Drive train slack and clutch noise

[Dalamar]

I suspect I have a failing clutch and would like your thoughts please.

My 95 Chimaera has progressively worsened over the past year in terms of drive train slack that appears like shunting. Low revs kangarooing. The noise sounds like it is coming from the clutch area of the gearbox when driving and when the car is in gear (any gear) and one of the rear wheels is raised and is rocked to and fro taking up and releasing the drive train slack. It sounds like the springs are rattling in the clutch plate and a lot of slack can be felt (>10 degrees). The slack in the drive train is getting worse and is worse at the lower revs where shunting usually occurs. Clutch housing bolts look nice and firm.

When the car is in neutral there is none of this noise. My gut feeling is that one or more of the springs has failed and that I need to get the clutch sorted.

Here is a link to the noise on YouTube where I'm under the car, rear driver's wheel raised and I'm rocking the rear wheel with my foot whilst filming. Tricky and a bit silly I know but everything was supported and chocked etc. https://www.youtube.com/watch?v=DN6smGG9Bvs

Please let me know your thoughts.

[Zener]

Sounds like the cushion springs or assembly have failed in the driven plate , not that common nowadays but have witnessed a few over the years use to be quite common on diesels pre dual mass flywheels , dont ignore it if it grenades it will/may damage the flywheel or worse still the gearbox input shaft splines

[Dalamar]

Zener said:

Sounds like the cushion springs or assembly have failed in the driven plate , not that common nowadays but have witnessed a few over the years use to be quite common on diesels pre dual mass flywheels , dont ignore it if it grenades it will/may damage the flywheel or worse still the gearbox input shaft splines

Thanks, I removed the exhaust at the weekend and the prop shaft UJs are all ok. I had another look into the bellhousing and could see the clutch hub move through the main spring fingers around 3mm each time I twisted the prop shaft and could hear the cushion springs clatter.

Here is another short clip of the noise just rocking the car on the drive.

https://www.youtube.com/watch?v=z_5RlicQ0o0

Definitely going to remove the clutch now and replace. Do most owners do the needle bearing mod on the spigot bush these days?

[rev-erend]

Did you check the diff.

Take off the 4 prop shaft bolts and check how much free play you have.

On my old Griff, the big nut to the diff was loose giving the symptoms you describe.

Edited to say, mark the prop / diff to aid reassembly in the same place.

[Dalamar]

rev-erend said:

Did you check the diff.

Take off the 4 prop shaft bolts and check how much free play you have.

On my old Griff, the big nut to the diff was loose giving the symptoms you describe.

Edited to say, mark the prop / diff to aid reassembly in the same place.

Will do. Next step is prop shaft off. I noticed very little movement so far at that end when the car is in neutral. Maybe 1/8" movement at the circumference of the prop flange. A TVR garage checked the slack a couple of years ago during an inspection and didn't notice anything. Seems to me the noise from the clutch is something that has developed this past year.

[Dalamar]

Dalamar said:

Will do. Next step is prop shaft off. I noticed very little movement so far at that end when the car is in neutral. Maybe 1/8" movement at the circumference of the prop flange. A TVR garage checked the slack a couple of years ago during an inspection and didn't notice anything. Seems to me the noise from the clutch is something that has developed this past year.

Pinion nut on the GKN diff was fine and with very little backlash. See video below:

https://youtu.be/AbYaJu6f-j4

Next is to drop the gearbox, bell housing and clutch itself.

[Dalamar]

So, removed the T5 gearbox. I used the method of disconnecting the linkage from the transmission tunnel first. Not too bad using a transmission jack adaptor on a small trolley jack. Bell housing removal was OK with just a sticky dowel on the drivers side. Not too much debris and oil in the bell housing so I think the rear main seal is still OK.

Clutch off and found lots and lots of play with the cushion springs. At least 5mm play on each as seen in the video below.

https://youtu.be/mU65OgX-Onk

Spigot bush looks in great condition but the flywheel looks a bit crazed. I can just feel the cracks with the back of a fingernail running across them. There aren't any ridges, grooves or pits in the flywheel. Just this light crazing across the wear area.

Should I just clean it up with some sandpaper and forget it or does it need a grind?

By the way, does the spigot bearing take a little high melting point grease on re-assembly?

Appreciate your thoughts.

[Sir Paolo]

Hi, you could get away with resurfacing the flywheel yourself, but it would make sense to get it done at an experienced machinists, then you could get it lightened at the same time.
I’ve had the benefit of lightened flywheels in the past, and for a Chim, you don’t really want a big heavy millstone that is fitted to a mud-plugging Range Rover.

[Steve_D]

The flywheel needs skimming at the very least.
Are you sure about the spigot bearing? Do you have any 15mm copper water pipe? With the end cleaned up and de-burred it should be a nice snug fit in the bearing.

Steve

[Dalamar]

Steve_D said:

The flywheel needs skimming at the very least.
Are you sure about the spigot bearing? Do you have any 15mm copper water pipe? With the end cleaned up and de-burred it should be a nice snug fit in the bearing.

Steve

Thanks, I'll try the water pipe idea. It did measure as close to 15mm as possible with a set of digital calipers. It was a little awkward underneath the car.

Here is another pic of the spigot bearing.

[Dalamar]

Thanks everyone for the suggestions and feedback and the job is now done.

I got the flywheel reground as people suggested. It had never been skimmed before. Used a piece water pipe with a straight connector as a clutch alignment tool. I filed the centre stop out of the straight connector so that the 15mm pipe could go straight through. A few rounds of electrical tape and it was a snug fit into the friction plate centre.

Here's a pic of the tool. I used an oddment from garage from a bath I removed years back.



Before I refitted the flywheel and clutch I changed the rear main seal and crucifix seals as I could see they were leaking. That was a bit of a job as I think the rear bearing carrier had been over torqued. I had to chock the engine well with blocks of wood against the chassis and then a decent breaker bar cracked them both open. One bolt was wet with oil and the other was dry. When I put them back I lightly oiled them. Removing the rear main bearing wasn't too bad and I checked the bearing condition.



Yes the bearing is quite worn but will do for now as I want to enjoy the car this summer plus the oil pressure isn't too bad (~30 psi).

Anyway, doing the crucifix seals and rear main seal wasn't too bad a job plus having the sump off allowed me to give it a good clean out which it needed.

Afterwards, I simply took my time and rebuilt the drivetrain, regreasing the propshaft, painting the exposed chassis bits and so on.

Finally, drove the car again today and the car sounds a lot happier! That noise is 90% gone now and no obviously clunks coming on and off the accelerator.

One final question: before I put the propshaft back on I measured the slack on the input side where the speedo castellated wheel is (my car has the GKN diff) and I measured the slack to be 8 degrees (3/4 of one tooth of the speedo wheel and there are 32 teeth all around the wheel).

Is 8 degrees slack at the propshaft OK?