last week I drove my '80 Stardust. Discovered I had way too much toe in. but the real kicker was seeing my left rear wheel proudly wobbling. I had rebuilt the rear. new axle shafts. New bearings. New LSD. Only used parts are the housing and the ring and pinion. I swap the rear wheels , wobble stays on the left. so its unlikely the wheel. I pull the axle shaft and attempt to run a dial indicator. unfortunately I'm not really set up to get accurate readings and I could find the tolerances in the FSM anyways. at least for hub runout. I go to the local axle shop. 70 years of service to my town. Ask them if they repair axle housings. at this point I'm thinking the axle housing is compromised. Dude suggested to check the wheel at a tire shop and seriously doubted it was the housing. but not an impossible situation. Tire shop says the tire was a bit off balance but ok. Google searches always lead to these culprits. Wheel, hub, bearing or housing. For the sake of it. I removed all the brake hardware, including the brake rotor and mounted the wheel directly to the hub.

its the damned brake rotor. wheel wobbles with it on, stays true when it's off. placed the rotor on a glass surface and used a feeler gauge and there is a definite warp. I was nearly road ready. I took a few days to step aside because I was sure I was going to need a new axle housing. So its off to buy a new set of rear rotors.

 

Always feels good when you find the culprit!

 

Great post, great work figuring it out!

 

Weird. I'm wondering if at the factory that particular rotor was put on the lathe incorrectly or there's a bad batch of rotors out there.

 

I don’t understand the defect. All I know is when the disc rotor is removed, the issue goes away. I’ve got a set on order.

 

Where did you get the rotors? What brand? Glad you sorted it out.

 

Rotors are old and history unknown. I’m going to try a Rock Auto solution first. I’m getting some on facebook that claim it has to be the axles. Honestly, I have a hard time believing what my results are myself.

 

parts quality has definitely gone off a cliff in recent years.

 

Can't you check the runout of the axle face with a dial indicator and then put the rotor on and check it?

 

Had the same issue with rear wheel wobble, and did the same thing Kansas suggested. (May even have been following his advice!) In my case I had movement on the dial indicator with rotor on and with rotor off, meaning axle itself was bent. Double checked my findings by marking the rotor at its extreme amount of wobble deflection, then rotated it by 180 degrees on the axle... point of extreme deflection was now at the opposite side of where I marked the rotor so proving issue was axle. Its a quick test, especially if everything is already off so the axle end is accessible.

 

From a mechanical engineering standpoint, it's more likely to be a bent axle on both sides than a brake rotor machined out of dimension. OP said he put them on a glass pad and can confirm it's the rotors that are the problem, so new rotors will tell the tale. Please report back, and let us know what brand to avoid,

 

it's surprisingly difficult to check axle and rotor face runout, mostly due to surface corrosion.

 

It could be crusty crud on the axle face or the rotor surface that mates to the axle. I would swap rotors left to right and see of it follows as well.