 225/50/16 RE71Rs on a 16x7.5?

It'd be CS legal on the 2017 cars (being that a 17x7.5 is a stock option).

For now I'm running the factory 17x7s, but I'll upgrade when I burn through these tires.

My initial thought would be that they may be a bit floppier than the 17s, but the recommended rim width is lower for the 225 16s than the 17s, which to me seems to suggest the sidewall may be a tad stiffer. The combo would be about 1 lbs lighter a corner than running 17x7.5 RPF1s with 225 tires.

The lightest 16x7.5 wheel on tire rack with 225/50/16 RE71Rs runs under $900 a set. Barely over half the cost of the 17s. Awfully tempting if the performance is a wash.

[G_Ride]

Originally Posted by dutchman1

Has anyone ever run 225/50/16 RE71Rs on a 16x7.5?

It'd be CS legal on the 2017 cars (being that a 17x7.5 is a stock option).

For now I'm running the factory 17x7s, but I'll upgrade when I burn through these tires.

My initial thought would be that they may be a bit floppier than the 17s, but the recommended rim width is lower for the 225 16s than the 17s, which to me seems to suggest the sidewall may be a tad stiffer. The combo would be about 1 lbs lighter a corner than running 17x7.5 RPF1s with 225 tires.

The lightest 16x7.5 wheel on tire rack with 225/50/16 RE71Rs runs under $900 a set. Barely over half the cost of the 17s. Awfully tempting if the performance is a wash.

If you're worried about responsiveness, it's probably a safe bet that the 225/50/16 would feel less responsive than 225/45/17. There's still more sidewall for the 16s.

[dutchman1]

Originally Posted by G_Ride

If you're worried about responsiveness, it's probably a safe bet that the 225/50/16 would feel less responsive than 225/45/17. There's still more sidewall for the 16s.

Yea I don't doubt that, it's definitely not gonna be better lol.

I'm more worried about rollover than responsiveness. If I wind up having to over-inflate the crap out of them to not be driving on the sidewall, they're not gonna work too well.

[Biggins]

Originally Posted by Locust

Guess I got lucky with my current FR-S. -1.7 on both fronts but only -0.9 on both rears. Koni Yellows w/ centering washers + crash bolts.

Originally Posted by Shark_Bait88

I reckon I hit the jackpot with -1.9/-1.8 in the front and -1/-1.1 in the rear. Also Koni Yellows w/ centering washers + crash bolts. When I first saw the alignment sheet I was worried that I must've installed the centering washer incorrectly to have achieved that much camber. Went outside and checked it, installed properly! #stancelyfe

I'm on Koni inserts from 2013 before the full body fronts were available. I guess you still get a bit more from the full body Konis even with the washers.

[JermMX5]

Originally Posted by Shark_Bait88

I reckon I hit the jackpot with -1.9/-1.8 in the front and -1/-1.1 in the rear. Also Koni Yellows w/ centering washers + crash bolts. When I first saw the alignment sheet I was worried that I must've installed the centering washer incorrectly to have achieved that much camber. Went outside and checked it, installed properly! #stancelyfe

How in the world are you guys getting this much camber?? Does the whole loosen everything with a bushing and leave it tensed up with a jack overnight, then tighten it down actually do that much??

And yes I was using chalk, but I was understeering a ton into one turn like an idiot so maybe that was the issue.

What are everyone's take on the TRD springs? I have them in my living room but I still haven't had a chance to measure and make sure I wont hit speed bumps with them on, are they worth it?

[Cueman]

Originally Posted by JermMX5

How in the world are you guys getting this much camber?? Does the whole loosen everything with a bushing and leave it tensed up with a jack overnight, then tighten it down actually do that much??

-1.8 seems a bit beyond the norm, but I think you should be able to find a degree and a half with a jack and some ratchet straps.

[Twinz]

I only got to -1.5 on my setup. I think the RE71's wear a lot faster with heat. I just did the first of two events to scuff in a brand new set for Bristol and I am going to flip them on the wheels before the second event. (Sw FL summer heat)

Don't get me wrong, they will probably be great for the next event just as they are now, but the next event for me is not Bristol, it's another local.

I'm running 31f and 28r and had to spray after each run.

I was going to sell the pair of brand new Rival 1.5's I have sitting in the garage, but I may buy another pair for the rest of the summer (they seem to like heat) and plan on a single event to scuff in a new set of RE71's before Nationals.