8 3/4 pumpkin change info

[Y07Roadrunner]

Reference vehicle is a '70 Roadrunner.
I currently have 3.55 gears in my 489 case 8 3/4 rear end. Great gears for cruising around, but in the interest of doing more comfortable highway driving (legal speeds and otherwise) I picked up a 489 case with 2.76 gears. The "new" case has been rebuilt and all clearances set properly. Supposedly it is also from a B-body, so I'm hoping there are no axle compatibility issues.

Now my Q for you guys: Exactly what is the process for swapping this center pumpkin? I think it is a pretty easy job, but I don't have a FSM, so I was hoping someone here could guide me thru this. I don't want to overlook anything. Thank you!

 

[Cranky]

It's not hard but for a first timer, you would do well to at least have an FSM or maybe a Motor's manual. One important detail is setting axle end play when going back together. How well are you versed in spinning wrenches?

You have to pull the axles out first....after getting the car up on stands and the rest is pretty straight forward.

 

[Longknife]

It's really a simple job for an old gear head like myself but if you are not mechanically inclined I would definitely get a SM. Pull rear axles, pull drive shaft, Pull pumpkin, reverse process and ADD OIL!!!!!!!!! Sent you a PM on that take out 3.55...Ed

 

[Fran Blacker]

Make sure the u-joints are the same on both.

 

[davek]

 

[Fran Blacker]

About 34 nuts to remove and put back on,what can go wrong?

http://www.mymopar.com/index.php?pid=109

 

[493 Mike]

You may want to clean and repack the axle bearings/check oil seals while you're in there.
Mike

 

[tonysrt]

And if your an old guy like most of us here the weight of that thing is close to 75 lbs. so have a jack ready to help you remove it. We can remember when we didn't need a jack but that was a long time ago.

 

[NJRR]

Reference vehicle is a '70 Roadrunner.
I currently have 3.55 gears in my 489 case 8 3/4 rear end. Great gears for cruising around, but in the interest of doing more comfortable highway driving (legal speeds and otherwise) I picked up a 489 case with 2.76 gears. The "new" case has been rebuilt and all clearances set properly. Supposedly it is also from a B-body, so I'm hoping there are no axle compatibility issues.

Now my Q for you guys: Exactly what is the process for swapping this center pumpkin? I think it is a pretty easy job, but I don't have a FSM, so I was hoping someone here could guide me thru this. I don't want to overlook anything. Thank you!

I have an extra FSM i was going to list for sale here. $50 plus shipping. PM me if interested.

 

[Demonic]

Replace the inner axles seals. The FSM says do it any time the axles are disturbed. They're cheap enough.

https://www.rockauto.com/en/moreinfo.php?pk=5566539&cc=1495028&jsn=463

 

[Y07Roadrunner]

Awesome info, guys. Thank you very much!

 

[Cranky]

Replace the inner axles seals. The FSM says do it any time the axles are disturbed. They're cheap enough.

If I know the seals have been replaced before and aren't all that old, I'll be really careful pulling out the axles and not slide them on the seals or let the axles rest on them. Some will pull them out only a few inches and then let them 'rest' on the seals while swapping out the chunk. Have never liked doing that. Also pulling them out all the way will let you get a good look at the splines to make sure they haven't been twisted. Used to do a lot of third member swaps and didn't change the seals each time and never had any problems with them leaking.

 

[Steve009]

I swap mine every summer for a long drive to Syracuse nationals. 4.10s get swapped to 3.23s. Longest part of the job is peeling off and cleaning the silicone and gasket off the pig and housing (important for no leaks). Jack the car up pull off rear tires and drums. Take off springs in the drum (take a picture so you remember how they go back on). Take off the bolts holding the axel in. Pull axel out. Repeat on other side. Take the drive shaft out by removing the caps (2 bolts/cap) holding the u joint. Wrap tape around the caps holding the needle bearings cuz my god you don’t want those going everywhere). Loosen all the nuts around the pig then use some brute strength to break the seal and let it drain. Put a jack under the pig, take off the nuts and pull the pig onto the jack. Clean all surfaces, reinstall with gasket and silicone, top up rear end (add some sure grip additive if need be) and then reverse everything I just said. Final step, check the end play of the axel. Should be a tiny tiny amount of movement in and out. Hard to describe this but just a bit. Someone can probably tell you the amount as Cranky mentioned this above. Think I got it all here?

 

[Fran Blacker]

Ever try the reusable gasket from dr diff? Nice gasket, ran into a problem with axles. Pulled it apart a nd reused gasket. I admit it was only together for a few days.