Shawn Stanford

If this is true, then your center bearing support is fine, don't mess with it.

knfeparty

If anyone wants a lightly used (1000 miles?) vertex EPS support, I just ordered a Colorado driveshaft.

mikew968

From what I am seeing most of the quoted solutions/repairs seem to work for the 955 but not neceasarily for the later versions. Colorado DS doesn't have a DS for a 958

mikew968

I am getting the thumping (like going over expansion joints) upon accelerating. if I lift the thumping goes away and once at speed it is not there. The center support bearing looks OK and is not all walleyed out. When we power brake the CS there is not a lot of deflection. We did notice the front sport for the rear diff seems to be moving a lot...like an inch. Not sure if that is the issue or not. Does anyone else have any ideas?

Shawn Stanford

Hmm... There are two sounds typically associated with the center bearing support failure. The first is a 'wummering wummering' as it starts to go bad, the second is the 'small person with a hammer' after it's gone. Both come from the area under the center armrest. I don't remember anyone talking about an 'expansion joint thump'. It almost sounds like the shaft isn't flexing properly when the drivetrain is under load. That would cause a 'thump' as the shaft forced itself through the 'sticking point'. I've never heard of the u-joint going out in a cardan shaft, but I suppose it's possible.

Can you drop the shaft - just the front section will do - and make sure it flexes properly?

mikew968

We are going to check all the driveline out but after a ride with Porsche tech we think is the transfer case. A path I was hoping to avoid!!!

knfeparty

I think I would spend $400 on a rebuilt driveshaft, just to be sure it wasn't the driveshaft, before I started working on the transfer case.

primm907

I've had an increasingly "rough" ride in my '09 GTS. Felt like a wheel balance problem at first, but I just put the OEM 21's back on with new tires and road force balanced to acceptable levels.

The check engine light has came on a day before swapping wheels and tires, but I don't have any specific warnings. Definitely going to purchase a Durametric soon. For now, it's going to the shop tomorrow to get checked.

Does the broken coil pack issue sometimes manifest itself with similar symptoms as this? It could be cardan shaft related, but I'm not getting the vibration/noise in the center console everyone has mentioned. Weird thing is feels almost like some slack in the drivetrain at times. And, the vibration is primarily in my seat and steering wheel.

primm907

Well, the check engine was a bad thermostat. So, got that fixed. It does seem to be running a little smoother, but there's still an odd slackness that can be felt. I may have to end up exploring the transfer case as well...

knfeparty

I would say that if you're feeling the drivetrain slop, check the tightness of the cardan shaft bolts where it attaches to the rear diff and up front at the flex disc. It's free to do.

Shawn Stanford

That sounds like nothing more than 2+ tons of P!g trying to get out of its own way!

hahnmgh63

On my '06 CTTS with 65K at the time, my center support bearing went pretty suddenly. With that said I do have a 4 post lift in my shop and at least monthly put all of my cars up in the air to do Mx and just sometimes to do a little inspection. I inspected the shaft on numerous times and the rubber on the center support bearing looked pretty good when attempting to pry the shaft a little sideways or up & down so it can go real suddenly. The day it went I drove to work (20K mi.), then was only about 5K from work on the way home making a right turn and accelerated moderately hard and wham, thump thump. I was able to drive at real light throttle all the way back home and if it started to thump real bad I knew I had to let off a little, did get up to 60mph with light throttle and all was pretty fine, good thing there were no big hills that required some torque for the pig to climb.

FCS

Did you ever figure this out? I just replaced the driveshaft and center support bearing from Colorado Driveshaft, as well as a new flex disc.

While it has pretty much fixed the vibration, it does the same as yours. Feels like someone is taking a jackhammer to the transmission under heavy load, although with the replacement its not as bad as it was before....

FCS

Ok, on my 2nd rebuilt driveshaft from Colorado driveshaft, same issue. I doublechecked bolts from the shaft to the rear diff, and to the transfer case and flex disc. Also checked the center shaft bearing support.

Still vibrates on low speed when accelerating semi hard, hard acceleration produces the jack hammering sound under the shifter console.

Any ideas? Frustrating

Shawn Stanford

How much flex was there in the shaft before you mounted it? It should more-or-less flop around like a rag doll. If the rebuilt shaft wasn't assembled correctly there won't be enough play, and when the torque goes up under hard acceleration it will do that.