8.5 rear axle

[82GPLJ455]

Im getting an 8.5 rear out of a GN.the problem is it has a bent axle tube.i have not seen it with my own eyes yet.i figured at worse ill need to replace the tube and maybe the axle.

Would my 7.5s axle and tube fit it?i have all the necessary equiptment to replace the tube if it cant be straightened.

if the 7.5 tube and axle wont work,what will?i can shorten a tube and weld brackets if needed.

Im getting a smokin deal on it.gotta replace fuel and brake lines on a chevy truck for it.id be stupid not to snatch this deal up.

 

[82GPLJ455]

Well,here it is(on the right).im gonna say the tube needs to be replaced.


Soooo will the tube and axle from the 7.5 work? If it wont i can get a tube from something that will work and weld my brackets and backing plate flange to it if i have too

 

[ssn696]

You might wish you tied a longer string to this idea-balloon. This is not a job for an amateur. When manufactured, the cast iron center section is heated in an oven, the axle tubes are pressed in using a jig that aligns them properly, then the tubes are anchored using three plug welds on each side. When it all cools, the tube is gripped in the housing tightly.

The plug welds have to be drilled out, the axle tube cut off, then the center section machined precisely to remove the remains of the axle tube. You might ask a place like Moser if this something they do for customers, just to get an idea of what's involved and ballpark cost. By the time you pay for all this, it might be cheaper to wait and pounce on an 8.5 in better condition that is not damaged.

 

[theoldsone]

I tell you right now that a 7.5 tube is smaller than a 8.5...or it looks like it to me.

You definitely need to replace the axle. Id make sure your spider gears didn't take a hit either. How did this happen? In all honesty for a 8.5 like this...how cheap was it, because its not all bad. All it really is is bent 2-3 inches from the end of the housing. If i where you id straighten it out.

It would take a couple of special tools like a dial indicator a level (measuring in degrees) and a heat torch and a jack or press. It may seem like a hack job but thats how its done. The tube isn't kinked or pinched its just bent. Its probably the best way to save it. Gut it out inspect it for cracks etc. You want to figure out how "bent" it is first. How far off is it from the center line. If i had a chance to grab this rear id straighten it out and you would never know.

 

[82GPLJ455]

I got it cheap.replacing brake and fuel lines in a pickup for it.im gonna take it to a machine shop to see if they might be able to straighten it.

The tube looks the same size as the 7.5,was hoping someone might know.


Im far from an amateur,been wrenching everyday of my for 21 years(think its time for a change).swapping a tube can and has been done many times without the "special tools".if it dont work out im out a couple hours labor on the truck and i find a housing that needs the guts.

 

[ssn696]

I will freely admit that I am ignorant. If you can pull it off with a torch and some perseverance, then you will have earned your 8.5 more gloriously than this punk (me) did by laying down some cash. Do us a favor and take pictures and report your progress.

 

[truracer20]

You need an alignment bar, a press and a couple of dies that match the diameter of the axle tube. The alignment bar bolts to the bearing caps, and centers inside of the outer wheel bearing bores. You mount the bar to the caps and center it in the straight tube(hopefully that side didn't get tweaked as well) then press the bent tube using a die on top and a couple under the tube until you can center the bar in the bearing bore on that side. I've never looked to see how available alignment bars are for these rears. They are widely used for building 9" rears, maybe one of those would work on these as well. An actual alignment bar is dead straight and will not flex under its own weight. You do not want any toe-in or toe-out period. A degree of camber +or- won't hurt you but it is still undesirable.
You may need a slide hammer to get that axle out.

Heat can be your friend and enemy when doing work like this, the heated area will bend easier than the unheated area which can lead to kinks.

 

[chophead]

I have been in a machine shop for 28 yrs, (I have my own now) I would straighten it. But I would also reinforce it afterwards. If you truly feel the need to replace it heating the center with a torch after doing all your prep work 1st will be fine to seat the new tube in place and then plug welding it. I my self would weld new mount on rather then taking the chance of them being off after welding and cooling takes place. I have worked at a shop that did narrow rears for drag and circle and thats how we did it. We even respline axles if we had to cut and narrow a rear. But myself if I had to take the road of repair I would sell the parts from that and weld up everything for a 12 bolt. But if you want to do the work try straighting it 1st. But as mentioned check for cracks before and after. Good luck

 

[vanrah]

Good Morning 82GPLJ455 & all; I have an axle out of my 8.5 that is in very nice condition & another that isn't. I'd like to sell one or both. Generally after years of use the right one will have bearing damage on the race & that leaves you with one good one. But a good welder that spray welds can repair bearing race damage? I don't know what they are worth, but a couple of years ago a guy was interested & I went to UPS to get a shipping cost. To ship one then was about $43.00 & both was like $60.00 if memory serves. Make me an offer, I would like to get them out of my garage. Bob Jr.

 

[82GPLJ455]

Might not have to mess with the bent one.a buddy found another one he was gonna buy for his cutlass.he doesnt want to deal with having the driveshaft cut.so he wants to go buy it and trade it to me for my 7.5 3.73 posi installed into his car.