Weird Rumble from the Rear.....
 

Well, this is odd. From the right rear of my car, i get a distinct, deep rumble (both sound and vibration) when i corner hard in either direction. It happens at a lower threshold when i turn left. At first, i thought my tire was rubbing on something when the suspension compressed, but i looked for evidence of tire contact and cannot find any.

It seems to me that the only things that could potentially cause this are a bad wheel bearing or cv joint. I've never had a wheel bearing go bad and NOT make noise while driving straight, so i'm not sure if this is the culprit; there's no issue when driving straight or cornering leisurely. The sound / vibration is VERY similar to that of a front wheel drive car in mid turn with a bad CV joint. I visually inspected the boot; it's in good shape. It seems strange to me that there would be enough deflection in the rear suspension to move the CV joint past its 'normal' working angle.

Does anyone have any similar experiences or ideas? Also, i have found INNER CV joint kits for the Boxster. Is there an outer kit available? Thanks for the help.

I have lots of weird rumbles coming from my rear too...... :)

change your o-ring

I would if I could!!!

I notice the same symptom. A steady vibration, around 10 or 20 Hz, only when cornering hard, in either direction. But the sound comes from all around, not just from one corner. I'm puzzled.

It could be your center motor mount. My car was making strange noises almost like a CV joint going bad around corners. Changed the mount and the sound went away.

Insite I think you have it narrowed down to the 2 most likely sources. If you have wheel bearings you've never changed I bet they need it. With your 3.4 I'd keep a close watch (ear?) on the CV joints too!

For brief moment I thought this was a treatise on Mexican food. Guess I've been in Texas too long.

You're responding to a 9 year old post, lol :D

Holy crap guys :D ! http://986forum.com/forums/uploads01...1434666157.jpg

Hmm. Say, tommy583, might an aging center motor mount also explain thunking and shuddering when accelerating briskly from a stop sign in second gear (tiptronic's default)? There's no shudder when accelerating in 1st, or gently in 2nd. (This car has about 100k miles on it. I've had it for a year. Sixth owner.)

Yes that is another common symptom of a failing motor mount. When I say center I mean the front, not the side (transmission) mounts. Although they could be getting to the end of there life as well. I would definitely say your front mount needs changing. There are plenty of DIY guides on how to do it. If you took it to a shop I would figure on a couple hours labor at most.

Oh, I was so glad to see insite posting! I wondered why he didn't already know this. This was before IMSB days! :o

Made an appointment with a mechanic. I'll follow up here in a month with his diagnosis of the rumbling and shuddering.

Yup, as tommy583 guessed, engine and transmission mounts. The couple hours of labor isn't the big deal, but it's almost $1500 in parts, so I'll have to save up for that.

I too have a similar rumble, 10 to 20hz when cornering hard and accelerating. I had assumed it was the front wheel bearing but this is making me think twice. My front engine mount is indeed in a horrible state (all of the symptoms of a bad front mount). I ordered a new one and will install most likely this coming weekend. ~$140, hopefully my vibration problem will be solved.

That seems really high for the parts, I would get another quote.

You meant $500, right? :eek:

$1500 wasn't a typo. I'm in the middle of nowhere (90 miles to the nearest dealer, only one guy in town who does Porsches).

Epapp: 1. If the rumble is absent when *coasting* and cornering hard, that shows the problem to be drivetrain, not wheels or suspension. 2. $140 is nicer than $1500, even if it's only the center mount, at least it's an improvement. You ordered WVO-986SSEM from Pelican Parts? Should I also buy their $40 wrench?

(Pelican also stocks the transmission mounts, left and right, for $370ish each 986-375-093-04-OEM and 986-375-094-04-OEM, or $115 "Rein OEM." That's closer to EJ-Fresno's $500 estimate.)

According to Pelican; Replacement Boxster transmission mounts include the triangle-shaped bracket. At about $250 each, they're pretty expensive. While performing the installation of the Porsche 996 engine into the Boxster, I discovered that the engine mounts from the 993 are functionally equivalent, and are sold without the triangle bracket for about one-half the cost of the Boxster mounts. You will have to carefully remove your old triangle bracket off of your old mount and install it on the new one if you decide to go this route. The stock 993 transmission mount part number is 993-375-049-05.

I would do this... buy from Sunset Porsche (http://www.************************************************************************.com/) and have them ship the parts to you.

Motor Mount $138.62 987.375.023.05

993 Transmission Mounts - Two at $163.89 = $327.78 993-375-049-09

Total $466.40 plus shipping.

Sunset sells the Boxster transmission mount with the bracket for $295.02 each. If you bought two of those and the motor mount from Sunset your at $728.66 plus shipping.