rear end setup from 3.08's to 3.73's. ring and pinions are GM 7.5 I did some searching, but I haven't quite found someone asking the question that I want to know. so I 3.08's in my truck now and I have a set of 3.73's and the pinion does not have a bearing on it, my question is why can't I just have a machine shop take the bearing and shims of the 3.08 pinion and have it pressed on the the 3.73 pinion and have the right depth right there in one shot? GM did make this stuff pretty easy, as long as you stay "GM". Put the pinion in with my new crush sleeve and seal and be done!!! Then when I put the posi diff that I have in, just get the correct mesh with the pinion by using a bright color paint on the ring gear to see how it meshes with the pinion. as long as it's in the housing at the same depth as before...right?
you have to start some where so you can do that but you still need to check the depth of the pinion in the ring gear. You can't assume it will be ok but you may get lucky. You should find a friend with a good pinion bearing puller and a press then add or remove shims as required by blueing the ring gear. Don't forget to check the backlash once thats done, shims may be required here too. I did my 331 to 373 a few weeks ago and it took me aaaallllllll day, and it was a long one....have patience and good luck.
Ok...Here is another problem. 3.08 is a 2 series carrier in a 7.5 rear and the 3.73 gear is a 3 series gear. I do not know if you bought the correct carrier too or are using the exsisting one in the rear that is posi??? Now as stated the 3.08 if it was in that housing from the factory will be a good starting point for sure, and very well maybe the correct one. You will still need to double check the pattern AND most definetely reset the backlash (carrier shim pack) I high doubt that will be the same. Just from experience. Best to get your self a shim kit for the rear or hopefully you have some other factory shims laying around. First need to know if you have the correct carrier for the 3.73 gears. Most imporatant before even getting started. Jim You can call any time 216 464 2313 x240 10 -5 or ask at jdrace.com too. 24 -7 Good luck, Jim
Just as I thought it was going to go, I think this will only work if you stay gm like I did, and save and re-use as much as you can from the old stuff, I didn't have to shim a darn thing, all the original shims worked great, and no extra ones where needed!!!! Amazing huh??? and she kicks posi trac, belieeeeve me
well the guy I bought the carrier and gears off of, (poloservices - ebay) basically said what I just stated, he said he sets up rears for a living, so I don't know, It worked in my case tho. also the guy at my local machine shop said your starting off the right way buy using the original pinion shim, he said your gonna be pretty darn close. hey all I can say is I'm happy
