I have been working with Steve on the problems associated with the clutch hydraulics and have produced the following document which I hope will help other owners to sort out the problem they are having:(I have not include the photo of the slave cylinders and the seals as I have already posted them)
1500 and possibly 1300 Dolomite clutch hydraulic problems. June 2020 update (I have only ever owned and worked on 1500’s hence the comment about 1300)
My belief is that there are more failures of replacement slave cylinders than the replacement Master cylinders. In part I have come to this conclusion based on the fact that Steve Waldenberg, the editor of Dolly Mixture, the Triumph Dolomite club magazine has advised me in May 2020 that he has had three fail during the last year having driven very few miles. I believe he obtained the replacements from a number of different suppliers but the suspicion is that they have all been manufactured by the same manufacturer. Steve has been in contact with a number of suppliers and one advised him that over the last two years they have sold about 40 but only had one complaint so the supplier had not taken any action about the quality of the items supplied with the manufacturer. However if you look on the MEV spares website it asks “Does your Dolomite slave cylinder pop every 6 months?” They have obviously become aware of this problem and go onto state that when the slave cylinders were re-made the manufacturer used a seal that was too thin and not up to the job so MEV spares now supply an upgraded item that has been made with the correct seal and piston so it will last.
Out of interest I had a look at the old slave cylinders that I have stripped and been keeping in my garage. Luckily I still had the old seals so I have been able to compare them. (See photo Girling and another slave cylinder)
There are significant differences between the pistons and the associated seals. If I had a damaged Girling body but the piston was still serviceable I would be tempted to fit the Girling piston with the original design of seal in a remanufactured body.
(See photo of seals)
Moving onto the clutch master cylinder.
I do wonder if the later 1500cc dolomites were actually fitted with 0.7inch or ¾ inch bore diameter master cylinders at build as the Official Triumph Dolomite range 1976 onwards parts catalogue indicates that the 1500cc cars are fitted with a part number 158695 which is different from the other OHV engine cars which use a part 138928 (This item has been superseded by a part GMC1023). I have been unable to find any details of Part number 158695. Rimmer Brothers documentation indicates that they can supply part 158695 at a cost of £122.40p. Rimmers were unable to tell me what the difference is between this part 158695 and the GMC 1023. Most other suppliers quote the GMC1023 as being the Master cylinder for 1500c engine but there are a number that do not quote a part number for the 1500cc engine. I accept that a GMC1023 will work if the system is bled completely of air and there is very little or no wear in the pivots that make up the clutch system.
When I actually checked the bore size of a number of old ex 1500cc clutch master cylinders I found that the majority were 5/8th inch bore but there was also a 0.7 inch and a couple of ¾ inch in the batch that I have collected.
If you look at https://www.demon-tweeks.com/uk/girling ... ir-249578/
you will see that they can supply master cylinders with either 5/8, 0.7 or ¾ inch bores at a cost of £72.91 which look to be the same design as used on the 1500 dolomite. There would be a need to change the push rod, (so retail and fit the original). I have not been able to identify a current part number for either the 0.7 or ¾ inch bore master cylinders or the relevant seal kits on the demon-tweeks web site.
My assessment is that by fitting a master cylinder with a larger diameter bore the hydraulic system would move the slave cylinder piston slightly further for the same movement distance of the clutch master cylinder. This as a result, I believe, would mean that the system would be able to cope with a small amount of air being accidently left in the hydraulic system and it would also be able to take up any wear that had taken place in the various linkages.
If you do any work on the clutch hydraulics there will be a need to bleed the system to get all the air out of the system. The various workshop manuals make it seem to be a simple task just like bleeding the brakes. However from my own experiences and from the comments I have read on Facebook etc it is not that simple. In this article I hope to identify the various methods that owners have found that work.
The method that I have used successfully for a number of years is to remove the slave cylinder from the clutch bell housing and hold it up above the master cylinder in the engine compartment with it tilted, so that the bleed nipple is at the highest point. Just one point I should state here is that the bleed nipple should be at the top of the slave cylinder when the cylinder is fitted. It is then just a matter of bleeding the system which is made easier, if you have an assistant to operate the clutch pedal. Some people like to use an easy bleed kit but I consider this to be more trouble than it is worth and I stick to just adding a non return valve to the bleed nipple such as in the vizibleed shown in the photograph, if I am doing it on my own. (See photo Bleed non return valve.)
There is also a need to ensure that the slave cylinder when refitted is pushed fully forward before it is clamped up.
Note added June 2020 I believe this is quite a common problem and Richard Warner reported in edition 195 of Dolly Mixture that he had to use a hammer and a drift to shift his slave cylinder as far forward as possible before he clamped it up tight. Having done this the clutch worked normally.
I have found that some of the after market, slave cylinders will not pull back out through the slave mounting bracket because of the type of dust cover that has been fitted and that this means the mounting bracket has to be removed along with the slave cylinder.
A simpler way that Colin Whitely recommended on Facebook is to use a syringe and back bleed, bottom to top. This is definitely a way I will try in future.
Again another method identified by Derek Wadsworth on Facebook is to wedge the clutch pedal down and leave it over night. I am assuming this is after you have bled the system normally and are just looking to get any trapped air out by letting it bubble up from the slave cylinder / hose into the master cylinder reservoir to escape from the system.
On the 9th February 2019 Dolomite 135 posted on the clubs discussion board the following: “After I put my Toledo (1300, but the hydraulic system is the same) back on the road after its 15 year slumber, I had issues with my clutch barely disengaging. Having read that repro parts were best avoided if possible I had also put new seals in the original master, and slave cylinders during re-commissioning. After removing, inspecting, re-bleeding the system a number of times (off the car) I identified that the master cylinder was not returning fully on its stroke, and that I only had approx two thirds travel. This was not immediately obvious on the car, and being hydraulic it had self adjusted to the reduced stroke during bleeding so the last two thirds of the master moved the first two thirds of the slave. On inspection it became apparent that the return spring in the master cylinder had weakened over time and was not strong enough to fully return the piston to its resting position. Using a second spare spring I doubled up the springs (coiled together to maintain the correct overall length) which finally allowed for the master cylinder to operate through its full stroke, and the clutch to disengage normally.” This is obviously something that I am glad that he has brought to our notice as it is something a number of owners could suffer from.
Note added June 2020 I consider this might be a problem that could easily be missed because when the master cylinders are put together some rubber grease is usually applied to the outer end of the bore / piston end, before the rubber dust cap is fitted. My assumption is that the grease is there to catch any dust etc and to stop any rust forming in the bore which would restrict the movement of the piston. It also needs to be noted that the return spring is not very powerful and the movement of the piston can’t be seen once the rubber dust cap is fitted. As the push rod is not connected to the piston the piston can stop short of the end and this would not be noticed as the clutch pedal has its own strong return spring. Any failure to return to the end of travel would result insufficient hydraulic fluid volume being available to move the clutch slave piston the necessary distance to disconnect the clutch. My recommendation is that there is a need to remove the rubber dust cap and push rod before the master cylinder is fitted to check that the piston can be pushed in and will return to its full end of travel before it is installed. This is especially important if the master cylinder has been on the shelf for a long time as the rubber grease may have gone somewhat hard or some rust may have formed and be stopping the pistons free movement. I also consider it would be worth checking if you are having a problem with the clutch hydraulics.
If none of these methods solve your problem, is it something as simple as do you have a mat in the foot well that has moved and is restricting the clutch pedal movement. I believe that some owners have been caught out by this happening. However more than likely it may be as a result of wear in the clutch operating mechanism. There are a number of parts that can and do wear from my own experience. First start at the clutch pedal. There could be wear in the hole through which the clevis pin goes (See worn hole in clutch pedal photograph)
Note added June 2020. I was surprised to discover that one of my cars was suffering from this problem and when I was talking to a retired Triumph engine fitter he told me that the garage that he used to work at used to regularly fit bushes to take out the wear at this point.
Wear can also have taken place in the clutch pedal clevis pin (part number PJ8808) itself or the push rod (part number 122296). Next moving onto the slave cylinder, again there is a push rod (Part number 109182) and clevis pin (Part number 112516) that wear over time (See clutch push rod and pin photo).
The photo does not show up the wear very well in the push rod but the hole had become enlarged. The lower push rod is an example of an aftermarket re- manufactured push rod. The problem you have, if there seems to be wear here is that you need to take the bell housing off to sort out the problem. At the other end of the clutch arm there is another pivot (Part number 129410) and a tolerance ring (Part number 129412), which causes a problem when it wears and this allows the pivot pin to drop out. This can be overcome by using a pivot pin (part number ULC 2713) which has a top hat to stop it falling out if it is fitted from above (See clutch arm pivot pins photo) I believe this was a modification that was introduced during the dolomites build run.
Although I have stated, that to make a repair there is a need to take the bell housing off I do believe there is a work around which is to extend the push rod. Tony Keogh on Facebook stated that he had to extend the push rod and did this by cutting down a small socket and wedging it onto the end of the rod. I would suggest that a small blob of an epoxy resin would ensure it did not come loose. Tony extended his push rod because he suspects that aftermarket clutches do not have a high enough bite but I believe that the same method could be used to take up the wear in the various bits.
The one bit of the system that I have not discussed is the hydraulic pipe (Part number 155956) that connects the master and the slave cylinders. I have heard that these can cause problems as the originals were made of plastic which can go soft and expand when hot, or split or be damaged by rubbing on the cars bodywork. However in my 40 years of Dolomite ownership none of my cars have suffered from any of these problems with the plastic type hydraulic hose. Alun Nicholas has advised that he believes that the problems mainly occur on Sprints and 1850’s as their original OE hoses have a rubber section which suffer from aneurysm in old age. However the club has recently arranged for a supply of braided hoses to be manufactured if you think you have a problem with the hose on your car. These are available at a cost of £45 which includes postage.
On February 10th 2019 there was yet more good advice on the clubs discussion board, if you have no reasons to suspect the hydraulics, the very respected, Jeroen, advised that the first thing to check when the clutch isn’t disengaging totally is to check the engines thrust bearings for wear or they may even have dropped out.
Note added June 2020 I was advised by Steve Waldenberg that Rob Marshall has advised him that Dolomite/Toledo/FWD OHV cars are not fitted with adjustable clutch pressure plates (unlike many modern cars), the clutch pedal becomes gradually heavier as the clutch friction plate wears and the 'fingers' of the pressure plate move inwards to compensate. This places more strain on the hydraulics, which may be the cause of clutch slave cylinders failing. Two of my Toledo’s have their original clutches that are pretty worn and have very heavy pedals indeed. Another Toledo has a fairly new clutch, as has my 1500HLs and the clutches are far lighter.
My own recommendation (Richard Old) is only change the clutch kit once you have eliminated all the other items that I have identified.
One final suggestion. Most owners know that it is recommended that the brake system hydraulic fluid is changed every couple of years but I have not seen any recommendations about changing the clutch hydraulic fluid. A few years ago I purchased a hydraulic fluid tester which measures the amount of water that the fluid has absorbed and I regularly check both the brake and the clutch fluid. I realise that the clutch system fluid does not suffer from the water boiling which can happen in the brake system but my hope is that it may reduce the chance of corrosion occurring within the systems parts. Then if either or both of the fluids are recording a high level of water I change the fluid. I must confess that on respect to the clutch fluid I just use a syringe to suck most of the fluid out of the master cylinders reservoir and then top it up. This saves having to re-bleed the system.