boxdriver

I have a noise coming from my car when cruising down the highway. It is similar to an exhaust drone. It is very annoying and I was ready to purchase a new exhaust. I set up another thread asking if my exhaust was normal since I didn't want to purchase a new exhaust and have it sound the same way. After further research and help from many on this site, I have concluded that it isn't my exhaust that is the issue. I thought it would be a good idea to set up a new thread on this since the old one focused heavily on the exhaust.

After further studying the sound, I have noticed that it is speed and load related and not dependent on RPMs or the gear the transmission is in. My current thoughts are that it must be coming from somewhere after the gears in the transmission and before the rear wheels. Possibly the transaxle to CV joint? The noise is the worst when driving down the highway at a steady speed. If I let up on the throttle just slightly, the noise goes away. So if there is no load coming from the engine going to the wheels, there is no noise. The faster I drive, the louder it gets regardless of gear or RPMs .

The car is a 2014 Cayman S with manual transmission and standard factory exhaust.

I have included a video below of the sound the car is making. In the video I get the car up to highway speed then i play with the throttle so you can hear the difference when it is at load and off load, as well as different RPMs and speeds.

If you are familiar with the sound, please let me know. If you have ideas of things I can check I will be very grateful. I don't have a Porsche dealer in my state, so it would be a long drive to get someone there to listen to the car. I will probably have to take it to an indy locally, but I would like to have a good idea on what it might be before that since there isn't anyone locally with much experience on these cars.


Thank you all in advance for your help.

boxdriver

Could this possibly be a pinion bearing in the differential? I have seen a few threads on that on 993s but haven’t seen any dealing with the 981. Has anyone run into this issue on a 981? I changed the oil and it made it quieter but it’s still there. I’m hoping it’s the bearing and not the ring and pinion themselves since it doesn’t look like you can get those parts.

thecajunboy

After watching that video a few more times, I think you're on the right path by thinking it's being caused by something in the final drive. The pitch of the noise doesn't seem to change as I would expect from those differences in engine RPM. Can you get it to make those noises at half the speeds shown in the video? What about the oil from the diff? Anything in it? Do you have PASM (which I believe gets you the LS diff)?

981KMAN

Could be related to this recall??

Power train: Axle assembly

Recall date
2021-08-31
Recall no.
21V679000
Porsche Cars North America, Inc. (Porsche) is recalling certain 2013-2015 Boxster, 2013-2014 Boxster S, 2014-2015 Cayman, Cayman S, 2015 Boxster GTS, and Cayman GTS vehicles. The rear-axle carrier side sections may fracture.Recall consequence
A carrier fracture may cause a loss of control, increasing the risk of a crash.
Recall action
Dealers will replace the rear-axle carrier side sections, free of charge. Owner notification letters were mailed January 6, 2022. Owners may contact Porsche customer service at 1-800-767-7243. Porsche's number for this recall is AMB7.
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chaos2984

That sounds like a diff noise. Either ring or pinion related. Probably going to have to get noise ears put on the car to figure out where its coming from. You eliminated the engine with showing it does it in either 4th or 5th gear and it was road speed dependent. I would have the diff looked at.

boxdriver

I talked to my local indy about it. He is going to get it in the shop sometime this winter. It's going to be a labor-intensive job. We are both pretty sure it is in the differential. Probably a bearing but won't know exactly until it is torn apart. Looks like my driving season ended a few weeks early this year. I will update this thread when it gets in the shop. Looks like it is time to pay the Porsche tax.

boxdriver

I finally was able to get it to the indy this morning. They have been really busy lately. Hopefully I get some answers soon. I will keep this post updated as to what I find out in case anyone else runs into this on theirs in the future.
I had to dig a path to the garage to get it out this weekend. It got me excited to see it again, but with summer tires and 8 degree temps, I wasn't able to do any fun driving while it was out.

bldn10

https://rennlist.com/forums/gt4-spyd...track-use.html

boxdriver

I got the car back from my local indy yesterday. They checked it with a stethoscope and confirmed that it is coming from the differential. He thought it was the ring and pinion carrier bearing. You can't get parts for this gearbox from Porshe, so the only option is total replacement.
The price breakdown that he gave me is as follows:
Remanufactured Transmission - $7640
Clutch - $1050
Flywheel - $1375
Freight - $750
Labor $3000
Total $13,815 + tax
He charges full MSRP on all parts he orders and thought I should have the clutch changes while he was in there already. I can supply the parts and save myself about $2000.

So, after I picked my jaw up from off the ground, I decided to call GBoxWeb since they specialize in Porsche gearboxes. He was very nice and helpful. He said that he was almost certain that the noise is from the pinion, not the bearing. He told me that they can't get parts to fix these and that I should look on Ebay for the lowest milage one from a 981 GT4 with the LSD. There are several of them available because Porsche did a recall on them for the 3rd gear issue even if the car didn't have any issues. He told me that the swap was a fairly easy job and only took about 4 hours to do. I'm sure it will take a few hours longer for anyone who hasn't done it before. But I figure it should be less than the $3000 that my local is quoting.
I also asked him if I should avoid driving the car at all until it is fixed. He said to go ahead and keep driving it, just have a plan in place for when it does fail. I guess if you have to replace it anyway, it doesn't matter if you make it worse by driving it. He said that you usually see this issue when the car has been tracked a lot or driven hard. The car had 62k miles when I purchased it, so I don't know it's history. I think the car probably always had this issue since I've had it, but I just figured that it was the exhaust until it started to annoy me, and I wanted to do something about it.

Has anyone done the gearbox swap and know how difficult it is? I am pretty mechanically inclined, but don't want to be working on it for weeks. Is this a job that a backyard mechanic could do in a weekend?

dextern27

Hey boxdriver, I seem to be having the same problem. 2014 Boxster S Manual (38k miles), and I hear the high pitched whine/whirling noise at around 72-80mph on the freeway with only very light throttle pressure in 4th, 5th, but more predominately in 6th gear. Please see videos below.



I've dropped off the car to a local indy as well, and the first one thought it may have been my two rear wheels that were bent, so I replaced all 4 wheels and got new tires (didn't work). Then they thought it might be a rear diff issue, so they replaced the rear diff fluid (didn't work as well). They referred me to another indy shop that has more specialized Porsche mechanics, and I am scheduled for next week on Tuesday. I will update you when I get their thoughts on it.

Any updates to your situation? Thanks

boxdriver

Dexter27, I think you do have the same issue. Your video sure sounds like mine. It will be nice to hear their thoughts on it. Mine seems to be getting worse lately. I can hear it pretty easily at 30 mph now.

I have found a used trans/diff with only 2,000 miles on it. I picked it up for $4500. Now I just have to find a weekend that's clear so I can install it. It doesn't look like too bad of a job and my dad has a lift, so we are going to do it ourselves. I will keep this thread updated when I get the replacement in.

Meanwhile, I am taking this time to teach two of my boys how to drive a manual since I will be replacing the tranny anyway.

dextern27

Awesome find - good luck with the install! I will keep you updated and let you know the quote they give me. Take photos if possible! I'd like to see how it all pans out. I'm not going to worry too much about it - if it's going to go, nothing we can do about it at this point! That previous thread that bldn10 shared was insightful as well.

dextern27

Update:

We found the problem! The indy shop told me that it was a worn "ring pinion" - described it as the part that connects the engine to the transmission. They found that there was one "level 5" over-rev at 9500, which may have caused the excess wear. The solution is to eventually/ultimately replace the transmission, which they would be able to source a new one for me and install it as well ($10k+). They recommended that it wouldn't be a bad idea to add some fluid to the differential that would help the synchro, so I will be following up and doing that next week. Nice guys - very helpful!

In terms of the over-rev, I definitely believe I remember when it happened. My buddy who has an M2 wanted to drive the car and check it out, and he money-shifted from 2nd to 1st (missing 3rd). I almost couldn't believe that it happened because for some reason the car kept driving perfectly fine right after... and I've always thought if that happened the car would instantly cease to work... Funny that it happened that way since I've taken it on track a number of times and didn't have any mishaps!

In terms of how I'm going to go about this, they told me the issue won't leave me stranded or anything, and to continue driving the car/tracking the car since eventually I'll have to swap the transmission out anyway. I feel relieved actually - half the battle is figuring out what it is. Good thing I had allotted a decent amount for this hobby anyway!

boxdriver

dextern27, It's nice to hear that they gave you the same diagnosis as I got. Not that I am happy you also need a new transmission, but that they probably got the reason for the noise correct on both. I was also told that I could continue to drive it, but to just have a plan in place for the future. However, mine has gotten so loud that it is not fun to take on the road anymore. My youngest son plays high school sports and since it is his senior year, my wife and I have been going to all his out-of-town games. I would love to drive the car to them all but the noise on the highway is just too much and we can't even talk in the car, so we end up taking the SUV instead.
I have a graduation party this weekend and the ceremony next weekend, then I am hoping to get it on the lift the following weekend to do the switch. The clutch is on order and should be here next week.
It's interesting that they want you to add a fluid that would help the synchro. I have been researching which fluid to fill the trany with and the things I read on here and elsewhere said that Porsche does not recommend an additive.

Here is another thread about worn ring pinions and discussion on which fluids to use. I personally plan on sticking with Porsche's recommendation of 75w-90 fluid. I'm planning on using Fuchs Titan Sintopoid.
GT4 - Gearbox R&P wear - track use - Rennlist - Porsche Discussion Forums

boxdriver

I got the transmission swapped out this weekend. It was about a 12 hour job for me and my dad to do. Nothing too difficult, just time consuming. I put in a new clutch while we had it off. The old one wasn’t too bad but it was right there so it would have been silly not to do it. I watched a few videos online first but they were all on older Boxsters. The main difference was that mine had a heat exchanger that ran antifreeze to cool the transmission fluid. So I had to figure out the best way to disconnect that. I had read in the past that it can be hard to get any air out of the coolant on a mid-engine so I left it hooked up to the coolant lines and pulled it off the transmission. Bleeding the clutch was a pain because there isn’t much room around it. We did it before putting the mounts back on so we had a little room to get at it.
For some reason I could only get 2.4 liters of trany fluid in the fill plug before it would run out. I measured how much we took out of the new(used) transmission and it measured 2.8 liters so I stuck the rest in a plug on the top back.
I replaced the spark plugs so that took about an hour of the time. Wow that is tight to get those plugs swapped!

Old Transmission coming out.

Old out, new clutch in, ready for new transmission.

Old one (close) had 66,000 miles. New one (far) is supposed it have only about 2,000 miles.

The car sounds so much better now. I feel like I can take it on a road trip now. Before it was just too loud for a long drive. Now if Porsche would just get the PSE back in stock I could put that on and really enjoy the music of a Porsche flat 6!