Thumping noise in rear passenger wheel - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ArticBoxster · 01-22-2009, 07:07 PM

Have anyone of you experienced this or can give me some advice. I drove my car home from work yesterday and the car felt like I had a flat rear passeger tire. When I checked it looked fine. I stopped off at a gas station to check and fill air if needed. My digital gauge showed all both rear tires are 51psi (good for my 3piece 18"). Went home and took the wheel off to check for any damages..nothing to wheel, axle, or suspension. Anyone have ideas? Much appreciated for some insites!

944boy · 01-22-2009, 09:36 PM

I would check all the tires front and rear just cause. Sometimes a bump may feel like one corner and actually be another. In the same story as below, I thought that I had a bad wheel bearing and it turned out to be a broken cord in a tire on the other side of the car, even the passenger thought that it was the passenger side when it was actually the drivers side.

Another thing to look for if you didn't is any unevenness across the tread of the tire. It could be a broken cord. This is uncommon but not unheard of. I broke cords in 3 race tires that were old but had tread on them, i abused them bad enough to snap all the belts before they wore out. It caused a vibration and depending on the construction could cause a thumping.

FTD · 01-23-2009, 06:22 AM

I had weird noise that sounded like a flat tire noise and it was resolved with new drop links / verticle stabilizers. To my eye, they looked fine but replacing them solved the problem. I think RandallNeighbor will suggest after market replacements instead of OEM, if this is your case. I didn't come across this info in time for my situation.

ArticBoxster · 01-24-2009, 04:34 PM

Thanks for sharing your experience and knowledge with me so I could try to resolve this issue. I will check for the drop links and for broken cords..hopefully it's one of these. My front and rear tires are pratically new but for some weird reason my front tires have even wear marks only on the inside..is that normal? The wear marks are identical on both front tires..about 2 inch from the inner edge of the tires...I bought these Kuhmo's at Discount Tires and was installed by them August 2008. By the way, my neighbor suggested for me to replace the rear axles after sitting with me to listen to the thumping. He also agreed that it sounded like a flat tire but suggested that it was a bad axle...I'm a little skeptical about that.

RandallNeighbour · 01-25-2009, 06:01 AM

What year is your car? I think I missed that.

There are many things that can causes noises in the rear end. Bearings, axles, worn control arms, those inexpensive tires on which you're riding, etc. Or, it could be something very simple such as a loose strut top mount.

Best thing to do is get a professional opinion. Armchair quarterbacking it is just too hard with all these variables.

Get it to a mechanic and duplicate the problem for him and he'll tell you what's wrong with the car and go from there. Beats the tar out of scratching your head and wondering how much it's going to cost you.

renzop · 01-25-2009, 06:37 AM

Isn't 51 psi insanely high? If your 3 piece wheels "need" 51, I would be looking at fixing that. Do your 3 piece wheels leak? Is that why you run 51?

I am partial to the broken belt idea. Could the high pressures have broken a belt? You might not see anything abnormal.

Also what about a bad shock? Get under the rear and look for a leaking shock on that side.

ArticBoxster · 01-25-2009, 12:18 PM

I got a 99' and the rims are AT Itailia Riva's 18X8.5 (forged 2-piece and not 3 my mistake). I got these rims from Tire Rack with different Kumho's from the ones I'm using now from Discount Tire. The tire reads 51psi max. These tires are Kuhmo Ecsta MX. Did the Fabspeed exhaust system, intake, and Brembo cross drill brakes with fire red Brembo calipers. I'll have the dealer look at it, just wanted to use the money on upgrades not a repair that maybe easy to do myself. I couldn't believe how much Porsche Barrier charged me for replacing the coolant resevoir, $1,600 bucks............ Thanks everyone!

944boy · 01-25-2009, 04:02 PM

Hey I just realized your in seattle area as well. If you want me to take a look (for free) I can maybe help diagnose it.

I would never take anything to Barrier unless it was under warranty. They can be good but also tend to take people to the cleaners for maintenance. Thats why I do all of my own work. I think you have some good advice from here for things to look at.

51psi is max you should be running considerably less. MX's are good tires however.

Topless · 01-25-2009, 04:33 PM

Quote:

Originally Posted by ArticBoxster

I got a 99' and the rims are AT Itailia Riva's 18X8.5 (forged 2-piece and not 3 my mistake). I got these rims from Tire Rack with different Kumho's from the ones I'm using now from Discount Tire. The tire reads 51psi max. These tires are Kuhmo Ecsta MX. Did the Fabspeed exhaust system, intake, and Brembo cross drill brakes with fire red Brembo calipers. I'll have the dealer look at it, just wanted to use the money on upgrades not a repair that maybe easy to do myself. I couldn't believe how much Porsche Barrier charged me for replacing the coolant resevoir, $1,600 bucks............ Thanks everyone!

Factory tire pressures- 29F, 36R might ride and handle a lot better. FYI