6 replies to this topic

[Royalasaforce]

I've given this a search and only found people mentioning going back to the single line master cylinder.
Basically while my clutch master cylinder is out for a rebuild I thought I'd remove the bracket that holds the brake servo for a clean and paint as well as the servo itself. I've unbolted the servo to find it full of brake fluid.
The only search result I found was saying the servo needed to be rebuilt or replaced which is £90 or over £200 for the later.
I wouldn't go back to a single line system but I've seen that the later MPI minis had a master cylinder which is twin line and no brake servo fitted ( https://www.ebay.co....emis&media=COPY )

Could I remove my servo and master cylinder and replace it with this? Obviously would need to move the return spring.
Is this feasible or am I looking at the worst accident when I brake and nothing happens? 🤣 I'm sure the servo wasn't doing crap anyway.

If I have too I'll replace them but this seems like an alternative to me.

[Icey]

That’s a ‘yellow tag’ master which wasn’t fitted to MPis it was fitted prior to servos being fitted (i.e minis made prior to ‘89).

You can retro fit but you’ll need to make up new hard lines and change the pedal (or entire pedal box).

You’ll likely have to change the rear cylinders as well, or fit a bias valve to ensure the rear wheels don’t lock up.

Edited by Icey, 15 May 2024 - 08:37 PM.

[Royalasaforce]

Thanks for the reply do you happen to have a link to the bias valve? I'm guessing the manifold under the master cylinder is just there to divert fluid equally front and rear?

I was thinking for the pedal to just track weld something to the pedal and inner the dash and fit a spring or is that too botched for here 😂

[Icey]

It’s nothing to do with springs, the pedals are different - different size hole for the clevis pin and different lever angles (for want of a better phrase).

As for the bias valve, I’d suggest first reading the section on Keith Calvers website that covers brake setups before you go any further, it should explain what you need to think about re: balancing the system. It may be that you won’t need to change anything but you need to consider/understand the impact your change will have on the whole system.

Edited by Icey, 15 May 2024 - 10:02 PM.

[Royalasaforce]

Ok I'll do that appreciate the help

[Ethel]

Don't invalidate your insurance, square any modifications with them first.

 

Brake fluid in the servo will be down to the master cylinder. you might get away with a seal kit, but even at £90 it's unlikely converting it will be much, if any, cheaper.

 

Are you certain it isn't condensation?

[PeterG]

I had this issue. Leaking gland seal on the master cylinder. I did a servo rebuild and installed a new master cylinder. Job done.