differential question
Thread Starter
Instructor
Joined: Jan 2005
Posts: 146
Likes: 1
From: Roanoke Rapids NC
differential question
hey fellas,
i want to put a 3.70 gear set in my differential, is this something an average mechanic can do or do i need to send it to a shop? what else might i need for installation
i want to put a 3.70 gear set in my differential, is this something an average mechanic can do or do i need to send it to a shop? what else might i need for installation
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by stingraydriver74
hey fellas,
i want to put a 3.70 gear set in my differential, is this something an average mechanic can do or do i need to send it to a shop? what else might i need for installation
i want to put a 3.70 gear set in my differential, is this something an average mechanic can do or do i need to send it to a shop? what else might i need for installation
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by wombvette
The best thing to do is get another hogs head and install it. Save or sell your old one. The average Joe is not capable of setting up the gears.
C3 rears are pretty complex and the potential of messing up is big if you haven't done it before... I personally do 95% of the work on my Vette myself.. but I won't touch differential internals, rear wheel bearings.. Those are tasks that are not too easy to accomplish with average mechanical knowledge...
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
It is sort of falls into the "if you have to ask..." catagory. If you're familiar with how differentials are setup and how to shim the carrier and the pinion, go for it. If you have no idea how any of the shimming works, perhaps get some old junk rear end (probably a straight axle, C3 rears aren't going to be easy to find for cheap) open it up, take it apart, play around with it. See where the shims are, how it goes together. You might find once you get your differential open that it needs a complete rebuild. Check side yoke end play and see where that's at. No point in only changing gears if the whole thing needs a rebuild.
Tech Contributor
Joined: Aug 1999
Posts: 15,114
Likes: 3,909
From: Connecticut, USA
Depends on your mechanic. Corvette rear ends are a little different but an experienced MECHANIC can handle them. He would have to be able to read and understand a micrometer and use an indicator. I'm not trying to be funny here, as many "mechanics" can not. A lot of garages and vette shops take the job, charge you a couple of grand to remove it,rebuild it and replace it. What this means at a lot of these places is they send it out for rebuilding and mark it up.
I'll PM you some info so you can think about what you want to do before spending your money.
Gary
I'll PM you some info so you can think about what you want to do before spending your money.
Gary
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
Is it really all that different than say a 12 bolt chevrolet rear end? My dad and I replaced the 4.11:1 ratio in my daily driver with 3.08:1 for better gas mileage. It was an "open" carrier but I wouldn't think the posi-unit would present any more of a challenge. that 3.08:1 rear-end gear in my old truck was fine through the day I sold it 10 years after the swap... Neither of us are ASE certified, just shade-tree mechanics or "bubba" as I've been referred to here in the past 
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
I feel if you can do other rearends you can do the vet. To me is is no different. That said people who have done thousands of rearends over the last 30 or 40 years still do not know how to set up spider gear backlash, never heard of it.
You do need special tools, patience to do it over and over and a knowledge of how things work.
I feel the average person can not do this.
Mechanics do not normally know how to do rearends, this is not part of what most do.
Again the mechanic who does them just removes and repladced the gears and does little else to the rearend.
I thought I know alot about setting up rearends but I have learned alot more in the last few months from Gary and feel I finally know how to do it properly.
You do need special tools, patience to do it over and over and a knowledge of how things work.
I feel the average person can not do this.
Mechanics do not normally know how to do rearends, this is not part of what most do.
Again the mechanic who does them just removes and repladced the gears and does little else to the rearend.
I thought I know alot about setting up rearends but I have learned alot more in the last few months from Gary and feel I finally know how to do it properly.
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Race Director
Joined: Dec 2000
Posts: 10,896
Likes: 2
From: CO
I bought my 3.70's. It was kind of expensive but after researching it and finding out that if your off just a tiny tiny bit it will wear out FAST. Heck even the little RC car gears go to crap very quickly if your off just a smudge, let alone a real car rear end that is much more costly and difficult to get to.
Of course I do have a friend that thinks everything is a piece of cake, which is the first indication that its not the right person for the job.
Of course I do have a friend that thinks everything is a piece of cake, which is the first indication that its not the right person for the job.
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
Originally Posted by GrandSportC3
C3 rears are pretty complex and the potential of messing up is big if you haven't done it before... I personally do 95% of the work on my Vette myself.. but I won't touch differential internals, rear wheel bearings.. Those are tasks that are not too easy to accomplish with average mechanical knowledge...
That's basically what I've done. I'll take my chances on everything except differentials, rear wheel bearings, and painting.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
It can be done if you follow the manual closely and have the right tools - including a 25 in-lb full scale torque wrench. I think there is someone out there that makes a steel shim set for the backlash/side bearing preload setting. The factory service shims are soft and it is difficult to get the preload set correctly without shaving the shims. C2 Corvettes with threaded side quills are MUCH easier to set up.