Help diagnosing trans noise
 

After a spirited drive in the mountains the day after Thanksgiving, on the return home the transaxle was very noticeably more audible. I would discribe the noise as a whir or howl. It is only under load, in all forward gears, and most prominent in 4th. The noise builds as I go through the gears. Goes away under coast. The sound travels up the center tunnel, and is most noticeable with the windows up. It quiets down some in 5th, but still very noticeable, especially when on and off the gas. Sounds like an old truck transmission.

I spent several hours last night searching PP for like symptoms. To me, it sounds like ring and pinion. But there were so many threads that have other causes that manifest itself into this same issue.

Pinion bearing race spinning, CV joints, clutch, shift guide fork could all be potential culprits. I've recently started experiencing the squeel at the shifter and a bit more resistance when engaging first and third. From what I read, this is common when the shift guide fork comes loose. Could this also cause the howl I'm hearing under load? Possibly gears aren't fully engaging due to this? Otherwise the transmission shifts fine. The Swepco in it is only a year old.

I've rulled out shifter linkage bushings as they are all only a year old and I inspected all of them. I'm on the fence with the CV's. When on the ground and twisting them with my hand, there is some slight axial play. I had the car up on jackstands with the engine running and in gear. I hear zero noise from the CV's but do hear noise from the transaxle, but there is no load on either in this scenario. I've also ruled out wheel bearings do to the location of the noise and the fact it occurs under load only.

My next step is to drain the fluid and see what I find on the plug and pull the shift fork guide plate and see if it is loose. If it is, I'll tighten, reinstall, throw in some GL-5 and do a test run to see if it solves the problem of the howl. If not, it will come out and likely be taken to a shop.

Anyone want to way in with an opinion or a similar issue and what it was? Anything else I can do while it's in the car to rule out potential suspects before taking it all apart? Did everyone have a good Thanksgiving?

Thanks in advance!

Déjà Vu !

I have a long thread on the same symptoms...

http://forums.pelicanparts.com/porsche-911-technical-forum/701647-mystery-quiet-clicking-now-loud-clicking-gear-whining-trans-diff-pics.html.

After tearing down the diff, replacing both axles with new ones including 4 new CV joints I stopped throwing money at the problem and after getting some good advice I dropped engine and removed/removing rear wheel bearings discovered my rear bearings were/are completely dry of grease, notably loose with wheel off and axle out etc. this leads me to believe the sound all along was the rear wheel bearings.. Under load the force would put the load on the bearings in such a way that they made noise that coasting without a load wasn't appearing.

My suggestion is if you haven't already remove the rear wheels, CV joints/axles and spin the hub. Most likely you will hear and feel the bearing failure. I could hear the ball bearings knock into each other as they spun past the 12 o-clock position, a result of zero lubrication. My hubs are frozen onto the bearings as well, clearly a result of failure from heat as the lubrication was non existent.

Lots of good threads on R&Rwheel bearings.

I also have a thread on frozen hubs/bearings...

Good luck and PM me if you need a better explanation or specific pics etc.

Something tells me that this is what is wrog with my 72. I find it hard to believe that both trannies I have had in the car in the past year make the same exact noise. I'm now thinking that the drivers side rear bearing, which has not been replaced, and the passenger side axle, which slung grease all over the place, might be the noise I'm hearing.

I sure would rather it be the wheel bearings! My instincts tell me no, but you are probably right!

Get under the car and put her in gear and lock the e brake, then grasp the CV Axle shaft for and rotational slop.

Mine finally wore so bad it would feel like my wheels were off balance.

Probably bearings :(

I did do that and there was some slight play. I'm thinking I may just do the CV's and wheel bearings. Still cheaper than going through the trans and diff. But if I blow all that cash and it winds up being the trans/diff, I'll probably end up divorced!

Oh poop, then we need to be accurate, we don't need another brother sleeping in the 911.

Have you considered draining the gear lube to look for critters?

Search for 911freak's video on his trans noise to see if it is similar.

I had sever snapping in the rear on turns and developed a whirling sound on canyon runs or long fredway rides then finally what felt like a wheel wobble but my wheels were verified true, I checked my cv joints and they were sloppy as heck. Removed and confirm against new ones and they were like day and night.

For extra measure I replaced the bearings.

Snapping, whirling, wobble all gone. Better off the line response as a bonus.

Jim

Here you go http://forums.pelicanparts.com/porsche-911-technical-forum/701647-mystery-quiet-clicking-now-loud-clicking-gear-whining-trans-diff-pics.html

That's my next step. Also plan to let another Pelican ride/drive the car and get his opinion.

Drove the car in to work this morning and something stood out. The whine I'm hearing changes pitch in different gears, even at same speed.

For example, it sounds different at 60 in 3rd than it does at 60 in 4th. Could this still be the wheel bearings and the transfer of noise vibration through the transaxle changes with the gear selected, or am I back to this being a tranny/diff problem and not wheel bearings?

Noise change when rpm change? Check the pulley scrubbing against the fan housing. Mine came loose. Also listen to fan, bearing may need servicing.

Ring and pinion gears, I know it all to well. I just had it done on my G50, not cheep but upgraded some stuff while I was in there. I hope for your sake I'm wrong but your description is spot on. Oh ya drain your trans and look on the plug for metal. My G50 has a magnetic speedo that through my MPH off quit a bit. Good luck!

I checked my R&P, easy enough. Pop out axles, pull out axle flages from diff and pop off side cover plate of diff. Pumpkin should slide right out. Oh, drain fluid and drop clutch helper spring assembly first. That's tell yah real quick without dropping engine and trans etc.

So what did it turn out to be just curious.

Turned out to be a hashed 4 point bearing and worn bearing retainer on the output shaft.

I replaced the bearing and the bearing retainers with a billit one from CMS, and no problems since going on two years.

Here's the fix thread:

http://forums.pelicanparts.com/porsche-911-technical-forum/726348-found-my-noise.html