Help diagnose rear wheel wobble

N

NVRL8

Huge Member
Joined
Oct 27, 2006
My driver's side rear wheel wobbles when the tire is rotating (from positive to negative camber). Here is what I have done so far:

Properly torqued lug nuts, changed wheel for known good, changed out drum for known good. After this I put the car on jack stands, removed the wheels and drums, and watched the axle shafts with the car in drive. The driver's side axle shaft wobbled. I changed the outer axle bearings (old ones in good condition), and swaped axle shafts for new Moser's. Buttoned it all back up and the problem remains. Not sure where to go from here.

The car doesn't make any unusual noises or have any vibrations.
 
How severe is the wobble? If you swapped the parts that spin with known good ones and you still see it then it pretty much has to be an illusion. I would think that if you really had a wobble you would feel it when driving.
 
The tire wobbles about 1/2 inch side to side. On the passenger side there is no visible wobble. Could it be the carrier or related parts? The driver's side drum gets much hotter than the pass. side. I'm guessing this is from the drum contacting the shoes as it rotates out of round.

As far as driveability, on occasion during a slow left turn I can feel a slight drag but its really difficult to tell where that's coming from and may or may not be related.
 
It's not the tire. I have swapped rim/tire with same results. No u-joints in rear axle assembly.
 
I would pop off the rear cover and see if the carrier is causing it. Maybe bad inner bearings. I would assume it doesn't do it so much under weight as that type of movement would probably make the car undrivable if it persisted with weight on it.
 
The only way you can get a wobble on a rear wheel is, bent axle, bent axle flange, rim not seated on the axle flange or a problem with the rim. if you can get a dial indicator, set it up to run against the axle flange and see how it changes as the axle is turned. I would bet someone slide the rear into a curb or the axle is twisting.

HTH
David
 
NVRL8 said:
It's not the tire. I have swapped rim/tire with same results. No u-joints in rear axle assembly.
Click to expand...

How hard was it to get the axle in and out.My right side axle tube was bent and I had a similar problem.
 
BlackBandit said:
I would pop off the rear cover and see if the carrier is causing it. Maybe bad inner bearings. I would assume it doesn't do it so much under weight as that type of movement would probably make the car undrivable if it persisted with weight on it.
Click to expand...

When the cover was off from swapping axles there were no teeth missing on the gears or any unusual wear. How do I inspect inner bearings or carrier? What do I look for?

DavzGN said:
The only way you can get a wobble on a rear wheel is, bent axle, bent axle flange, rim not seated on the axle flange or a problem with the rim.
HTH
David
Click to expand...

Exactly what I thought. The the thing is I have swapped all those parts out for known good ones and the problem still remains.

chopped39 said:
How hard was it to get the axle in and out.My right side axle tube was bent and I had a similar problem.
Click to expand...

The driver's side definitely did not move in and out as freely as the pass. side. I could move it by hand, but it required some effort. I thought that a bent housing wouldn't cause the wobble type of movement?
 
Even if you swapped axles for Moser's, the axle flange could still be off...I know this by experience as I do have Moser axles and several years ago, I had to remove one of them and have the flange machined to straighten it. No problem since...Also, could it be a tire that's "out of round" ? Even if you replaced them, you could've gotten another bad one!

Claude. :smile:
 
My exact tire has had the same problem since I bought the car. I bought another axle a few years ago and still haven't put it in, lol. I just haven't had the time. In my mind I just assumed the axle was bent and what else could it be? One of my T wheels has some moderate rash and I just assumed somebody slid the car into a curb (probably hammering the sh*t out of it, you know?). I haven't worried much about it, but the axles still on my "to do" list.
 
Did this problem really turn-out to be just a bent axle tube? If so, can someone please explain "how" a bent axle tube can cause a wheel to wobble? I could see that happening in conjunction with some other problem, like a broken differential carrier, badly worn carrier bearing (maybe from driving with a bent tube for a long time), or a bad side gear, but not a bent tube alone.

I once cracked the bearing flange on my stock carrier, so now I use an Auburn diff. The car drove fine with the cracked carrier, but made odd noises. I wouldn't be surprised if a wheel was wobbling too during that time.

This thread implies that a bent tube alone was the cause and I'd like to better understand that, or get the thread clarified so others are not deceived. In my experience, the axle shaft itself must have been the cause, presuming it wasn't a bent wheel, bad tire, or one of the other conditions above.
 
the bent tube changes the flange position , the axle is flexible and follows what it is in and the small axle flex transfers to the flange which shows as bigger issue at the rim edge
if you replace the axle it will do the same thing

the tube can be bent from launching hard or potholes but usually its from a flatbed tow truck winch using hooks on the axle and cinching it down

pull axles , pull posi , install an axle center jig and check it , bend to correct .
i use an axle narrowing fixture kit with a 1.25 stainless shaft and then use a steel beam, 3" straps at each end and a 20 ton bottle jack , have even bent them back with axle still in the car on the lift
 
Last edited:
pacecarta said:
the bent tube changes the flange position , the axle is flexible and follows what it is in and the small axle flex transfers to the flange which shows as bigger issue at the rim edge
if you replace the axle it will do the same thing

the tube can be bent from launching hard or potholes but usually its from a flatbed tow truck winch using hooks on the axle and cinching it down

pull axles , pull posi , install an axle center jig and check it , bend to correct .
i use an axle narrowing fixture kit with a 1.25 stainless shaft and then use a steel beam, 3" straps at each end and a 20 ton bottle jack , have even bent them back with axle still in the car on the lift
Click to expand...

I understand that the axle shaft flexes if the tube is bent. However, unless the bend in the tube somehow changes as the axle shaft rotates, or unless the axle shaft flexes differently at different rotational angles as it rotates, the lug flange angle relative to the road should be constant as the wheel rotates. Sure the camber or toe could be way off, but it shouldn't vary with wheel rotation, and thus the wheel shouldn't wobble.

If the axle shaft is straight, made of good steel, and accurately machined, it should bend the same throughout its rotational range... meaning it should take the same amount of force to bend it to a given angle regardless of where it is in its rotational range, as it acts like a spring is when the tube is bent. The axle tube should also stay bent at the same angle throughout the axles rotational range unless something else causes the bend angle change. So why would the wheel wobble if only the axle tube is bent?

The tubes on my axle aren't perfect. As I recall there is some minor camber and toe angle, but not enough to affect tire wear or the way the vehicle tracks, that I know of. It has been that way for more than 200K miles. I have twisted axle shafts before, which certainly causes the wheel wobble. I have had a new axle shaft that had its lug holes drilled wrong that caused wheel wobble when using tapered-lug-centric wheel mounting. New shafts fixed the wobble in both cases. However, my axle tubes have been bent for 27 years and the rear wheels don't wobble at all, or at least enough to be noticeable.

It must be a function of how bent the tubes need to be for big problems to occur. Perhaps you can prescribe some rear wheel alignment numbers (camber and toe) beyond which the axle should be straightened.
 
Last edited:
not sure why you need an alignment spec for rear axle ...its a solid axle
solid axles should only have a thrust angle which should be centered to the chassis
you could have a thrust angle thats not at 0 from worn bushings , worn bolt holes, bent mounts
stock arms arent adjustable . aftermarket adjustable arms allow for correcting thrust and pinion angle

if you want the camber toe specs of what a solid axle should be heres the alignment numbers...
0* camber 0* toe or 0.0" camber 0.0" toe and for metric guys thats 0.0mm camber 0.0mm toe
i its not zero its bent , if you have a wobble its excessively bent
 
pacecarta said:
not sure why you need an alignment spec for rear axle ...its a solid axle
solid axles should only have a thrust angle which should be centered to the chassis
you could have a thrust angle thats not at 0 from worn bushings , worn bolt holes, bent mounts
stock arms arent adjustable . aftermarket adjustable arms allow for correcting thrust and pinion angle

if you want the camber toe specs of what a solid axle should be heres the alignment numbers...
0* camber 0* toe or 0.0" camber 0.0" toe and for metric guys thats 0.0mm camber 0.0mm toe
i its not zero its bent , if you have a wobble its excessively bent
Click to expand...


I have never seen a solid axle vehicle show 0.0 camber and 0.0 toe, regardless of the units. However, I prefer degrees, and if you're measuring 0.0 degrees, you probably don't have enough resolution to see 1/10th of a degree. I was hoping for a rule-of-thumb for how much is too much, as perfect toe and camber seems like an unreasonable goal for a street car. In Michigan, if I were to get it to 0.0 degrees, it would be that way for about 1 city block before a pot hole changed it.
 
ive seen some vehicles with adjustable rear suspension and they look for 0 and 0 but acceptable on a rav 4 spec that popped up on google search showed acceptable specs for camber at -1.8* -0.3* and for toe 0.1* 0.018*

http://www.rav4world.com/mods/ALIGN0311.jpg

but keep in mind those suspensions that can be tweaked by moviable arms and a spindle that moves the bearing with the tire flange as one so no bearing bind , they dont have a sold axle with a solid tube connecting them with a bearing thats fixed that should by all rights should be true and at 0.0 ( dont care what measurement you use zero is zero! ) .. anything else is bent

i have had cars that literally bounced on the rear wheel and the garage that had it replaced the axle with another stock axle only to still have the same problem.
I pulled the axle , straightened the tube ( could see it was bent and didnt have the jig just went by the axle position as it slid in and bent accordingly ) , reinstalled the same axle and problem was solved
 
Last edited:
You must log in or register to reply here.

Similar threads

ttypewhite
SOLD
Replies
0
Views
531
ttypewhite
ttypewhite
Big Dawg
Longtime .... Update on my 1985 Grand National
2
Replies
35
Views
5K
Big Dawg
Big Dawg
B
Extreme Driveline vibration. Help!
Replies
12
Views
2K
BOP Nutt
B
B
Alignment techs jump inside and help me out here - long read
Replies
4
Views
509
BuickMike
B
U
Had a little Mishap with the LS1 brakes today...
Replies
4
Views
851
novaderrik
N
Top