How do you seal the cap on an early Clubman style plastic master cylinder? The ones with the rubber thinggy that goes in teh cap?

My GT has 2 (as it should), both with the rubber thinggys, but they both have a very slight leak. Doing the cap up tight or just nipped up makes no difference.

Can you buy new seals for the caps?

I kept the levels a little lower so it wouldn't splash around the cap, but I also made a couple of gaskets using gasket material.

Never really solved the problem however, it still leaked unless i kept the level a little lower.....

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Karcraft sold me a repair kit, it included a new rubber thingy.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

ta guys.

I just had a read of the Service manual, and it shows a gasket under each diaphram. I had 2 spare ones, that I actually got with the original 'Pops'

I have just wacked them in, so I shall see how I go.

Kev, does the 'repair kit' include master cylinder seals? I will need to kit both of Reg's master cylinders.

Yes.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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http://www.youtube.com/user/Hanras

Anton,
My MK2 S use same style for clutch master cylinder, I tried making gaskets out of different thickness gasket papers, but still leaked which drove me mental. Tried running lower reservoir levels too Mick, but still NG. In the end I traced the outline of the cap and carefully measured, the bldy thing was out of round! It seems these caps only have "purchase" (grip to you and me) of 1 or 1 1/2 threads, so it is (apparently according to local clutch and brake guy) quite common that they go out of round due to overtightening. I found a PBR cap used on a few Datsuns and other local master cylinders is the same and has about 3 threads - very successful for fixing leaks! But still not original, so I used it for a while until I was able to find a decent lockheed one. Hope this helps,
regards Gavin

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Are they big? I like 'em big!

hmmm....thats very intersting. I will have to check the caps for roundness. Cheers for the tip!

if all else fails put a couple of old socks over them to collect any drips (saving paintwork) until you find some good caps

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real men race downhill - keiichi tsuchiya

I don't know whether this would work but as a temporary measure could you place a small amount of glad wrap over the opening and then place the cap back on.

Don't know whether the fluid will do anything to the plastic though so its best to test it out first.

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Cheers,
Rob.

It seems that the gaskets (shown above - thanks Harna) may have solved my issue, but the sock idea and out of round cap are good tips.

Motorbike fellows sometimes put a beer cooler type device around their master cylinders. It almost seems the right size for one or two of these. And you can personalise them!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

A stubby holder? hahahaha nice!

Some racers use wrist 'sweatbands' nice and adsorbent!

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Sir Alec! we are not worthy!

hahaha.... Pat Cash chequered style?