RV4Flyer

At a DE last weekend my 03 996 develped a grinding/rumbling noise from the right rear when making a sweeping acelerating left turn which puts a lateral load on the car. I had the wheel bearing replaced as my indy said it was a classic wheel bearing noise. Unfortunately that was not the problem and it is still there. I'm now concerned it may be from the Tiptronic. Has anyone else experienced this symptom and found out what caused it? At the track I had on track tires and wheels and at home my daily street tires/wheels were put back on, that made no difference. I changed the brake pads, no change. There is nothing visibly rubbing. Help would be greatly appreciated.

69gaugeman

Many times the actual location of the noise may not be where you think it is. It may be the front wheel bearing. If there is no noise when traveling in a straight line and it only occurs when turning, that would be my guess that it would be a wheel bearing or much less likely a drive shaft.

Of course the info you have provided is very limited and any diagnosis is really just a crap shoot. A good mechanic would be able to discern these noises, I would think.

roadsession

It is the transmission mounts. Replacement fixed the identical symptoms

RV4Flyer

Interesting. Can you explain a little more on this? I'm trying to picture where a bad mount(s) could cause the sound, perhaps a mis-alignment somehwere with the lateral forces of the turn? How much did it cost you to fix it?

roadsession

It was a couple yrs ago - about a grand at dealer

RV4Flyer

Took my car over to my indy yesterday and he put it up on the lift. Sure enough the bushings on both sides of the transmission mount were broken and broken pretty bad. I'll take it back to him Friday and he will install a new one. Cost of the mount is $258. He thinks 1-2 hours labor. Looks like an easy enough job I could do myself but just do not have the time over the next week. You can't just replace the bushings in the mount, the entire mount needs to be changed out but it would probably be a wash price wise. Labor to press out the old and press in new bushings vs. just paying for a whole new carrier mount. I've also noticed since this started a clunk as the car downshifts from 3-2. Hopefully this repair will fix that as well. I'll post a progress report after the repair.

inlandsurf

Do you know the part number, or have a link, to the new mount? I also need a new mount and my indy quoted a much higher price. Said something similar about pressing out the old bushings is not the way to go due to vibrations. But the new mount was quoted at $1200 plus 8 hrs labor!

RV4Flyer

Pelican Parts has it for $251.50 with probably free shipping. 997-375-033-03-M100 http://www.pelicanparts.com/cgi-bin/...2529%2520%2520


Here are some posts about the mount I was able to find. I found them very helpfull.
http://www.renntrack.com/forums/show...t=transmission

https://rennlist.com/forums/996-gt2-...ier-mount.html

inlandsurf

Thanks!!

RV4Flyer

I had the transmission mount replaced and wow...what a difference! No more grinding and the whole undercarriage feels solid as a rock now. It took my guy about 1/2 hour to make the change. This is actually a very simple job if you find you need to do it yourself. The hardest part will be jacking up the car and supporting the transmission. There are only four bolts that hold on the carriage plus the two that mount it to the transmission. They were all easily accessable. If you have the plastic cover over everything that may add a few minutes to remove that first, mine is long gone.

The new 997 part number mount has much beefier bushings which should last much longer. Here are some pictures from the broken one. All four bushings were completely broken.

https://www.dropbox.com/s/p1z7mim2n6jaiho/IMAG1266.jpg
https://www.dropbox.com/s/ni0yvol8eotg82r/IMAG1267.jpg
https://www.dropbox.com/s/43o46oq1f9ts7f2/IMAG1268.jpg
https://www.dropbox.com/s/95x7lxh7vfprjeq/IMAG1269.jpg

roadsession

Glad it was the same problem as I diagnosed! But frankly you should complain to your indy that replaced the wheel bearing. My dealer diagnosed it correctly within 10 seconds of me describing the problem.