Steel cap for Dana 44

[tracdogg2]

As everyone knows the weakest link in a 80-82 Dana 44 is the driver side aluminum cap. This is the part that always breaks. The only solution is to swap in an earlier iron diff.
Until now.
Here you can see the obvious design defect. The stock cap is sitting on my steel blank.




After machining








The finished product







This won't make the diff as strong as a 12 bolt or allow you to launch with slicks but it does eliminate the weakest link. It is good upgrade for engine mods or if you have a broken cap.
I will be adding it as an upgrade to 80-82 rebuilds.

Mike]

 

[Kid Vette]

Looks pretty simple. How come nobody has done this before? Do you need to do any machining in the case? What type steel did you use? Will this make the Dana 44 as strong as the earlier iron Vette diffs? Didn't the earlier diffs provide side support for the caps that the 44s do not? OK, no more questions for now. :drink:

 

[BBShark]

Looks pretty simple. How come nobody has done this before? Do you need to do any machining in the case? What type steel did you use? Will this make the Dana 44 as strong as the earlier iron Vette diffs? Didn't the earlier diffs provide side support for the caps that the 44s do not? OK, no more questions for now. :drink:

Mark, VetteMOD policy is 6 questions per post, you still have another left:lol:

 

[tracdogg2]

It depends on the case. This particular case had very flat and even bosses even though they weren't machined from the factory. My cap extends all the way to the case for side support. Each case is different so the cap has to be machined to the case. I made a boring bar that goes thru both sides to machine the race boss (The lip inside the cap) even with the case and parallel to the opposite bearing.
The posi carrier is stronger than the iron unit and the stub axles are larger. But it is still an aluminum case so in my opinion the overall unit still isn't as strong as an iron diff. Every failure I have seen has been the cap so I can't judge the strength of everything else.
One reason for doing this is price. To swap to an earlier iron diff you're looking at $600+ before you rebuild anything. Granted the iron diff swap is a good upgrade but not everyone is willing to do it for a mild motor. These caps would break with low horse motors and since there are no new caps available people were stuck with buying another diff. This is much stronger than a D36 so it should handle at least 300hp. Of course hard launches, speed shifting, and bad driving will break anything. The threads in the case are not heli-coiled so I think the case is the next weakest point.
Mike

 

[Kid Vette]

Really glad you posted this since this has been in the back of my mind for a while. Reducing weight is my highest priority in my Vette since there are so many benefits - improved acceleration, braking, handling, mileage, etc. Also I don't do anything crazy in my Vette, no drag racing and am running stock width tires. I know swapping the Dana 44 in my 73 would be relatively easy but I keep hearing how fragile it is.

I'm an ex tool & die maker and supervise an 8 man tool shop so I have the usual mills, grinders, EDMs at my disposal. It would be no problem to make some caps like you did or do some machining on the case or helicoil some threads. My question is, in your opinion, could the 44 be made strong enough to hold up on the street with a little machining and fabrication? It seems like the weight savings would be worth a little work to beef it up.

OK, I guess I used up my allotment of questions. :harhar:

 

[tracdogg2]

I'll do more comparing this weekend. At the moment my opinion is it won't be as strong as the iron diff due to the aluminum case. The cap will just eliminate the one part that always fails.
Mike

 

[GTR1999]

Nice job Mike, I hope the guys who have you rebuild those 80-82 diff's go with this cap. I know how much "fun" it is to fit a steel cap!

 

[Kid Vette]

I'll do more comparing this weekend. At the moment my opinion is it won't be as strong as the iron diff due to the aluminum case. The cap will just eliminate the one part that always fails.
Mike

Thanks. :smash:

 

[BBShark]

Does the C4 D44 use the same internal parts as the 80-82 D44? I see that someone is making a thicker aluminum housing and batwing for the C4.

http://www.newmancarcreations.com/differentials.html

 

[Twin_Turbo]

No, they are not the same. You can however interchange some parts. The D44 uses a larger sized pinion (shaft, D60 sized) but you can use the carrier. I have a 80-82 D44 here with a C4 D44 carrier. Both have a 8.5" ring gear (the D36 uses a smaller one)
Here's the 80-82 with the original guts



and this is the C4 Dana 44



I don't have a pic of the other one at the moment, I will try to take one sometime soon, it's the same case as the top with the same carrier as in the 2nd pic.

Also, not how the C4 unit uses forged alu caps. Mike needs to make some billet caps for those You can also just see how the C4 unit has a faced surface where the cap sits, the 80-82 unit is as cast, on both the case and the cap.

I think it was TOMs who was working on a billet C4 D44 case.

 

[69427]

Outside of the cap issue, has anyone documented exactly what the strength deficiency issues of the C3 D44 are? It certainly gets a bad rap, but I rarely see any actual details.

 

[tracdogg2]

69427,
I'm doing comparison tests right now between the iron diff and the C3 Dana. I'll post the pics.
If you look at the pics Marck posted you can see the changes they made to the case to support the bearing in the C4. They eliminated the lip inside the cap and the cap is no longer having to withstand the lateral forces of the carrier. My steel cap does the same thing, using the case to also support the carrier.
Marck,, all I need is a C4 case and caps to make the billet caps. (Hint Hint)

 

[Twin_Turbo]

Here are some better internal pics of super D44 (C4) cases. I don't have an empty case I could send a cap

 

[big2bird]

Looks like when I change the 81's gear set, it's off to Mike for the killer upgrade.

 

[BBShark]

Mike, Did you post that the 80-82 axle yokes are 1330 series u-joints for automatics and 1350 series for 4-speeds? The 1350 must be pretty rare (not many 4 speed 80-82's) or are they the same as the iron rear?

 

[Twin_Turbo]

All 82s use the 1350 joint, the yokes with the larger bolts and the 3" halfshafts so if you get your stuff from an 82 you already have the HD (cough) parts

 

[tracdogg2]

80 and 81 automatics use the 1330 joints
80-81 4speeds and all 82 use the 1350
Nothing interchanges between the iron diff and the dana.
If I ever get over this cold I'll get out to the shop and take comparison pics.
Mike

 

[69427]

Just curious. Has anyone measured the weight difference between the iron and aluminum cases (with complete internals), without the covers preferably?

 

[GTR1999]

An iron unit with cover and yokes is 100 lbs. I don't have any of the 80-82's.

 

[Twin_Turbo]

I think the 80-82 unit is 35-40 lbs. I weighed it some time ago and posted the results on CF in a very long thread aotu either weight reduction or swappings diffs (could be the road racers thread). Can't find it however.