Hydro Handbrake?

[Damo666]

I'm just wondering how many people are currently using a hydro in their Excel?
If so, how do you have it set up?

The master cylinder has two lines coming out of it, leading to the bias valve/splitter thingo on the firewall, which then provides a separate line running to each corner of the car - I'm thinking that I can either;

1) Ditch the splitter, tee one of the master cylinder lines off to run the front brakes, and then run the second line back to the hydro and on to the rear brakes, or;

2) Keep the splitter, and just join the two 'rear' lines with a t-piece, and run this to the hydro and onto the rears.

I'm thinking that the first option will make things a bit cleaner in the engine bay, but am not sure how badly this will affect the bias or the residual pressure needed for the rear drums (even though i'll most likely use an adjustable valve before the handbrake).

Any clues as to how yours are setup?

[matt mead]

whitey and mr race brakes will have the answers ;)

[Crazy Dave]

Just be careful with whatever you do as you can change the brake bias badly making the car dangerous if you do something wrong.

No 2 option is out as it could cause problems if you developed a leak in either circuit. You need to realistically redsign the system so that instead of having diagonals which is done for safety (if you lose one circuit then you still have a front and a back from opposit sides of the car) to a front circuit and rear circuit set up which was used on older cars but is less safe in that if you have a leak in a front circuit then you only end up with a rear circuit. If you have a fully registerred car then this causes problems against ADR's but if it is rally rego then you can do this.

Due to the bias being setup for each being equal, you will need to bias down your rears which is easy and provides a good benefit in adjustability in the long run with a simple bias valve fitted inside with the hydraulic handbrake unit. There is a fair bit of work in remanufacturing all the brake lines and running the lines through the car. Make sure you use the correct (steel) material, and have the correct valving as such. Race Brakes should have the stuff and I think I would check Motorsportbits.com.au as well as I think I saw a kit on there.

[Whitey]

Hi Damo,
Just be careful with whatever you do as you can change the brake bias badly making the car dangerous if you do something wrong.
Crazy Dave has some good advice... :)

DO NOT ATTEMPT THIS MODIFICATION YOURSELF, YOU NEED TO GET A BRAKE SECIALIST SUCH AS RACE BRAKES TO ASSIST!!!

I don't know whether i would jump into the process before i built and drove my car for at least a full year first. It maybe a good end of year project once you decide you need (want) to do it.

There is also a downside, which is that in the event of a front circuit failure you will have less than 20% of normal braking effect.

I went thru a great deal of heartache to get it right, including a couple of high speed off road excursions. You can think you have your bias correct (even a little to the rear) with normal braking at moderate speed BUT when you are braking later from higher speed, there is huge front bias.

In short the pedal feel was very unpredictable.

The first step is to uncross the lines and plumb the fronts into one circuit and the rears into the other.

In the rear circuit add a proportioning valve (use a quality one such as Tilton rather than a cheapie as the adjustability is better) and hydraulic handbrake nearest the rear wheels.

The guys at Specialised Brake & Clutch (owners of Race Brakes) put pressure gauges onto the brakes and found that with all the plumbing done and brakes bled correctly there was 400psi in the front but only 100psi in the rear circuit.

They then adjusted the master cylinder so that the pressure in each circuit was the same and so that the rear brakes are applied marginally before the fronts.

The proportioning valve is used to fine tune the bias for surface and weather conditions. (i used a screw tye rather than a lever).

[dazzler]

Wouldnt it be simpler to run twin cylinders on the hydraulic handbrake with each side plumbed in seperately? :confused:

[Whitey]

Interesting thought, it was never an option that came up when i was investigating. I spoke to heaps of people.

I don't know whether such a dual cylinder exists with a threaded inlet and outlet. Usually the dual cylinders have a resevior on the top. The plumbing would be a nightmare.

I know PWR advertised something along those lines in Auto Action ages ago but it was about $1500.

Maybe Matt from Race Brakes can shed some light on whether a suitable dual circuit cylinder is available and what the pros and cons of the setup would be.

[Damo666]

Thanks Guys,

I'm thinking that option 2 still might be a goer...

Essentially, I'll not be stuffing with any of the factory biasing or the diagonal splitting of the circuits - all I plan to do is join the two rear lines after they leave the splitter, so I can run them through the hydro and then onto the rear calipers.

This should still keep close to standard pressure at the rear calipers, and in the event of losing one of the Master Cylinder circuits, it will still give pressure to both the rears via the diagonal splitting (??).

Is there anything that I'm missing?

Cheers
Damo

[Whitey]

Hi Damo666,
I would definetely NOT do this as you are joining the two circuits together and defeating the purpose of a dual circuit brake system. If you get a leak anywhere in the system you will have NO BRAKES !!!!:eek:
You have effectively removed the split
I think Crazy Dave may have said this already, but it cannot be stressed enough. (He is a S3 scrutineer.)

[Damo666]

Thanks again Whitey.....I'd missed the bleeding obvious bit!!

[dazzler]

My off road buggy had a twin setup. The lines ran from the master cylinder into two closed master cylinders (without reservoirs) one for each side.

The circuit is normally open so that normal braking flows through the master cylinder, when you pushed it one way the fluid in the line downstream of MC is pressurised andlocks the wheel.

No idea what the MC's are called but the system worked perfect.

[luke_how]

Quick question, when creating separate brake circuits for front and rear how did you go about this? did you still make use of the bias valve assembly and just remove the bias valve internals?

[ae86trueno]

I thought i would update this thread with another option, as i have been looking at fitting one in the evo and it has the same type of system as the excel, its not cheap but is a little less complicated and compact as running 2 cylinders and can bemounted to a standard handbrake

basically you need one of these AP dual cylinder jobbies

http://www.apracing.com/info/products.asp?product=Hand+Brake+Type+%3Cimg+border %3D%220%22+src%3D%22http%3A%2F%2Fwww%2Eapracing%2E com%2Fpics%2Fproductpics%2Fcp6026%5F1%2Ejpg%22+%2F %3E%2D+CP6026+Type_2394_2393

and mount like this, or to any other handbrake lever. then run some flexable lines, as the cylinder moves.

http://www.rallyandracing.biz/out/oxbaseshop/html/0/dyn_images/4/dsc04704_p4.jpg

pretty nifty, just speak to Matt at race brakes to get you sorted out.

Ben.

[HMCA]

Harv put a similar thing in the Brinkman evo 9, is was a bit more compact then that(Kinda like a Cuban cigar) but like Ben said it was made of about an ounce of gold- check current gold prices:lmao:

[Latho]

Could you not just run two seperate normal master, arranged in a similar mount fashion to a pedal box, but with even bias, or is it just an issue of simplicity and packaging as you say Ben?

[ae86trueno]

Nope you can run a setup like that,
This way is just neater, and will probably weigh less.

[penut]

I am a newby, but i did notice one excel competitor would sticky tape the button on the handbrake lever.

they also reversed brake booster tube as they felt it gave better feel.

this was a front runner.

How many seconds could be gained/lost using above method and technical cost of hydraulic one? benefit?

And yes tape was off before park ferme.

[HMCA]

I am a newby, but i did notice one excel competitor would sticky tape the button on the handbrake lever.

they also reversed brake booster tube as they felt it gave better feel.

this was a front runner.
.

It depends on how many rallies in Canberra you intend on doing where the std handbrake cables end up a foot longer after each rally.:attack:

Paul used the reversed booster hose method, having driven that car like that both Geoff Portman and myself prefer it left std.

[Damo666]

I am a newby, but i did notice one excel competitor would sticky tape the button on the handbrake lever.

they also reversed brake booster tube as they felt it gave better feel.

this was a front runner.

How many seconds could be gained/lost using above method and technical cost of hydraulic one? benefit?

And yes tape was off before park ferme.

I reckon I used the handbrake probably a total of three time in the last three rallies...(and I'm the one who started this thread!). Just tape up the button as you have sugggested.

SFA to be saved in terms of stage times. Save the money you would have spent on this and put a new set of tyres on the car, and you'll make up MUCH more time.

[HMCA]

Save the money you would have spent on this and put a new set of tyres on the car, and you'll make up MUCH more time.

The best perfromance enhancement you'll make "All day"

[fro]

SFA to be saved in terms of stage times. Save the money you would have spent on this and put a new set of tyres on the car, and you'll make up MUCH more time.

Quoted for truth.

[ae86trueno]

Yep everyone is totally right, money is better spent on tyres on an excel, i was just pointing out what can be done as i am in the middle of doing it for the Evo, where unfortunatly its a little bit bigger and quicker then an Excel :)




and a set of WRC pirelli's set you back 2K :(

Ben.

[Matty C]

i am in the middle of doing it for the Evo, where unfortunatly its a little bit bigger and quicker then an Excel :)




and a set of WRC pirelli's set you back 2K :(

Ben.

Awww....

Sucks to be you. Let me get my minature violin out :slap:

[penut]

can this mod be done to a road car which will be used to rally?

i thought this mod would be done in reverse to a burnout linelocker system? or have i seen this too simply.