17 replies to this topic

[Dylpants80]

Hi guy's some help please. I have a 1980 mini van which is a bare shell and I want to know if I fitted it with a master cylinder with a brake limiter fitted in the engine bay will the brake pedal be hard compared to a Brake servo set up. Thanks

[Maccmike8]

Youd have to press harder yes. 

[Dylpants80]

Is the pedal really hard to push ?is there to much resistance or it's not to bad? Thanks

[Maccmike8]

After a modern car yes its harder to push. I personally fitted a remote servo to mine. But thats a personal choice and most dont feel the need.

[Dylpants80]

Thanks for the info

[sonscar]

Once upon a time very long ago brake servos and power steering were like a myth that people had heard about but never seen.Everyone managed.Yes it is harder but not noticeably so,the Mini servo being about 1.5 times to 1 assist or thereabouts.Steve..

[Ethel]

I think there could be some confusion...

 

Pretty much all cars have some form of brake limiter. Just like hitting the front brake on a pushbike hard will try and throw you over the handlebars, cars too have a torque reaction that transfers effective weight from the back to the front wheels the harder you brake. This makes it easier to lock up the rear wheels because there's less force pushing the tyres against the road. A brake limiter cuts off the fluid pressure to the rear at a level lower than will lock the wheels (hopefully) so all additional braking effort goes to the front only.

Minis being light cars, with the engine etc in front of the front wheels need even less rear braking compared to the front.

 

A Servo will typically about double the line pressure.  But, the size of the brake discs, ratio of hydaulics, friction area & material are all equally important.

 

Then, you can never have more braking than you have tyre grip and if you're anything like me, you'll run out of talent first with pretty much any Mini brake setup.

[Maccmike8]

The fluid doesnt compress, thats the reason for using it. The pedal movement is from the calliper piston moving.

[Tornado99]

My car has a servo. I recently had to roll it down a ramp with motor off, so no vacuum assist to servo. Had to perform some braking and was surprised how hard I had to push the pedal. Now it may be that a proper non servo setup uses a different master cylinder to caliper piston ratio, changing the pedal force needed.

There are those that advocate for going non servo on the mini as the brake feed back is improved. I'd suggest test driving a few examples like that before doing a conversion.

[splintercat]

I have just done this myself, the pedal may be a little harder to press than usual, but to be honest I like the swap. I have much more room in the bay with no big servo sitting there and I used a brake bias valve so the brake set up is just how I want it to be, and easily changed to suit......

[Tornado99]

I have just done this myself, the pedal may be a little harder to press than usual, but to be honest I like the swap. I have much more room in the bay with no big servo sitting there and I used a brake bias valve so the brake set up is just how I want it to be, and easily changed to suit......

What engine & wheel combo do you have? Did you change the MC to something different in size compared to the servo MC unit?

 

I recall my '84 GTi Rabbit/Golf had a rear ride height sensing (by way of a spring & lever) rear brake proportioning valve. As weight shifts forward during a hard stop, rear ride height increases, brake pressure ot rear wheels reduced. Have not seen such a system on other cars of similar era but seems like a good approach in principle. 

[splintercat]

I just used a yellow tag master cylinder with a generic off the shelf brake bias valve. I have compomotive crx  13 ins  wheels ( to die for), 1.8vvc engine.

[Ethel]

Lots of vans have load sensing valves like you describe. An inertia valve is even better, it senses exactly what you need to reduce rear brake effort for.

[splintercat]

whats the difference?

[Tornado99]

Lots of vans have load sensing valves like you describe. An inertia valve is even better, it senses exactly what you need to reduce rear brake effort for.

has anyone tried adapting something like this to the Mini?

Ive also wondered why we never see ABS being adapted for older cars. Should be pretty straightforward as all components are available from other vehicles.