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-   -   New CVs Clunk on Cornering (http://forums.pelicanparts.com/porsche-911-technical-forum/704072-new-cvs-clunk-cornering.html)

na2ub 09-11-2012 05:21 AM

New CVs Clunk on Cornering
 
I just replaced my rear wheel bearings and 4 CV joints. All went together well. However, now, when cornering, I get a single clunk, as something is shifting. Turning left or right.

I have checked the axle nut, sway bar mounts, strut bolts, bearing play, spring plate bolts, and all is good.

I can reproduce the sound by yanking on the axle (rear in the air). It seems that the lateral play in the axle bottoms out with a clunk when I pull it towards the wheel.

This issue is new, to the wheel bearing cv joint replacement, so I am fairly certain these assemblies are the cause of the problem. I did get the spring cup washers and circlips installed correctly on the axle. I put the groove in the new lobro CVs towards the outer side of each axle.

Who's been there? JW?

na2ub 09-14-2012 10:11 AM

Anyone? I will be missing my DE if I can't solve this tonight.

More info ... I figured I messed up my CV installation somehow, so I ordered 2 new halfshafts with CVs already on them. Same problem, although now it seems I can get 2 clunks on each turn. If I turn right (hard) multiple times, it only clunks the first turn. Then it will clunk again if I turn left. It still seems like the axels are sliding back and forth.

Joe Bob 09-14-2012 10:51 AM

Rear sway bar?

na2ub 09-14-2012 11:23 AM

Possibly. I check the mounts and they seemed fine. But the car will not make a sound on a SECOND turn (in the same direction). I think this would rule out sway bar. Looks like NorthCoastCab had the same problem, remedied by replacing the bearings, but I just replaced mine, and that's when the problems started. I might over-torque the axle nuts to 250 ft/lbs, to see if that does anything. Right now, they are torqued to 225 ft/lbs, which is correct for the castle nuts. It took a lot more than 230 ft/lbs to remove them!

na2ub 09-14-2012 12:49 PM

I did hear a little rattle back there when going over a bumpy bit of road. Hopefully it is the sway mount. I did look at the mounts, but maybe I missed a small crack. I will jack the car up and really yank on the when I get home, to see if anything appears loose / cracked.

Separate question, how much play should the rear wheel have in the bearing. In the air, I can't really budge it, holding on the top / bottom of the tire, but on the ground, if I push at the top and rock the wheel, there is a slight amount of play (kinda like the front wheels).

E Sully 09-14-2012 02:46 PM

I would look at the sway bar again. Check the drop link bushings.

winders 09-14-2012 03:06 PM

Take the anti-roll bar off and try the same test. You will eliminate or confirm the anti-roll bar as the problem once and for all.

Scott

na2ub 09-14-2012 07:18 PM

The rattle is solved. It was the inner race from my old bearing that I had dropped down the hole in the trailing arm. I was certain that was the clunk, too, but unfortunately that remains. It has changed from a single clunk, to two, then three and four. Usually in rapid succession when I crank the wheel to turn. I am starting to think that it IS the (new) bearings. I did put some extra torque on the axle nut, but that did not help. I will see about disconnecting the sway bar.

JP911 09-15-2012 06:54 AM

Maybe the bearing, but (if it helps) a good friend had the same issue with new axles. There was enough travel in the CV that hard cornering would shift the axle enough to cause a clunk sound. We greased the joint liberally which helped to reduce the noise.

john walker's workshop 09-15-2012 08:29 AM

repetitive knocking is typical of cv joint balls skipping, not sliding on their races. maybe a better quality grease, like swepco will help.

michael lang 09-15-2012 08:46 AM

The one thing that comes to mind that I would try (I know is a total pain in the ass) is to switch the axle shafts left and right and then retest.
That really sucks if you missed your track time because of this.

na2ub 09-15-2012 09:11 AM

Current plan.
1) Take the day off. I ain't doing **** today. Weather is beautiful and I should be squealing tires around mid ohio. Ain't that a *****!

2) Pull the axles, get some high quality grease and a grease gun, and nail all the joints.

3) JP911, I would have sworn that was my issue to start with. At some point I neglected to verify, but, I am going to add some silicon gasket (flat rubber mat) cut to shape, on the inside of the hub and transmission flange. This should verify if the axle ends are making contact. - if you think about it, the CVs allow the axle to shift back and forth, what, about an inch? How deep is the hub flange, about an inch? Clearance would be pretty tight for the axles to not contact the hub.


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