fv64olds98

I have been chasing for months a rear end vibration, I was told by a shop it was the drive shaft. I had it rebalanced, and the vibration was still there. I lifted the rear end and put the car in drive. I could notice wobble on the rear driver wheel. I changed the wheel for one that is just balanced and the vibration still there. I took of the brake drum and the brake drum is completely worn out (thin wall) on one side and almost new on the opposite side (thick wall).


This caused the drum to be unbalanced. Got a new drum and shoes and the vibration is almost gone, but when I brake I can feel the braking is very uneven and when I turn the rear wheel by hand I can feel the shoes rubbing against one side of the drum and then turning smoothly once past that part of the turn.


The conclusion I have is that the only way this can be happening is that the axle is not turning on its center and that either the axle or flange are bent


Is my conclusion correct? or could it be as simple as a bad axle bearing? The axle seems to rotate smoothly and without play once the drum is removed, and there are no noises.


Can the Axle be fixed or does it need to be replaced?

Junkman

Axles rarely bend, before they break, so I doubt that it is a bent axle, but it is still a possibility. Jack up that side of the car, and put a long pry bar under the wheel, and lift. Is there any play in the bearing? If so, you need to determine if the bearing is bad, or if the housing where the bearing resides, might have gone bad. My guess is that it isn't the axle, but either the housing, or it could be that the bolts that hold the backing plate on, might have come loose. The wheel and drum turn on the axle, so they can't effect the imbalance, however, if the backing plate has come loose, it can change the plane that the brake shoes are supposed to take in relationship to the brake drum. There is definitely something drastically wrong, and only careful examination, and comparing it to the other side of the car is going to tell you exactly what. Time to trade your tools for a magnifying lens, and a ruler, and start taking measurements. Possibly the brake cylinder is wrong. What is the history of this car? If someone was in there before you, and you bought it like this, then you will just have to keep searching until you figure it out. If you did a brake service on the car, then possibly you put something back together incorrectly. Without being in front of it, all I can do is make an educated guess. Good Luck, you might need all of it that you can get..
Junk

oldcutlass

Is this vibration only during braking? Did you true your drums? They may be warped do to heat.

fv64olds98

I replaced the drum that was worn out uneven with a brand new one. The old one was worn out way more on one side than the other. The only way this could happen is that is not spinning on its center. Even if the brakes or backing plate was not align, the drum would have still worn the same amount across the entire circumference. The new drum makes the brake brake pedal vibrate, probably because it is braking harder on the new surface which was worn out on the old drum

Sugar Bear

I have never seen an axle bearing do this. Bad axle bearings usually make a whirring or growling noise and if the bearing was that bad it would probably cause the seal to leak.

Use a dial indicator on the other axle and compare the specs to the one with the problem or swap the axles from side to side and see if the problem stays wit the axle or the side of the car. If it stays with the side of the car the backing plate is probably bent.

I am guessing by your username the car you are working on is the 64 98. Does anyone know if the axles can be swapped left to right?

Is the centering hub on the axle in good shape and is it a snug fit to the drum?

Good luck!!!

RandyS

I would vote for the bent axle. I had the exact thing happen back in the day, wet roadway, heavy foot, slid sideways into a curb, broke the aluminum rim and bent the axle.
You can check it out by swaping the axles side to side. If the problem moves to the other side of the car, you know what it is.

nsnarsk65cutlass

X2 bent axle flange.

fv64olds98

Thank you all for your replies. I will take it apart once I get back from Thanksgiving. I have a dial indicator, I will compare both sides and carefully inspect.


I bought the car 2 years ago and just finished restoring it. This is one issue that I had not noticed till recently.

oldcutlass

You can figure this out with a runout dial gage or look for the tire to wobble.

fv64olds98

Hello All,


I measured the Axle run out from the face plate of the Axle the lowest reading I got was 87 and largest 94. That is 0.007 in.


I also pulled the axle with my hand as much as I could and got a reading of 105, then I pushed it in and got a reading of 65. That is 0.04 in of end play from and to the direction of the differential.


Are the values above within spec.


There seems to be no radial play (that is I cannot move the axle from side to side or from to bottom.


I have a slight vibration at 70mph. The vibration used to be real bad until I changed the drums and shoes in the back. One of the drums was worn out in a non centric way and was totally out of balance.


I am trying to figure out why that happened, and the only conclusion I have is that either the axle is bent, the wheel bearing is bad, or maybe something bad with the differential.


Now that I have the new drums and shoes in, I am getting vibration when I step on the brake, as if the new drum is not rotating centrically and the shoes touch harder on one area of the drum.


If I turn the drums by hand with the rear on the air, I can feel there is a spot where it rubs. I can also notice that the drums seem to wobble a very slight amount when measuring perpendicular against the drum outer diameter (about 0.015 in)


Any help would be really appreciated. Trying to figure out what to do next

oldcutlass

If your getting a vibration when hitting the brakes, I say the drums are out of round. I always true new ones lightly to be on the safe side. It could also be the front brakes causing the vibration as they are applied. If you mount a wheel and run your gauge on the outer rim facing and on the edge of the rim bead is there any deflection?

coppercutlass

I had a visibly bent axle housing and axle no vibration what so ever. make sure your tires don't have flat spot . My car sat all summer first time I drove it had horrible vibration at low speeds to more I drove the more it went away. Worn out tires and our of round tires will do it. My daily beater had it real bad I thought it was brakes it was just really badly worn tires. Just a thought. With out of round tires it can get worse as you apply the brakes and the car noses down and there is more pressure on the imperfections. that would be on the front and you would feel it in the steering. Rotate tires and see if it changes rears In front the fronts in the rear. Unless you got bigs and littles or some other offset wheels etc etc. My dads car has new t/a radials but the car sat for some time and they have flat spots over time they have gotten better but at 70 mph you feel it. it used to be at lower speeds.

Ozzie

Hollander says that both axles on the 1964 98 are the same. They will interchange back to 1959. (Newer and the Jetstar 88 are different.) The older ones have right & left hand studs. They have 31 splines and are 30-1/2" long.

droldsmorland

Lots of people miss the drum or rotor being out of whack when trying to chase down vibes. So you are on the right path. Run it up on stands while the drums off to see if the axle has run-out. You've likely got another bad drum. If the shoes are adjusted too tight this will cause chatter when the shoes get hot. Id inspect for signs of heat then have the drum shaved for good measure. My bets on drum run-out.