C3 differential width difference: Iron vs aluminum

JeffP1167 said:
69427 said:
Checked the Tech section for some C3 differential weights. IIRC, the D44 weight was listed as 68# with the batwing cover. The batwing is 19#, netting a weight of 49# for the D44 pumpkin.
The iron differential weight is listed as 92# with cover. Subtracting 15# for the cover yields 77# for the iron pumpkin.
The difference in weights appears to be 77-49= 28# (if I understand the listed weights correctly).
That 28# difference is about 1% of the car weight.
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I think the tech section might be a little wrong.

1990 parts

dana36, batwing, spring, tie rod stuff 82lbs

complete knuckle assemblies with all parts 61lbs per side

rear sway bar 10lbs

driveshaft 8lbs

rearend001_zpsf7ea2571.jpg
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????

Why are you copying my C3 parts weights and posting C4 stuff?
 
69427 said:
Has anybody been in contact with the guy (tracdogg?) who builds/modifies the late C3 rear ends? I haven't seen much of him lately.
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I have a Dana 44 at Mike's shop right now. Here is the thread, My Next Project. Mike is very busy; he's had my diff since last May. I haven't been pushing him though because I haven't had much time to work on the Vette lately anyway. So I think he has been sliding other jobs in front of mine.

Mike says the Dana 44s with the steel cap will handle up to 400HP. I'm guessing they can handle more than that if you aren't drag racing. Try to get a dif from an 80-81 manual trans or any 82 - they are set up for the 1350 u-joints
 
Is the 80-82 width the same as the earlier? I may have missed it in the thread.
 
BBShark said:
Is the 80-82 width the same as the earlier? I may have missed it in the thread.
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Well, it appears that they are darn close, if not the same. Given that the cover gasket bolt patterns are (basically) the same, I wonder if the Corvette group was hedging their bet when they went to the aluminum rear end. My pure speculation is that if the warranty numbers went sky-high with the D44 parts then the old iron units could be bolted into the cars rather than GM having to buy back a bunch of lemons.

Just my speculation.
 
If that was the case, they would have to swap over the camber rod arrangement also since on the alus it bolts over the diff/cover mating flange
 
Twin_Turbo said:
If that was the case, they would have to swap over the camber rod arrangement also since on the alus it bolts over the diff/cover mating flange
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Not a big deal. Everything is just a simple bolt-on operation. Very conducive to getting the corrections done quickly at the dealership. The factory would just supply a parts kit to the dealer for each car that needed the conversion (or truckloads of kits in the event that the entire Corvette fleet was affected).

Again, it's just my speculation. But the fact that the cover bolt pattern and the output yoke dimensions are essentially identical to the older setup seems to be a bit more than just coincidence.
 
A few months into 2012, I stopped asking Tom when his aluminum differential housing to replace the 63-79 (?) cast iron diff housing would be available. I just decided not to pester him any more. My last conversation with him was to ask if the aluminum cover, for the aluminum housing he had in works, would be separately available. He didn't want to sell the housing separately since he didn't want to get involved in differences of aluminum/cast iron temperature expansions. Just an aluminum cover would be great...7.5 pounds less weight and better heat transfer.
 
I fabbed something like that for a rear end pump however it was driveshaft driven

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