19 replies to this topic

[paulrockliffe]

I'm slowly gathering bits and making plans for a Micra engine conversion; I have the engine, subframe, driveshafts, some throttle bodies, a fancy computer and a few other bits.  

 

The current setup is 7.5" Cooper S discs, with a servo.  The car is a Minus, so the servo already sits above the bonnet line, so regardless of how I end up doing the Micra conversion, I want that gone so I can fit a bonnet without a massive daft bulge.  No experience of the brakes without a servo, so interested in whether it's worth swapping to 4-pot calipers when the servo goes?  I understand the argument that you can still lock up all the wheels, but that's the same argument people used against disc brakes on mountain bikes.  It's really about pedal feel and how much work you have to put in to stop, rather than ultimate power.  I don't want to lose the 10" rims, so interested in the best performing 10" setup that doesn't need the pedal mashing too hard.

 

Secondly, if I go the ITB route, the master cylinders are then in the way; I know Willwood will sell me a pedal box for lots and lots of cash, but are there any options that are more sensibly priced that are worth looking at?  Is suitability for the mini determined by the diameter of the master cylinder, or is it a combination of the diameter and the leverage ratio that the pedal applies to the cylinder?  ie the volume of fluid for a given amount of pedal travel?

 

Not in a rush ont his, but would be handy to have a better idea of what I would be after in case something comes up second hand etc.

 

Thanks!

 

 

[nicklouse]

single or dual circuit brakes.

 

put the servo behind the dash passenger side.

[paulrockliffe]

How do you do that?  Some sort of linkage, or a different setup?

 

I have dual circuit brakes, definitely don't want to go to single circuit do I?

[nicklouse]

ok so you have the whole lot as an assy.

 

bin it fit a old dual circuit MC and fit a remote servo on the front brake line where ever you want and put a regulator in the rear line..

 

been a few threads about this type of thing.

[nicklouse]

some reading

http://www.theminifo...lain-something/

 

there is another thread as well i will post if i find it.

[nicklouse]

http://www.theminifo...ake-conversion/

[Arthy]

I recently converted to non servo brakes! I used the dual line master cylinder (yellow tag I think?) while retaining the compensator valve. I’m also running alloy 4 pots up front. I found the brakes at first to be strange but after adjusting the rear drums I find them perfectly adequate. You can easily lock up with enough force. I’d say there’s a little more travel but that makes it easier to heel and toe with me!

[Spider]

If you still have your Mini on the road (doesn't sound like it though), you can get a feel for brakes without a servo for yourself.

 

Simply disconnect the Vacuum Line to the Servo and block up the engine side of it. That will have the same feel as if the Servo has been removed altogether.

 

If you still wish to retain a Servo, you need to look for remote types that are Vacuum over Hydraulic rather than the Mechanical over Vacuum type you currently have. The original Cooper S, for one example, had a Vacuum over Hydraulic type Servo.

[paulrockliffe]

It is still on the road, well it's not but it'll be MOT'd in the next few weeks.  The Micra is still sat waiting to be dismantled and I'm just collecting bits at the moment with the plan to start the swap either next winter or the winter after.  I'll test that maybe and have a read of those threads.  

 

Cheers.

[paulrockliffe]

Right, I think I understand most of that now.

 

I think I'm inclined to lose the servo as it's a complication and people seem to be happy enough driving without them.  

 

My second question was about losing everything from the engine bay as I'm not sure I have room for the master cylinders there if I go for throttle bodies.  Can any pedal box work, so long as it's driving the right diameter master cylinders?

 

Quick Q; how is the servo setup different to just running a larger diameter master cylinder that pushes more fluid for a given stroke?

[dotmatrix]

with a servo you dont need to push the pedal as hard as you do without a servo to achieve the same breaking effect.

[paulrockliffe]

I know that, but isn't the same true of a larger master cylinder as it generates more pressure?

[nicklouse]

I know that, but isn't the same true of a larger master cylinder as it generates more pressure?

nope.

 

larger MC creates less pressure.

 

some reading

 

http://www.minispare...s-how-they-work

Edited by nicklouse, 02 November 2018 - 12:00 PM.

[Spider]

The other aspects to consider when swapping pedal boxes is pedal ratio, pedal length and pedal travel.

[paulrockliffe]

Yeah, that was sort of my question, how do all those things interplay with each other?

 

If I decided to remove the servo and mitigate that by going for the best calipers that aren't ridiculously priced and will fit 10" wheels, ie the Minisport ones, with decent pads (and is it worth getting cross-drilled discs?) and then I decided to remove the master cylinders by fitting a Tilton pedal box, how would I work out which size master cylinders to fit?  

 

For a mini setup, would you go for different sized cylinders for front and rear circuits, or would you just use the bias adjustment or a restriction valve to get the balance right?