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 Post subject: Thrust race noise
PostPosted: Tue Nov 07, 2017 6:31 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 231
About 5 years ago the 2 had a noisy thrust race. I wasn't sure how long the clutch had been in so I fitted a new Register clutch and thrust race. The thrust race we pulled out looked and sounded fine spinning it by hand.
A few months ago the thrust race again became noisy. Not too bad and sometimes, usually when warm, it disappeared. The noise all but disappeared on the Tassie tour and the few times it did make a noise it was very mild.
However, when driving over Mt Hotham on our way to the Adams house we stopped at the top of Hotham for the views. The race was noticeably noisy and remained so till we reached the Adams.
The next morning it wasn't as bad and by the time we had driven for 30 minutes had again disappeared.
The noise has returned now we are home but not too bad, nowhere near as bad as it was at Hotham.
It is a bit of a job to pull the box and replace the bearing so I don't want to do it until necessary. It is probably wishful thinking but a noise that isn't there all the time doesn't seem critical too me.
Has anybody had one fail totally and what where the symptoms before it did?


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 Post subject: Re: Thrust race noise
PostPosted: Wed Nov 08, 2017 10:46 am 
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Joined: Thu Dec 19, 2013 9:35 am
Posts: 62
It should be able to make a lot of noise every time before it actually fails, (probably get the neighbours complaining) however I would advise against letting it disintegrate as this will supply a handful of debris and a way of destroying the clutch and probably various other items as it flails around.

Having the bearing fail again would prompt me to check the throw out clearances as the clutch may have been set up with different fork or carrier or there is not enough clearance in the cylinder to push rod.
Perhaps the return spring is not quite up to it?
If the cylinder push rod clearances and spring are good, then there might not be enough clearance between the throw out bearing and the clutch for worn clutch plate if using a diaphragm or maybe finger alignment if std. I think they should not fail in less than clutch lining or say 80,000 road miles or half that in constant traffic?

Rob


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 Post subject: Re: Thrust race noise
PostPosted: Wed Nov 08, 2017 2:27 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 231
Thanks Rob.
I also suspected the clutch adjustment, the thrust race touching the pressure plate with the clutch engaged. However, a couple of things count against this. It is only the last two bearings I have had this problem, the previous 37 years driving it wasn't an issue. Also, I have to put the clutch in a reasonable amount to get the race to engage with the pressure plate to make the noise so there is a fair clearance between the race and the pressure plate.
I agree that letting it fail could cause a great deal more heartache. I will have it repaired before the noise gets consistent and/or intense.


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 Post subject: Re: Thrust race noise
PostPosted: Wed Nov 08, 2017 2:54 pm 
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Joined: Fri Dec 20, 2013 10:19 am
Posts: 117
I have already mentioned this to John but will post it here for the interest of others. One of my vintage cars developed a tinkling noise and after about 50 miles there was a huge bang. I stopped and looked underneath but all was in order so I drove on with the continuing tinkle till I was almost home, about 100 miles later. Another huge bang but nothing obviously wrong so I went home. When dismantled I found that a trunion in the fork that holds the thrust race had fallen out. It sat on the flywheel bouncing around until on two occassions it managed to fall down the side of the bellhousing but the gap was too small to let it fall through so it jammed, and flew back upwards. The result was that the trunion was totally mutilated, the input shaft on the gearbox was twisted, the clutch plate was cracked and the spigot bush disintergrated. The good new was that no teeth were broken off the flywheel. P.S. Jenny never got back in that car.


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 Post subject: Re: Thrust race noise
PostPosted: Wed Nov 08, 2017 6:26 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 231
I was under the car today and there is a good amount of clearance on the slave cylinder rod and the spring looks to be ok. The clutch doesn't appear to be over adjusted to keep the race on the pressure plate. I still don't discount it as a cause it just doesn't seem to add up.

I did notice that the clutch operating shaft has a bit of play in it. I can move it with the lever maybe a mm or two for and aft but not up and down. it also moves sideways about 5mm against the spring. Is this normal?


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 Post subject: Re: Thrust race noise
PostPosted: Thu Nov 16, 2017 9:07 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 231
I can answer my own question now.
The thrust race noise had all but disappeared since getting back from Tassie and using the car for a number of local trips.
I took the car down to the local exhaust people today (about 2kms from home) to get a flexible piece welded in and reattach a exhaust mount.
Job done I drove home and realised I had left my extractors behind. I turned around and picked up the extractors.
The thrust race was very quiet all the time until half way back home and it suddenly became difficult to change gears. No noises from the clutch just hard to get the car into gear.
A couple of gear changes later and horrible noises from the clutch and total loss of clutch action.
The car is in our garage so the gearbox will come out over the next couple of weeks. I have a spare clutch but will probably get the box checked/overhauled while it is out as I have done somewhere near 80,000 miles since it was last looked at.
Glad it happened near home not at the top of Cradle Mountain or Mt Hotham.

The moral of the story, thrust race noises should not be ignored until they get loud as they won't always get noisier before failing. This one wasn't making any noises in the couple of drives before it failed.


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 Post subject: Re: Thrust race noise
PostPosted: Sat Nov 18, 2017 6:23 pm 
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Joined: Thu Oct 22, 2015 5:20 pm
Posts: 15
Location: Armidale NSW
Hello, I bet it's a Chinese release bearing, these don't last very long. I suggest NSK or Timkin. 5mm axial play is a bit too much. You may need a new clutch fork and release bearing sleeve. All the best!


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 Post subject: Re: Thrust race noise
PostPosted: Tue Nov 21, 2017 3:40 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 231
With Brian Richards help and his gearbox removal hoist we got the box off this afternoon. Multiple issues inside.

The clutch thrust race is noisy but hadn't failed and would probably have continued working for some time yet.

The clutch failed because of a broken pressure plate adjuster meaning one of the three forks wasn't working. I can't see whether one could have caused the other as the thrust race was noisy but working normally. Maybe the adjuster was working loose over time before it broke.

In dismantling the operating shaft I unscrewed the fork pin to find it has broken and the broken piece stuck inside is preventing the fork sliding off the shaft. I have another broken gearbox for spares and when I inspected it I find that the same pin is broken on it and also prevents the fork coming off.

Does anybody have a solution to getting the broken pin out or getting the fork off the shaft? If I can remove the pins on both boxes I could use the shaft off the spare box which looks in ok condition.


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 Post subject: Re: Thrust race noise
PostPosted: Tue Nov 21, 2017 9:12 pm 
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Joined: Thu Oct 22, 2015 5:20 pm
Posts: 15
Location: Armidale NSW
Hello,
Looks like you'll need a new fork anyway. Using an angle grinder cut a leg off the fork and drill a hole towards the pin and then use a pin punch to drive out the broken bit. New fork needed. Probably be idea to upgrade to a '4A diaphragm type pressure plate while your at it. All the best, Rob.


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 Post subject: Re: Thrust race noise
PostPosted: Tue Nov 21, 2017 10:42 pm 
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Joined: Mon Jan 06, 2014 10:25 am
Posts: 90
Hi John
I have a new fork, operating shaft and strengthened taper pin that I didn’t use in the rebuild if you are interested. In which case you can just cut through the shaft to remove it. If the pin is broken the hole in the shaft will now be oval and the taper pin will no longer effectively lock the fork and the shaft together. The UK Tr Register forum folk suggest the pins commonly break and that cross drilling with a 4 mm roll pin to help the taper pin is a good idea. Could the broken pin cause an uneven push on the pressure plate?
Cheers
Jim


Last edited by Jim Allen on Wed Nov 22, 2017 9:59 am, edited 1 time in total.

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