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So.... When I bought the car I noticed that it had a "pinion gear" whine - or at least that's what I presumed it was.
Rebuilt trans with Roger at CMS, re-installed. Still present.
OK fine, it's in the front diff due to running 19" wheels without the proper tire setup for gear ratios. Bought a known-good diff (Thanks Capt Obvious) from a board member. Installed that. No change.
Had the driveshaft out twice, and nothing obviously amiss with the guibo or u-joint.
Wheel bearings??
Here's the thing. Up through the gears, no noise. Car is silent. Noise, which sounds like a pinion gear whine under decel, is *ONLY* present on decel.
If you are coasting down a hill - say - 4th gear, and depress clutch, noise disappears. Rest of drivetrain still rotating - but noise is gone.
This car has a brand new clutch, release bearing, etc, etc. I"m struggling to figure out what else it could be.
Wheel bearing noise would be present regardless of acceleration/deceleration.
Honestly noise on deceleration is usually attributed to loose preload on the pinion bearing (probably your front diff since you had the transmission rebuilt).
The front diff is noisy since it's right by the driver FYI. Even if bought used and in good condition, why don't you just try running the car for a short while without the front diff to see if the noise goes away?
Test car at speed on a lift so you can determine exactly what is making noise. (Top suggestion)
Or
Pull driveshaft, drive, and see is noise on decel. If still there, not in front.
Or
Test car downhill as before, clutch in, and match engine RPM at that speed with light throttle. Many have been fooled looking for driveline noises actually on engine/accessories.
Just drive it. I've noticed since solid mounts everywhere and trans cables I hear some noise and gear lash on/off throttle. But I' should probably look at my guiibo too. You've been working so long, just use it.
Well, it's going down for a suspension refresh. I just want it fully sorted. I've got a couple of longer drives coming up and do not want to be stranded!
I'll pull the front driveshaft and see what is going on without it installed.
If you are coasting (decel) it increases or decreases in pitch with engine RPM, presuming the clutch is out (drivetrain spinning).
If the clutch is depressed, then it all becomes silent. I have not pushed clutch in and held rpm high (4000 or so). So I need to test that, but the whole thing just seems odd.
I suppose the one thing that was not replaced was the pilot bearing for the input shaft of the trans. It's possible that's toast. (boy that would be a pain).
That's the only engine/driveline I can think of aside from driveshaft, but driveshaft with AWD is still spinning at rpm, even with clutch depressed. So that doesn't really make sense that it's driveshaft/guibo, etc.
If you are coasting (decel) it increases or decreases in pitch with engine RPM, presuming the clutch is out (drivetrain spinning).
If the clutch is depressed, then it all becomes silent. I have not pushed clutch in and held rpm high (4000 or so). So I need to test that, but the whole thing just seems odd.
I suppose the one thing that was not replaced was the pilot bearing for the input shaft of the trans. It's possible that's toast. (boy that would be a pain).
That's the only engine/driveline I can think of aside from driveshaft, but driveshaft with AWD is still spinning at rpm, even with clutch depressed. So that doesn't really make sense that it's driveshaft/guibo, etc.
Re: pilot bearing.
With the clutch out the pilot bearing is stationary because the engine crank and transmission input are spinning the same speed. With the clutch depressed the pilot bearing spins. Based on your description the pilot bearing is not the problem.
Also, I thought you installed a new DMF? Every DMF I have seen comes with a new pilot bearing.
What happens when you ride the clutch a little bit, just enough to take up the play and get the throwout bearing spinning?
Hey prf, I"ll have to see tomorrow. But i'm 99% certain that there is no noise then. I've got a tight garage, and usually have to wiggle in and out between first and reverse - the noise is never heard when doing that wiggle.
It was a new DMF, and no new pilot bearing was included.... but it wasn't a standard kit. So I dunno... but I don't believe it's the pilot bearing. It's difficult to hear the noise under 15 mph.
Seems to appear over 15mph, and seems to be more noticeable when warm than cold. I'll see if I can post a video.
As theprf mentioned. The new DMF have "new" pilot bearings installed from the factory LUK.
Many folks have mentioned disconnecting the driveshaft. At a minimum it will allow you to track front and rear drivetrain.
The next option is to start recording different areas under your car. Get one of your old cell phones and zip tie to your slave cylinder.
While there are commercial recording wands available for automotive troubleshooting>>Cell phone is cheaper..
03-31-2023, 12:23 PM
Whine....diagnosis help
