My factory rear-end is howling like crazy these days so its time for a new one. I do not want to spend $2K plus a 9" or 12 bolt plus I am interested in road racing so I do not want the extra weight. My car is my DD so I want something fun for the street and something good for track. I know for serious road racing applications a 3.90 is not the gear of choice because you will end up shifting more, but in my case I will just be taking it to the track every now and then for fun. Unfortunately, I understand that the new torsen (T2R) sucks so I will probably avoid getting it. Right now I'm looking at the Auburn "racers" diff from Strano and getting Motive 3.90s. I would just do a gear swap and get the install kit but only one wheel spins a lot of the time with my current stock diff. For those of you that are running the 3.90 what do you think of it? I understand they're a little stronger than the 4.10s right? Any input would be greatly appreciated. Thanks guys.
3.90's aren't really going to be noticeably stronger than 4.11's, especially in a 10-bolt. If you do something that breaks the 4.11's, you would most likely have broken the 3.90's.
I had 3.90's in my 12-bolt when I first got it and didn't have any problems witht he gears themselves. Catastrophic pinion bearing failure caused a need for a gear swap and I just went to 4.11's. There's very little difference between the two performance wise as far as I can tell.
Point taken. I guess I should have also asked how you guys liked the performance gains? I have 3.42s right now and they just seem sluggish and long. I've read that you don't really notice much of a difference when going to 3.73s and I don't really want 4.10s in a Road Racing app. So I figured I'd compromise with 3.90s. Plus when I upgrade to bigger wheels it'll make the ratio a little lower. Anyways, have those of you with 3.90s noticed a big difference over the 3.42s?
Point taken. I guess I should have also asked how you guys liked the performance gains? I have 3.42s right now and they just seem sluggish and long. I've read that you don't really notice much of a difference when going to 3.73s and I don't really want 4.10s in a Road Racing app. So I figured I'd compromise with 3.90s. Plus when I upgrade to bigger wheels it'll make the ratio a little lower. Anyways, have those of you with 3.90s noticed a big difference over the 3.42s?
Dude!, I feel your pain!....LOL!!
I spent about 6 mo. researching this same thing before my gear swap!
From what i found out about 3.90's is that in a 10 bolt there noisey no matter what brand (something to do w/how there cut to get that ratio)
& not much dif. than 4.10's!! I know nothing about road racing but I can tell you that I went w/4.10's & it actualy feel better in every gear & I can still do 150mph no prob. just get there faster!!! LOL!!!
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01 WS6 VERT -KOOKS LTS,ORY , MAGNAFLOW(AND STILL SLOW)
How do you like 3.90s in your 10 bolt? 
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