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Old 01-22-2009, 08:07 PM   #1
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Thumping noise in rear passenger wheel

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!

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Old 01-22-2009, 10:36 PM   #2
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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.
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Old 01-23-2009, 07:22 AM   #3
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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.
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Old 01-24-2009, 05:34 PM   #4
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Thanks

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.

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Old 01-25-2009, 07:01 AM   #5
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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.
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Old 01-25-2009, 07:37 AM   #6
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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.
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Old 01-25-2009, 01:18 PM   #7
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Dealer it is

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!
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Old 01-25-2009, 05:02 PM   #8
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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.
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Old 01-25-2009, 05:33 PM   #9
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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
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Old 01-25-2009, 09:10 PM   #10
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The 51psi marked on ur tire is the Maximum tire pressure not to be exceeded, it's not a pressure recommendation by the tire manufactor, take down the pressure to around 36-37 psi and fronts to 32psi.

For instance, when the tire says 51psi Max. That means 51psi=very high, 52psi - Up=danger of tire failure. The max isn't a pressure recommendation, it's just a warning not to exceed that pressure.

As for ur thump, set ur tires to our recommendations then go for another drive and check for noises again and let us know if it's still there
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Old 01-27-2009, 08:46 PM   #11
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Thanks again everyone

Thanks for the tire pressure info, but resetting it did not help. I set it to the recommendation off the Firestone Website for this wheel and tire size (http://www.firestonecompleteautocare.com/tires/pressure.jsp) and the sound is still there. Maybe I did bust a cord but I'll wait until this weekend for the mechanic to check....It just strange that this suddenly happen. I was saving up to replace my Boxster body parts with fiberglass to lighten up the car...but thanks for the tire PSI education...very informative
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Old 01-28-2009, 11:35 AM   #12
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Slow down a bit. Did you read what the factory specs for tire pressure are? Set your tires to those pressures not what Firestone says.

Also since you drove around with 51psi you may have broken a belt in one of the tires. Just go to a tire shop and tell them you suspect that one tire might have a broken belt. See what they say. Stay away from the dealer because as you said they are expensive.
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Old 01-28-2009, 12:23 PM   #13
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Let us know what resolves it! I keep thinking drop links....
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Old 01-28-2009, 02:54 PM   #14
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I keep thinking there is a rabbit in the trunk.
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Old 02-08-2009, 01:31 PM   #15
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Unhappy Waste of money!

Dealer said the looked at my suspension and could not see anything wrong. CV's were fine. Said it could be caused by flat spot in tire. Took their advice, bought whole new Michelin Pilot Sport A/S Plus and XL to replace my already new Kuhmo MX. Damn, it drives so soft but that rabbit is still there. Went to friends house cause his dad works with German cars...he practically went backwards around the world and was under the car afterwards for about half hour and said he can't figure it out. I'm giving this car to my son but don't want to give it to him like this. I also have a 2003 S with none of the issue. I'm thinking of taking it to Highline Alignment and hope they can figure this out!. My son will be turning sixteen in May and my '99 has 70k miles on it but looks factory new. I guess my fiberglass bodywork will be on my '03.

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