Thread: Can you improve RRC BRAKES?

Originally Posted by PhilipA

What about the Defender master cylinder? Bigger or same bore as RRC?

Why would it have a bigger bore?
Fitting a bigger caliper and bigger MC would do nothing but reduce line pressure. Easier on your hoses but a complete waste of time.

Originally Posted by PhilipA

And the Defender has a towing limit and payload far greater Than a RRC and a different arrangement of the dual circuits.

4000kg for my 85 RRC, probably the same for early defenders, now they are all 3,500kg towing.
But yes the bigger defenders (110 and 130) do weigh more, which is why the brake calipers have bigger pistons. The split circuit makes no difference to function until a line is severed. When all lines are intact both MC circuits provide the same line pressure.

Originally Posted by PhilipA

As Pod said maybe the similar can be accomplished by changing the position of the rod from the pedal to the MC.

Regards Philip A

Go ahead, fit a 25% longer pedal arm and you'll get a similar overall result. If you can do that without the pedal interfering with the floor or sitting to high to be useful.

One thing I don't think there would be any argument about (go ahead, prove me wrong!) is that fitting vented rotors in place of solid ones is an improvement. There is a definite increase in the ability of the brakes to dissipate heat energy into the atmosphere. No noticeable improvement under normal conditions, but repeated braking on long descents etc will have less tendency to induce brake fade.

Why dont people look to upgrade the brake booster? the booster converts your ~25kg of force on the brake pedal to something like 500kg of force at the master cylinder.
A small change in the diameter of the booster will give you a dramatic increase in stopping power.

Originally Posted by Jim621

Why dont people look to upgrade the brake booster? the booster converts your ~25kg of force on the brake pedal to something like 500kg of force at the master cylinder.
A small change in the diameter of the booster will give you a dramatic increase in stopping power.

Have you got room for a 25% bigger booster?
If so, where do you get one from and at what cost? Will it fit or will it require a new MC and firewall mods?

The thing with the calipers is, they are close to a straight bolt on, proven to work and are still landrover parts so spares aren't a problem.

The 25 odd kg of force at the pedal is multiplied about 4x by the lever.
The vacuum booster is worth whatever vacuum you can pull multiplied by it's working area.
The MC sees a force of your pedal force + booster.
The line pressure is the MC piston force divided by area. (smaller piston gives higher pressure).
The force on the pad is the area of caliper pistons on one side of the caliper multiplied by the line pressure (bigger piston gives higher force on pads).
The torque on the disc is the force on the pad x pad friction x 2 x radius to the centre of the pad.
The braking force at the ground is the torque on the brake disc divided by the wheel radius.

Originally Posted by Dougal

Have you got room for a 25% bigger booster?
If so, where do you get one from and at what cost? Will it fit or will it require a new MC and firewall mods?

The thing with the calipers is, they are close to a straight bolt on, proven to work and are still landrover parts so spares aren't a problem.

The 25 odd kg of force at the pedal is multiplied about 4x by the lever.
The vacuum booster is worth whatever vacuum you can pull multiplied by it's working area.
The MC sees a force of your pedal force + booster.
The line pressure is the MC piston force divided by area. (smaller piston gives higher pressure).
The force on the pad is the area of caliper pistons on one side of the caliper multiplied by the line pressure (bigger piston gives higher force on pads).
The torque on the disc is the force on the pad x pad friction x 2 x radius to the centre of the pad.
The braking force at the ground is the torque on the brake disc divided by the wheel radius.

Ive got no idea what booster is 25% bigger, or what has to be changed. just throwing around ideas about how to improve landrover brakes.

When you think about it you only have to increase the diameter by 10% for you to get a 21% increase in area – hence 21%increase in force (ie go from a 20cm diameter to 22cm diameter booster).

Do newer vehicles have larger boosters than their predecessors? ie disco 2 Vs disco 1? i might have to do some googling.
Steve

I wonder what amount of vacuum a diesel vacuum pump generates eg Defender vs petrol engine vacuum . ie would it help just to fit a vacuum pump to the current booster.
Regards Philip A

Fit Defender front calipers and pads and fit ventilated front discs - the Defender front calipers and pads are bigger than standrd RRC fitments

C H T

whats the procedure for converting from dual line to single line? and is the standard rover brake bias valve adjustable? thanks in advance. Mat