Jim3142

iTrader: (2)

Previous threads -

2019: https://www.evolutionm.net/forums/mo...iscussion.html
2018: https://www.evolutionm.net/forums/mo...iscussion.html
2017: https://www.evolutionm.net/forums/mo...iscussion.html
2016: https://www.evolutionm.net/forums/mo...iscussion.html
2015: https://www.evolutionm.net/forums/mo...iscussion.html
2014: https://www.evolutionm.net/forums/mo...iscussion.html
2013: https://www.evolutionm.net/forums/mo...iscussion.html
2012: https://www.evolutionm.net/forums/mo...iscussion.html
2011: https://www.evolutionm.net/forums/mo...iscussion.html
2010: https://www.evolutionm.net/forums/mo...iscussion.html
2009: https://www.evolutionm.net/forums/mo...iscussion.html
2008: https://www.evolutionm.net/forums/mo...iscussion.html
Pre-2008: https://www.evolutionm.net/forums/mo...ep-thread.html

Anybody joining the class this year? I hear of some people building E9X M3s for the class, should be a fun year

LV///R

iTrader: (36)

I'm still 100% set on joining STU this year! So at least there will be another evo out there at Nationals.

I currently have the vast majority of parts I need, it's now just waiting on getting a few odds and ends. Then I'll start piecing this thing back together!

Current list of things to install:

Exhaust - manifold, 02 housing, DP, high flow cat, Tomei catback
Intake
OEM upper and lower intake piping
OEM boost solenoid
Superpro offset bushings for front LCAs
Lithium battery
JRZ motorsport triples - mounting the reservoirs hopefully won't be too much of a pain since they extend off the lower struts up front
rear anti-sway bar
All new fluids - Brake, coolant, power steering, trans, rear diff, TC
Girodisc rotors
Roll the rear fenders
align it
Get some 265/35/18's in the A052 and RE71R variants to do some testing hopefully!
Get it tuned for pump gas
Throwing in the NRG seats and putting ballast on them to get them to min weight requirement


Question:
1) Re-stack the rear diff - I'm ASSUMING this is OK for STU?

Construct

iTrader: (4)

Looks like a solid list. Depending on your rear wheel offset and rear camber, you might not need to roll the rear fenders much at all.

Re-stacking the rear diff is okay, yes. The service manual shows the plates alternating every other, so you're technically rebuilding it according to spec.

You can also experiment with different differential fluid. I bought the rear diff fluid without any included friction modifier and then added my own smaller amount of friction modifier.

Butt Dyno

iTrader: (10)

You have the 18x10 +35 Weds, right? will definitely be curious to see if / how much spacer is required.

LV///R

iTrader: (36)

Thanks! I know I might be missing some things here and there, but it's only due to my crappy memory!

What rear diff fluid did you go with out of curiosity?



That's me! Well, I can safely say spacers aren't needed for these assuming your front coilover has the correct spring length and has the independent height with separate preload adjustment. So they were fine with my Reinharte's I had previously. The JRZ's will need a spacer up front to allow them to clear, I'm quite certain! I'll find out for sure here sometime in February. I'm guessing a 5-10mm spacer up front. Maybe less since I was running 285mm tires prevoiusly, now 265mm. Rears should be free and clear.

Jim3142

iTrader: (2)

Glad to see you'll be joining the class!

On a side note, I'm assuming most people have seen this by now: https://www.scca.com/articles/201339...asses-for-2020

Pros just got tougher for us, but at least DS and STH got hit hard with their 2020 PSI values. On the downside, SM got noticeably softer compared to STU and SS (NSX is AWD) got a little softer comparably, as well.

Construct

iTrader: (4)

Major changes proposed to STU in the latest Fastrack: https://www.scca.com/downloads/49412...ition/download

Proposal would increase tire limit to 315 for all cars, actual open boost, clutch allowance, single differential allowance, and adds a few cars.

Would be a significant change to the class. Any thoughts on how the Evo would compete with 285s, open boost, and a single upgraded diff? Seems like some of the proposed additions to the class would be tough to compete with.

Dallas J

iTrader: (1)

It is very ASP like at that point minus E85. But 285s would also require fender mods and don't recall seeing that being open, did I miss it?

And Evo with a wavetrac front (reliability mod to get rid of stock torsen), Cusco or TRE rear, a real clutch, and a bit more power... That could be a pretty potent car. But its hard to say if the incoming cars wouldn't just walk away. Didn't re-read it but wasn't there something about C5z's?

Dallas J

iTrader: (1)

Downside, I can see this costing 5-10k over current fully built STU cars.

Construct

iTrader: (4)

Street tires and pump gas are still reasonable limitations over ASP.

I thought I read speculation that 285s could be stuffed under stock fenders with rolled lips if you could make the stars align just right. You're probably right that it's not reasonable to fit under stock fenders without either pinching them on small wheels or additional allowances for rear trailing arm clearance.

The proposal only allows a single diff change, so you couldn't do wavetrac + clutch rear. Just the clutch rear.

I'm also wondering about those incoming cars. I'm not familiar with how much tire those newer cars can fit, though.

How? The only expensive bits would be a new rear diff and maybe a new intercooler. Or are you budgeting for motor rebuilds due to all the extra boost?

Dallas J

iTrader: (1)

I would characterize a wavetrac front diff as just a maintenance item. Its purely to get rid of the fragile OEM diff once you have more clutch. Which I havent kept up with the wording of what you can improve in the drivetrain for reliability being all in SM, but seems it should be fine. Any marketing jargon on the wavetrac is just that. Its a good torsen but doesnt really function different or better than OEM.

You can certainly stick with OEM, but Id replace it every 2ish years if doing a lot of pro's with a more aggressive clutch.

As for cost. Im assuming new wheels (1-3k), New Tires (1k). Rear diff (1-1.5k, more if you refresh at the same time), Front diff (1k), New clutch (1-2k), FMIC and piping(500-1000),

So going with the low end and OEM torsen thats around 4500.

For tires, you'll want to be on 265 A052s and 18x10.5 wheels. 285 A052s arent going to fit under stock fenders and the 265s may be tough also. Dont necessarily think about the number on the tires tho, its a dang big tire. The 295 is definitely 305 in size on my pinched 10.5" wheels .

LV///R

iTrader: (36)

So, someone please clarify Fasttrack for me? If this is going to happen, when would these changes take effect?

Im glad I just sold my rear TRE/Cusco differential....-_-

Construct

iTrader: (4)

Currently just a proposal. Open for feedback. If you have any thoughts on it, now is your time to write a letter. They really do read and consider the letters.

I understand the argument, but I don't see this holding up under protest. Wavetrac doesn't market their diff as an OEM equivalent, they market it as a performance upgrade over the OEM diff. Regardless of how true that is, we can't swap it for the same reason we couldn't swap clutches.

Front diff strength shouldn't matter for normal, non-Pro Solo autocross though.

I see where we differ. We're already running 265 tires and 10" wide wheels in STU, so I didn't include those in my estimate. Also, I didn't count the front diff swap because it's a no-go. And I'm not in a rush to replace my clutch until the day it starts slipping, which is something I budget for. Being able to upgrade the clutch should save money over time.

I'm not convinced 10.5" wheels are going to fit under the fenders within the STU rules. It could work if we could get the rules expanded to allow some fender pulling and/or trailing arm replacements, but I don't know if I see that happening.

LV///R

iTrader: (36)

Is it safe to say this won't have any impact on the 2020 rules/season? Thanks!

Construct

iTrader: (4)

Correct. Major changes like this are for the following year. They wouldn't change the rules like this mid-season.