I was referring to the Y axis not the Z. Since BeeJay had to redrill the mounting hole about an inch forward on the mounting flange I assume the centerline of the axles are shifted toward the back the same amount.

 

IIRC, while Bee Jay did raise the diff relative to stock height in the chassis when previously installing the batwing with his iron diff, I don't believe he changed the diff yokes' location longitudinally. So, unless the batwing's frame mounts have been moved since, the answer to your question depends on where the D44's yokes are located in comparison to those of the 10-bolt relative to the cover/batwing. And, while we're on the topic, it seems logical (tho perhaps overly obvious) to inquire whether they're at the same height as are the 10's also.

 

The half shafts will be in the same location.........But!
My 80-82 smart strut brackets arrived today from VBP. It is obvious that the strut rod mounting points have moved back significantly. The strut rods will now angle forward to attach to the trailing arm. I'm thinking that this must be the case for all post 80 Vettes because they didn't change the trailing arms for post 80 cars. Is this a problem?
Edit, I just remembered that the trailing arms are at full drop. When they are raised, the shock/strut mount will move back.

 

Yes, I think you are correct. The strut rods do angle with the D44 as you can see at the following link: CORVETTE STRUT ROD, 1980-1982

So if the halfshafts are in the same location, then there is a difference in the distance from the centerline of the axles to the pinion mount, correct?

 

Yes, the Dana 44 pinion yoke is longer. I barely could get the driveshaft in, I thought I was going to have it shortened again. But with enough wriggling and prying, I got it in. I guess 80-82 chassis frames had the front diff mounting point further back to meet the front of the diff. I'm not moving the batwing brackets. I'm trying to keep this convertible, just in case all of bad reputation the Dana 44 is true. I'll be able to easily put my iron diff back in.

 

The half shafts are finally in. What a PITA! I ruined the flanges by trying to press the u joints myself. So new flanges, new u joints, shipping charges, and labor to have the joints professionally pressed, and $250 later, this what I have. All that is left is to hang the exhaust system.
Bee Jay

 

Looks good! I guess its bad news for me though. I am planning to swap a 82 rear into my 73 and I was planning to use the front differential mount to locate the diff and weld the bat wing brackets on. Now it looks like that may not work. I'll need to measure the distance from the front mount hole to the C/L of the stub axles on both the new and old diff.

 

Yes, that's looking good. I have got to get on with my batwing conversion.

 

OK, it's done, what a pain. Going from the iron rear end to the aluminum Dana 44 was not a simple plug and play. You need Dana 44 shorter half shafts, you will need to modify your nose mount, and I had to do 1350 to 1330 conversion u joints to get the half shafts to match up to the Dana 44 drive flanges. Do not try to press the ujoints yourself on the outboard flanges. I ruined mine.

I added rear end fluid, hung the exhaust, torqued everything, put the wheels on and set the car down. I drove it for about 15 miles. I didn't expect much difference going from 3.55 to 3.73 but the difference is significant. The car is peppier in the lower gears, and the engine is still just lugging along in OD. The rear end noise is louder, but my old rear end had about 100,00+ miles and was well worn in. I have no idea how many miles this Dana 44 with 3.73 gears has on it, but I suspect it was a recent rebuild. I need to do a longer drive and get the alignment checked. I also will have to change the speedo gears. I've got about 3/4 of a tank in now, so when I get it down to 1/8, I'll weigh the car. I lost 20 lbs with this mod, and 20 lbs by going to the Odysey Battery, and 7 lbs with my Master Cylinder mod, so I'm getting close to my 3000 lb goal, hopefully. Lightweight A Arms next, and I still want to do the Rack and Pinion mod. I keep getting conflicting information on that mod, so I will have to do it to finally nail down the weight savings by doing that.
Bee Jay

Bee Jay

 

Wow... That looks amazing!!!!!!!

 

BeeJay,
Can you take some pics with the car on the lift, looking straight up at the suspension? Or to put it another way, raise the car up, lay on your back on the ground directly under the diff, and take pics showing the entire rear suspension. I interested in the "forward to back" angle of the halfshafts. This may help Kidvette in positioning his diff.
Thanks,
Mike

 

Charlie,
I'm doing a 12-bolt right now. I have a C3 D44 batwing I'm going to cut in half to see how thick of a spacer plate is needed to mount the 12-bolt to the batwing.
Mike

 

Thanks Mike, that will be helpful.

When I take out my iron diff I'm going to measure from the C/L of the stub axles to the front mounting hole on both the iron and the aluminum diff just to make sure I get it right. I was hoping they were the same on that dimension.

 

I will try to get that picture this weekend. But to be very helpful, I need to take that picture with the car sitting on the tires, not hanging. Maybe I could drive it up on a muffler lift or some drive up ramps. As far as I can tell, the half shafts are straight, and the camber rods straightened out as the trailing arms moved up to their natural positions.

 

Here are some measurements that might help.
The overall length of the Dana 44 minus the batwing is 15 1/4".

The distance from the back of the Dana 44 to the stock front mounting hole is 14".

The distance from the back of the Dana 44 to the middle of the output flange hole is 2 1/8".

The distance from the back of the Dana 44 to the middle of the driveshaft flange is 14".

I left my batwing in the same spot it was in with the iron rear end.

 

I haven't attempted to mate mine to the batwing I have on hand yet, so I don't know for sure that one is absolutely required in order to clear the ring.

If not, I'd think the function of the mid-plate I've previously advanced (in lieu of a basic spacer) to make up for the two missing bolt holes in the batwing could likley be accomplished with a couple of well fitted dowel pins, if such work might be worth doing. Just thinking "out loud" here, FWIW...

...back to regular programing...

 

When you do your speedo any chance I can buy the set your using for the 3.55 gears

 

Thanks for the measurements Bee Jay. OK, according to my precise calculations the distance from the front mount hole to the C/L of the stub axles is 14" - 2 1/8" = 11 7/8".

So does anybody have an iron diff handy to measure?

 

Nice looking job. Alway like to ready your posts. Very informational.

 

Loving your work