10 replies to this topic

[yeti21586]

Hi guys, I'm in need of some advice, I need a new master cylinder or a repair kit and don't know which one I need, I've also been advised that I need the bias bit replacing I'm going to attach some pics, I can't find the bias on the minispares website, and could you tell me if there is a repair kit for my master

Thanks

YetI

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[slidehammer]

Hi

Would need to know what year the mini is to identify which repair kit you need, but they are listed on Mini Spares website by years of fitment. The bias valve is part no. FAM 7821 and around £87.00 with VAT.

What I would do is get the master cylinder off (quite a fiddly job getting the clevis pin out from under the dash) and inspect the bore and piston for corrosion and scratch marks, if there are any the cylinder is junk and you will need a complete replacement. If they clean up well then just the repair kit will be required.

[Spider]

That's a GMC167 Master Cylinder.

[yeti21586]

You sure Moke Spider? If it is then I can get a rebuild kit

[AlexMozza]

Why have they advised that the Bias Valve needs replacing as the rarely fail?

[yeti21586]

It's just what Mr AA man said

[Spider]

You sure Moke Spider? If it is then I can get a rebuild kit

 

Yes. The original (crap anyway) fail switch has been removed (or broken off) and the cap has been replaced with a later one that has the float switch in it.

 

Kits are available, one of our local suppliers has them here under P/N K7800X. Someone else was after a kit in the UK recently and I think we managed to track one down for them. They are still being made and definitely available, just not popular so may take a bit of looking and it may not be under that P/N I've given here.

 

<Edit: I'll just add that as a suggestion, pull your old MC apart before buying a Kit. Like so many of the brake hydraulics, if the cylinder's play up, then inevitably they need replacing rather than a kit put through them. A kit really isn't for repair per se, more of a maintenance item. When the cylinders start playing up to the point where they can be noticed, then 99 time out of 100, the bore is rusted and it's 'game over'. Yes, you can hone them 'clean' again, but they will play up again from my experience usually within 12 months. New Cylinders are still available.>

Edited by Moke Spider, 07 April 2015 - 08:58 PM.

[yeti21586]

Yeah I added the float bit, what would you say about the bias needing to be replaced??

[Spider]

They do 'fail' from time to time and if the M/C has a rusted bore, then with the pressure valve being so close, it's not uncommon for them to also be rusted.

 

New ones are available.

 

If you don't want to mess about, then just replace them.

 

I'll just add that I hate (with a passion) that type of pressure valve. In my own cars, I replace them in the whole set up with the propotioning valve that was fitted to the side of the rear subframe as these are a true proportioning valve) or if not, the earlier pressure shut off valve that was fitted to the front rail of the subframe. Obriously, either of these require a considerable re-plumbing of the brake system, but do result in better and far more reliable system.

[eol321]

I'm just fitting a seal kit I got from minisport a few years ago, bore is rust free! 
 
Looking for some help though! 
 
After changing the seals on both plungers I had these seals left over (see pic).
 
The only problem is I can't get the rod etc. out of the top chamber, is there a knack to this?
 
Got a needlenose around it but it's solid!

 

 

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[MrBounce]

When I did mine to get the top piston out I tapped the MC body on the wooden workbench which got it moving. I did get quite brutal at one point but it did start moving on about the 4th "tap".