What do I need to watch out for when I have a shop remove the mono-leaf perches from my 12-bolt, and weld on new multi-leaf perches?

A bent housing when they are done.

I'd ask them if they've ever welded something on an axle tube before. Welding can warp the tube if not done right.

Be sure they don't gouge the axle tubes when they cut off the old mounts.

How hard is it to warp the housing? I have to do this to fit a 8.5 from a 79 into my 68 and will be welding it myself. what technique should I use? (Hobart 135 mig welder)

Thanks.

Could you not find a 8.5 from a '71-'74 Nova or a Nova clone? They bolt in with no modifications.

The 8.5 I am using from an 81 TA with rear disc because I want 4 wheel disc (I have the C4 conversion stuff for up front). that and I got it for $150, it was too sweet to pass up. When I read your post I got a little nervous about ruining the axle tubes when I weld on the perches because I am a beginer with the mig.

you could score a Nova 8.5 housing pretty cheap- i think mine was $50 3 years ago, and they took it out. your brakes will bolt right on to that rear, and you could sell off the newer housing to offset the cost of installing the gears and everything into the nova rear.

I wanted to bring this up again because I am just about to do this. If I take a 8.5 from a 71 - 74 will the AXLES & Posi unit from the 81 Trans Am fit into the 8.5 nova housing??? Its important because the axles lip is slighly longer to accomedate the thickness of the rotor over a drum.

Thanks!

The axles are longer they wont fit in the Nova housing.

Hmmm, another stupid question. I am wondering if I can use these instead of the multileaf spring perches, http://www.detroitspeed.com/AdjustableLeafSpringPads.html But I can't figure out how they work? how do the springs 'bolt' to it???

I am also looking at installing hotchkis multisprings onto an 8.2 10 bolt 67 housing. It had a new 4;10 Eaton Posi installed just before I got the car so I want to keep it. What kind of a perch do you buy? is it a part you can get new or do you need to find one on an existing car? Somebody told me Ford perches (???) Help pls

Micky Jegs or summit has them. I think Moroso makes them. Ricks first generation has them also

It's also possible to damgage the bearings when they are arc welded. Not sure how, but my chassis builder INSISTED the bearings be not yet installed when in welds the perches on.

Welding can cause arcing between the ball bearings and/or cage assembly causing microscopic dimples/burns in the balls making them ware out faster. graemlins/sad.gif

Another note ... do not shake or spin new bearings, this will trash them too. graemlins/sad.gif
Always pack a bearing properly.

you can weld on the housing with the bearings installed as long as you keep the welding ground clamp close to where you are working so the electrical path doesnt have to travel through the bearings to reach the ground clamp. Welding in short spurts will minimize warpage.

Interesting stuff about the bearings being damaged by the welding process. I would have guessed that the shop would not want the bearings in place as they would have to be out in order for the jig to be put in place during the welding process. I am glad someone spoke up about the bearing issue.