8.5 swap ??

dickeymoore

dickeymoore

Greasemonkey
May 6, 2009
248
20
18
Atlanta,Georgia
#21
Yep axles too of you remove the backing plates,just remove the e brake cables
 
TURNA

TURNA

Geezer
Jul 24, 2009
6,575
8,448
113
Socialist NY
#22
That is absolutely nuts to do all that just to avoid doing the brakes!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
836
916
93
Upstate NY
#24
That is absolutely nuts to do all that just to avoid doing the brakes!!!!!!!!!!!!!!!!!!!!!!!!!!!
Only if you are willing to be driving the car with crappy brakes on the original 7.5.

FWIW, us here in the north country of rust belt USA rarely find anything original in the braking system that would be considered anything other than sketchy at best.. When we originally were using the stock 7.5 we rebuilt the factory drums, i.e. new hardware, shoes, cables, and freshly cut drums. When we swapped everything over to the 8.5 it was literally a 1/2 hour job and some piece of mind knowing everything was good and functioning correctly.

FWIW, 'all that' is 3 bolts per side other than pulling the axles. But pulling the axles would be a normal situation when upgrading anyway IMO.
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
24,191
9,405
113
Kitchener, Ontario
#25
axles shoudl be pulled on an unkown rear end to inspect them and new axle seals are a good idea since they are cheap and easy to replace.
 
bertscova

bertscova

Apprentice
Jun 27, 2015
83
36
18
#26
Axles are already out. But the backing plate on the 8.5 is much better than the ones on the 7.5. Plus the entire axle case has been sandblasted and repainted. I'm just removing ebrake cable from old 7.5 backing plate and connecting it to the 8.5. New raybestos shoes hardware and adjusters. Only old piece being used are the ebrake levers. New bearing and seals. New stainless lines and a braided hose. New drums ext...
 
ssn696

ssn696

Comic Book Super Hero
Supporting Member
Jul 19, 2009
3,401
2,169
113
New Mexico
#27
Isn't the backing plate different on the 7.5 and the 8.5?
I hope this advice is not too late to be useful. Unlike the front springs, the rear ones are basically impossible to launch once you disconnect the shock absorbers. The axle drops low enough on the control arms that you are more likely to have one drop out and have to chase it down the driveway before it rolls into traffic. The 8.5 and the 7.5 axles are identical from the pumpkin outwards. The difference is the axle spline count. Brakes are identical. Good advice about using a small hose clamp to compress the three fingers on the P-brake cables to get them out of the backing plates. I assume you painted the axle flanges and backing plates while you had the 8.5 out of the car. Sandblasted steel will rust quickly if untreated. The other tricky part about swapping the axle is the 10mm adjusting nut on the parking brake. Don't lose it - it has a fine thread with a plastic insert and it's hard to find a replacement (ask me how I know :rolleyes:). Do yourself a favor and take a picture of the cable routing so you can replicate it on the new axle. I have also used a pair of vice grips on the brake hose to minimize the amount of lost fluid - if you don't leave it on too long you will probably not damage it - this speeds up bleeding the brakes later. May not want to do that with braided lines...
Since you have all new control arms with new bushings, ovaled bolt holes on the factory sheetmetal arms are a non-problem. Save yourself some trouble and bolt the new ones ontot he frame while the axle is out. Dopn't tighten them down all the way...the right way to set preload on the bushings is to tighten them down once the car is on the tires. If doing this on your back, put jack stands under the axle tubes and then tighten them down. This way the bushings are not under a torsional load when the car is on the ground. If they are greasable, do that. If the axle is dry, fill it whent he car is close to level and don't forget friction modifier lube if you got a posi. Put a little vaseline on the axle seal lips before you slide them in so you are not spinning them dry before the gear oil distributes itself. Make sure the backing plate brake adjusting holes are open and clear so you can set the brake shoe star wheel. There is a specific too to do this, but a large flat-bladed screwdriver will do. The brakes will self-adjust, but you'll have no rear brakes if you don't get them close, but not dragging. If the fuel hoses are old, consider dropping the tank and replacing them now while the axle is out of the car. Harder to do later, especially with the transverse muffler in the way.
 
bertscova

bertscova

Apprentice
Jun 27, 2015
83
36
18
#28
Great info ssn696. Thats the stuff im looking for most of it I knew but some was new thanks
 
bertscova

bertscova

Apprentice
Jun 27, 2015
83
36
18
#29
Any tips for putting the upper control arm bushing in the rearend housing. I have some big hammers a freezer and a torch if you see where I'm leaning
 

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