GTR1999
Gearhead
Just about done. The Axles are fit to 005" and the flanges bolted on. Cover is fit, just need to install the gasket and cover and ship it.
12 Bolt Differential build
- Thread starter GTR1999
- Start date
GTR1999
Gearhead
Finished with the Diff, now on to the 1/2 shafts and T/A's.
Twin_Turbo
Der Maulwurf
- Joined
- Mar 5, 2008
- Messages
- 7,575
You have my address right? 
big_G
Blown Member
GTR, let me have the customers address. I'll deliver it for you free of charge...(ala DB).:evil:
GTR1999
Gearhead
Ha, I'd like to put this in my 69 or my son's 75 since he likes to break the 10 bolts in 1/2. As I mentioned this is not exactly like Tom's, I put a couple of extra things into it. It should perform pretty damn good and I'll be waiting for the feeedback once its in the 66. I learned a few new things doing this as well,one was they take some time. Granted the next one should go faster but they still take a lot of fitting. Watch for the 31 spline spindle install.
Will the halfshafts need to be shortened or are the stub axle u-joint (center to center) in the same as the 10 bolt?
GTR1999
Gearhead
I checked the finished position of the 12 bolt to that of a used 10 bolt I just got in. They look very close, the 1/2 shafts are Toms so everything should bolt in. Once I get the Spicers installed and the spindles built I'll double check.
I know that this is an older thread; but I have had a question about the 12 bolt conversion for some time. Has any one ever considered going with 8.5inch 10 bolt guts instead of a 12 bolt? They are much stronger than the 8.2 inch model that most people think about when they hear 10 bolt. The pinion shaft diameter is the same as the 12 bolt and the ring gear is only .375" less in diameter (for those who fear breaking the ring gear). Just a crazy thought.
BRUTAL64
Neanderthal
GTR1999
Gearhead
I guess Mike pretty much answered that, I don't have anything here but the vette diff's and those are the only ones I work on.
GTR1999
Gearhead
Shipped the 12 bolt back today along with these 3.5" 1/2 shafts, .134 walls with solid spicers, really nice pieces.
Nothing is impossible! I should have mentioned that you would need to start with the H.D. 8.5" carrier from a 98-up Truck. It uses the 3.062 Carrier Bearing.
Understood, Forget the number of bolts and imagine doing what you just did with the 12bolt and substitute a 1998 H.D. truck differential that you can get from the local wrecking yard. Oh ya, the ring gear is already 3/8" less in o.d. than the 12 bolt gear.
GTR1999
Gearhead
I haven't seen the truck posi case, but I have to machine the 12 bolt case to fit the flange location is important to housing location.
If this is something you have done or will do then post some pictures, I'd like to see them as I'm sure the others would.:thumbs:
If this is something you have done or will do then post some pictures, I'd like to see them as I'm sure the others would.:thumbs:
No, it is not something that I have done; but wanted to run by someone like yourself who has already tackled the 12 bolt conversion and is kind enough to share details with the Vettemod group. I have a 8.5" truck rear at my Dad's shop that I kept due to the fact that it was a Posi. I have to go down to help him finish an engine swap this weekend, so I will try to get some dimensions for sake of comparison. I will check in the mean time with the guys where I work to see if they have one that I can measure.
If anyone sees anything that would make the 8.5" idea a no-go, please chime in.
GTR1999
Gearhead
Check the posi type as well. I know a lot of the trucks used that ratcheting posi that will not work in this application. Those broke in use many times. Even my 85 S10 that I bought new with posi had one of those and it snapped.
If it's an Eaton with the 4 springs then it may work, but again I really can't say. I suspect if they were common and strong then Tom or others would have used them by now. The new bare Eaton 4 series cases are getting hard to come by, no longer stocked by GM and most suppliers are out. The last car using them was back in '72. I have 4 brand new cases sitting on my shelf now and those are very expensive not mention require machining to use in the vette carrier.
Shoot a picture if you can of your posi.
If it's an Eaton with the 4 springs then it may work, but again I really can't say. I suspect if they were common and strong then Tom or others would have used them by now. The new bare Eaton 4 series cases are getting hard to come by, no longer stocked by GM and most suppliers are out. The last car using them was back in '72. I have 4 brand new cases sitting on my shelf now and those are very expensive not mention require machining to use in the vette carrier.
Shoot a picture if you can of your posi.
I did not make it down to my Dad's this weekend; but I will be going down for the holiday. All of the things that you mentioned above are reasons why I thought you might be interested in this type of swap. I will let you know as soon as I find out. Also, do you think that an open carrier could be used with one of the drop in locker products that is currently on the market? The off road guys are using them; but I don't know how well they would hold up.
I've definitely got this one bookmarked. Eventually my aluminum Dana 44 is going to do something spectacular, like the output shaft on my T56 once did. Golly, why ain't I going forward any more . . . what is all that noise and why is everyone looking at me. 
mrvette
Phantom of the Opera
I've definitely got this one bookmarked. Eventually my aluminum Dana 44 is going to do something spectacular, like the output shaft on my T56 once did. Golly, why ain't I going forward any more . . . what is all that noise and why is everyone looking at me.
It's related to that grease spot behind you on the pavement there, yeh, THAT one....:tomato::lol:
I've definitely got this one bookmarked. Eventually my aluminum Dana 44 is going to do something spectacular, like the output shaft on my T56 once did. Golly, why ain't I going forward any more . . . what is all that noise and why is everyone looking at me.
It's related to that grease spot behind you on the pavement there, yeh, THAT one....:tomato::lol:
Yeah, they love it when you leave a quart or two of trans fluid just out past the tree. :lol:
