CV / Half-shaft play - Need help.

[Grebbler]

Hey Guys,

This concerns my woman's FWD 2005 Chevy Cobalt with 120K miles.

She says that it shakes when she's getting off the freeway and applying the brakes, but it doesn't happen all the time. She had the brakes done, a wheel alignment, and the front tires replaced last winter and had a hub or two replaced early last year. I was out of town a lot and told her not to wait for me.

I took it for a quick spin to scope it out. I didn't go on a freeway as, quite frankly, I hate driving that car. We have [censored] broken pavement roads around here and her front end makes a heck of a racket going over bumps and tracks. Her plastic front clip is held on by a prayer as most of the mounting tabs are broken off. I zoomed up and down an industrial drive and the brakes felt fine to me but the front clip rattles seemed to have a metallic sound this time.

I jacked up each corner and spun the wheels. No grabbyness I could feel so I repeated that with her lightly pressing the brake - still good. None of tires had any bulges or slipped belts that I could feel. I yanked the wheels in all directions and none had any steering or bearing play. At the front passenger corner I pulled the wheel and put a dial indicator on the rotor as I maybe felt a ghost of a tug while spinning the wheel. There is about 5 thousandth run out but I didn't feel anything on the road test. The caliper bushings felt solid with no metallic noise when whacking with my fist. While testing the rotor runout I thought I heard a faint clunk while spinning.

While under the car, yanking on things and looking for loose parts, I found play in the axle shafts at the transmission. I don't know a whole lot about FWD cars but I know the axles have to slide in and out to allow for suspension travel. The sloppiness I am getting is vertical and side to side. I only get a bit of in/out travel at the wheel bearing - no side play.

I searched the net for hours trying to find some definitive info on allowable play and testing half-shafts. Most everyone says to check for torn boots or listen for clicks while turning. Between her rattles and my poor hearing I didn't and her boots are fine.

In the hope that you good folks could help I made a short video of the play I am concerned about:



What do you think?

 

[NJC]

EDIT - after watching video a 2nd time, that's radial play. It also seems excessive ... anyone else seen this?

But would braking and cause vibration in an axle - I can't answer. Hopefully others will chime in.

How are the suspension components?

 

[The Critic]

0.005 of lateral runout is excessive, 0.002 or less is what you need for most rotors.

I would fix that problem first, as that much lateral runout will lead to brake pedal pulsation in short order (if not already).

That amount of play in the axle does seem a bit on the high side, but the one on my Prius has some play as well. Perhaps someone who services a lot of Cobalts can comment on how much is normal.

 

[Grebbler]

She was told during the earlier repairs that she needed struts pronto (another thing I know little about).

I didn't notice any wheel hop, towers look good without stress or cracks, bolts and springs are tight, no oil stains, and a bounce test came up to a smooth stop.

The sway bar bushings are tight and pliable. The rubber donut style motor mounts seemed a little weak as the center bushings are below centerline, but the rubber was soft and I didn't see any chunks missing. The small sag I saw could just be engine weight. I could move the motor a little when I pushed up on it while I was under there but I don't know how much give a transverse engine should have.

Tomorrow I will watch it while she revs it in gear.

 

[229]

Needs OEM axles.

 

[Trav]

As other have posted that seems like way too much play.
I would say the inner joint has well had it. You wont get a clicking or popping noise from the inboard joint just the outboard.

This can cause vibration. Any clunking shifting into reverse then drive?

 

[yonyon]

That doesn't look like a worn joint to me. It looks more like a bearing or bushing in the transaxle isn't there anymore.

 

[Trav]

That was my first thought too but wouldn't that cause a leak?

 

[yonyon]

I would expect so also, but then again, by the time it's worn down that far maybe it's already leaked enough that there's not enough to leak out?

It's like when you leave your headlights on. If you just leave them on long enough they eventually shut off.

 

[Trav]

Thats true.

 

[threeputtpar]

Couldn't watch the video here at work, but when you said that the shake first happens at the application of the brakes I'd say that one of the new tires is out of round radially. I've got the same problem with the A6, and I notice a difference from my summer to winter tires even though the problem is there with both sets. My summer tires are new, but I've noticed that one of them was out of round and when switched to the back the problem really dimished.

I have spent way too much cash changing parts looking for a lateral imbalance in the front of the car, until CapriRacer told me that my problem is a radial imbalance and not a lateral imbalance. In my mind, the physics said that the tire was wobbling in a lateral way but it seems that I was wrong.

I'm going to have them Roadforce balanced and indexed on the rims to relieve the condition.

 

[zzyzzx]

Were the wheels rebalanced?

Also, go to an auto parts store and look at a new (not rebuilt) axle for that car and see how much play is in it for comparison purposes. I have had them wear out like that, even with a boot intact.