Rear wheel wobble

[FestYboy]

I'm lost...

I have a 90L that came in for inspection. While in the air, we noticed both of the rear wheels (stock alloy) wobble when spun. Bearings are tight, wheels spin true on the balancer, pulled the RR drum an it spins true on the brake lathe. Put it all together an there's about 3/16" deflection at the wheel lip as it spins... Drums are under 1000 miles old as are the bearings ( I put them in and didn't notice it then). The thing that's really blowing my mind is that BOTH rear wheels do the same thing.

[1990new]

Could you have bent axle spindles? Drums warped...even if only 1000 miles could be possible.

[fastivaca]

It sounds like the wheel is seating fully on the brake drum. Is the wheel going fully over the hubcentric bit? A bent spindle wouldn't result in a wobble; the wheel would just be at an angle.

[FestYboy]

Everything external seats as it should. I can only think that the roller/cage is malformed...
But I'm open to more ideas.

[jbibb1]

Are the four mounting bolts for the spindle tight?

[WmWatt]

Check to see if the brakes pulse?

[tooldude]

If there is one high spot in 360* rotation, it sounds like the problem could be between the mating surfaces that are between the wheel and brake drum - maybe one or two high spots where the lug bolts are - on either or both. If you mark them and turn the wheel 90*, does the high spot move 90*?

[WmWatt]

What are the chances of a bump on the back of the rim where it contacts the drum which was not picked up on the wheel balancer? I don't know enough about wheel balancers to know if it could happen. You say alloy rims which rules out an uneven surface due to rust. Another possibility is an uneven surface on the drums but they are pretty well protected from rusting.

[FestYboy]

Check to see if the brakes pulse?

Yes but minimally, and tooldude, all surfaces were cleaned with a cookie: no rust or high spots to speak of. The wobble doesn't change by clocking the wheel on the drum.

[Studebaker]

Bet you got two bad drums. Both came from the same batch. Both have the same problem.

[FestYboy]

I'm starting to suspect the same thing, but I had the worst one on the lathe, and I didn't see any issues... It vexes me.

[Studebaker]

Put it back on the lathe. Use a dial indicator on the mating surface. It does not have to be much at the drum to be way out at the edge of the wheel. Or put a known good drum on and see if problem still exist.

[FestYboy]

Issue is, it's not my car and I don't have access to it at my leisure, but I do all the work to it.... A sticky web we weave. When I get a chance I'll lathe them because they are new units (milage wise anyway)

[WmWatt]

You could take off the rims and check the drums for wobble? If the drums wobble it could be bad drums or the bearings are seated unevenly?

[FestYboy]

Drums move on the spindle but not on the lathe. I installed the bearings... Proper tools and all. Not saying that it couldn't be the case, but it's a LOW possibility. The car sits for a week at a time (aka groceries once a week).