Master Cylinder Options
Turbo Mini Forums

Hi guys,

I'm running KAD 4 pots and was having a persistent problem with a varying brake pedal and air getting into the brake lines from somewhere. I thought it was a problem with the rear brakes, so blocked them off. I then thought the master cylinder had given up, so bought a new replacement yellow tag MC. Problem still persists. I'ved checked all the lines and im at a bit of a loss.

I also realise the original MC is not really up to supplying the 4 pots with the necessary volume and i'm looking at alternatives to solve the above problem and minimise the travel in the pedal.

I realise you can buy something like the OBP kit, but id rather not spend £600 if it can be avoided. Is there anything off other modern cars that can be used or cheaper alternatives to hte above that just beef up the brake MC?

Cheers,
Nick

Why isn't the yellow tag up to supplying 4 pots? Plenty of people use that configuration.

Are the calipers the type without the dust seals on the pistons?

Joe C had these fitted when I drove his car. Bloody death trap.

The MS (if in good order) is up to the job.

In the 13's at last!.. Just

I'd be checking the bleed nipples up front if one isn't quite seating right it is possible that it can Suck air in and not fluid out

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

I cant imagine its the mc at all, id be going through brake lines and compensator/regulator valves before wasting any more money

Do KAD four pots use a different size piston to the metro four pots? If they are the same, the yellow tag master cylinder is perfectly adequate since the piston area of the four pots is exactly the same as the two pots!

What fluid are you using ?

I have started posting on Instagram also my name on there is turbomk1golf

Nothing is impossible it just costs more and takes longer.

What brakes did it have as standard ? If it was on drums i.e.. with the old square type pedal. Swap the pedal for a later hexagonal, type from a disk braked model.
Had exactly this problem with my minispares 4 pots.

Thanks for the replies guys. Its these: http://www.kentautodevelopments.com/shop/p...vented-disc-8.4

I had heard that the MC would always introduce a bit more pedal travel when moving to 4pots - might be nonsense though.

I will double check the 4 bleed nipples but pretty sure i checked this out before.

Not sure re the piston size but im pretty sure there are dust seals.

I'm using halfords dot4 or 5.1, cant remember which, but will check. The car is only used for sprinting, so never really gets hot and new fluid is flushed through every event when the pedal starts to get really spoungey.

Original car was a mini 30 but ive fitted a non servo MC and pedal box setup, unsure if this was from a drums or discs car. What do you mean square type and hexagonal type?

Edited by nky_84 on 9th Jan, 2014.

If they were single bleed nipples I'd ask if you had them mounted the right way up, but with two per caliper I can't see that would be the problem.

Metric is for people who can't do fractions.

By Square and Hexagonal, I mean the actual shape of the bit your foot goes on. But seeing as it's a thirty, it'll have the later Hexagonal pedals.
The thirty brake pedal has a plastic/nylon bush, where the pin goes through the pedal. It's riveted to the extension piece, rather than a pin and split pin. So the hole in the pedal is too big, if it's had the bush removed so the later pedal can be fitted there would be loads of slack around the pin.
You'd need to use a matching pedal and master cylinder.

Do you still have a standard proportional bias valve fitted?

I've had no end of problems with these. Bit it and either fit a bias valve in the rear line, or one of those spangle Wilwood adjustable replacements.

The master cylinder should be fine.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

@ dilligaf - its a 30, but i replaced the pedal box and servo for a non servo type. Unsure what date this came out of, so will check pedal shape at wknd.

@ wil - i dont have the standard bias valve fitted, ive got a willwood in the rear line (rear brakes were shut off for most of the season though and this was still happening)

Now that i know the MC is up to the task, im going to take everything to bits and ensure all the connections are good.