TRev's BRZ RTR Autocross Build

[TRev]

Originally Posted by autoXracer

That's strange... I checked again, my Koni's are front 1 7/8 adjustments, and rear 2 1/4 adjustment.

My setup:
Koni shocks
Strano front sway bar
225 Z1's (yes still have the old tires lol.. next are 225 Z2's)
OEM camber bolts
0 toe front, .24 total toe-in rear

I understand that depending on setup, course condition, and driver, the shock rebound should be adjusted. I'll take your advice and start off with full soft rebound and adjust from there.

Looks like the Ginko Biloba I picked up at the Farmer's market isn't working quite yet! I have 1 7/8 up front and 2 1/4 rear as well. I saw it in my suspension notes and verified last night. Sorry for misinformation. Please let me know how it goes and what type of front/rear balance you find works best for your driving style/setup.

[autoXracer]

Haha no problem! I thought I had a different version of shocks or something.

[TRev]

I ran the Dunlop Z2's for the first time on Enkei RPF1's. This was Lance's old setup but he swapped the tires on the rim for me as part of the purchase (thank you for the very good deal Lance!). I was frustrated in the beginning as I was a ways off of Jeff's time in his MSR. Lance warned me that it would take some scrubbing in to get the tire to level out (center rib was worn to make it off camber when flipped). On my last run, I got within .165 of Jeff.

We had some extra runs at the end of the event and I dropped .3 seconds (60.5) under Jeff's best time of 60.8. I ran two 60.5's back to back on my second and third runs which were basically hot laps after the first. The fourth and fifth were a 60.8 and a 60.7. That last run was with a passenger. The Z2 definitely seemed to handle heat better than my Z1's did. That is the best I have done against Jeff in his MSR other than at Lincoln on the first day when I was about .3 seconds ahead raw time on the Rivals.

The car behaves much differently on the Z2's. Turn in is quicker and I am seeing about .1 G more lateral grip. Longitudinal grip is definitely less and the rear has some decent over steer now even with about 1/2 more rebound up front. It had some throttle over steer on corner exit which is not there with the Rivals. Tomorrow I am going to try the Z2's up front and the Rivals in the rear. I think that could be a good combo with my current setup.

Here is a vid of one of my 60.5 runs. The last corner is completely off camber and pretty much all the cars were pushing at the beginning of corner exit.
[ame]http://youtu.be/_HYpO_7YDO8[/ame]

[Kido1986]

When you take the .1G increase, are you doing that on the same location on similar days?

Kinda surprised to see the Z2s appearing quicker.

[TRev]

Originally Posted by Kido1986

When you take the .1G increase, are you doing that on the same location on similar days?

Kinda surprised to see the Z2s appearing quicker.

The Z2's definitely have more feel to them, turn in faster, and over steer more where as the Rivals feel more numb and I can not get them to throttle over steer on corner exit (longitudinal grip seems better). Much of my comparison is based on a very similar surface at a different event last weekend with similar temps, end links unchanged and the rebound similar though more rebound in the front at Milwaukee to try to correct some of the excessive over steer. I do have a significant amount of data at Milwaukee with the Rivals but their have been setup changes between much of that day (end links, rebound, alignment, tire pressure, etc).

I still plan to run the Rival at the Milwaukee Match tour for contingency on the first day. If I don't win contingency, on day two, I will either run the Z2's solely or possibly the front/rear combo I am trying tomorrow.

One other thought is that the Rivals are possibly starting to fall off. I am just about at the wear bars in front and between 3-4 32nds in the rear. They have 100'ish runs on them and a few thousand street miles.

[TRev]

Started off the day with the Rivals in the back and the Z2's up front. It was a cooler day today (similar to yesterday). Ambient temps of 65 degrees and wind was 15-20mph off the lake with 20-25mph gusts. The car was really loose in the rear until I got heat in the tires. Ran a 61.8 and a 61.6 on my first runs and then ran a 60.5 on the last run. I blew wide on the finish and coned. Definitely cost me 2-3 tenths.

I switched back to Z2's front/rear and ran a 60.4 on my very first run. The rear was a bit loose but nothing like the Rival without heat. Made a couple mistakes on the second run and ran a 60.6. I was behind by .07 in class and then put in what felt like a really good run and came in with a 60.0 to take the class win by .243.

The Milwaukee surface and temperatures seem to favor the Dunlop. The only two events I have won in Milwaukee this year were on Dunlops. The first event on the Z1's we ran at Nationals on John's car last year and now the Z2's. BIG class today with 52 competitors.

[Kido1986]

Do you mean 52 in class?! Or just total?

I didn't think about the fact that you have these moderate temperatures. The Z2s are known to be really good is cooler temps.

I'm in Florida, we don't get 65F midday air temps often in January, much less June/July. It was near 100 today before the clouds and rain came. Hankook's awesome hot grip level is helpful here.

Guys here are liberally spraying Z2s after only two runs because heat + concrete

[TRev]

Haha, 52 in class. 161 in total. Lots of great drivers as it was our Tri-State (TriPod) challenge this weekend. Wisconsin vs Illinois/Minnesota.

Yesterday and today the highs were about 68 degrees. Strong winds though off the lake so any heat generated quickly dissipated. I used tire warmers even with the Z2 as hot lapping them yesterday afternoon for five laps did not see times falling off.

I did 20'ish hot laps at Lincoln on the Evo Advantage course and the Rivals never fell off. They seemed to actually peak on the fifth run and stay there (mid 30 second course).

[Kido1986]

I am more jealous of your weather than you can ever comprehend. Since Im looking for a new job, if I wasn't stuck in a new lease, I'd be looking for a new job further north. This Florida summer is awful. If it wasn't for autocross, I would never step foot outside in this crap hahah

52 driver class... jesus. Largest I've ever run is 9. Me, MR2, Mustang and 6 NB Miatas.

[TRev]

Originally Posted by Kido1986

I am more jealous of your weather than you can ever comprehend. Since Im looking for a new job, if I wasn't stuck in a new lease, I'd be looking for a new job further north. This Florida summer is awful. If it wasn't for autocross, I would never step foot outside in this crap hahah

On the flip side, we have about 6 months of winter and no autox'ing during that time...stuck indoors much of it. I will eventually be moving somewhat further South.

[jprice130]

Your Rival/ZII staggered experiment definitely intrigued me even though it didn't appear to be as successful as staying with Rivals or ZIIs all around. I'm actually considering running 225/45 Rivals up front and 235/40 ZIIs in the rear and wondered what your thoughts on that would be?

I have the wussy automatic transmission (No ProSolos for me!), so running a smaller diameter 235/40 (24.4" diameter) tire in the rear versus a 225/45 (25" diameter) tire seems like it would help offset the longer gearing of the automatic. As you may know, the ZIIs are the only tire you can get in 235/40 that's worth running in RTR.

So why not run 235/40 ZIIs all-around? Well it's just a matter of cost....A friend of mine has two 225/45 Rivals that he's going to sell to me cheap and he only used them for one event. It's hard to pass up that deal, so I need to pickup another pair of tires to run in the rear and I'm on the fence between another pair of 225/45 Rivals or giving the 235/40 ZIIs a try. Any thoughts you have on that would be much appreciated!

[TRev]

Originally Posted by jprice130

Your Rival/ZII staggered experiment definitely intrigued me even though it didn't appear to be as successful as staying with Rivals or ZIIs all around. I'm actually considering running 225/45 Rivals up front and 235/40 ZIIs in the rear and wondered what your thoughts on that would be?

I have the wussy automatic transmission (No ProSolos for me!), so running a smaller diameter 235/40 (24.4" diameter) tire in the rear versus a 225/45 (25" diameter) tire seems like it would help offset the longer gearing of the automatic. As you may know, the ZIIs are the only tire you can get in 235/40 that's worth running in RTR.

So why not run 235/40 ZIIs all-around? Well it's just a matter of cost....A friend of mine has two 225/45 Rivals that he's going to sell to me cheap and he only used them for one event. It's hard to pass up that deal, so I need to pickup another pair of tires to run in the rear and I'm on the fence between another pair of 225/45 Rivals or giving the 235/40 ZIIs a try. Any thoughts you have on that would be much appreciated!

I definitely feel like the setup was as good or a bit better than running the Rivals all the way around in the temps we had though definitely not as good as running Z2's on all four corners.

Living in NC, the heat should not be as much of an issue. Having the Rival on the front should allow you to more easily get the heat in the tire that I think it needs to be effective.

Since gearing is your primary concern, sounds like the setup could work to your benefit.

[jprice130]

Originally Posted by TRev

I definitely feel like the setup was as good or a bit better than running the Rivals all the way around in the temps we had though definitely not as good as running Z2's on all four corners.

Living in NC, the heat should not be as much of an issue. Having the Rival on the front should allow you to more easily get the heat in the tire that I think it needs to be effective.

Since gearing is your primary concern, sounds like the setup could work to your benefit.

Thanks TRev! I think I'm going to give the setup a shot. Our local club is going to start a weeknight series over 5 different dates this summer. They'll be putting out the same course for each event, so it will be a good opportunity to experiment with different setups and see how they pan out.

[des]

TRev, curious about your thoughts on our situation in SF Bay region. Until now, our main venues have been very close to the water, so it's usually cool and often windy. We just got a test date at a concrete site on the other side of the mountains that is huge (we expect 90-second courses, minimum) but often hits 100 degrees. It may be used quite a bit as a shared site for several local clubs if we don't screw up the opportunity.

I'm a big ZII fan, but if the site pans out I'll buy another set of wheels and tires for use there. I haven't really loved the Rivals I've tried and wonder if RS3s would be the wiser choice.

Happy to hear suggestions from the hot-weather folks. Anybody successfully keeping ZIIs cool in this kind of heat?

Thanks/Des