Hello guys. Im here again with a big problem.

Last year I changed the AYC rear diff in my evo 4 for an Evo 9 rear diff.
I changed too my tcase for an Evo 5 tcase with LSD. (Evo 4 came with open diff in tcase).
The ratios its ok (3.312 in tcase and 3.308 in rear diff), for that no problem.

The car runs great and race very well in roll, until I made a launch three weeks ago and broke the LSD unit.

Its broke of the output to goes to gear box (picture attached).



After that, I think the LSD was bad because It never happen that before I change the tcase and rear diff.

I bought a new LSD and when I made the second launch its broke again.

Now, I dont know what can I do. Today I will take off the gear box to take a look but I want to know if I can have other suggestion of you.

BTW, my Evo its an Evo 4, with Evo 5 transfer case. Evo 9 rear diff.

The gear box its the original from Evo 4.

I made this sawp because a friend of mine has an Evo 5 with Evo 8 rear diff and the car runs great constantly in 10s seconds.

This is the first broke LSD


And this is the second one.

 

If those are stock LSD's, they are inherently weak. TRE does work to the to make them stronger though. Iy's likely with how quickly you're seeing failures that these already had cracks in them that you couldn't see. I would upgrade to a wavetrac and then you won't have to worry about it...

 

OK, thanx for you answer.

But before that I use Evo 4 OEM ope diff and no problem.

Its better open diff? because I never cracked like this lsd´s.

 

You could also think about getting the metal treated. WPC and/or cryo treatment. Race teams use that stuff when their parts start breaking.

 

These are failures are somewhat beyond a treatment. I think there is an underlying cause. Either far too aggressive on the launch, or these diffs were already cracked and waiting to go..

 

Nice, I will to consider the front diff treatment. Today I bought an Evo 5 transfer again, I will see when the part come to my country shipped to TRE or do something, because in my country that doesnt exist

 

In the first failure I think the LSD was already cracked, but a friend sold to me a new one in perfect condition, almost new, and cracked again.

The thing is, I dont know why in the first launch is broken. I belive you if cracked after to made like 5 drag races but in the first one?

 

improper install? make sure all clearances are correct?

 

I don't think so, because the first time that it's cracked I install the tcase complete without open it. The second time yes, we desamble the tcase and install the new lsd and happened the same.

 

Hello guys.

Yesterday we finished to take off the gear transmission and found this:


I think this is the problem, the center diff thats connect with tcase (and directly with the LSD).

 

No, that's normal. That tube is splined into the driver side spider gear of the center diff, and is only held in place with a c-clip. They all wiggle around like that because they aren't part of the gear like the big outer shaft is.

 

did you check clearances with the new (3rd) lsd? if you broke one in the same case and another one id say there is something wrong with the case

 

I will install a new complete tcase.

 

[/LIST]Hello man, really? Are you sure that´s normal?

I dont know because I´m not a mechanic or an expert, so I´m ignorant in this area.
That sad because I think I found the problem. because center diff shaft in LSD output. (I hope you understand me because I'm not good at explaining this).

 

Yes, really, I'm sure that's normal.