Shorten Rear Diff - Need a little advice

[Tacfire11]

First, thanks to everyone who contributed to my postings and helping this fledging Mopar newbie . It's been quite a learning experience, but finally see some light at the end of the tunnel. The Dart is coming together, and the final piece will be the Rear end. Thanks to the many responses, and a trial fit I definitely need to shorten the rear. Through some research, found a reputable shop at a descent price. So the next question, is how much to shorten the tubes, and move the flanges in.

Since they say a picture is worth a thousand words, here's the rendering I'm taking to the shop. However, before I proceed, I wanted to ask for your feedback and any advice on the measurements or placement. For Wheels and Tires, I'm planning on 15" Wheels (8" in the front, and 10" in the rear).

Thanks again to everyone for having such a great forum.

Pat

 

[340mopar]

Is this a top view? because if it is, a bodies have the pinion offset to the passenger side and this shows to the driver side off of center. But if it is a bottom view it looks about right.

 

[66dartman]

After much hassle trying to fit a B Body 8-3/4 rear under my 66, I just put the wheels and tires in the wheelwell where I wanted them and measured inside to inside of the wheel flange. The shop I had narrow it took it from there and it came out pretty good.

 

[1972Dart]

It looks pretty good but all the shop needs is the flange to flange dimension unless you plan on centering the rear which it doesn't look like your going for. I would lose the old flange location and only provide the dimensions of what you want. The dimension for each side, passenger side from center of pinion to center of flange = 24.475" and from center of pinion to center of flange on drivers side is 28.725". I only say this if you decide you need to move it on one side more than the other. If your only doing what your print states just tell them to lop off 3.5" off of the ends and weld your perches 3.5" inside of that and include the new perch dimension you want (it's not on there now). But you'll probably find that your rear is sitting about 3/4" or more to the passengers side. So if you want your tire to sit dead center in the wheel well on both sides and your drive shaft to stay exactly where it was then you need to compensate for this dimension and have more cut off the passengers side than on the other. If you have them just cut off the 3.5" off each end your rear will be shorter but you won't be able to get the maximum size tire to squeeze in there because on the drivers side it will fit nice and even and the passengers side will hit the outer wheel house. Only way to compensate will be to get two different wheel offsets and that would suck! You can move the rear a little left and right with your perch dimensions but can't go crazy with it or your driveshaft may get close to the tunnel (not good). Hope I helped and didn't confuse anyone, any questions or clarification let me know. Been down this road, just trying to help if I can.

 

[Tacfire11]

Is this a top view? because if it is, a bodies have the pinion offset to the passenger side and this shows to the driver side off of center. But if it is a bottom view it looks about right.

Sorry, had to find a nice hard wall to run my Head into . This picture is from above, and it's been the story since I started this rear. The Pinion is offset to the Left (Drivers Side) by 2 1/8". So I can still center the Pinion, since I have several inches to play with. Would you happen to know how much the offset is?

Here's some pictures....

View from the Side...

View from the Top (Front)

View from the Top (Rear)

Thanks for all your help....

 

[1972Dart]

Is that a Ford 8.8? The pinion offset is different then, not the same as the 8 3/4. Center the pinion and then measure each side for sure because it will be different cuts off each end.

 

[Tacfire11]

Is that a Ford 8.8? The pinion offset is different then, not the same as the 8 3/4. Center the pinion and then measure each side for sure because it will be different cuts off each end.

What is the offset for 8 3/4, would you happen to know?

Thx

 

[1972Dart]

I don't think the center section matters on this one ie, 741, 742, or 489 but it may, you'll have to check. I know you visit this site as well did you go here yet?
http://www.bigblockdart.com/techpages/875axle.shtml
Adam

 

[Ace]

What axles are you going to use?

 

[Tacfire11]

I'm planning on MOSER Axles, 5 on 4.5 bolt pattern. I was lucky and got rear disc brakes from a 95 Explorer, which bolted right to the flanges. The only issue I had was the original Axles are 5 on 5.5, and the Rotors are 5 on 4.5. This helped push me to use standard wheels all the way around.

 

[Ace]

So if you already have the axles, why not just pull out the old ones that are in there now and compare measurements? If the new mosers are two inches shorter take 2 inches out of the housing.

 

[Tacfire11]

So if you already have the axles, why not just pull out the old ones that are in there now and compare measurements? If the new mosers are two inches shorter take 2 inches out of the housing.

I originally ordered the Axles at standard measurements, but put a hold on shipment under the housing is shortened. I would be very happy if I could find the factory offset for A Body Diff's. I know what the offset is for the Rear I'm trying to put in. Hopefully I can get under the car this weekend and pull the old rear and get the final measurements.