OK, my current housing has a bad vibration in it, my local Mopar guy pointed out that it looks like the housing is bent...all driveline parts are new, U-joints, driveshaft, bearings, pinion angle is correct (street setup) etc, etc...

What local Detroit shops are capable of checking the housing for being straight? I have a spare one that I'm thinking of cleaning up and getting ready for a swap.

I'm thinking DTS??? Anyone else?

Thanks!

I would think that you could test the housing for straightness by using a kit that is used to shorten or build a housing. You know, the kit with the pucks and the bar. You should be able to find that kind of kit locally from someone who shortens rear axle housings. I know a few guys who have them. One guy might loan me one.

DTS...

Ring and Pinion Shop...

Warren Gear...

Joint Clutch and Gear...

Take the time to check it yourself take two straight edges or two steel yardsticks and a helper, take the rear wheels and brake drum off and measure out about 15 inches from the center of the alxes, keep the straight edges tight to the axles flanges and measure to the front of the yard sticks parrelel to the ground, then measure to the back at 15 inches and then as high as you can in the car up and then the same distances down, IE 9 inches up to clear the subframes and then 9 inches down Compare your readings, if it is within 1/8 or less forward to back and up and down your golden, if it is more than that then worry Roundy round racers like to see about 1/8 inch toe in on the front they will also cocked(set the housing in on a angle) the rear end in the chassis depending on the track, short or long and so on Let us know what you find

A bent housing alone cannot cause a vibration.
Bent axles, perhaps but the bent should really obvious to see.
You can take out the axles yourself and check them for straightness.

I suppose you have excluded the engine as the source of vibration with the usual checks?

I have a narrowing fixture I used/made when I narrowed my Dana 60 housing. I would imagine it could be bolted up to an 8-3/4 & when the center shaft was inserted if it won't slide straight thru it would tell you if the housing was bent or not.

I did bend up a stock non back braced 8 3/4 housing up in my Duster with ladder bars, it ended up breaking the ladder bar brackest oof of it on a run The car was talking to me, the right side axle had to be driven in with a block of wood and a hammer I had that housing narrowed and out a 35 spline spool and axles in it, stupid me didn't listen to the car When in doubt, about anything(especially women )on race cars, check it out, it is probally not correct or right

A 4 wheel alignment would tell you also and I agree a bent housing would not likely cause vibration. Tire scrub maybe, funny handling maybe but not vibration.

Thanks you guys!

Let me explain the symptoms and why it was suggested to me that the housing is bent.

SYMPTOMS
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1) with the rear end up in the air, so tires are off the ground, in fact tires can be removed, drivetrain in N(eutral), I can turn the wheels forward easily, but they are extremely hard, nearly impossible to rotate backwards, brakes are not a problem since you can remove the drums and turning by axle flange produces the same result (my local shop buy pointed this out as a proof of a bent housing)

2) the rear tire thread has a wear pattern, the pattern is nice and even across the tire on the pass side, but on the driver side the pattern is off-center and towards the inner sidewalls of the tire

3) at higher speed, so around 30-40 mph a noticeable vibration is present, it is cyclical, almost like a repeated SG clutch chatter that you might get going around a sharp corner

The rear end in question is using a '741 carrier, 3.91 SG ratio. New MP clutch kit, only about 500 KMs of use since rebuilt. All new bearings. Fluid is a synthetic mix with the SG additive.

Driveshaft is brand new from DynoTech in Troy, MI...as are the U-joints, yoke, etc.

Engine assembly was balanced at the machine shop, I do not feel any vibration when revving on it's own.

What I can tell you though is that this very same housing, but a different carrier were previously used in another car of mine. I do remember having a similar vibration and back then, not knowing much about Mopars and drivetrains, I simply attributed the 'shake' to bad driveshaft (it was a stock piece), bad U-joints (stock as well) and so forth. So the housing is he only consistent part that seems to 'move' with the vibration.

An auto trans will allow easy movement in one direction and hard in the other. This is normal and has nothing to do with a bent rearend.