Odd sound at the track today - 986 Forum - The Community for Porsche Boxster & Cayman Owners

pilot4fn · 06-05-2020, 10:20 AM

Cheers all chaps with buch of Boxster 986 knowledge here!

Today was the first track day for this year at the KymiRing Finland. It was a rainy day, but a whole lot of fun with my 2001 Boxster 986 2.7 with Manual transmission.

After driving 5 laps, on a fairly tight lefthander the car gave up a NOT very loud grinding-shaking-rattle for a moment and it sounded coming from right side (both, me and co-driver felt the sound to come from same direction), but we're not certain if it really came from rear while it kind of sounded like that. I continued the lap to end a bit slowler speed and went for the pits. Could not find anything loose or out of place while inspecting the car.

Waited our next heat approximately 45 minutes. Same thing happened again exactly same way. Just like some part had to get warmed up before giving up the noice. Inspected again at the pits and have no any idea what this could have been. Had to try again third time and same saga continued exactly same way.

Car drives otherwise real well, while I could feel the tired two suspension parts (rest of the front and rear parts were replaced last August):

- 996 341 053 07 Wishbone (Coffin Arm?)

- 996 331 045 12 Track rod

And, to make this even more strange investigation work, after the day at the track, I drove home for 120 km and I could not find anything wrong with the car on the road conditions.

Would you have any ideas where this wierd and difficult to describe noice could come from? Could the old Wishbone and Track rod give too much play to cause driveshaft joints to make noice after being warmed up or maybe the rear bearing is giving up and acting up when it warms up or completely somethign different causing this? Last September I drove the previous track day with no any issues and car sat thru the winter. I have used the car almost as a daily driver during last 1,5 months.

All help and possible causes for this noice would be most welcomed.

tonythetiger · 06-05-2020, 11:10 AM

With a 2000 S with 145K, I had a wheel bearing that acted up on hard turns after warm up, sounds like what you are experiencing. (right rear bearing on hard left turns?) I was only driving 3-4 miles at a time, so this went on for a few weeks until I pulled the hub and swapped the bearing. I was ready to change them already, so I had the bearing "in stock." I never had the issue again. Note that the bearing I took out seemed OK, but the sound went away forever. Also, the bearing for the base boxsters are much less expensive, so lucky you. Let us know what you find.

pilot4fn · 06-05-2020, 11:33 AM

Thanks Tony,

The right rear bearing is also my suspect but the sound is pretty odd. I have had bearings gone in couple of other brand cars before, but those never gave up this kind of noice...

I got some video clip of the sound here:

https://www.dropbox.com/sh/uavc6ra9pwfsijk/AABSNGa4QgIjzSXKx9dN3hTta?dl=0

I did not drive over the curbs even that it might look like it on the video, so the sound came up on super smooth asphalt lefthander and kind of sounded coming from right rear.

Any help would be most appreciated as of where to look with this noice.

tonythetiger · 06-05-2020, 01:19 PM

its still amazing to me that you feel things in this car, one of the cool things about the hobby.
I would still look at the bearing, but again, my experience was swapping out, and I couldn't condemn the bearing even after removal. Only thing I can think is the bearing would get hot and thats when the race and bearings would lose perfect synchronicity. I wish I had more.
Don't think it is the suspension, given that it is a grinding noise, yeah? I noticed that you could feel the rough bearing, however slight the grind was. whatever happens, let us know. Im interested.

tommy583 · 06-05-2020, 03:26 PM

Another possibility is the front motor mount. They have been known to make strange noises while turning during high throttle.

pilot4fn · 06-05-2020, 10:51 PM

Quote:

Originally Posted by tonythetiger

its still amazing to me that you feel things in this car, one of the cool things about the hobby.
I would still look at the bearing, but again, my experience was swapping out, and I couldn't condemn the bearing even after removal. Only thing I can think is the bearing would get hot and thats when the race and bearings would lose perfect synchronicity. I wish I had more.
Don't think it is the suspension, given that it is a grinding noise, yeah? I noticed that you could feel the rough bearing, however slight the grind was. whatever happens, let us know. Im interested.

Thanks Tony,
I'll try to find out what's the issue over the weekend. Tough issues is, that I probably can't replicate the yesterday's stress to the car on the streets... When the issue is sorted out, I'll follow up here.

pilot4fn · 06-05-2020, 10:55 PM

Quote:

Originally Posted by tommy583

Another possibility is the front motor mount. They have been known to make strange noises while turning during high throttle.

Thanks Tommy,
This is possibility, but I think that probably not, since I swapped the front engine mount last August, approx 8.000km ago.Then again, this sounds like a good option if the rubber 'flaps' on both sides of the engine mount are giving in too much - IIRC those were somewhat loose as the new engine mount went back in...

Anker · 06-06-2020, 06:04 AM

Its the front motor mount. When it gets worn and under strong acceleration, the exhaust makes contact with the chassis and gives exactly this rattle. It could also be one or both transmission mounts.

pilot4fn · 06-06-2020, 11:32 AM

Quote:

Originally Posted by Anker

Its the front motor mount. When it gets worn and under strong acceleration, the exhaust makes contact with the chassis and gives exactly this rattle. It could also be one or both transmission mounts.

Thanks Anker,
The transmission mounts could be a good suspect, since those have not been replaced ever. Those do not have any leaks yet, but are old - probably do not have the qualities left like new ones.

tonythetiger · 06-06-2020, 05:33 PM

Quote:

Originally Posted by pilot4fn

Thanks Anker,
The transmission mounts could be a good suspect, since those have not been replaced ever. Those do not have any leaks yet, but are old - probably do not have the qualities left like new ones.

As I ponder this, I would lean towards the transmission mounts also and a scrape on your exhaust. My turns on a bad bearing did not reach the g's im sure you were pulling on the track, and it was so slight; sounds like your feedback was a touch more determinant. Its also really easy to check.
Not suggesting that you don't know this, but for everyone out there:
Do yourself the favor of buying the canister piece separately and attaching them to your existing brackets. It'll save you hundreds. you can find the REIN AVT0307P for around 70 bucks each. (the forum blanked out the site where I sourced, but its the same part available on pelican) The 993-375-049-05 will fit too, but much more expensive. NOTE: you will need a VERY large external torx socket to remove from the bracket, it was one size up from the set I have, so I needed help there.

Race on

pilot4fn · 06-07-2020, 06:08 AM

Quote:

Originally Posted by tonythetiger

As I ponder this, I would lean towards the transmission mounts also and a scrape on your exhaust.
Race on

Transmission mounts it is. Those are not leaking, but are in my opinion pretty much out of shape compare to new ones. This allows the header to downpipe flange bolt to touch to support frame on hard cornering. Also the right side does lean a bit lower compared to the leaft side - maybe this is why the rubbing happens only on the right side during 'fast' lefthanders.
Pictures show the rubbing point I found today and also right side transmission mount.
Thank you for your help on this! Now is time to order new mounts.

Then, I looked at the mounts to buy without the support brackts and came by this site offering the REIN AVT0307P mounts approx 1/2 price compared to next offering: "nsbomarket dot com". Have any of you ever purchased anything from there or is this just a scam...?

edc · 06-07-2020, 01:52 PM

You can refurb your gear box mounts with poly. You can replace the hydraulic fluid on one side and/fill around the stud the other.

pilot4fn · 06-07-2020, 09:38 PM

Quote:

Originally Posted by edc

You can refurb your gear box mounts with poly. You can replace the hydraulic fluid on one side and/fill around the stud the other.

Thanks edc,
I have read of these partially poly filled mounts, but if not mistaken that will make the resut stifer than original mounts and would allow more vibration to come thru - not desired for me, since the car is my daily driver during summer.

steved0x · 06-08-2020, 09:22 AM

I think Gilles might have a set of semi-solid transmission mounts for sale - I have them on my Boxster and a set waiting to go in on my Cayman. Adds a little vibration at idle but not bad. I would recommend those.

edc · 06-08-2020, 10:35 AM

Quote:

Originally Posted by pilot4fn

Thanks edc,
I have read of these partially poly filled mounts, but if not mistaken that will make the resut stifer than original mounts and would allow more vibration to come thru - not desired for me, since the car is my daily driver during summer.

Not for me. Been using them for a few years. No harsh vibrations.

tonythetiger · 06-11-2020, 08:27 AM

Quote:

Originally Posted by pilot4fn

Transmission mounts it is. Those are not leaking, but are in my opinion pretty much out of shape compare to new ones. This allows the header to downpipe flange bolt to touch to support frame on hard cornering. Also the right side does lean a bit lower compared to the leaft side - maybe this is why the rubbing happens only on the right side during 'fast' lefthanders.
Pictures show the rubbing point I found today and also right side transmission mount.
Thank you for your help on this! Now is time to order new mounts.

Then, I looked at the mounts to buy without the support brackts and came by this site offering the REIN AVT0307P mounts approx 1/2 price compared to next offering: "nsbomarket dot com". Have any of you ever purchased anything from there or is this just a scam...?

i am running those REIN, this is my second time on 2 cars. They are flawless.

NOTE: you will need a VERY large external torx socket to remove from the bracket, it was one size up from the set I have, so I needed help there.

pilot4fn · 06-11-2020, 11:49 AM

Quote:

Originally Posted by tonythetiger

i am running those REIN, this is my second time on 2 cars. They are flawless.

NOTE: you will need a VERY large external torx socket to remove from the bracket, it was one size up from the set I have, so I needed help there.

Great, thanks Tony,
Where you purchased the REIN transmission mounts from?

BYprodriver · 06-11-2020, 12:25 PM

I believe this is the 4th time this year I have posted on various Porsche forums, too check for bad wheel bearings, drive close to a wall at night to listen for noise from the wheel bearings.

tonythetiger · 06-11-2020, 01:18 PM

Quote:

Originally Posted by pilot4fn

Great, thanks Tony,
Where you purchased the REIN transmission mounts from?

I think I sourced the last set at rock auto, used a coupon and every other trick I could muster, but a quick google search shows most suppliers in the 70-80 buck range. Pelican has them for 107.
Interested in modifying my old ones now...as people said, we can fill them with poly? What's involved with that? is there a tech talk on that madness?

BTW, I couldnt find nsbomarket dot com, but pricing is all over the place for these...I saw one site selling them for 57 bucks each, others wanted up to 150. Pretty sure this mount is more common then just the porsche line.
I was happy enough with ~70 bucks and had them in a few days.

tonythetiger · 06-11-2020, 01:41 PM

Quote:

Originally Posted by BYprodriver

I believe this is the 4th time this year I have posted on various Porsche forums, too check for bad wheel bearings, drive close to a wall at night to listen for noise from the wheel bearings.

thats the first thing I brought up, based on a past experience. It was weird and fleeting, a grinding noise after warm up on hard left hand turns. I commented earlier how we can feel things in this car, even slight things. Within a few weeks, I was swapping wheel bearings anyway (long story) and the passenger rear was just a little funky. I could feel a difference between them, but it wasnt "wasted". After the swap the sound never came back.
This issue seems to be worn transmission mounts and has been tentatively confirmed with evidence of an exhaust flange rub against the cross-brace.
Im holding out for confirmation from this crazy racer. :+)