Full brakes, rear handbrake

[dblack]

I have a mini dune buggy that I built several years ago that I am redoing partially. Right now I have just rear brakes via a single motor cycle disk and caliper on the rear axle. I am adding front brakes to it but I want to keep the ability to use just the rear brake at times. All of my brakes are hydraulic. Any thoughts?

PS I am new here

 

[fowler]

Well some people use 2 pedals

Or i am going to install a bias bar and set it to give more rear brakes

Iv got a brick for a hand brake

 

[Doc Sprocket]

Welcome to the forum!

Here's what I'd probably do-

Two separate brake systems (F&R), with the pedals quite close together beside each other. The pedal that you "naturally" would push is for the front system, the pedal you have to "reach for" actuates the rear. Now- install a bar on the front brake pedal arm just above the pedal pad, so that it rests on top of the same spot on the rear pedal arm. Now- when you push the "front" pedal, ALL brakes are applied because the bar pushes the rear pedal arm. Since the arm is not actually attached to the rear pedal, pushing the "rear" pedal results in only the rear system being actuated.

Once the hardware is in place, you can adjust the stroke/leverage to the two master cylinders to balance nicely when all brakes are applied.

 

[dblack]

Welcome to the forum!

Here's what I'd probably do-

Two separate brake systems (F&R), with the pedals quite close together beside each other. The pedal that you "naturally" would push is for the front system, the pedal you have to "reach for" actuates the rear. Now- install a bar on the front brake pedal arm just above the pedal pad, so that it rests on top of the same spot on the rear pedal arm. Now- when you push the "front" pedal, ALL brakes are applied because the bar pushes the rear pedal arm. Since the arm is not actually attached to the rear pedal, pushing the "rear" pedal results in only the rear system being actuated.

Once the hardware is in place, you can adjust the stroke/leverage to the two master cylinders to balance nicely when all brakes are applied.

Do you think this would be a better system than a rear handbrake (driving wise) I am wanting to do some drifting.

 

[OzFab]

That's why you're the master, brilliant idea & simpler than what I had in mind:
Two masters side by side, pedal in between & a sliding bar between the lot, which requires tools & time to change, your idea requires... well, nothing.

true drifting doesn't involve brakes, it uses power to the back wheels to break it loose but, yeah, it'll work

 

[Doc Sprocket]

Do you think this would be a better system than a rear handbrake (driving wise) I am wanting to do some drifting.

Yes, I do- because at times when you need full braking, you do not have to coordinate the two brakes manually.

That's why you're the master, brilliant idea & simpler than what I had in mind:
Two masters side by side, pedal in between & a sliding bar between the lot, which requires tools & time to change, your idea requires... well, nothing.

Thanks! Every now and then I get hit by a less-than-entirely-stupid idea!

The slide bar is straight outta the tractor book. The problem being that you cannot change function on the fly.

 

[dblack]

Yes, I do- because at times when you need full braking, you do not have to coordinate the two brakes manually.

I was thinking a brake pedal that would operate front and rear and a handbrake just for the rear.

 

[Doc Sprocket]

you could- but having two seperate controls acting on one brake caliper might prove difficult...

 

[OzFab]

The slide bar is straight outta the tractor book. The problem being that you cannot change function on the fly.

That's why your idea is better

 

[dblack]

I was thinking a mechanical linkage between the hand brake lever and the master cylinder but maybe I should add a second caliper to the rear rotor and a separate master cylinder on the hand lever, or just use the 2 pedal setup. Ill have to figure out which would be more intuitive for my style of driving.

 

[fowler]

U would use the rears as the primary brakes
It's a dirt racer not a track

Fronts will just lock up and u will oversteer

The slide bar works simply but it isn't very effeicent
It has been tried before many times but no matter how much u adjust the strokes u end up with equal braking front and rear
Also using a cable and spring has been tried
Also useing a propotioning valve

But really the only methods that actually work is a bias bar (google it) and electronic bias

Although it all depends how serious u are

 

[Doc Sprocket]

Fronts will just lock up and u will oversteer

I disagree. My car has 4-wheel-braking...

The slide bar works simply but it isn't very effeicent

It would work fine- but you cannot "select" the function while driving.

It has been tried before many times but no matter how much u adjust the strokes u end up with equal braking front and rear

Again- I disagree. It's quite doable. It WILL take trial and error, but doable. A proportioning valve IS one potential solution, but not the only one.

But really the only methods that actually work is a bias bar

A bias bar COULD be adapted to act as the actuator bar I describe. Similarly, the actuator bar could be designed to provide a bias.

 

[fowler]

U are saying it would take trail and error
I'm saying Iv seen the trail and error on all those systems

By watching the West Australian superlites club

Like I was saying it depends how serious u are
The bar system works but it isn't very effeicent

Your car has 4 wheel brakes because it is a road car not a rally car
The idea is for the rears to be always more powerful

Also don't forget a car has a great big engine over the front wheels and most modem cars have nothing but some sheet metal over the rear
A buggy has some tubing and your feet and over the back is the engine and most of your body weight

 

[Doc Sprocket]

When you say a bar isn't "efficient", what exactly do you mean? I can't see how efficiency would be a factor.

My point about my car was missed... At any rate, dialling in two independant brake systems may prove to be a challenge, but I doubt very much that it's impossible. My point overall was more to the fact that it could indeed be done this way.

Even if the OP had all brakes on one circuit, it would still require tweaking to balance the bias according to his needs. Ideally (and this is all about what the individual is trying to accomplish), you want to be able to hit the brakes and have niether front nor rear lock ahead of the other. If the fronts lock first, you can't steer (understeer). If the rears lock first, you fishtail (oversteer).

Yes, the buggy has it's weight biased rearward. However, let's not also forget that with a plush suspension and soft tires, applying the brakes can shift the weight bias forward by quite a bit.

It's really too bad I have nothing to demonstrate this on- because I bet I could do it.

 

[youtheotube2]

What if you use two calipers for the one rear disc. One is your brake pedals caliper, and the other is a mechanical hand brake caliper. Hydraulic brakes are expensive and not really needed for a hand brake.