Had my 64 S3 on the road now for about 200 miles, I am getting a clunk from the rear when accelerating or decelerating and I remember a thread about diff crown wheel bolts coming loose, but cant find the thread. My question is. Is there any other noise when they start coming loose? and what series did it happen on? Thanks before I pull the put or start looking elsewhere. Q 2 dose a "full sync" gearbox bolt up where a no first sync box is now used, again before I pull my no first sync box to replace syncros. Thanks Tony.
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Rear end clunk
- Thread starter oLD lIMEY
- Start date
RootesRacer
Donation Time
Do you have wire wheels? If so, that's probably the source of the clunk.
Other possibility is that the rear hub(s) are loose and the keyway has gotten buggered by the key (I had this happen to me).
Having someone watch the hubs while you brake and accelerate at slow speed should help you determine if the above is the cause as you will see the axle nut turn a bit in each direction.
Other possibility is that the rear hub(s) are loose and the keyway has gotten buggered by the key (I had this happen to me).
Having someone watch the hubs while you brake and accelerate at slow speed should help you determine if the above is the cause as you will see the axle nut turn a bit in each direction.
RootesRooter
Donation Time
If not the wire wheels as suggested, could also be a worn u-joint. Diffs with problem crown wheel bolts sometimes squeal first before suddenly going out with a BANG! or, if they're going slowly enough, will simply lock up as the bolt head drops into the gears, but I haven't had a diff go CLUNK! on and off the gas first.
RootesRacer
Donation Time
If you have wires and they have clunked, all the tightening it the world isnt going to keep the clunk from returning.
What causes the clunk (aside from the axle hub having been loose and the keyway has lots of wear) is that the splines on the hub or in the wire wheel hub receiver are worn.
In this case one would need to likely replace both the hubs and the wheels.
alpine_64
Donation Time
I'd vote with checking wear in the spline's and hubs, when they get really bad you will hear them clunk under braking as they rotate on the spline even under deceleration.
As a side note the final tightening of wires should be done with wheels ON the ground.
Eleven
Platinum Level Sponsor
I had a persistent clunk also and had a dickens of a time finding it. I pulled the rear end and that did not solve it (BTW, do it anyway, I had only two unbroken bolts and they were loose-another way of looking at that is that the diff is way over engineered if it ran fine that way)!!! Anyway, that did not stop it even though I am glad I did it. I tried every technique I could read to tighten wire wheels and nothing worked. So I got a bright light and a magnifying glass and saw that the splines on the hub were worn and laid over. The wheel was ratcheting apparently. And to make it real fun, replacing the hub that did not stop it but I picked up another from the front. A tool mark across the threads in just the right place to make the wheel feel tight but wasn't was on the right front!
Moral, check them all and the u joints, did that too.
Moral, check them all and the u joints, did that too.
I have wondered about this "fix" for years: Lapping compound on the inside of the wheel where it presses against the hub.
I had some diamond lapping dust years ago that was sold to prevent screwdrivers from camming out of the slot. It worked so well that I broke the tip off of a Philips screwdriver using the stuff.
Anybody tried this?
Bill
I had some diamond lapping dust years ago that was sold to prevent screwdrivers from camming out of the slot. It worked so well that I broke the tip off of a Philips screwdriver using the stuff.
Anybody tried this?
Bill
RootesRacer
Donation Time
But its the splines that keep the wheel from clunking on the hub, not the tightness of the wheel in the hub on its knockoff.
If you look closely at hub splines that are in good condition, they are knurled along the length of the spline and presumably broached for final fit.
The knockoff when it is tightened onto the wheels center probably shrinks the
wheel center to the hub splines, but with time, the sharp splines deform and all the torque you can reasonably place on the knockoff will not keep the wheel tight on its splines.
If you look closely at hub splines that are in good condition, they are knurled along the length of the spline and presumably broached for final fit.
The knockoff when it is tightened onto the wheels center probably shrinks the
wheel center to the hub splines, but with time, the sharp splines deform and all the torque you can reasonably place on the knockoff will not keep the wheel tight on its splines.
RootesRacer
Donation Time
The tightening of the wheel between the knockoff and the hub end distorts the wheel splines into the hub splines and provided that the clearances are tight, there will be no "clunk".
As things get sloppy, the hub splines develop a sawtooth shape (I imagine the wheels inner splines do the same).
alpine_64
Donation Time
Indeed they do, that's why you have to change the splines on the wheels when you change the hubs and vice versa, otherwise your new hubs get chewed up by your sharp old wheels, or your new wheels get worn quickly by the sharp teeth in the old hubs
While I do not totally understand how the splines control movement, that is not important.
The problem is they are no longer able to do their job. I'm wondering if a little grit would "lock" the two parts together to do the job the splines no longer are capable of doing. Diamond dust would be superb as it is very sharp and does not break down as readily as conventional lapping compounds.
Bill
The problem is they are no longer able to do their job. I'm wondering if a little grit would "lock" the two parts together to do the job the splines no longer are capable of doing. Diamond dust would be superb as it is very sharp and does not break down as readily as conventional lapping compounds.
Bill