Whirring from TT/gearbox
10-08-2013, 11:33 PM
#1
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Whirring from TT/gearbox
Just started seemingly out of nowhere... factory 5-speed w/ LSD box.
I tried recording the sound but my phone didn't get it. Basically, it makes a whirring noise (almost a low whining). If I had to assess the frequency of the noise, I would say it's too slow to be TT (i.e. 2-4k rpm), so the final drive is probably my best guess. CV joints? Some sort of bearing? ...not my pinion..please...
It's most prominent on acceleration and while power is constant. It goes away on decel and clutch-in. It crops up mostly in 4th/5th, but probably only because revs are lower and I can actually hear it over my louder-than-I-care-to-admit exhaust.
I tried recording the sound but my phone didn't get it. Basically, it makes a whirring noise (almost a low whining). If I had to assess the frequency of the noise, I would say it's too slow to be TT (i.e. 2-4k rpm), so the final drive is probably my best guess. CV joints? Some sort of bearing? ...not my pinion..please...
It's most prominent on acceleration and while power is constant. It goes away on decel and clutch-in. It crops up mostly in 4th/5th, but probably only because revs are lower and I can actually hear it over my louder-than-I-care-to-admit exhaust.
10-09-2013, 10:36 AM
#5
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Thread Starter
It started on the way back from Cale's the other day... I wonder if that lockup you got on the highway was something happening? Not saying it was your fault, but maybe crap started acting up coincidentally when you were driving it.
10-09-2013, 02:28 PM
#6
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Oh Wow...I Feel SO bad..all I did was shift from 5th to 3rd...I double clutched it and everything and when I went to go from neutral to 3rd even though I revved matched, it wouldnt go into gear..with 146k on the box, something might have let go. When was your last fluid change? might be a good idea to drain the fluid and examine it. Michael I swear I had nothing to do with that happening, I feel SUPER bad now. Does it go into all the gears smoothly? Does it make noise in neutral, either driving or stopped? I'm guessing CV axle or a layshaft bearing in the trans.
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10-09-2013, 03:32 PM
#8
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Nah dude it locked up, wasn't your fault. I was sitting next to you and saw exactly what happened.. had I ever gone 5 to 3 (which I don't think I've ever done at 70) it would have happened to me haha. I'll drain as soon as I can.
In the meantime am I ok to drive about? I drove home over an hour and I was fine.
In the meantime am I ok to drive about? I drove home over an hour and I was fine.
10-09-2013, 04:32 PM
#9
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My tranny with the LSD does that with certain diff fluids in it. Mainly Royal Purple.
My non LSD tranny doesn't care what oil is in it. But the LSD gets picky and whirrs or whines with certain oils. It could also be because my LSD is 30 years old.
My non LSD tranny doesn't care what oil is in it. But the LSD gets picky and whirrs or whines with certain oils. It could also be because my LSD is 30 years old.
10-09-2013, 04:35 PM
#10
Burning Brakes
I haven't checked to see if I have an LSD, maybe that would explain it. I hate that my options sticker is missing, it'll be a PITA to check the code on the trans. Anybody know how to get options from the VIN?
10-09-2013, 04:44 PM
#11
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I drove mine with that whirring noise for about a month and it had no repercussions (That I know of). Just don't beat the hell out of it in the meantime. And of course, turn the radio up.
10-09-2013, 04:55 PM
#12
Jack up your rear end and spin a wheel, if the opposite wheel spins the same direction you have lsd...if it spins the opposite way you have an open diff.
10-10-2013, 06:21 PM
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Michael, from what I know of the 944 differential, here is my take on it.
Differential carrier bearings will whirr or howl all the time, with the frequency related to speed and not rpm or throttle load. Putting the clutch in or being in neutral will generally not effect this.
Torque tube bearings obviously will be at same frequency and dependent on engine rpm.
Which is why I think it is a pinion bearing, since it will also whirr at a frequency relative to the speed of the final drive, and it IS dependent on throttle loading through the gearbox. From doing some reading, I've found its a big issues with the manual 968's who's pinion bearing preload was not set properly at the factory. This is not generally an issue seen in the 944 boxes from the factory but is becoming increasingly common as our diffs collectively age. Special tools are required to install a new bearing properly.
I would say that if you drain the oil and dont find chunks of R&P then I'm betting it is slop in the pinion bearings. If the diff was going to explode, I suspect it already would have though. Still doesn't explain the lockup.
Differential carrier bearings will whirr or howl all the time, with the frequency related to speed and not rpm or throttle load. Putting the clutch in or being in neutral will generally not effect this.
Torque tube bearings obviously will be at same frequency and dependent on engine rpm.
Which is why I think it is a pinion bearing, since it will also whirr at a frequency relative to the speed of the final drive, and it IS dependent on throttle loading through the gearbox. From doing some reading, I've found its a big issues with the manual 968's who's pinion bearing preload was not set properly at the factory. This is not generally an issue seen in the 944 boxes from the factory but is becoming increasingly common as our diffs collectively age. Special tools are required to install a new bearing properly.
I would say that if you drain the oil and dont find chunks of R&P then I'm betting it is slop in the pinion bearings. If the diff was going to explode, I suspect it already would have though. Still doesn't explain the lockup.
