A Lesson in Triumph 2500 Clutch Hydraulics.

How many of you have had problems with the Triumph 2500 Clutch not releasing or releasing just off the floor of the car? It is quite a common problem, apparently with the TR6, Vitesse & GT6 as well. I have been fighting the problem for many years, first in Dunedin with my 2500 Man O/D. We were going on Holiday to Peel Forest, but as Murphy would have it, I needed to replace my clutch. So I diligently set about removing it from under the car, my God are they heavy when lying on your back and balancing it above you head, not for the faint hearted. I then proceeded to replace the pressure plate with a reconditioned Borg and Beck one, and a new Clutch plate. Fitted it back in the car etc, but alas not a good pedal. It was a bit spongy so bled it again and it was perfect. So Boxing Day arrived and off we set with Trailer full of camping Gear. Everything was going really well until I had to stop at the lights in Timaru. I was unable to engage 1 st Gear so had to turn off motor engage 1 st and move car with the starter motor to get it started and continue our journey to Peel Forest. Very strange as it was fine when we left. We duly arrived at our destination pitched our tent etc and started our holiday. Some holiday, I had to remove the master cylinder and take it to Geraldine get it checked and re-kitted ( A nice man at the camp took me in ) hoping this would fix it of course, but not to be. Just had to put up with it until our return to Dunners. Once back home I visited an old friend of my departed father who lived just a few doors down the road, and was considered the clutch Guru of Dunedin. John Recon’d a pressure plate and set it up his way and it worked very well, no more problems, but it didn’t last, it need replacing prematurely but luckily I had a spare which John had also done for me. That was my first encounter with the problem, but alas not the last. I sold the 2500 and purchased a 13/60, still got it, and proceeded to modify it with Triumph 2000 dome topped pistons (High Compression) flowed head and a lumpy cam grind. Unfortunately it didn’t go well at all as it needed high octane fuel which was hard to get. 95 wasn’t good either. Then a divorce got in the way and I eventually moved to ChCh. Awful drive up in the Herald, as it had no ooomph at all. So it sat around for a year or two until I bought a house in Hoon Hay. About this time BP put 98 into some of their sites, one being Halswell. Out came the car and I spluttered off to Halswell and put some in and virtually drove out with a different car. Then a rush of enthusiasm came over me and that’s when the trouble started. I decided, come hell or high water I was going to adapt a 2500 O/D G/Box to a Herald motor. Yes it can be done, see previous article of a few years ago, or I can forward a copy if wanted. You would think I would have learnt by now, but I am a stubborn so and so and reckoned I could sort it somehow or die trying. Of course the clutch problems started again, and I was unable to find anyone who could do what my Dunedin man did to make it work. Whatever he did worked but I now think it wasn’t the proper answer. So I had to find another way to fix it. It was clear to me that the hydraulics were not pushing the release bearing far enough to clear the clutch from the flywheel and the clutch plate was still touching the flywheel and making gear changes difficult and the whole driving experience unrewarding. So think about how it works, the master cylinder pushes fluid down a pipe to the slave cylinder which pushes the push rod forward to activate the clutch. Simple right? No not really. I tried all sorts of crazy things to try and get the push rod to push further. Smaller diameter hose between master and slave, no change, larger master cylinder to push more fluid, worked but the clutch was very heavy to push and very rough and jerky, again very unrewarding. I removed G/Box and put a packer behind the release bearing to make sure it stayed about 1/8” off the Pressure plate, you guessed it no difference. I then had a rush of blood to the head and got sick of the 1300 and set about modifying a Marina 1800 TC motor to the 2500 Box, now one stage better than MGB tune. You may ask why, when you are having trouble with the Bloody clutch. Truth is I was certain the clutch problem could be solved eventually so proceeded with the job. When that was all in the car I then went about removing any excess play in all pivot points to make sure I wasn’t losing any forward motion at the release bearing. All to no improvement. Rocky came up with an article from a triumph club out of the states who were having problems with GT 6 clutches, same problem as mine. They discovered that the diaphragms they are using are thicker than the originals and therefore were too strong for the hydraulics. They managed to find some original Pressure plates which worked perfectly but as soon as they fitted after market recon’d ones the problems started again. I went on the hunt for a lighter diaphragm and found that Repco use to supply most of them for NZ in differing thicknesses but now it is one size fits all and that has created problems not only for triumphs but other cars as well from the same era. As I had gone from 5/8” Master Cylinder to a 3/4” one and it had sorta worked I thought I would compromise and get one sleeved to 11/16”. This very knowledgeable man from CBC (cylinder resleevers) asked what I was trying to do. So I explained all about the clutch problems and how I had attempted to remedy them. Well he said that’s easy to fix, you do not increase your master cylinder you decrease your slave cylinder size. That way you do not alter the pressure but it will push further and open your clutch. I must mention here that I had my master and slave cylinders sleeved to their correct sizes hoping that would help. So I decided to get that slave sleeved down to 13/16”. He also said he had a 3/4” slave on the shelf if I needed to go smaller for $40. My one worked but was a bit close to the floor, but very smooth to operate. I tried the 3/4” one and have stuck with that, it is smooth and a pleasure to drive. I have a 13/16” one if anyone is having a problem and wishes to try it. Mob 021793939. I trust this will be helpful to somebody out there.

Cheers Jim McGowan

Print Friendly, PDF & Email