Rear Diff Options - Power Oversteer Found Here
Wish I can say the same when I had the 12 plates in them. Used no friction modifiers. About 1/4 turn of the wheel, rear locks up right away on throttle. Rest of the car is loud anyways so I didn't mind it.
Thats good news about the noise factor! What are everyones thoughts on the 26mm RSB? Leave it on or go back to stock and relearn how to drive the car with the restack mod. I have Hankook V12 and RS3 tires if that makes a difference.
restacked plates wont change the car behavior that much - and the majority of the change will be on corner exit
Take my commentary with a grain of salt because it's not from an Evo platform, but I swapped in an Evo 8 rear diff with the 12-plate weir package into my 99 Eclipse GSX time trial car. Prior my car didn't really produce oversteer on throttle in most cases (of course with weight shifting I could get it to happen). With this setup holy crap my car scared the **** out of me. I'm not sure yet if it was my lack of driving ability or what but the car became very scary to drive. Felt like I was threading the needle. The speeds though are 120+ turns where I noticed it (lower speeds i'm not sure i noticed much difference, but I just might not have adjusted my driving to get the new diff to kick in), where prior I could get on the throttle a decent amount at apex but now the rear felt like it was on glass when I went into the throttle. I don't know though if this netted a faster lap time as I had changed so much simultaneously with the rear diff (though I did net about 3.5 seconds faster a lap this trip than last), but it did make the car a bit hairy to drive. I added more rear wing which seemed to help but wasn't satisfied at the end of that day, and next time out I'll try even more rear wing.
I wonder if perhaps the locking is too much for my current configuration, and this thought comes from reading about tuning rear differential locking torque on various websites. I'm still running street tires (Nitto NT05), albeit 285 wide ones, but only maybe had 350 wheel torque during that outing. I'm going to give it a few more track sessions before i decide what to do, though I'm considering inverting a few of the plates (similar to how the US evo rear diff comes stock) to remove some of the locking torque. I'm also tossing around going to 315 tires with r-compounds and if I do may delay any differential changes as that may make this setup work better.
Does anyone else have high speed track experience with the weir upgrade?
I wonder if perhaps the locking is too much for my current configuration, and this thought comes from reading about tuning rear differential locking torque on various websites. I'm still running street tires (Nitto NT05), albeit 285 wide ones, but only maybe had 350 wheel torque during that outing. I'm going to give it a few more track sessions before i decide what to do, though I'm considering inverting a few of the plates (similar to how the US evo rear diff comes stock) to remove some of the locking torque. I'm also tossing around going to 315 tires with r-compounds and if I do may delay any differential changes as that may make this setup work better.
Does anyone else have high speed track experience with the weir upgrade?
Updated the OP a little. Let me know if there's anything else I should throw in there. If anyone's got a direct link to a review post they want me to put, I can do that. Can't believe it's been 3 years since the OP - hopefully every evo in the US has this mod by now 
Amazingly, not everyone. Out of all the Evos in my area, not one of them heard of this. I'm the only one that took my diff out and did something to it. Good thing most of them are on the FB page for Evo Owners. A couple are interested in getting this done when spring actually comes around.
I have the weir 12 plate in my rear diff. My case was to tight with the stock spring plates. I contacted weir and he sent me out two thinner spring plates and now it is flawless. Rear diff locks up amazingly with limited added noise. I'm running redline 80w140 in the diff. Definitely a great product and not hard to install at all. I did it with a buddy in about two hours. Definitely recommend it to the average do-it-yourself evo owner. It's a way cheaper alternative and it completely changes the car. Great product and excellent customer service!!
If you recall I made comments on how I felt there was way too much power oversteer from what I believed to be excessive lockup torque in my time trial widebody DSM. My setup then was:
1) 285-wide Nitto NT05 street tires
2) OEM spring plates
3) Redline Heavyweight Shockproof fluid
I made some changes to the setup:
1) Adding Redline Friction Modifier, I think it was about 1/4 of a bottle? to my Redline Heavyweight Shockproof fluid
2) Switched to Nitto NT01 315-wide r-compounds tires.
How did this change things? Sweet merciful crap the rear diff is AWESOME!
1) Lower and mid speed turns I can easily throttle control my oversteer which is fantastic. I'm still able to get heavily into the throttle and power around turns in a very fast yet controllable fashion. A massive improvement.
2) Just GRIPS at high speeds. Oddly, I swear I have more grip at full WOT in high speed turns than I do at part throttle. In high speed turns with part throttle the car feels like it wants to slightly slide out the rear, but when I go WOT the rear tucks and holds the line.
Now I'm VERY happy with this diff change!
1) 285-wide Nitto NT05 street tires
2) OEM spring plates
3) Redline Heavyweight Shockproof fluid
I made some changes to the setup:
1) Adding Redline Friction Modifier, I think it was about 1/4 of a bottle? to my Redline Heavyweight Shockproof fluid
2) Switched to Nitto NT01 315-wide r-compounds tires.
How did this change things? Sweet merciful crap the rear diff is AWESOME!
1) Lower and mid speed turns I can easily throttle control my oversteer which is fantastic. I'm still able to get heavily into the throttle and power around turns in a very fast yet controllable fashion. A massive improvement.
2) Just GRIPS at high speeds. Oddly, I swear I have more grip at full WOT in high speed turns than I do at part throttle. In high speed turns with part throttle the car feels like it wants to slightly slide out the rear, but when I go WOT the rear tucks and holds the line.
Now I'm VERY happy with this diff change!
i had the restack then decided to bump up to the TRE max lock with added goodies! only have one race so far but the car feels amazing. i'll be doing a more detailed write up covering the differences after my next couple races.
but short story - going from stacked to TRE is like going from stock to stacked; it makes that much more difference!
but short story - going from stacked to TRE is like going from stock to stacked; it makes that much more difference!
I restacked and found the car to be a little better on throttle at exit, but by no means the crazy RWD beast others report. It'll still push everywhere if you drive it wrong. We were at Thunderhill last weekend which is full of elevation change and off camber descending corners and not once did the car want to chase it's tail.
Somewhere down the line I'll look at going with the Weir 12-plate. Restacked with Diaqueen there's no noise nor harshness.
Suspension is GTWorx/HDs, WL FSB, RSB (soft), RCK, offset PSRS, rack bush, ES trailing arm bushings. RPF1 17x9.5+18 F, 17x9.5+38 R, 255/40 RS3's.
We've also got the RS front helical LSD.
Somewhere down the line I'll look at going with the Weir 12-plate. Restacked with Diaqueen there's no noise nor harshness.
Suspension is GTWorx/HDs, WL FSB, RSB (soft), RCK, offset PSRS, rack bush, ES trailing arm bushings. RPF1 17x9.5+18 F, 17x9.5+38 R, 255/40 RS3's.
We've also got the RS front helical LSD.
I restacked and found the car to be a little better on throttle at exit, but by no means the crazy RWD beast others report. It'll still push everywhere if you drive it wrong. We were at Thunderhill last weekend which is full of elevation change and off camber descending corners and not once did the car want to chase it's tail.
Somewhere down the line I'll look at going with the Weir 12-plate. Restacked with Diaqueen there's no noise nor harshness.
Suspension is GTWorx/HDs, WL FSB, RSB (soft), RCK, offset PSRS, rack bush, ES trailing arm bushings. RPF1 17x9.5+18 F, 17x9.5+38 R, 255/40 RS3's.
We've also got the RS front helical LSD.
Somewhere down the line I'll look at going with the Weir 12-plate. Restacked with Diaqueen there's no noise nor harshness.
Suspension is GTWorx/HDs, WL FSB, RSB (soft), RCK, offset PSRS, rack bush, ES trailing arm bushings. RPF1 17x9.5+18 F, 17x9.5+38 R, 255/40 RS3's.
We've also got the RS front helical LSD.
Upgrading the rear diff has much improved reducing understeer coming out of a turn, allowing me to get on the throttle sooner. This is both for autox and higher speed courses like at road courses. I don't feel that the upgraded rear diff or my acd reflash improved to reduce turn in understeer as much as exit turn.
My main suspension mods are oem kybs w/ Robispec springs, 255/35/18 star specs, tre max lock 1.5 rear diff with redline NS fluid for track days, GruppeS acd race flash.
At Thunder hill I did find myself starting to get too much oversteer coming out out the fast sweepers, running the ccw configuration, mainly at turn 2 and that fast transition at turn 8. I would not get enough front bias coming into turn 8 to keep me tracked where I wanted to go because the rear end would want to step out. Rear were doing more of the work on fast sweepers and I would have to let off a bit to get the car tracked where I wanted it.
I later installed a Tanabe FSB and went back to Thunderhill. That same turn I was able to take turns 7 and 8 at full throttle, and going into turn 11 I was able to take it in 3rd gear without letting off. Before the fsb I would understeer where I would have to scrub off a bit of speed to get through turn 11 and 12 smoothly.
That's my experience anyhow, ymmv.
thought i would post this for future people looking to purchase the Weir plates.
the price went up its ~ $218 shipped.
the kit is a 14 piece kit now. they are shipping it with their spring plates since not all diffs have the same tolerances from what Spence told me. the thinner spring plates help with ease of install, similarly to a few post above.
just ordered mine, cant wait!
the price went up its ~ $218 shipped.
the kit is a 14 piece kit now. they are shipping it with their spring plates since not all diffs have the same tolerances from what Spence told me. the thinner spring plates help with ease of install, similarly to a few post above.
just ordered mine, cant wait!
