to be more detailed:
- i got the cusco type rs 1.5 way, sent that and the pumpkin for TRE to dial in off the bat, which i ran for about 10 years
- after i moved toward track, i wanted to try something that was not as aggressive as the cusco, particularly off throttle.
- i went to OSG, with the specific instruction that I wanted the diff to be more aggressive than their OTS stuff. they're pretty secretive about the springs and other preload stuff they do, so they said ok and sent it to me
- got one wheel spin for the first time in a very long time on this diff. i was like ok, this thing sucks.
- sent the diff to TRE so he could fix it, and the diff feels better now. setting solid times and its less aggressive than the cusco still.

 

Yeah, have had some time on the streets and back roads plus two autox events before covid-19 did its number. I will first say, these are some seriously agro diffs. When they grab, they grab hard. Maybe they'll soften up after more events but for now with about 600-700miles and 2 auto-x events they are still quite chatty and want to lock up when asked. They much more prefer to be at full lateral load than driving around a parking lot.

But for how the perform where I care.. Its pretty epic so far but I havent gotten to really get to play at speed. The events I ran were on a small lot where I am pulling out of digs a lot. But the diffs really showed here that they are putting the power down and letting me get to heavy or full throttle waaaaaaayyyyy early compared to the broken and worn out diffs. I also was playing with new and custom ACD tunes but I think those really showed to be a support role and not a hindrance as I feel the should be at this point. Its truly to the point now I wish Marshal and I could have driven this car at Solo Nats to see what we could have dont to overall pax. Yeah, I think its that good.

Its really hard to explain what was wrong to people who didn't get to drive the car at the overly rubbered nats concrete, but Marshal and I both struggled thru a car that just would not accept power but now its a totally different thing.

Results:
Saturday was dampish, tires never even got past the "just pulled out of the garage" temp. Totally cold all runs.
https://scorekeeper.wwscc.org/result...5/tt?counted=1

Sundays course we ran last so had the best conditions and I was able to get some heat into the A052s single driving in 45 deg sunny weather.
https://scorekeeper.wwscc.org/result...5/tt?counted=1

Now this is SM level of crazyness. So the question is what would I recommend for an all out 110% STU build? I would get this rear diff and OEM (equivalent) front diff. The rear gymkhana diff is stupid aggressive but set it up to lift an inside rear off throttle and then let that 90ft-lbs of preload help to get weight transfer started till both wheels are down, and magic will happen.

I do love the TRE diff for a streetable application. But Im sold on tight turns need to unload a tire which then means a tight diff is needed to put power down. And the mitsubishi diff TRE modifies has a fundamental limitation in the way it applies preload in that the cone springs are high rate low travel. So as the diff wears the preload goes away really fast. The Cusco diff with coil springs is a lower rate but high travel so same load but the force falls off much less severly over time.

75% Build or just getting ramped: up absolutely get the TRE diff and let Jon hook you up with a best of both worlds setup there.
Trailer queen or trying to win Nats: Cusco gymkhana 1way rear with high preload

 

This, but for an Evo?

https://www.vividracing.com/cusco-ty...151647585.html

 

the cusco is basically locked as soon as u get on the gas. whether you want that or not depends on setup, grip, power, etc.

 

Extra frustrating when the car had so much power to give yet couldn't take any. If there are ever any autox events again I would be very interested in trying out the new and improved version.

 

Correct. The part number for the Evo 8/9 is 141 FG.

I can't compare to the TRE 12 plate, but I loved the 141FG for the short time I had it. Looks like I'll have to buy another one all over again if these rule changes take place for 2021.

 

If I was building an 8/9 for STU under the new rules, I'd re-arrange the rear diff plates to the correct order (free mod) and get an upgraded front diff.

 

Lots of talks about 8/9 diffs, but I have to think about AYC rear end. So, few questions here about that part:

• How is it reliability wise X diff compares to 8/9 ones?
• Back to the proposal there are two things that are interesting to me:

1. Tuning for automatic/dual-clutch transmissions and electronic differentials
2. AWD vehicles may substitute one differential regardless of how many it came with from the factory

Am I off on this?

 

Interesting theory. Care to go in depth further as to why you'd go that route?

I've never had the opportunity to experience an evo with an upgraded front differential. To those that have, would you agree with BigT? Does the front differential have a much more pronounced impact than the rear? I'm also unfamiliar with how much of a difference the re-stacked rear diff plates makes, so maybe there is truth to this?

 

Assuming you start with an evo that has a front torsen, i would absolutely do an upgraded rear diff over a front upgrade.

 

Talking just about EVO 8,9 or X as well?

 

i assume talking about 8/9. evo x, either u can go front lsd and leave ayc or get a mechanical rear for more reliability

 

Speaking from my own and a very good friend's experience. Keep in mind that not all driver's have the same driving style. Some rely more on the front end to work, some the rear end. Some driver's can adapt on the fly.

My buddy has an ASPish Evo 9. (suspension, wheels/tires, but not on e85) First, he had TRE redo his rear diff. Amazing job and he loved it. Fast forward 2 years, and he had a Wavetrac installed up front when his transfercase took a dump. He was even more amazed. I discussed with him in lengths and he said the front diff made a bigger difference in making the car easier to drive.

My STU evo X obviously had all the stock diffs so not much to comment there. However, it would do some weird things when a wheel would lift off the ground. If in the rear rear, it would land hard and do a smokey burnout. When the front lifted, it felt like the trans got into neutral. Very weird feeling. But, this might have only been an issue at my local lot since we have some big bumps and waves in the surface. Had no issues on the track or on flat surfaces like at Lincoln.

The first diff I changed on my talon was the rear diff. I installed a stock evo 8 diff with the plates arranged correctly. It was an absolutely amazing upgrade and very fun to drive. I put in a Cusco front diff a few months later and it had a dramatic affect on how early I can get on the throttle in corner exit. Rear diff made the car faster and more playful while the front diff simply made the car faster.


The way I look at it... the rear diff can be a free mod and a decent upgrade. Do that and add good front diff. 2 upgrades are better than 1.

 

If you felt a difference going from the OEM Torsen to Wavetrac front it was only an effect youd feel in the first few events before it broke in and was exactly the same as how the OEM works. There is no point putting a wavetrac in for performance only durability.

The way I feel an evo setup should be done with a heavy rear bias would lean towards a rear LSD with good preload would have the advantage between front and rear. If you have more of the European style setup which uses transitions to rotate the car rather than max front grip, then I could see the front 1way clutch diff being more effective. But thats only because the front on theirs usually run higher rates than rear which would keep the rear touching ground so the rear clutch has something to bias against.

But for AutoX, the European style is not the fast way. Thats just going to make you sad because you dont have room to setup every turn for transition and you dont have momentum to keep things moving.

 

The restacked plates were a massive improvement over OE. When I started prepping in 2011 it was set up very much like a Civic/WRX, lots of real roll stiffness. After the diff restack I dialed that back a bit.

However, having driven my car with the restacked OE diff, and a top level STU STi, my car does not rotate under power anywhere near the way the STi did.