Hello all: I own an 06 MR with a plethora of track upgrades. It was solely a track car on E85 from 2011 till last October, then I went back to 93 an registered it on the street again. Since then it has been mostly track and a little spirited street time now and then.

In April I broke the rear diff while attending GripFest at NCCAR hosted by Tarheel SCCA. Well I wouldn't say broke, as much as it pissed out all the fluid. I never dug into it and really have no desire to. I just want to pull it, send it out and get a good diff back to install..

I have spoken with Trevor from Shep Racing for the past couple months. He states that the Cusco MZ diff is by far the best option for this car. I asked about OS Giken, Wavetrac, KAAZ, the Cusco RS and others.. He said the MZ is the one to have..

He also said that the 12 plate upgrade with the HD side covers is another option, and while much cheaper it will maximize the stock LSD..

So my question to all of you.. Which diff is the one to beat? Is going to an aftermarket diff really that much of a difference, versus maximizing the stock diff? I have no problem going big, so long as the realized difference is going to be quite noticeable. If it isn't, I have two other vehicles and about a million other things to do with the money...

Thanks
Jeremy

 

I presume you've read this entire thing?

https://www.evolutionm.net/forums/ev...ound-here.html

 

I highly recommend the TRE max-lock. Night and day on the autox course, and it's held up fine to countless 700hp dragstrip launches.

I would not, however, recommend him for trans work.

 

 

I have not read that link, but I am going to now..

I have heard horror stories about TRE's customer service, and therefore have written them off...

 

Actually, now that Ive read it I do remember looking at that thread last year some time..

 

Shep can do the same upgrades to the rear diff that TRE can. I have the TRE max-lock with his billet HD side cover, it work a lot better than even the stock diff with the plates restacked. I can't comment on an actual aftermarket rear diff unfortunately.

Yes, Jon's customer service is abysmal. The next time I get drivetrain work done will probably be with another shop so I don't have to wait 8 weeks after being told it would be 1. The trans work he did for me is awesome though, car shifts amazing with his full "stage 3" build. I even saved about $500 between shipping and labor by only sending him the guts of the trans, and taking it apart/putting it together myself..

 

TRE's customer service does suck. However, he knows what he's talking about with the rear diff. He recently just salvaged mine albeit in a much more lengthy timeframe than quoted (3 weeks vs. 3 days). It was something I knew going in and I just figured that the time without my car was more than worth it to know my diff is properly set up.

 

restacking the OEM diff is night-and-day difference. i can only imagine a 12-plate, etc.

 

Hmmm. That had not been my experience.
I sent my diff to Jon with a whining pinion bearing and for other upgrades.
After he received the Diff he called me and we discussed many things. I went for the full treatment. He said he would be done in a week. In a week it was in the box and back in my hands.
I couldn't be happier.


I had previously installed the DIY 12 plate and the difference between the two is significant.

 

Do not get me wrong, I'm very happy I went to him. I upgraded from my Weir DIY 12-plate, which I cannot recommend to anyone after seeing mine after one year and 3k miles. I'm still breaking it in but I have full confidence I made the right choice.

 

Its huge. The TRE 12 plates drives smoother for street cruising, but locks harder when you're on the throttle.

 

Why do you say that about the weir DIY? More info?

 

TMZ Performance can do the 12-disc Weir upgrade for you. He's great at returning calls, answering your questions, and does terrific transmission and diff work. He's VERY up front about every little cost and won't upsell you on anything you don't need. He supports my DSM that I time trial and I have had the Evo rear diff with 12-disc in the rear for three years now with zero issues. It's wonderful with helping the rotation of the car on throttle and a must have for road racing at least. Tuning for big street tires (285 wide from my personal experience) can be done with adding friction modifier alone to the diff fluid, though that might not be enough for smaller tires (i.e. might need to deactivate a disc or two). Not needed for r-compounds.

http://www.tmzperformance.com/

 

When I went to install the kit I didn't have to use any clamps to marry up the two halves of the diff carrier. This concerned me but I wanted to get my car back on the ground and running. I could tell the car would step out easier but I never really noticed a huge difference. I put in a Wavetrac up front at the same time so I just chalked it up to the front gripping so much more I couldn't notice the Weir. I broke in the rear diff for 500 miles before getting onto it due to a clutch install at the same time as well. I changed the fluid and everything looked good.

Fast forward a year and a few thousand miles (car probably saw a dozen auto-x events and one HPDE) and I had a slight bearing noise coming from my driveline. I also had some lockup sounds that I had never heard before coming from the rear end, only when turning left. I changed the LSD oil again and it looked fine. The bearing noise went away briefly with the new oil until after the next event. Then it returned with a vengeance and could be heard in gears 3-5 under heavy load.

I had a high suspicion my diff was toast so I pulled it down and ripped it apart to see if I could see anything wrong on the inside. Upon getting the diff carrier apart and inspecting the plates I had one plate that had galled itself quite a bit onto the carrier. There was also some slight scoring on a couple of plates but nothing horrible. I ripped the Weir kit out, threw in the stock plates, and sent it to Jon @ TRE.

In one of my conversations with Jon I was telling him about the condition of the plates and he mentioned that he was not really a fan of that kit. He said if he was he would use it in his Max-Lock but he doesn't. He then stated that the factory plates are a much better design as they allow oil to get between the plates and also can discharge any trash that might get in there. He said it's definitely possible to overheat the plates and have them gall up like I saw on mine.

Due to the condition of my diff when Jon disassembled it I definitely had some other issues in there as my pinion bearings were toast and the side cover had some scoring on it from launches. However, it is the design of the plates that makes me say I won't recommend it.