Hi guys,

I hadn't driven the mini for about 2 months, that was until about 2 weeks ago. I've driven it about 5 times (75-150Km approx) in the last 2 weeks and all was fine until this morning when I went to go on Mini's in the Gong fun run. I put my foot on the brake and it went further down than normal. Pumping it didn't help. I still had brakes but wasn't going to risk going on the run. I topped the master cylinder up and checked for any signs of leaking slaves but all looks good. I drove the 2km home and by the time I got home I had almost normal pedal pressure. I stopped on a hill and the brakes held without the pedal dropping.

More info:
7.5inch discs/spacer drums.
Small tin can style MC (4yrs old)

I will get an expert to check it over, but what do people think it is? My money is on MC rubbers

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Ryan Filippi
Minis In The Gong
[email protected]
www.minisinthegong.com.au

Have you adjusted the rear brakes recently? That can make your pedal a bit low. And is the brake fluid getting old?

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Hey Tim, how was the run?

I haven't touched the brakes. The fluid is about 5yrs old.

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Ryan Filippi
Minis In The Gong
[email protected]
www.minisinthegong.com.au

MC seals worn, OK if used regularly because the pressure holds the seal lip out. But when parked a while the seal misses the bore. Then it comes good after repeated use. I have same problem with my clutch, seals are now 20+ years old. Will fix this week.

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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.

My car has the small tin can type of master with disc brakes. Should I be upgrading to the larger tin can like these?

http://minisport.com.au/cooper-s-brake- ... n-can-type

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Ryan Filippi
Minis In The Gong
[email protected]
www.minisinthegong.com.au

Forum 'rules' will likely say that you must use a large can master cylinder with disc brakes. This is the foolproof approach used by factory, as there is enough fluid in the can to allow a set of disc pads to wear right down to metal and still have enough fluid left to keep up pedal pressure. This is the kind of pad wear you might get under really arduous rally conditions.

I have been running small can master cylinder with S disc brakes setup for many years - reason for this is that I could not get a 5/8 inch small bore master cylinder with large reservoir. But this is for road use, not rally, and with the type of use I give it the pad wear is pretty minimal.

Short tin can MC is OK with discs, just put one of those nylon extensions on top. This adds a bit of volume and let's you see the level. Sorry I don't have the p/no.

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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.

BHA4661
http://www.minispares.com/product/Class ... A4661.aspx

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Thanks guys,

I'll pull it apart and get the experts to check it. Then I'll put it back together with an extension on the tin.

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Ryan Filippi
Minis In The Gong
[email protected]
www.minisinthegong.com.au

Now days With the crap steel used for brake wheel cylinders I find I need to replaced drum brake front or rear cylinders every 2 to 3 years.
Just replaced the rear wheel cylinders on my two disk braked cars. The front calipers seem to last for 10+ years with no worries.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

I think it is inferior seal rubbers, not the cylinders. I had 2 S rear cylinders leak ( not at the same time) when 18 months old. I put a seal kit in and they are fine, 5 years later.

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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.

Interesting. So is it possible to buy decent rubber seals and put them in from new or ar you using NOS rubber seals?

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Is he only sign of a slave cylinder failing an obvious leak? I can't see anything on the outside of the brakes at this stage.

_________________
Ryan Filippi
Minis In The Gong
[email protected]
www.minisinthegong.com.au

I bought new seals from Karcraft. Not NOS. But obviously better than what was fitted to the cylinders.

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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.

Seven years on my current set of rubbers. I used to get this issue a lot, but don't seem to get it so bad anymore.

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SooperDooperMiniCooperExpertEngineering

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