Wow, say that 3 times real fast! What is the difference between a 79 & earlier and an 80, 81 & 82? I was looking at gear sets and most everything refers to "up to 79". My car is an 81 with 4 speed.

 

If it has the cast iron case it is the early style, aluminum it is the later.

 

And the '79 and earlier can handle more torque.

 

When you find the best price on a R&P for your 81 let it be known. They are kind of bastard children.

 

ZZ383, Why do you refer to the aluminum housing as the "bastard children?" Is it due to the aluminum housings being weaker and therefore not used widely on performance set-ups/and fewer aftermarket gears (ring and pinion) available f/ these housings? Thanks in advance.

 

Will the aluminum housings handle 350 to 400hp?

 

That's part of it. They were only built for three years so junkyards aren't teaming with them and the aftermarket has never showed up like it has for the more plentiful earlier rear. It's often referred to as a DANA 44 which is a good axle but it really isn't a DANA 44 at all. DANA 44 parts will not interchange.

 

talk to tracdogg2. He builds rears and is very knowledgeable. My understanding is some handle 500 with no problem and some won't. He can explain to you more and what you can have done to make it stronger. He's a great guy and you can be comfortable in knowing he will give you good answers, not guesses.

 

I would like to know how much horse power/torque these aluminum housings can handle. I've read that they can stand about 400hp, but torque is another thing, however I would like to hear from someone who really knows, like has been mentioned, this gentleman "tracdog" who knows these set-ups. AlsoI'd like to know exactly what and who carries the aftermarket goodies f/ these housings. Thanks f/ all the info.

 

The case? Really don't know how much torque it will handle. HBZ_81_C3 is trying to find out but hasn't been able to break it yet. The aluminum caps are a whole different story. Some handle 400+, some break at 200. I've gone into great detail about this in other posts.
The D44 diff is not a bad piece, it just has several problems that GM took shortcuts on. In some ways it's stronger than a stock iron diff, other ways it's weaker. There are no aftermarket parts available for the D44 other than the steel cap that I machine for them and the hardened shaft from Toms. It is one of the hardest diffs to correctly rebuild. It's just a matter of using the best parts and a lot of machine work. I will say I have never seen one built correctly. Just in case Justin from Zip is reading this, I don't think I have had one from them on the bench. I do have one here right now from another well known company, not a vendor here, that is a disgrace.
Mike

 

Mike,
Thanks f/ the input. Are you saying that w/ the caps you machine and the hardened shaft from Tom's that this Dana differential should beable to take a beating from a 450hp ie; 383c.i. w/ the average amount of torque that a built 383 would produce ? Also, what did you mean when you said, "not a vender here, that's a disgrace." Thanks again so much f/ the input.

 

It's a little more complicated then that. But in a nutshell, yes. These are not bad diffs but they have problems. Poorly designed caps, almost zero lateral support, non-machined mounting pads, and inferior metals. But they do have large stub axles, ribbed carriers, a better designed preload system for the clutches and oversize stub axle bearings. All I do is what GM should have done in the first place. Use a few C4 D44 parts, some custom machining, and a steel cap. GM knew about the problems and completely redisgned it for the C4 corvettes. They were just never designed to handle more than 200 hp. Their main focus was emissions.
I was referring to a diff that was sent to me for modifications. This is a fresh rebuilt unit from a major corvette rebuilder that had not been installed yet. First things I noticed were the gear pattern was just horrible and no preload on the bearings. It was painted inside and out. Everything was painted. Gobs of silicone everywhere and assembled with wheel bearing grease. Gears and clutches were dry as a bone. Upon disassembly I found that the left stub axle bearing was driven in so hard it broke the seat driving pieces of aluminum into the left carrier bearing. But it sure looked pretty.
I also have been sent a set of expensive trailing arms from another company also not yet installed. For $1500 this person got no name bearings, undersize imported spindles, bent caliper brackets, seal surfaces that had been sand blasted and left rough, and white lithium grease instead of wheel bearing grease. And very little of it. I will not openly give the name of the company since they are very well known. But I'm sure they will read this so I have a question for them. Is the quality of your work, your customers' corvettes, and possibly their safety worth the additional $20 you made from shortcuts and inferior parts?
Hope this helps.
Mike

 

Mine has for 10+ yrs but that's with street only use, no drags/SCCA/etc

 

Mike,
Great info on the differential, thanks. Can you give me a ball-park figure on what a respectable differential costs, w/ you doing the work ofcourse. If need be you can "message" me if you don't want to discuss money openly on here, completely understood. I, in the future, will build a 383 f/ my '81, and since I have to install all new bushings, etc., like now, I'm thinking that this may be a good time to get the differential up to snuff. Again, I sincerely appreciate the info on the diff..

 

The weakest part of the Stock Rear is the U-Joints and since You have a 4 speed 81 You are allready a Jump ahead of most cause they use the Spicer 1350 and not the weaker 1330. This means You have the good Yokes 1/2 shafts and Axel Flanges that go with them. All the HP and Torque dosn't matter if don't have Tires that grip. These Rears hold up well with Street tires its when You go to Slicks or Drag Radials and a preped Strip that the parts start to break. Since you probably have a 2.72 Axel now You will probably be in there changing ratios anyway unless You install a 5-6 speed with a deep 1st gear, so You might as well do the Mods at that point. If You search the site there is a lot about this subject.