Thanks Doug! I appreciate it!

I did write a letter voicing concerns about that chassis and why it's simply not in STR. I know a couple others have voiced their concerns as well. To anyone reading this, if you have any concerns, take the time to make them known here. I know I had to attach a Word document, rather than typing it all out in the box they provide for whatever reason: https://www.soloeventsboard.com/

So seemingly I haven't had the chance to launch much with this set up this year. This is ONLY when I'm launching off my launch limiter!!! From what I remember, I haven't had the issues I've had until recently. Frankly I've owned 3 evos over the course of many years and have never experienced it! It's nasty enough that I'm having to let off and then get back on the gas again, else I have the feeling drivetrain parts may suffer some consequences. I did start checking to see if anything was loose, drivetrain related. However I haven't had time to check everything over just yet.

I'm still on the stock engine/trans mount bushings. The car has about 105,000 miles now and was thinking about going with the Torque Solution bushing inserts, as the billet aluminum mounts they offer weigh less than stock (Another dumb SCCA rule but I digress).

I'm launching at an RPM enough that it doesn't completely bog, but it doesn't spin the tires either. Maybe I should try slightly higher to get some tire spin?

In regards to my settings, I have cranked up the rear rebound to help settle that end down and it has worked in my case. Keeps that corner/end planted once it moves from compression into rebound. Even prior to cranking it almost to full stiff, I did get wheel hop there. I'm running max low speed compression and middle of the road high speed compression (which I'm quite uncertain if I'm close to where I need to be with high speed or not yet...Still some trial and error to go.)

Yep, Mark has the 18x11 and 18x10 combo as well. Unsure if he's running a 265 or 255. I believe we're the only two doing this so far, although a STI driver at nationals did come up to me and ask me about my setup. He is also running a 295/255 combo on a slightly narrower wheel I believe - however that car wasn't there as he was running in some other class those days. I know Carpenter mentioned he'd like to try that, but unsure if he will.


Which brings me to my next question: Since the diameter difference of the 295/265 is like 3 tenths of an inch (25.1" vs 25.4" respectively), what is the factory allowance in regards to tire diameter differences front to rear? I've searched and searched, but couldn't find anything. The 265 is a half inch wider than the 255. I don't think it'd hurt to have a tad more rear grip, but I'm unsure if that center diff would be loving life with that much of a difference in tire diameter? This car wouldn't be driven on the street with said setup. When I've been driving it this year to Lincoln and back, I run on my square rain tire setup.

 

I mean this is true.

 

In my experience, more rear rebound doesn’t settle the chassis it pulls up the wheels and creates hop. At least on my flags hop on corner exit is the threahold of where I tune rebound to. Launching my situation is different with the rear uprights and added anti squat.

 

So to clarify as I probably didn't word it the way my brain was intending:

I'm only dealing with wheel hop on launch now. I haven't experienced any of the bouncing/hopping/pogo stick feeling on sweeper type turn exits, ever since I went down in rear rate and also lowered the hell out of the rear of the car. It's super low partly because of a 200lb drop in rate. Unsure if the change from an 8" to 7" spring has any impact on that.

I'm wondering if I'm now TOO low and because I'm sitting so low I don't have much compression travel? My thought process was to keep it low to try and tame the rear down.

Here's a pic for reference!
Evo IX RS

 

WIth your rate change based on tire difference front/rear I wouldnt expect you to have exit hop issues cause you probably arent lifting a tire nearly as long as square setups. But launching should be same thing, its definitely worth trying dumping a large amount of rebound to see if that helps. After that raising the rear will get you back anti-squat which should help.

 

Worth a shot. Rarely do I get to launch so it's a minor concern for now. I appreciate the insight!

 

Can the factory clutch handle feather dumping? Obviously you don't need to do it at local events but at Nats I would think that would warrant it.

 

ST rules now warrant replacing the factory clutch (Pressure plate/disk).

 

yeah, but then you'll blow up the diff :-(
increase your stationary rev limiter, we have to change ours all the time based on the available traction, and with those big front meats I could see that being an issue.

and yes, it is possible to feather the clutch out slightly when launching (I've done that in desperate situations, up against Heitkotter for example, lol) but if you slip it too much it'll obviously overheat and then your next launch is screwed. (edit) I haven't launched the car in anger with the new STU 2.0 setup though, so it's conceivable that the stock clutch can't handle that at all anymore....

 

No way!?! Tell us more!

I don't have a definitive answer for this but I doubt it's a good idea, maybe others can chime in?

 

Maybe I've been completely lucky with my ownership, but I've probably launched at least 500 times +/- over the course of the years. That's split between 3 different evo's I've owned. I've NEVER had any trans/TC issue ever. I'm knocking so hard on my wooden desk right now!

I started autocrossing I believe back in 2008. Had a 2003 Evo 8, bought it when it was a couple years old with fairly low miles. Owned it until it crossed 100k miles. We run NASA rules locally, so I just modded it to mod it, not to mod it for a class like SCCA. 400whp/400wtq with most bolt ons/e85, etc. Car was a blast. Sold that for a MKIV supra. Missed the evo, so I bought another one ('05 SSL) while owning the Supra. A very MILD ASP build and took that car to my first Nationals in 2018. The year of the flood! What a way to start, hahaha! Placed 5th for my first time there, granted it was a small class.

Sold that '05 evo because I wanted to go back to something more simple and that I could still street drive if wanted. Looked for almost 2 years for an IX RS after traveling to view a handful that were "clean" and ended up being far from it. Finally found this current IX RS all the way in AZ. Wasn't as clean as I wanted it to be when I first bought it, but I'm happy I did. Lots of paint correction, ding pulling and the car looks better than most 40K IX RS's I viewed. This current one has 105,000 miles on it.

Pictures of all 3 evos over the course of time:

 

So the more I've been thinking, the more I'm wondering if I should go with the same 1.0way 141FG diff that I previously had in my old ASP setup.

Again, this current car is an RS / no ABS. Thoughts on if I should go with the 1.0 or 1.5 way rear diff?

I'm thinking about keeping the current staggered setup, but at some point may want to try the 285 square (maybe on an an 11" F 10" R wheel setup).

Thanks for any input!
Brent

 

With your stagger setup, I would stick with the standard rear diff. I dont have the right catalog page here for the part numbers and preload but with the 141FG you really must be picking up the tire through a corner or it wont want to turn. And the magic about it is that with the tire in the air it can still transfer torque.

So if you have all 4 down with your stagger you only need a little preload in comparison.

 

So I would like to clarify. I know there are times I'm lifting a rear inner tire. Nothing near what I see other evos do, however.

Would you suggest a 1.0 way front instead for the staggered setup?

http://www.cuscousainc.com/downloads..._lsd_guide.pdf

https://cuscousainc.com/search/vehic...year=2005-2007

Thanks!

 

In STU you can still only do 1 diff right? I would stick with front torsen because even a TRE rear diff would still be more useful. The Cusco has the benefit of coil springs (low rate, high compression) compared to the cone spring (high rate low travel) of the OEM diff and the upgrade variants. The effect here is the preload doesn't reduce with diff plate wear.

I would still stick with a 1way in the rear but don't recall if that's an option outside of the 141FG.