Worrying noise after gearbox rebuild

[CaptainNewman]

Hey crew! It's been a while.

Just had the gearbox (FSSR30A) rebuilt on the old RB30, after 400k the synchros on 2nd and 3rd were getting a bit crunchy. Full bearing kit, synchros plus a a few hard parts (4th/input and countershafts, 5th, reverse). Did the clutch as well.

Unfortunately something seems to have been missed or the box has been installed wrong, and the things are sounding more concerning than ever did before...Hopefully you can see this video (google drive link - https://drive.google.com/file/d/11Q1...ew?usp=sharing). Video is coasting from 40km/hr to a stop with the clutch in (pedal to floor) the whole time, shifting between the gears and neutral.

A few diagnostic details - the noise only happens with the clutch in (i.e., pedal to floor). It's a cyclic 'chatter' sound that turns into a shudder that shakes the vehicle at low speed, like the handbrake's been left on and dragging. Noise corresponds to the speed of the vehicle (noise gets slower as speed gets slower). Noise is the same in all gears and in neutral (i.e., doesn't matter where the gear shifter is, only that the clutch is in). When driving along as normal (i.e., gearbox/clutch engaged) the sound isn't there.

Has anyone heard this sort of thing before, of have any ideas what could be the matter?
Cheers fellas

[mudnut]

I wonder if it is a dry or old spigot bearing. Seeing as it is the same in all gears it does point to the clutch. A long long time ago I had a couple of brand new thrust bearings from Repco fail. it was a pain in the rear having to pull the gearbox three times to fix it.

[CaptainNewman]

Hmm thanks Mudnut, a bearing of some sort was in the back of my mind.

I took it back to the mechanic today. Apparently the sound is so intermittent they couldn't reproduce it at all, even after a couple of test drives. The handbrake had been adjusted WAY too tight (i.e., full hold on first click), so they adjusted it back to normal, and driving home I thought "it's fixed" cos I couldn't get the sound to come back, and everything actually sounded normal...

But rolling down my home street, I pulled the handbrake on a little to test and the sound comes straight back. Now it's as bad as it ever was, possibly worse.

It has to be something clutch or driveshaft related, rather than the gearbox, as the sound goes away when the engine is driving the wheels. Noise comes back when clutch pedal is to the floor and rear wheels are driving the gearbox/driveline.

Now I'm thinking it's something going on in the driveshaft or handbrake shoes... will keep updates coming here.

[mudnut]

Years ago my Old Trol presented such weird noises. It turned out to be the hand brake not releasing, properly when the nose was pointed slightly down hill. Fixed itself eventually. I am a little confused though. Does the noise manifest itself all the time now, since you used the hand brake?

Or is it only with the brake lightly applied. Mine judders a bit when applying the handbrake while moving. I think water ingress has allowed a couple of patches of rust on the inside of the drum.

[CaptainNewman]

Years ago my Old Trol presented such weird noises. It turned out to be the hand brake not releasing, properly when the nose was pointed slightly down hill. Fixed itself eventually. I am a little confused though. Does the noise manifest itself all the time now, since you used the hand brake? Nah, still only noise with the clutch pedal to floor

Or is it only with the brake lightly applied Nah, I literally just pulled the handbrake lightly and then released, and that made the noise came back. Mine judders a bit when applying the handbrake while moving. I think water ingress has allowed a couple of patches of rust on the inside of the drum.

That's good to know - things are pointing toward something within the handbrake drum (or cable) that might have been knocked when the driveshaft got taken off to remove the gearbox.

Yeah so to clarify, the noise only ever occurred with the clutch pedal to the floor (rolling). Coincidentally (or not), that noise went away when the handbrake got adjusted (i.e., no noise at all, even with clutch pedal to floor). But as soon as I nipped the handbrake (pulled then released), that must have moved something and made the noise come back. Still only happens with the clutch in though (with handbrake released).

You'd think if it was on the tailshaft, the noise would occur ALL the time. But maybe, if it's a 'friction noise' of the rear wheels driving the tailshaft, it must be overcome when the clutch pedal is out and the engine starts driving the wheels again...

Booked in to a brake and clutch specialist next week so we'll see!

[CaptainNewman]

Handbrake was inspected by the specialist last week. Apparently drum and shoes are in good order, they couldn't see anything obvious that would be producing the weird noise.

They suggested replacing uni joints as the grease looked ancient, and given the tailshaft would have been taken out and left sitting for 1 month+ while the gearbox was rebuilt, there's a chance the needles might have got misaligned or something. I'll admit I try to grease regularly but the nipple closest to the rear diff was broken off around 20,000kms ago... Another mechanic I spoke to bet a carton on the noise being from the uni joints.

So next port of call is new uni joints on the tailshaft. Will report back with the results.

[mudski]

Another mechanic I spoke to bet a carton on the noise being from the uni joints.

So next port of call is new uni joints on the tailshaft. Will report back with the results.

But rolling down my home street, I pulled the handbrake on a little to test and the sound comes straight back. Now it's as bad as it ever was, possibly worse.

I bet its the hand brake. Solution to fix the problem. Don't pull on the hand brake when the car is moving.

If it were the uni's, it would do it all the time, but if they have never been changed it won't hurt to do them regardless.

[Shalee]

I had a 105 Land Cruiser years ago a mechanic did some work on. Driving home the whole car started to shake .
Thinking he didn't do up a wheel I pulled over and checked them all- all tight.
I got home and had a look under the car with my thermal camera to check all the bearings.
The rear park brake drum on one side was twice the temperature of the other side.
I adjusted the park brake and then took it for a drive. All good.
If you want to check your car out with a thermal camera message me and we can catch up.

Cheers Shane