896 Knocking noise from rear quarter passenger side - 986 Forum - The Community for Porsche Boxster & Cayman Owners

kouros · 02-26-2008, 01:52 PM

I have been experiencing knocking noise from the rear quarter of the passenger side....this noise seems to be worst when driving around 15-20 mph around the bumpy urban street.

The knocking seems to be more evident when the car is cold and in the mornings.

I have already changed the passenger side longetudial arm .... yet it only dampened the noise and did not eradicate it.

Any clues ?

Many thanks

super66 · 02-26-2008, 05:53 PM

sounds like you are suffering from the dreaded "896" rear quarter passenger side knock..all too common

Lil bastard · 02-26-2008, 08:26 PM

maybe CV joint?

Lucky · 02-27-2008, 04:45 AM

CVs make a tick-tick-tick sound (that gets faster with speed and then tends to go away at higher speeds) as they start to go, not what I would call a knocking sound -- but we all use words differently, so maybe that's what it is. If you ignore that for too long you may get a more meaty knock just before catastrophic failure.

It's very easy to diagnose CVs by feel. Just crawl under the car, grab the 1/2 shaft in the middle of it's length and slide the half shaft in/out (that is towards and away from the tranny flange) and see if it moves smoothly and is well damped by grease. If you feel any roughness then you've got problems. If it moves too easily, but still feels smooth then you need grease, but should be damage free -- and in this case doesn't explain your knocking sound. Check both sides to compare feel. Since you have no noise on the driver side, I'd start there so you can learn what CVs should feel like first.

If you are a complete n00b it may be best to take to a shop. CV (and/or suspension) failure can be a safety concern, so it would be $ well spent if you aren't sure how to diagnose.

Good luck.

Topless · 02-27-2008, 06:28 AM

How old is you car? How many miles? Another common problem is worn /slipping motor mounts that cause knocking over rough surfaces and hard cornering. Get her up on a lift and start poking around. There is a good motor mount repair DIY over on Renntech.

Padawan · 02-27-2008, 09:13 AM

I have the same exact issue, and have not yet been able to determine what is causing the noise. Please keep me updated.

stcroixdrew · 02-27-2008, 01:35 PM

I have a 98 Box w/ 55000 miles...I had the exact same sound..BUT it would move now and then from side to side..weird. It turned out it was my front engine mount...swapped it out and all was better and my car felt tighter and new again. Unfortunately..you have to remove it to check it out. I got a great deal at Sunset Imports in Oregon for the part. Its a pretty simple DIY project...I belive I did it on ramps in about an hour.

Tony Roma · 02-28-2008, 10:26 AM

Could also be this DIY - Replace Rear Upper Control Arms (Track Arms)

CJ_Boxster · 02-28-2008, 11:06 AM

Quote:

Originally Posted by kouros

I have been experiencing knocking noise from the rear quarter of the passenger side....this noise seems to be worst when driving around 15-20 mph around the bumpy urban street.

The knocking seems to be more evident when the car is cold and in the mornings.

I have already changed the passenger side longetudial arm .... yet it only dampened the noise and did not eradicate it.

Any clues ?

Many thanks

When you say "Longetudial Arm", which arm in this picture are you talking about???

If you replaced what is listed as "Upper Control Arm (Track Arm)" and the noise was dampened... chances are you need to replace the drivers side as well cause they usually fail around the same time.

Mine both were rattling at low speeds from 5 - 40 mph over bumps & cracks. Also i noticed on cold days the noise wasnt as noisey but on hot days they were louder.

ragman · 07-16-2008, 01:37 PM

New to the forum so I'm checking to see if there are any updates. I have the same problem with knocking in the rear passenger side quarter panel (2003 S) over bumps at low speeds (10-30mph), but I've also noticed it only happens when coasting. When I apply throttle the noise goes away. Took it in and the repair shop said it was rear struts, which they replaced but the noise is still there. They have had it apart for a couple of days but have not been able to isolate the problem. Any updates?

TIA. Ragman.

CJ_Boxster · 07-16-2008, 03:15 PM

Quote:

Originally Posted by ragman

New to the forum so I'm checking to see if there are any updates. I have the same problem with knocking in the rear passenger side quarter panel (2003 S) over bumps at low speeds (10-30mph), but I've also noticed it only happens when coasting. When I apply throttle the noise goes away. Took it in and the repair shop said it was rear struts, which they replaced but the noise is still there. They have had it apart for a couple of days but have not been able to isolate the problem. Any updates?

TIA. Ragman.

Its the rear upper control arm which makes that low speed knocking noise over bumps and cracks in the road... visual inspection of the arm will not show that the part is faulty, even shaking it around or hitting it with a rubber malet will not cause it to make any noise... so its pretty hard to a repairman who isnt experienced with that particular problem on that particular car to diagnose it. We have a site sponser by the name of Delubozparts who sells an Adjustible version of those control arms at less than half the cost of the OEM Upper Control Arm. Thats where I bought mine from and I love them!

ragman · 07-18-2008, 08:36 AM

CJ, thanks for the reply. I spoke with the shop yesterday and they said they had already tried a replacement upper control arm but the knocking was still there. It's back to the shop on Tuesday for more diag.

I may take it to another shop for a second opinion.

Ragman

RandallNeighbour · 07-18-2008, 09:33 AM

Vertex is now selling rebuilt upper control arms and lower control arms for the boxster. They state they use better bushings that will not wear out as fast.

The price is a lot cheaper compared to Sunset's price on these items.

Deluboz's stuff is adjustable and cheaper, but other threads show 2 issues with them: added weight and they're thicker and can create problems with one's rims and tires on the back.

I'm about to buy a bunch of suspension stuff and I'm going with the Vertex rebuilt items. Had I decided to buy lowering springs or coilovers, I'd have no choice but go with the adjustable aftermarket stuff to correct the alignment issues caused by dropping the car an inch or more.

Food for thought for owners of older boxsters in need of suspension parts... the things that go bump in the night (and day).

ricorico · 10-01-2008, 01:14 AM

hi just thought i'd mention my 2000 2.7 drove horrible creaking front suspension and loud knock on passenger side rear all these on bumpy roads at 15 - 30 mph it really felt like a bag of s--- like riding on rusty bed springs and loose. Thought what a lemon i'd bought. Went to indy and replaced front coffin arms I am in UK(lower track control arms) and rear forked control arms (lower control arms) no 8 on the pic and car felt good and tighter. Dont know how a new one drives but the bumps now feel and sound like my 3 year old peugeot so acceptable as i cant envisage dampenend remember we're talking about bumpy roads

mmontfort · 10-01-2008, 04:06 PM

Mine was the rear bumper heat shield. It wouldn't make noise at high speeds but driving slowly through the neighborhood and running over sewer plates it sounded like the rear was going to fall off. Tightened all the fasteners and used thread locker and it all is nice now.