The Triumph Dolomite Club - Discussion Forum

I have owned my 1980 Carmine red 1500HL since August 2018 and driven it approximately 4,000 miles since then and now has only 64,000 miles on the clock, which the records indicate to be the true mileage. The records also indicate that it had a new clutch fitted about 10,000 miles ago but it does not indicate if the pressure plate was replaced or just the clutch.

Recently I drove the car from my home in Bristol to Salisbury and the clutch mechanism worked fine, however when I parked and released the clutch pedal I heard a knock/clonk, which was able to repeat if I pressed and released the pedal. I had to drive a further 30 miles to where I was staying for the night and the clutch system still worked fine during this drive. The following morning before we moved off I repeatedly pressed and released the clutch pedal there was no knock/clonk and the system worked fine with no knock / clonk for a relatively short drive. However after the long drive home I found the noise had returned. I have taken the car for a couple of runs since and the indication is that it takes a considerable time / distance before the problem appears. This is a considerable time after the engine has reached it’s normal running temperature.

My local garage has confirmed that the noise is coming from within the bell housing and I think it sounds as if the clutch release arm is not initially returning to its fully disengaged position despite moving far enough to release the clutch pressure plate. I am aware that the fingers on the clutch pressure plate (diaphragm spring) can wear and I am wondering if this could be causing the problem or could it be that their physical property / spring changes when they warm up.

It has been suggested that I should change the crankshaft thrust washer’s but I do not believe that there is any excessive play. I did attempt to measure the play but found that I could not get my clock gauge in with the radiator in place. Plus I would expect the play and noise would be present all the time both when the engine was cold and hot if it was the thrust washers.

Has anyone else had this problem and what did it turn out to be as I do not want to struggle to remove the bell housing if it could be something else.

Yes had the same. It were the thrustwashers...

Jeroen

Many thanks for the quick response. I will have to get a selection as they are not too expensive before I drop the sump. It does raise the question should I plan to change the bearing shells while I have the sump off?

Should check the end float first. Sounds like thrust washers to me but super easy to check and takes less than 5 mins

Hi Richard, If the car was an 1850 I'd be suspecting the clutch-fork pivot was breaking up. I think the 1500 clutch fork is different though ( ??? ) and there is not a history of 1500 clutch forks breaking ?
HTH,
Tony.

Many thanks Tony for your comments. Like you I am not aware of problems occurring with 1500 clutch operating arms and this car has only done 60,000 miles.

The only damage I have seen is some wear on the pivot end see attached photo. I do not know the history behind this particular arm. The shape of the wear does not align with the shape of the porous bronze bush that it should have been resting on. see attached photo. The only thing that might have happened was that the pivot pin might have fallen out and this might have allowed the arm to move and so damage itself but I do not think the damaged is sufficient to cause any problems.

Out of interest I have as Matt ask the previous owner if the pressure plate was replaced when the clutch friction plate was changed.

Today I investigated further what could have caused the wear on the operating arm by taking the arm out of a bell housing that I had in the garage. Having done this I can see where the arm must have rubbed on the sharp edge behind the bushed pivot holes. See photo showing bronze bush.

The bronze bushes, part number 129358, fitted had obviously worn and were allowing some vertical movement of the arm but I did find and modify a washer to pack up the lower bush and so take up the wear. See photo packing out bronze bush.

The arm also has a tolerance ring, part number 129412, that fits inside the pivot hole. I have always assumed that it is there to stop the original design of parallel pivot pin, dropping out, so when I have replaced the original pivot pin with the flared top type I have not worried about any slackness between the pin and the arm. However considering the issue again today, if there is any play and this is combined with any wear in the bronze bushes this could allow the arm to move around a bit and possibly catch up. See photo showing the tolerance ring that fits inside the pivot hole.

Note I have found that part number 129410 is being used for both the original design of pivot pin which has parallel sides and the one with a flared top which will not drop out if fitted from above so you need to check which type is being supplied if you want the flared type.

I've only rarely experienced the pin dropping out completely, a partial loss is enough to cause a problem that merits investigation!

It's my thought that the flare topped pin is made so that it can just be fitted without replacing the tolerance tube, a much easier job than removing the gearbox just to replace that pesky tube.

Unfortunately for this theory, I HAVE seen a tolerance tube break into several vertical sections which rather ruins it's performance as a bearing, and still needs the box out to fit, these are the cars where the pin is missing as it's no longer fit as a retainer.

Since this design is also used on all the 4 cylinder small chassis Triumphs, i've been familiar with it since my earliest apprentice days. Knowing how clutch disengagement can suffer with as little as a couple of worn clevis pins, i'd never even think of leaving the tolerance tube out completely, it would introduce too much play into a system that barely tolerates any! Plus, of course, the steel pin will wear away the aluminium clutch fork, making things progressively worse.

Steve

Before I started any serious work to resolve this problem I had another listen to the noise and I suspected that the operating arm was getting stuck and then when it finally freed itself it was hitting the bell housing . The outcome was I decided to lubricate the pivot pin and tolerance ring with some 3 in one oil. Having done this I left it over night to seep in and pleased to be able to report that I have now taken the car on several fairly long runs and the problem has gone.