Rear Wheel Noise / CV ?

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sped372
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Rear Wheel Noise / CV ?

Post by sped372 » Wed Oct 06, 2010 5:47 pm

Another issue on the Ghia. Noticed a repetitive tock, tock on the final stretch of the carpool home. Seemed to appear after a braking session from highway 55 to in-town 25 mph.

On the street in front of the house, engine off, noise is still apparent and definitely coming from the LR wheel. Removed hubcap and trim-ring to make sure they weren't contributing. They weren't. Tightened lug nuts, they were fine, no change in noise. I'd say it's roughly once per revolution. Cotter pin is still there on the big nut, but I've lost light and time today to verify it's tight.

Also noticed it only does it when pushing the car forwards, not backwards.

I'm thinking CV?

The noise is hard to describe, but definitely sounds like something briefly sticking and then letting go. Almost like a brake shoe hanging up briefly and then releasing its stick-shion.

Any further test suggestions? Pull the drive-shaft on that side and repeat the push-test?
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Hippie
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Post by Hippie » Wed Nov 24, 2010 7:00 am

Sounds like a CV. Does it get louder and quieter when you swerve the car left and right or turn sharp corners?

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Post by Amskeptic » Wed Nov 24, 2010 10:16 am

Hippie wrote:Sounds like a CV. Does it get louder and quieter when you swerve the car left and right or turn sharp corners?
Rear wheel drive CVs are not sensitive to corners like the front wheel drive cars that tock tock tock like mad at the Dollar Store parking lot.

Off the ground, rotate the wheel and look at the axle. If it is jerking axially, the balls are "catching" in their wear grooves. Check for radial play. Place car in gear and rock the wheel back and forth. There will be gear train play, but look at the boots and see if you can spot the joint's play. You can try to hold the inner joint and feel for play there, then hold the axle shaft and feel for outer joint play.

I think these things are a whole lot tougher than people give them credit for. Even dirt-damaged joints, nicely cleaned and thoroughly greased, can give you hundreds of thousands of additional unexpected miles, like those insanely pitted Road Warrior joints at a half-million miles which are waiting for a chance at some more miles on the BobD.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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sped372
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Post by sped372 » Wed Nov 24, 2010 10:43 am

These symptoms didn't show up again this year and we just winterized the car. I didn't think I'd be able to diagnose if the symptoms weren't there so I have to wait for them to show back up and then jack the car up and spin the wheel. Otherwise I expect things to be less than conclusive.
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Hippie
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Post by Hippie » Wed Nov 24, 2010 6:48 pm

Amskeptic wrote: Rear wheel drive CVs are not sensitive to corners like the front wheel drive cars that tock tock tock like mad at the Dollar Store parking lot.

Off the ground, rotate the wheel and look at the axle. If it is jerking axially, the balls are "catching" in their wear grooves. Colin
I learn stuff everyday here.

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Tue Jun 28, 2011 5:47 pm

Ok, the Ghia's been out awhile this year and the symptoms came back in the last couple days. Got under there this evening and wasn't able to discern anything with the car on the ground. I pulled the drum and nothing looks out of place inside there - I think the brakes are fine. With the hub back on and the parking brake on, I can feel a noticeable amount of slop in the axle rotationally... I can grab the outer part of the CV and "tock" it back and forth. It's not a clunk, but it's bigger than a click. There is relative movement between the CV housing and the stationary drum assembly. I crawled under the other two vehicles and niether of them seemed to exhibit this behavior... they're tight rotationally. I can push/pull the axle axially (it is sliding on the splines inside the CV) but that's not what I'm referring to. I also double checked that all the bolts are tight, they are/were.

Should there be rotational slop in the joint? I'm thinking/hoping that's where the noise is coming from. I'm game for digging in and disassembling the joint to inspect it... but want to make sure I'm heading in the right direction before getting elbows deep in the sticky stuff.
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Tue Jun 28, 2011 6:13 pm

While I'm writing, what about the stub axle and it's associated bearings? There was some play there also... how much is acceptable? With the drum off I was able to wiggle the stub around slightly - can't imagine it's supposed to be that way.
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Amskeptic
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Re: Rear Wheel Noise / CV ?

Post by Amskeptic » Thu Jun 30, 2011 6:06 am

sped372 wrote:While I'm writing, what about the stub axle and it's associated bearings? There was some play there also... how much is acceptable? With the drum off I was able to wiggle the stub around slightly - can't imagine it's supposed to be that way.
I can't quite follow your descriptions, but

"I can grab the outer part of the CV and "tock" it back and forth. (??) It's not a clunk, but it's bigger than a click. There is relative movement between the CV housing and the stationary drum assembly.

Isn't this downstream of the CV joints? Isn't this between the stub axle and the drum? Check for play in the stub axle/drum splines. See if the axle nut has loosened up. It doesn't really "loosen", what happens is the spacer between the drum and the thrust surfaces of the stub axle wear, and allow the clamping force to drop down . . . this allows spline wear to ramp up.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Thu Jun 30, 2011 6:21 am

I started taking this apart last night. The car has had a pretty noticeable rumble since we've had it (did you notice it when you drove it when you were here?) and the stick/pop/tocking noise was definitely coming from the left rear. I figure it has to either be the CV or one of the wheel bearings. I was planning to clean and inspect all of the components for good measure. I've got the drive axle off, the stub axle out, and the bearing cover off so the bearings are exposed, but still trapped behind the grease seals.

Back to my poor description.... there are two separate observations I noticed:

1. The CV itself seems a bit sloppy. I was able to lock the brake drum in place with the parking brake (and therefore, by my assumption, the stub axle as well) but could still grab the CV where... wait a minnit, now that I think about it that doesn't make sense, does it. Ok, I think you're right. I'll look into the splines on the drum but that axle nut was on there tight.

What's the best way to check the splines? Just put the drum on there and see if there's any wiggle? Anything else I should be looking at?

I'm not overly worried about having it apart for naught... this is one area I haven't gotten into before on these cars and it's good to get a better understanding of it. But man, those grease seals were confounding me last night so I quit before frustration set in - they're really in there!
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Amskeptic
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Re: Rear Wheel Noise / CV ?

Post by Amskeptic » Thu Jun 30, 2011 6:25 am

sped372 wrote: The CV itself seems a bit sloppy.

What's the best way to check the splines?
The Road Warrior had stupid sloppy CVs. No noises, but well lubricated.

Stick the stub axle in the drum in operating position. Any axial play?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Thu Jun 30, 2011 6:28 am

Amskeptic wrote:Any axial play?
Wait, axial? Like, sliding along the splines? Do you mean radial? Or tippy-wise (not an engineering term)?
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Amskeptic
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Re: Rear Wheel Noise / CV ?

Post by Amskeptic » Fri Jul 01, 2011 9:30 pm

sped372 wrote:
Amskeptic wrote:Any axial play?
Wait, axial? Like, sliding along the splines? Do you mean radial? Or tippy-wise (not an engineering term)?
Axial play when bolted at torque is a problem.
Radial slop when drum is rotated against stationary stub axle is a problem.
ColinRadialAxialWhateverial
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Tue Jul 05, 2011 7:48 am

Amongst a host of other weekend projects I got the seals out. I've gotta pick up a set of decent snap-ring pliers to get the retainer for the inner bearing out, mine weren't up to the task. I started taking apart the outer CV when I was held up by the snap-ring... got the balls out but the cage won't come off without removing the joint from the axle. I can't remember if that's how it was when I did them on the bus or not. Anyway, the joint doesn't seem too eager to come off the axle (yes, I removed the circlip) so I might just clean it in place instead of risking damage. I got 90% of the old grease out with just paper towels.

Additional observations:

+ There was grease in the bearing housing, but not a lot and it looks old and somewhat dried out.
+ Both bearings seem to rotate cleanly by hand... again, I haven't removed them yet or cleaned them for fine inspection yet.
+ Outer CV looks good from what I can currently tell.
+ CV boots seem good... they're VW, not aftermarket
+ There is a very small amount of slop in the stub-axle-spline to drum interface, I can tick it "tippywise" by hand after sliding the two pieces together... should it be snug or is a sliding fit on the splines ok?

I don't have a way to check axial play in the assembly... I can put it all back together but there's no way I'll be able to torque the axle nut fully with the car on the jack stand. If it's worth it to do the test I can throw the wheel back on. The nut was definitely tight... I'd assume that if the spacers wore down it would have lost it's clamp...? Opinions?

I'm beginning to get slightly worried since I haven't found anything obvious yet. Hopefully one of the bearings will reveal a bad rolling element or something. Since I'm in it this far I'll replace the bearings no matter what but I'd love to know for sure I'm curing the problem.
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Re: Rear Wheel Noise / CV ?

Post by Amskeptic » Wed Jul 06, 2011 11:05 am

sped372 wrote:Amongst a host of other weekend projects I got the seals out. I've gotta pick up a set of decent snap-ring pliers to get the retainer for the inner bearing out, mine weren't up to the task. I started taking apart the outer CV when I was held up by the snap-ring... got the balls out but the cage won't come off without removing the joint from the axle. I can't remember if that's how it was when I did them on the bus or not. Anyway, the joint doesn't seem too eager to come off the axle (yes, I removed the circlip) so I might just clean it in place instead of risking damage. I got 90% of the old grease out with just paper towels.

Additional observations:

+ There was grease in the bearing housing, but not a lot and it looks old and somewhat dried out.
+ Both bearings seem to rotate cleanly by hand... again, I haven't removed them yet or cleaned them for fine inspection yet.
+ Outer CV looks good from what I can currently tell.
+ CV boots seem good... they're VW, not aftermarket
+ There is a very small amount of slop in the stub-axle-spline to drum interface, I can tick it "tippywise" by hand after sliding the two pieces together... should it be snug or is a sliding fit on the splines ok?

I don't have a way to check axial play in the assembly... I can put it all back together but there's no way I'll be able to torque the axle nut fully with the car on the jack stand. If it's worth it to do the test I can throw the wheel back on. The nut was definitely tight... I'd assume that if the spacers wore down it would have lost it's clamp...? Opinions?

I'm beginning to get slightly worried since I haven't found anything obvious yet. Hopefully one of the bearings will reveal a bad rolling element or something. Since I'm in it this far I'll replace the bearings no matter what but I'd love to know for sure I'm curing the problem.
Wheel bearings can hide imperfections in the races/rollers when not under load. A dynamic test is to run it in 2nd gear on jack stands and declutch, listen for rumble. Make sure your shoe adjustments are backed off so there is no brake shoe interference/drag.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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sped372
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Re: Rear Wheel Noise / CV ?

Post by sped372 » Wed Jul 06, 2011 5:00 pm

Got the circlip and bearings out. I cleaned about 95% of the grease out and although I think the roller bearing is fine, I think something's up with the ball bearing. If I go round and round and round, maybe every 5 revolutions or so I feel a 'snick' and every so often there's a noticeable scraping noise as well. The bearing has a plastic retainer holding the balls in so I wasn't able to get much of a look at the race surfaces. I'm soaking the bearings in gas overnight and I'll look at them again tomorrow.

Fingers crossed I've found the culprit.

Also, I did manage to nick the ID of the bearing housing surface with the punch a couple times when driving the inner bearing out... I was so worried about staying on the outer race (and not hitting the balls) that I managed to drift off the other way. I'm hoping I can take off the high spots with the dremel... bad idea?

Even if just one of the bearings is bad I'll replace both while I'm in there. Assume I repack the entire "housing" with fresh grease (along with the bearings, of course)?
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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