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The u-bolts should be 1/4" if the car still has the original rear end in an automatic. Had it been a 4 speed it would have 5/16" bolts. If You decide tp change the Gear Ratio I think You will find that 3:55 and 3:73 are your only two options despite what the catalogs list. Although I have not done this myself I really don't see any disadvantages of doing the Iron pumpkin bolted to your Aluminum Batwing conversion. If You keep the rear end You have now, Plan on buying new Yokes, 1/2 Shafts, Axel Flanges and 1350 U-joints. If it was me, I would start looking for a local C3 63-to 79 rear end for parts. The later the rear end is considered the better ones, and since the cars are less valuable the costs go down. If You are determined to go with the Dana 44, I have a complete 3:73 with 1350 1/2 shafts available but I wouldn't even be able to ship it till Sept.
A couple notes. Bairs in PA will do a rebuild and are excellent to work with. But they will not machine up a new steel cap. While I haven't seen commercially available steel caps, I have seen commercially available billet aluminum caps listed for Viper Dana 44's. These have to be fitted to your diff, but that is true anytime you replace bearing caps. And billet aluminum would be a much stronger than the existing sintered aluminum caps. Even the sintered aluminum have been reasonably reliable up to 400 hp. For an assessment of the issues with the stock caps see this thread.
As far as swapping gear ratios, as was noted above, your options are limited. I replaced my 3.07 with 3.54 and they are OK. I would have preferred 3.36, but they appear to be made of unobtainium. It is likely you'll need new stub axles as they had some soft lots at the time and they mushroomed out. And it's likely the clips holding the clutch packs together have broken per the photo of my '80 L82 when I pulled it apart at around 90k miles.
Need to ship a C3 diff? Get one of those plastic crates from a grocery store. The crate that milk or large bottles of soft drink is shipped in. Get some long zip ties and tie the diff to the grates in the crate sides. For the iron C3 diffs, you don't want to ship the cast iron cover. I made a custom made cardboard box. The box doesn't have to be too strong, since the crate provides all the shipping protection.
Last edited by 68/70Vette; Jun 20, 2021 at 11:25 PM.
This will be perfect if I decide to do the swap myself thanks! So this will drop right in correct?
I did get under and take a look. I see now why its easy to bust a u joint. Those straps and bolts are tiny!
Drop right in .
When I rebuilt mine I already had new straps and bolts from Van Steel but agree with replacing them while you do it . I also added the ARP ring gear bolts
a guy shipped me a borg t5 trans by wrapping shrink wrap around the middle and leaving the tail shaft and input as carrying handles. ups took it like that...
Well heck, sounds like theres a lot more to consider than just a simple rebuild. So to move up to the larger u-joints (1350?) and stronger caps would require all new shafts and yokes if I understand correctly? Do they make a stronger cap thats a bolt in? Are the Danas really that crappy? I am currently running a 5.3 vortec making just a bit over 300hp. Nothing crazy but certainly more than the original 350. Switching to an iron diff adds quite a bit more costs but if yall think its necessary for longevity, Ill bite the bullet. Thanks again. Im learning a lot of about the corvette rear I didnt know before!
The u-bolts should be 1/4" if the car still has the original rear end in an automatic. Had it been a 4 speed it would have 5/16" bolts. If You decide tp change the Gear Ratio I think You will find that 3:55 and 3:73 are your only two options despite what the catalogs list. Although I have not done this myself I really don't see any disadvantages of doing the Iron pumpkin bolted to your Aluminum Batwing conversion. If You keep the rear end You have now, Plan on buying new Yokes, 1/2 Shafts, Axel Flanges and 1350 U-joints. If it was me, I would start looking for a local C3 63-to 79 rear end for parts. The later the rear end is considered the better ones, and since the cars are less valuable the costs go down. If You are determined to go with the Dana 44, I have a complete 3:73 with 1350 1/2 shafts available but I wouldn't even be able to ship it till Sept.
I have a complete 3:73 with 1350 1/2 shafts available but I wouldn't even be able to ship it till Sept.
Hi, I'm still keen to purchase your d44 3.73 setup , please pm me
Thanks Phil
A couple notes. Bairs in PA will do a rebuild and are excellent to work with. But they will not machine up a new steel cap. While I haven't seen commercially available steel caps, I have seen commercially available billet aluminum caps listed for Viper Dana 44's. These have to be fitted to your diff, but that is true anytime you replace bearing caps. And billet aluminum would be a much stronger than the existing sintered aluminum caps. Even the sintered aluminum have been reasonably reliable up to 400 hp. For an assessment of the issues with the stock caps see this thread.
As far as swapping gear ratios, as was noted above, your options are limited. I replaced my 3.07 with 3.54 and they are OK. I would have preferred 3.36, but they appear to be made of unobtainium. It is likely you'll need new stub axles as they had some soft lots at the time and they mushroomed out. And it's likely the clips holding the clutch packs together have broken per the photo of my '80 L82 when I pulled it apart at around 90k miles.
C4 Dana 44's use larger diameter Bearings than C3 Dana 44's. Viper Dana 44's are much more C4 like and there might be a possibility of interchanging a C4 and a Viper Cap, but no possibility of exchanging a C3 Cap. But they all need to be fitted, which means machined after they are bolted in.
