12-bolt Tom's Differential Conversion
Racer
Joined: Feb 2010
Posts: 425
Likes: 2
Did Tom's ever come out with their own case that would allow 3 series gears as was written in "HOT ROD MAGAZINE" by Marlan Davis a few years back ? I'd like a 3.08 to go along with a Richmond 4+1 street 5 speed...anyone know anything ?
Burning Brakes
Joined: Aug 2009
Posts: 836
Likes: 8
From: Wrentham Mass
2018 C2 of Year Finalist
OK...who is this Tom we are speaking of here! 
And where (web site please) can I get more info on this setup?
And where (web site please) can I get more info on this setup?I recently got my 12-bolt differential conversion back from Mike Dyer(tracdogg2). This will be going in my red '67 convertible that I am putting a big block in. I was concerned about the strength of the factory diff so a Tom's was in order. I decided on the 1350 kit because I didn't want to have to cut the fiberglass on this car as you have to do with the 1480 kit that I currently have in my '67 632 car.
Tom recommended the HY-TUFF inner axles and Mike recommended the Billet Flanges.
I went with the following Tom's Differential components:
12V-KIT (12-bolt Corvette Conversion Parts Kit with 4.11 gears)
1350-VAK (1350 Vette Axle Kit with upgrade to HY-TUFF inner axles and Billet Flanges)
C10V-HDRC (H.D. Rear Cover)
Mike supplied his own custom left-side cap. At this point all of the work that Mike has performed is first class. Of course, the real test will be when I take it out to the drag strip.
I have included some pics:
Once I get the motor completed, my plan is to make a few DynoJet runs with the factory 3.70 rearend and then switch to this new 4.11 rearend and make a few more runs to see what the differences are.
Steve
Tom recommended the HY-TUFF inner axles and Mike recommended the Billet Flanges.
I went with the following Tom's Differential components:
12V-KIT (12-bolt Corvette Conversion Parts Kit with 4.11 gears)
1350-VAK (1350 Vette Axle Kit with upgrade to HY-TUFF inner axles and Billet Flanges)
C10V-HDRC (H.D. Rear Cover)
Mike supplied his own custom left-side cap. At this point all of the work that Mike has performed is first class. Of course, the real test will be when I take it out to the drag strip.
I have included some pics:
Once I get the motor completed, my plan is to make a few DynoJet runs with the factory 3.70 rearend and then switch to this new 4.11 rearend and make a few more runs to see what the differences are.
Steve
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
FYI, the original "Taxing the IRS" edition of the article from way back in the day mentioned that Pepe Estrada developed 12-bolt conversions for both Tom's Differentials and Henry's Machine Works. My 3-series (Eaton posi w/3.55:1) came from the latter, but AFAIK they haven't done any of them a long time.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
FYI, the original "Taxing the IRS" edition of the article from way back in the day mentioned that Pepe Estrada developed 12-bolt conversions for both Tom's Differentials and Henry's Machine Works. My 3-series (Eaton posi w/3.55:1) came from the latter, but AFAIK they haven't done any of them a long time.
I have an old 12 bolt 4 series case somewhere in my Camaro stuff I prepped/polished and shot peened around 1982 for my Camaro JL-8 differential build for my 69 Z/28, I went with 3.73 gears in the end. Sometimes I think I need to find that posi case but the thought of all those hours grinding the IRS case have kept me from searching for it.
12, bolt, c3, conversion, corvette, differences, differentail, differential, differentials, end, irs, open, rear, swap, toms
