Transmission whine

A_N_Other · 27-02-11, 10:39 PM

On the off chance (and blind optimism) that it might not be something terminal for the transmission somewhere, has anyone any ideas where to start hunting down a transmission whine that comes on with load.

If I back off the throttle, noise disappears, as soon as I bring the throttle up again to drive the car, whine appears.
Seems prop or driveline releated, not enigne speed as it's the same noise regargless of gear.

Wheel bearings aren't loose, although rear o/s seems to drag a little.
All the CV joints seem OK and have no split boots/grease in them

Here's the bummer though - I've just had the whole lot out to replace the subframe bushes and diff/transmission mounts and replaced all the gearbox and diff fluid at the same time (as it was out)
=> Now running solid aluminium subframe mounts, hard difff and transmission mounts, poly rear diff mount. Gearbox oil is new GL4/5 and rear diff is semi synth EP80 (GL5?)

Noise appeared as soon as it went back on the road.
=> Could it just be loads of noise transmission through the shell now everthing is hard mounted?

Anyone with any experience of running solid/hard mounts?

Struggling to believe the pinion bearing has suddenly expired whilst it's out of the car....

Any feedback or ideas gratefully recieved

Ta

SorenR · 28-02-11, 01:35 AM

I have, on my S4 2.7T, replaced my rear diff mount with an AWE mount (80 durometer) and added a DTS (AWE copy) on the subframe with a 80 durometer rubber mount to the gearbox... Drivetrain is now unmoveable compared to chassis, it no longer sound/feels like everything is trying to get out from underneath the car when I unleash all 516 NM from a standing start :-) ...

These is "only" rubber/poly mounts and i get a lot more transmission noise in the car. I would imagine alu mounts is like welding the drivetrain to the chassis and that I would expect would introduce a world of new noises ;-)

A_N_Other · 28-02-11, 08:32 PM

Thanks for the feedback Soren,

noise is pretty consistent (doens't seem to be getting worse) so I guess it is just the hard mounts.
Nothing quite as dramatic when I did the fronts, but then the drivetrain isn't mounted to that!
Guess the big one is the rear diff mount.

Will keep tabs on it in case anything does fall off though!

A_N_Other · 16-03-11, 09:13 PM

In other developments - noise has significatly reduced now the exhaust hangers have been replaced/tightened up with some cable tie assistance.....

Much more like transmission wine, rather than something trying to get out from under the car!

Note to self - always look into the tiny gaps you can't really see to check for clearnance, then add a bit for when the transmission winds up.....

Hanuman · 16-03-11, 09:45 PM

My 85wr got this. A definite whine on load, even light throttle. Front right shaft. It was like it or years, never any worse, just constant. I can't really say when it started, but my subframes was also on solid alloy mounts.

Hope that's reassuring even if not helpful (or misleading...)

A_N_Other · 16-03-11, 11:07 PM

Quote:

Originally Posted by Mark Hanman

My 85wr got this. A definite whine on load, even light throttle. Front right shaft. It was like it or years, never any worse, just constant. I can't really say when it started, but my subframes was also on solid alloy mounts.

Hope that's reassuring even if not helpful (or misleading...)

Reassuring I think.
Definately some whine in the diff or at the back I think - changes pitch as you go from positive to negative load (and there is a bit of backlash and clonking around here too..)
Reckon it must be the mounts as nothing has fallen off so far, all the grease seems to be inside all the joints, nothing appears loose, and it's not getting any worse.

Cross my fingers and keep fixing all the other little bits.... (paint, seats, odd rattles, door lining plastic sheet - Temporary Tesco bag rustles a bit!)

latent · 17-03-11, 01:14 PM

Transmision noise exsists on all cars it just depends on what the `speaker` is.

If you have hard mounted all the running gear to the car you have removed all the isolation, not one part from the car, but the parts from each other, Your new `mode` can resonate through the car and all the frequencies can sync up, sing together and use the floor as the speaker.

Id guess you have no mechical problem, yet. Bearing in mind the isolation is not only a noise reduction route but also durabilty, now youve hard mounted stuff you could see stress failures as its all hard bolted together... Id suggest removing all hard mounts for bushes, only drift boys need hard mounted rear subframes

MadderThanMax · 17-03-11, 02:33 PM

I'd go for end float on the layshaft = whine under load, lift off and no noise! I would go as far as to say that a bearing is giving up under load hence the noise...

The layshaft may be moving back wards and forwards during applied clutch and clutch realease.

Just outta curiosity check the oil levels and make sure that they are okay...

A_N_Other · 17-03-11, 09:15 PM

Hmmm,

Solid mounts were a concious decision as I'm putting a reasonable amount of torque throught the transmission (don't really want to have to replace maounts too often) and I could do with all the wheel still pointing in roughly the same direction under power!

As for layshaft - could be as the gearbox is a bit rattly when I disengage clutch in neutral and just spin up the input shaft on the synchromesh. All goes quiet when I re-engage the clutch.

Was pretty thorough when I filled up the difff and gearbox out of the car as it was easier to check level then, rather than in the car!
Might have to check again at the weekend though, as you say.

Maybe I should look at that 6 speed gearbox a bit sooner than I thought.
Clutch is slipping too, so that might force the issue!

16-03-11, 09:45 PM	#5
Hanuman Trickster Classic Audi Club Member Join Date: May 2009 Location: Heckling from the cheap seats, Phnom Penh, KoW Posts: 7,020	My 85wr got this. A definite whine on load, even light throttle. Front right shaft. It was like it or years, never any worse, just constant. I can't really say when it started, but my subframes was also on solid alloy mounts. Hope that's reassuring even if not helpful (or misleading...) __________________ I wish they would keep the damned Chinese away now that I can go home, so that I can enjoy Fish amok and a draught Angkor

17-03-11, 01:14 PM	#7
latent Grown up member Classic Audi Club Member Join Date: Dec 2009 Location: Just outside Nantwich Posts: 216	Transmision noise exsists on all cars it just depends on what the `speaker` is. If you have hard mounted all the running gear to the car you have removed all the isolation, not one part from the car, but the parts from each other, Your new `mode` can resonate through the car and all the frequencies can sync up, sing together and use the floor as the speaker. Id guess you have no mechical problem, yet. Bearing in mind the isolation is not only a noise reduction route but also durabilty, now youve hard mounted stuff you could see stress failures as its all hard bolted together... Id suggest removing all hard mounts for bushes, only drift boys need hard mounted rear subframes __________________

28-02-11, 01:35 AM	#2
SorenR Grown up member Join Date: Oct 2010 Location: Vesterlyng/Föllenslev, Denmark Posts: 563	I have, on my S4 2.7T, replaced my rear diff mount with an AWE mount (80 durometer) and added a DTS (AWE copy) on the subframe with a 80 durometer rubber mount to the gearbox... Drivetrain is now unmoveable compared to chassis, it no longer sound/feels like everything is trying to get out from underneath the car when I unleash all 516 NM from a standing start :-) ... These is "only" rubber/poly mounts and i get a lot more transmission noise in the car. I would imagine alu mounts is like welding the drivetrain to the chassis and that I would expect would introduce a world of new noises ;-)

28-02-11, 08:32 PM	#3
A_N_Other Grown up member Join Date: Jun 2010 Posts: 116	Thanks for the feedback Soren, noise is pretty consistent (doens't seem to be getting worse) so I guess it is just the hard mounts. Nothing quite as dramatic when I did the fronts, but then the drivetrain isn't mounted to that! Guess the big one is the rear diff mount. Will keep tabs on it in case anything does fall off though!

16-03-11, 09:13 PM	#4
A_N_Other Grown up member Join Date: Jun 2010 Posts: 116	In other developments - noise has significatly reduced now the exhaust hangers have been replaced/tightened up with some cable tie assistance..... Much more like transmission wine, rather than something trying to get out from under the car! Note to self - always look into the tiny gaps you can't really see to check for clearnance, then add a bit for when the transmission winds up.....

17-03-11, 02:33 PM	#8
MadderThanMax Grown up member Join Date: Oct 2010 Posts: 254	I'd go for end float on the layshaft = whine under load, lift off and no noise! I would go as far as to say that a bearing is giving up under load hence the noise... The layshaft may be moving back wards and forwards during applied clutch and clutch realease. Just outta curiosity check the oil levels and make sure that they are okay...

17-03-11, 09:15 PM	#9
A_N_Other Grown up member Join Date: Jun 2010 Posts: 116	Hmmm, Solid mounts were a concious decision as I'm putting a reasonable amount of torque throught the transmission (don't really want to have to replace maounts too often) and I could do with all the wheel still pointing in roughly the same direction under power! As for layshaft - could be as the gearbox is a bit rattly when I disengage clutch in neutral and just spin up the input shaft on the synchromesh. All goes quiet when I re-engage the clutch. Was pretty thorough when I filled up the difff and gearbox out of the car as it was easier to check level then, rather than in the car! Might have to check again at the weekend though, as you say. Maybe I should look at that 6 speed gearbox a bit sooner than I thought. Clutch is slipping too, so that might force the issue!