C3 differential width difference: Iron vs aluminum

Can measure an alu one this week, don't have a spare iron case anymore.
 
No they're probably not. Halfshafts arent the same length either but the 80-82 used yokes on both ends no drive flanges so that is part of the difference.
 
Twin_Turbo said:
No they're probably not. Halfshafts arent the same length either but the 80-82 used yokes on both ens no drive flanges so that is part of the difference.
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??? how in hell they hold the spindles on?? I think of the yokes in the '72 iron diffy, and so a yoke on the other end would need a corresponding tire flange bolted on from the tire/wheel side, NO??? seems weird to be changing all that around on the same t-arms.....thought I heard the 1/2 shafts were the same length....:oh:
 
The same way the pinion yoke is geld on and the drive flages splines shaft and a nut in the middle.
 
It's a little over 14", 37cm to be exact. that's from flange to flange where the cap bolts to. Didn't have u joints to take a dead center measurement, I'm sure it's a hair narrower than that as the joint centerline is not flush with the yoke face.
black markings on wood:
250ddc9aac6336.jpg
 
Twin_Turbo said:
It's a little over 14", 37cm to be exact. that's from flange to flange where the cap bolts to. Didn't have u joints to take a dead center measurement, I'm sure it's a hair narrower than that as the joint centerline is not flush with the yoke face.
black markings on wood:
250ddc9aac6336.jpg
Click to expand...

I got 14" even at the yoke/cap parting line on my old 2.73 iron unit, ignoring the slight endwear/slop in the yokes. I was always curious about the widths, given the use of different shaft and flange parts in the later cars.

The reason I was curious was I've seen several guys put the old iron units in late C3s, but I never heard how many parts they also had to swap out to make things fit. As I'm not into clutch-dump quarter mile stuff I've been curious if a well built C3 D44 would work (ie: survive) for track days (and obviously daily driving) in my '69. I'm always looking for additional sources of weight reduction in the '69. I'll have to take a peek at the Tech/Weight thread to see if there's a D44 weight listed.

Thanks for the info, Marck!
 
What about getting a C4 D44 to work? They are aluminum too IIRC. I know there is alot more fab work compared to just bolting in the C3 d44 but peace of mind that it will survive behind your BB might be worth it.
Arent you already running a batwing on your car? I know C3 and C4 batwings are different but at least its close
 
vette427sbc said:
What about getting a C4 D44 to work? They are aluminum too IIRC. I know there is alot more fab work compared to just bolting in the C3 d44 but peace of mind that it will survive behind your BB might be worth it.
Arent you already running a batwing on your car? I know C3 and C4 batwings are different but at least its close
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Most vendors want an arm and a leg for a C4 D44. I can (and presently do) have multiple gear ratio spare iron assemblies on the shelf for less money than one C4 D44. I looked at the C4 units several years ago, and the sheer size of the cases had me concerned that I'd have to cut the rear tunnel area to squeeze one in.

I've got a narrowed C3 batwing in the car. It was a semi hassle cutting and fitting it. I'm trying to avoid repeating that task. Also, depending on the particular C4 case dimensions, I might also have to cut out and reposition the frame tabs that the batwing bolts to.

And, my custom halfshafts weren't cheap to get made. I'd have to get another custom length set made to fit a C4 differential. I can see spending an easy $2000 to swap in a C4 unit. That's just too many dollars for the number of pounds taken out of the car.
 
I can help you out on a c3 dana44 and batwing. Not sure of the gearing but it's pretty high. 700r4 at 70'ish equals around 1800rpm 0r so.
 
Well, the last D44 I built is under a T56 LS1 combo and it's still there...and it does not get babied. Will report if it dies LOL

The C4 D44 is about the same wirdt, also right around 14". With your fab skills coming up with a pinion mount is not a problem. Those C4 D44s are almost identical to the viper super 44s, they are damn near indestructible. Unfortunately the C3 batwing doesn't bolt to the C4 case. The C3 batwing is also a lot deeper than the C4 one in the lid area.

The c4 batwing is only about a cm ifferent in width than the C3 one. I'll measure the width of the case if you wnat, I'm sure you will be able to run it and just use adjusting lower rods to get the alignment in check if you don't already have those. I'm sure you do.

The C3 cae is lighter than the C4 one.

Jef, yours prolly has 2.73s
 
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.
 
69427 said:
JeffP1167 said:
I can help you out on a c3 dana44 and batwing. Not sure of the gearing but it's pretty high. 700r4 at 70'ish equals around 1800rpm 0r so.
Click to expand...

Well, I'm slowly gaining interest in trying out one of these later differentials.

Let me know what gear ratio is in that rear end when you get a free moment.
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I am sure the differential is in good to excellent condition. I drove the car about 10 years ago and at that time went to san francisco and pheonix and it was never a problem.

just being pulled for the c4 conversion is all

gearing I have no idea. probably whatever they were stock in 82. last known mileage was about 123k miles. I would venture to say it is what marck said around a 2:73'ish
 
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.
Click to expand...

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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