Im putting in some 3.73's in my 95 6spd. Do I need to buy an installation kit from Summit or somewhere or has anyone done it without it? Any input will be greatly appreciated.

 

I definitely recommend all new bearings and seals and these are included in the install kits along with shims and a new crush collar. Ditch the crush collar and get a solid pinion spacer, also available from Summit.

RMG-4900461 for 3.73 3 series carrier (3.23 up OEM carrier) -- 179.88$
RMG-4900071 for 3.73 2 series carrier (3.08 down OEM carrier) -- 193.88$
RAT-308TK for Ratech install kit -- 94.99$
RAT-4111 for Ratech solid pinion spacer -- 17.99$

 

Hey, nut..
I'm about to set an appointment to get my 3.73's put in finally. First, I have a last question...I have an a4 with 114K on the dial and even if the bearings in the rear and axle are fine should I replace them anyways? I'm not sure what kit the shop is going to use if I have them replace bearings, shims and spacer and all that so I'm ganna have to ask but why would I need a solid spacer instead of a crush sleeve, just wondering cuz I hear people doing it.

 

Z06Z28 -- With 114k I'd definitely get bearings done. My 1st gear swap was included with replacing the dead OEM LSD so I figured I'd get 3.73s, too. All bearings, including wheel bearings and seals were done. That was summer 03. Spring of 04 I snapped the gear and had another set of 3.73s put in, new carrier and pinion bearings but they said wheel bearings were fine. By the end of the summer, the left wheel bearing was growling pretty bad. So now I have to tear it all apart to do wheel bearings. I think it's better to replace something questionable at the time than have to tear it all apart to replace "they looked good" bearings. Just my .02

The crush collar can compress slightly after being set up under extreme loads (launching ) and can cause the gear tolerance setup to change slightly, leading to premature failure. The solid spacer may take a little longer to setup but it won't change it's dimension under load thus keeping the tolerances consistent and helping the rear last longer. 10-bolts need all the help they can get. You don't need one but I recommend it if your gonna abuse the rear at all.

 

Hey thanks alot z28nut, was the install fairly easy for u to do? just wondering what to expect.

 

how would you set pinion bearing preload with a solid spacer? doesn't make any sense to me for some reason...


and as for new bearings, you might as well. my car has 96K and i replaced all the bearings even though all i have doing was changing the carrier. i inspected them and they had another 50K on em but why do i want to tear it all apart again 50K miles from now? and as for a seal you'll need a new one if you even touching the pinion which you will to install a new ring gear since you'll most likely have to adjust the pinion shims. you can do wheel bearins too if you can, i wanted too but didn't have the shop time or money to do so. and makes sure you use the right gear in your rear end, i was gonna go with syn 75-90w RP but i checked with auburn and they recommend non-syn 80-90w with the gm or ford friction modifier. just cuz its synthetic or expensive doesn't mean its the right kind. and be repared for it to stink, heavy oil thats several years and miles old can stink like hell if you've never smelled it before.

 

I believe you create a shim and spacer stack that equals the dimension of the original crush collar and shim stack, then adjust shim stack to get proper preload. I'm not sure cause I had a shop do it both times. First time rear was covered under warranty and I just paid for the hi-perf parts I wanted. That blew apart less than year later so a perf shop did the second one. They took the rear apart, put back together and drove it 3 times to get it right. So far, so good.

 

Z28NUT -Thanks for the info and I'll take your advice. I'll talk to the shop I chose and see if their cool with me using a solid spacer. Sometimes I'm kinda hard on the car with this shift-kit. I noticed that I break traction from first to second with this auto, I didnt realize I could since I rarely drive the Z" but it's happened a few times. I just threw in a Spohn TA today so I'm sure the rear end will have a fun time of me beating the snot out of it.

Thanks,
madmike

 

Oh, yeah, it'll enjoy it, I'm sure my 1st setup was not good because it whined like heck on deceleration and, well, all the time. I didn't know any better at the time so I thought it was normal to whine more since I went from 2.73s to 3.73s. The second install is much quieter with new Richmond 3.73s and solid spacer. Has held up longer to more power (a .7 reduction in 1/4 ET) and the stickier Nittos. My TransGo kit on a Street/Strip setting beats the hell outta the gears on the 1-2 shift. I know it's just a matter of time before I blow it up again so am saving for a 12-bolt or 9", haven't decided yet.

 

SO im gonna put 4:10's in my 132k M6 car..i am looking at the Ratech deleuxe kit and ill go with the solid pinion spacer...sound good?