switch to servo-assisted brakes?
Discussion
I'm wondering if anyone knows of a method of switching to a brake servo on a kit car where there's no room to fit a large booster unit into the space available. For example I have a spare master cylinder and booster from an MX5, but there's no way it would fit into the space in the engine-bay on the footwell firewall as it would be touching the bellhousing as well as blocking the exit point for the clutch cable completely.
Is there any way to do it differently? The clutch pedal is floor mounted on the same brackets as the floor-mounted brake pedal and in a very small footwell and the throttle is top-mounted, so it's not viable for me to swap the entire pedal assembly without major metalwork, assuming I could even find a set that fitted into the space.
Is there any way to do it differently? The clutch pedal is floor mounted on the same brackets as the floor-mounted brake pedal and in a very small footwell and the throttle is top-mounted, so it's not viable for me to swap the entire pedal assembly without major metalwork, assuming I could even find a set that fitted into the space.
If the pedal effort is too high for you, other alternatives you could try are:
1. Easiest option- new pads- grippier pads need less pressure to give the same retardation.
2. A master cylinder with a smaller bore- less fluid pushed per inch of pedal travel makes it easier to push, but with a softer/longer pedal feel.
3. Alter the mechanical leverage of the brake pedal to do the same as option two - probably not as easy and welding brake pedals needs to be done by a good welder.
1. Easiest option- new pads- grippier pads need less pressure to give the same retardation.
2. A master cylinder with a smaller bore- less fluid pushed per inch of pedal travel makes it easier to push, but with a softer/longer pedal feel.
3. Alter the mechanical leverage of the brake pedal to do the same as option two - probably not as easy and welding brake pedals needs to be done by a good welder.
downsman said:
If the pedal effort is too high for you, other alternatives you could try are:
1. Easiest option- new pads- grippier pads need less pressure to give the same retardation.
2. A master cylinder with a smaller bore- less fluid pushed per inch of pedal travel makes it easier to push, but with a softer/longer pedal feel.
3. Alter the mechanical leverage of the brake pedal to do the same as option two - probably not as easy and welding brake pedals needs to be done by a good welder.
Thanks, yes better pads could be a good starting point. It has quite large "Hi Spec" branded calipers so I'd need to work out what pads will fit them.1. Easiest option- new pads- grippier pads need less pressure to give the same retardation.
2. A master cylinder with a smaller bore- less fluid pushed per inch of pedal travel makes it easier to push, but with a softer/longer pedal feel.
3. Alter the mechanical leverage of the brake pedal to do the same as option two - probably not as easy and welding brake pedals needs to be done by a good welder.
I've found this dual-circuit remote servo which could also be an option, assuming I can find somewhere to locate it:
https://www.carbuildersolutions.com/uk/compact-dua...
What kit is it and what brakes do you have on it? It’s fairly unlikely that you really need a servo /booster unless it’s particularly heavy or you need an unusually light pedal
My old Fury had a remote servo fitted when I got it but I got rid of it after a while and changed the master cylinder slightly to suit; it was far better after, feel and response improved, and saved a few more kg
My old Fury had a remote servo fitted when I got it but I got rid of it after a while and changed the master cylinder slightly to suit; it was far better after, feel and response improved, and saved a few more kg
Yes it's a Fury. The issue is the insane amount of pedal pressure required. A previous kit car had a similar system but I don't remember it taking this much effort to stop, it feels like I am going to push the pedal through the firewall. It will lock up the wheels easily enough even on 888s if you go full Hulk on it but I feel it detracts from my enjoyment of the car a bit.
Having looked at the remote servo idea some more I'm not sure there is room to fit that in either, and it would require drilling one of the Jenvey throttle bodies for a vacuum take-off.
I think different pads is a better first option, once I can figure out what type it requires. It has Hi Spec calipers but I don't know anything about them beyond that as it's really the only part of the car left that I've not dismantled and rebuilt, the rear brakes are standard Ford English axle stuff with brand new drums, cylinders and shoes and new rear brake pipes.
Having looked at the remote servo idea some more I'm not sure there is room to fit that in either, and it would require drilling one of the Jenvey throttle bodies for a vacuum take-off.
I think different pads is a better first option, once I can figure out what type it requires. It has Hi Spec calipers but I don't know anything about them beyond that as it's really the only part of the car left that I've not dismantled and rebuilt, the rear brakes are standard Ford English axle stuff with brand new drums, cylinders and shoes and new rear brake pipes.
Edited by anonymous-user on Wednesday 19th September 11:40
Hmmm... doesn’t sound the best set up then, a Fury shouldn’t need a servo really (and mine was heavier than most). Does your pedal have really short travel? (/Do you know the master cylinder size)
Also do your front brakes lock up first? Is there anything in the system that could be reducing front brake pressure?
I’d try different pads first as that’s easy - make sure the discs and calipers aren’t knackered also -if still not good then try a smaller master cylinder unless you’ve been down that route already. Someone here or on the JPSC forum will be able to advise on an actual recommended diameter for your set up I’m sure.
Also do your front brakes lock up first? Is there anything in the system that could be reducing front brake pressure?
I’d try different pads first as that’s easy - make sure the discs and calipers aren’t knackered also -if still not good then try a smaller master cylinder unless you’ve been down that route already. Someone here or on the JPSC forum will be able to advise on an actual recommended diameter for your set up I’m sure.
Pedal travel seems fairly short, but I don't know the master cylinder size.
It has an adjustable brake bias and as it had all been in pieces during the rebuild I did some road testing with heavy braking and set it forwards so the fronts locked up, then backed it off a bit at a time until it was almost impossible to lock which I am hoping means I got enough bias to the rear to balance it. The car feels stable even under hard braking, and with 888s it stops fast.
Perhaps it just needs more driving to clean the brakes, it's only done perhaps 50 miles in the past 2 or 3 years due to being rebuilt and whatnot.
It has an adjustable brake bias and as it had all been in pieces during the rebuild I did some road testing with heavy braking and set it forwards so the fronts locked up, then backed it off a bit at a time until it was almost impossible to lock which I am hoping means I got enough bias to the rear to balance it. The car feels stable even under hard braking, and with 888s it stops fast.
Perhaps it just needs more driving to clean the brakes, it's only done perhaps 50 miles in the past 2 or 3 years due to being rebuilt and whatnot.
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