Triumphrat

Beemie · 06-01-2005

Opened the clutch master cylinder on the Thunderbird for the first time this week when the fluid level was low.

Just added a little fluid, but try as I may to get the cover sealed, there is a small dribble from the side of the cover. Took that darned thing off and reseated it half a dozen times to no avail.

Does the seal need replacing at each use?

[ This message was edited by: Beemie on 2005-06-01 22:43 ]

tridentt150v · 06-02-2005

I had to clean off paint/powdercoat overspray, and matt the surface with fine emery paper and in the end I still had to use silastic. I tried and tried over several months, but silastic was the only thing that worked [with the gasket as well]. It was just a very fine smear. Way cheaper than new gaskets. No leaks since.

MickMaguire · 06-02-2005

Here's the trick to this:

You have to make sure everything is totally clean and dry. So when you remove the diaphragm take it in the kitchen (or wherever) and wash it with plenty of water inside and out. Dry it thoroughly with a lint free rag. Do the same for the cover.
then back to the bike; carefully remove any signs of corrosion from the top lip of the reservoir then wipe this all round with a clean cloth, again to make sure it is totally clean and dry. Then you are ready to fit the cover. Make sure the diaphragm is collapsed flat and not extended and carefully put it into the m/c remember if any fluid gets up onto the seal you are back to step one. If you have filled the m/c anywhere above max this will become very hard to do. Next refit the cover and nip the screws down tight by hand (dont over cook em).

That's all there is to it. Since this method was detailed to me I have never had a leak, the same is true for others I have shown it to.

Good luck!

Beemie · 06-02-2005

Thanks guys.

Mick,
The manual says to judge the fluid level with the cylinder as "horizontal as possible". That's doesn't seem to be an accurate descrption. Do they mean with the bars turned to the lock to manke it square to the frame, or should it be with the bars straight ahead? It seems the former to me.

MickMaguire · 06-02-2005

No, do it with the bars turned and the cylinder horizontal (rotating the cylinder if need be). the cylinders are made by Nissin for all sorts of bikes and it's my understanding that the intent is that they should be filled on the horizontal. Doing it with the bars striaght ahead will almost always defeat my solution above as the fluid ends up closer to the lip and so is more likely to get onto the sealing area as you reassemble.

Beemie · 06-02-2005

"Horizontal" is the confusion or misnomer. Leave it to an Engineer to overanalyse this one.

I guess if the bars are turned near the appropriate lock, the cylinder is straight or level in one plane, but tilted, if that makes sense. Only the bottom pointed edge is actually level. Is that what they mean?

MickMaguire · 06-02-2005

Get the top face of the reservior level that's the key, you may need to loosen the clamp and rotate the cylinder to get it level in all directions. Just loosen, align and retighten, then put it back where it was when you have finished. the stock bars have alignment marks to help you work out where the cylinder was originally - it lines up with the split in the clamp. Which is helpful if you like the stock position.

Gdsila · 06-02-2005

I had weep from my clutch master cyl for a long time. I replaced the diaprham,rebuilt the master and actually bought a spare (just in case i screwed up the re-build)
still it wept. I finally replaced the hose(Haynes manual says replace every 4 yrs,my bikes a '99)and the weep stopped entirely. And yes I did all the fill it while level and clean the surface stuff as well. So if after all the other options are exhausted try replacing the hose. But the Triumph part is expensive.Try Spiegler or some such. Good luck.

MickMaguire · 06-02-2005

Gdsila, I can't see whay changing the hose should make any difference. It seems to me like there was a coincidence that you fixed it when doing the final refit of the cap after fitting the new hose. On the '96 Tiger that my wife had, she had the origianl hoses cylinders etc. all untouched. This bike had the leak. I did this procedure as described having to remove a bit of corrosion in the process too. I replaced nothing, just did the above and no leaks afterwards.

The fluid level is critical, just a smidge too high and you will end up with a wet diaphragm and a weep.

Beemie · 06-02-2005

Mick,
Your approach solved the problem. No more leak.
I was treating the seal like an oil filter rubber, wetting it.
Guess brake fluid particles are too slick or round to make that work.

Also, level is level. Duh. It never occured to me to rotate the assembly on the bars. That fluid was surely low for a bike with 1500 miles. But there don't seem to be leaks. Probably the clutch pack seating in and wearing.

Thanks again.

There was another lesson related to the experience. Unlike automotive master cyclinders, the Thunderbird's clutch MC doesn't react kindly to being pumped with the cover off...there is an "old faithful" effect.

[ This message was edited by: Beemie on 2005-06-02 15:12 ]