10 replies to this topic

[Alice Dooper]

Anyone ever tried fitting a bigger brake servo??

Any thoughts or results?

[Steve220]

The output would be less force for braking, which for a mini could make it difficult to drive as you need to feel the brakes to prevent locking up.

[nicklouse]

No.

What are you trying to achieve?

[Alice Dooper]

No.
What are you trying to achieve?

I've MS and am starting to have some leg problems. Just thinking out loud in case I need to adapt the brake pedal to needing less force. The purists will rip me apart on this one.

My first step is a set of new flexible hoses. Last brake output test at MOT passed but was a bit down on the past.

[tiger99]

You need a servo with the same master cylinder diameter (that is quite critical but in any case it is a loose master cylinder that bolts on) but a larger boost ratio. It will not necessarily have a larger vacuum chamber, as the peak pressure required at the output is unchanged. It is the control valves and other internal jiggery-pokery that will need to be different.

 

What you require is a "direct acting vacuum servo". What you need to know is the boost ratio of your existing servo, and that of some other vehicle with a similar servo. I have had a quick Google, and sorry to report that I can't find the necessary information. But with a bit of time, you may do so. Or talk to a servo supplier or reconditioner.

 

Good luck!

[nicklouse]

No.
What are you trying to achieve?

I've MS and am starting to have some leg problems. Just thinking out loud in case I need to adapt the brake pedal to needing less force. The purists will rip me apart on this one.
My first step is a set of new flexible hoses. Last brake output test at MOT passed but was a bit down on the past.

Right, now we know what you are looking to achieve there are a number of ways that you can get it.

I friend has had to do something similar for his clutch. (Ski accident)

Things you can look at are. Changing the brakes to some that require less input force.

Changing the length of the pedal.

Changing the lengths of the linkages that act on the MC/servo.

A lot will depend on what abilities you have and how it may process.

Ps. Sod the purists.

[Alice Dooper]

Less about bout force will be the thing.

Probably have to think about the clutch and slow speed steering weight in the long run too.

[nicklouse]

Steering is easy. There are electric kits available the use the corsa steering.

As to the rest you need to find a local engineer also you can bin the standard pedal box and look at some that the racers use and will allow you to have a play with hydrauliclic ratios.

[Dusky]

I've installed a quad servo in a Mustang for someone who had a spinal injury. I see no reason why it wouldn't fit in a mini ,
it's not that big. (http://www.armstrong...s/zroeffort.htm )

[Alice Dooper]

I've been looking at the power steering kits, expensive but I'm seriously looking. Just need to make sure its speed sensitive, I spent too many years cutting people out of cars and wouldn't fancy having to be removed from a Mini.

[tiger99]

You can't safely play with hydraulic ratios, as you would be in grave danger of running out of pedal travel. You can play with pedal ratio, but only as long as full master cylinder travel is retained, which is unlikely.

 

That is why I suggested changing the servo boost ratio, which is the only method that retains the essential amount of fluid displacement capability.