jsan1020

iTrader: (4)

subbed

Butt Dyno

iTrader: (10)

Wanted to add my experience here...

I'm an STU autocrosser. I just had Andrewtech do the FSM rebuild on my IX rear diff.

It is freakin' awesome. I wish I had done this in April. Other than wheels and tires, it is the thing which has most transformed the way the car drives.

Most of you probably aren't following my build thread:
https://www.evolutionm.net/forums/mo...ld-thread.html

So I'll skip you straight to the rear diff parts:
https://www.evolutionm.net/forums/9692866-post122.html
https://www.evolutionm.net/forums/9691715-post119.html

In particular, my first run today:
http://www.youtube.com/watch?v=9kuqVgRGdvI

You can see at :02, :18 and :24 how the car is squirming a little as I squeeze the throttle exiting the various corners. I can now spend a lot more time on the gas - I just have to be a little more judicious. But the power understeer is now minimal, mostly replaced by a bit of power oversteer It never did this before the rebuild. Obviously you can't change the laws of physics or the traction circle but it's a huge improvement.

I've only got 8 runs on it since the rebuild but I am really psyched at what a big difference it made. Huge thanks to the guys at Andrewtech for helping out the Dark Side

OfaceGrimmins

I bought my USDM evo 9 in april 2009. It had 58k on it, and appeared someone had at least tracked it more than a few times. (rear strut brace/stickers/no carpeting, etc....) I've now got 95k, changed the diff fluid at both 60k and 90k. I have never not had the rear end step out on me when accelerating in a corner. Suspect previous owner had the clutch plates re-organization done, but either way will find out when time to rebuild at 120k or so. (noise on deceleration/nasty metal fragments on the magnetic drain plug)

OR do the evo's naturally step out in the rear under hard accel, and would do even more so with this procedure performed?

Raptord

iTrader: (10)

On a road race track I can get the rear to step out in 1st and 2nd gears, and 3rd if it's wet. In 3rd or 4th on dry tarmac though it just starts plowing wide if I floor it. How much power do you have?

OfaceGrimmins

Guessing about 300-325 at the flywheel? Intake, exhaust, no cat... Nothing crazy. It's been quite awhile since Ive been to the track, but I seem to remember only light understeer. What chapped my *** was the inside rear tire coming off the ground and the rear diff just NOT sending any power to the outside.... Pissed me off something royal. I hate my suspension, I hate my diff. I keep hoping someone smashes into me so I can get some **** done to it. Arg. Damn economy.

<--- LOL

Raptord

iTrader: (10)

320 at the wheels (VD) on my road race map.

JDavenport

iTrader: (33)

No, I could not make the rear end play ball at all until I did the diff upgrade. And believe me I tried over 2 years and many, many track days. Rolling on throttle through a turn only produced anything from a somewhat balanced turn exit on some turns (banked in particular) to varying degrees of understeer (worst on slow flat sweepers).

I'm around 370awhp and with the Weir kit and running NS fluid, there are not many turn exits where I can roll straight to full throttle at Apex (at least not on NT01's). I can pretty much make the rear end step around at will, and by using partial throttle and some practice, you can get the car to rotate like it never would with the OEM setup. I also have the Shep Stg 3 Tcase with the Quaife up front. I can get pretty ugly with throttle in the middle of a turn and drive a nasty AWD powerslide all the way through, but you can almost feel the tires beaing eaten away......

On the lifting of the inside rear wheel. The diff upgrade will mostly eliminate that on turn exit, drive off the turn. If you are trail braking an Evo into a turn, that inside rear is still going to get very light. I have coilovers, front and rear sways, RCK, Bump steer, full poly u bushings and my friends that have followed me into a tight turn tell me I still lift the inside rear ever so slightly on entry. But as soon as I can start easing into throttle, you feel the weight transfer take effect (outside rear actually doing something) and you can feel the front unload somewhat. Our cars are just so front heavy and front biased, they like to lift that inside rear, mostly on trail braking.

Here's a pic the Forged guys took of my car at Turn 2 exit at NSS. This is about the time I will have rolled all the way to full throttle. Notice the front end lift? The rear is dug in here with the diff upgrade. Before that, this corner was an understeer nightmare.

kyoo

iTrader: (29)

Have you considered going back to stock sway bars? At least in the rear? I've heard that a lot of people who went with the rear diff mod actually switched back to stock sway bars immediately after.. There may be some benefit had in the lifting tire department by doing so?

JDavenport

iTrader: (33)

Not until I get some new coilovers with higher spring rates. Rear bar is adjustable and right now I have to run mid or high rate on it to keep body roll in check.

94AWDcoupe

iTrader: (125)

so I dont want to read 11 pages.

when you send diff in for upgrades from shep/tre all you are getting is rearranged plates??

metalsaber

iTrader: (9)

TRE/Shep offer a 1.5 way diff which is 12plates. Not the same as rearranging the factory plates.
TRE does offers a 1way which might just be rearranging of the plates. Don't quote me on that last one.

zabes

nvm

94AWDcoupe

iTrader: (125)

how do you know its not the same factory 12 plates rearranged?

kyoo

iTrader: (29)

because the factory diff comes with 8 plates

if you're interested you should really just give them a call. i have some info in the thread in my sig too

metalsaber

iTrader: (9)

Because the stock one doesn't have 12 plates.

Darn. Beat by mere seconds. haha