# hydraulic handbrake, anyone done it?



## Bogner_16V (Dec 29, 2002)

has anyone done it before? i'm starting to rally prep my 4KQ, and i'd like to get this done. i'm gonna talk to the local rally shop that preps most of the competion cars around here.


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## billzcat1 (Sep 10, 2001)

*Re: hydraulic handbrake, anyone done it? (Bogner_16V)*

Haven't done it - but get a Speedway catalog; they have the parts you'll need


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## StormChaser (Jan 3, 2000)

*Re: hydraulic handbrake, anyone done it? (billzcat1)*

Why would you want one? Seriously, educate me. I was thinking you would NOT want one because it is an EMERGENCY brake. If the hydrolics fail, you'd loose both the primary brakes and emergency brake...


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## glibobbo21 (Nov 11, 2002)

*Re: hydraulic handbrake, anyone done it? (duandcc)*


_Quote, originally posted by *duandcc* »_Why would you want one? Seriously, educate me. I was thinking you would NOT want one because it is an EMERGENCY brake. If the hydrolics fail, you'd loose both the primary brakes and emergency brake...









good point i was trying to figure out why too?


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## PerL (Jan 9, 2001)

*Re: hydraulic handbrake, anyone done it? (duandcc)*

Well, he said that he is rally-prepping his 4k, and with a hydraulic "parking" brake it doesnt take as much effort on the lever (and your arm) to do handbrake slides.


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## Bogner_16V (Dec 29, 2002)

*Re: hydraulic handbrake, anyone done it? (PerL)*

exactly what PerL said.


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## 4Wdrift (Dec 16, 2001)

*Re: hydraulic handbrake, anyone done it? (Bogner_16V)*

Here's my 2 cents. Sorry if I repeat some stuff you are already are aware of. 
With the diffs locked (like you will want on any gravel stage) the e-brake will do nothing but lock all the wheels and send you into the trees. What would be killer, is to have a dual master cylinder set-up behind the e-brake handle, connected with an adjustable swivel link (a double heim-jointed adjustable link would be perfect). One master cylinder could be routed to the rear brakes and join in with the existing braided line at the calipers, while the other could be used in conjuction with a slave cylinder that switches the center diff on and off. You would need to make it adjustable enough so that the diff would unlock just prior to the rear brakes being pressurized. WRC cars use a similar concept (albeit way more trick and computer controlled).
For the master cylinders, I would check out Tilton. They have very affordable set-ups that come in many different piston sizes. They also have all of the replacement parts available.
Sorry for the ramblings........its always been a pipe dream of mine as well. For more info and prolly some pics, go to http://www.specialstage.com, click on forums, then click on car construction. If that fails, search the topic and you're sure to find something.
peace. 
T.


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## yumyjagermiester (Sep 20, 2002)

*Re: hydraulic handbrake, anyone done it? (4Wdrift)*

I think you can lock either the center diff. OR the rear diff.


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## 4Wdrift (Dec 16, 2001)

*Re: hydraulic handbrake, anyone done it? (yumyjagermiester)*

I'm pretty sure that if you modified your diff selector to lock only the rear, the torque would be sent only to the front wheels, and only to one since the front diff is completely open.


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## PerL (Jan 9, 2001)

*Re: hydraulic handbrake, anyone done it? (4Wdrift)*

It is no problem to rearrange the vacuum hoses on the diff lock switch to first lock rear, and then lock center as well in pos 2.
Or you can get two diff lock switches from the Vanagon Syncro, as these are off-on pos only, when using two of these you can lock them separately.


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## billzcat1 (Sep 10, 2001)

*Re: hydraulic handbrake, anyone done it? (4Wdrift)*

I agree with Tommy on this one. Without a limited slip or open center differential, using the ebrake to initiate a slide would not be effective. 
Locking only the rear would be relatively pointless - torque would be sent to the open front diff. Of course, one could always Quaife the front diff








Using the handbrake (to the point of locking the rear wheels ) when center is locked would not only lock the front wheels but stall the engine as well, assuming the clutch was engaged. The problem is that the locked center diff is forcing EVERYTHING to rotate at the same speed.
I don't think it is meant to be. I think that hydraulic twin MC handbrake idea is an ingenious idea, although a little more complex than I'd prefer. It's obvious 4wdrift has spent quality time thinking about this. http://****************.com/smile/emthup.gif This is a good discussion!


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## VTRally (Sep 25, 2001)

*Re: hydraulic handbrake, anyone done it? (Bogner_16V)*

You can do this on these cars with an unlocked diff as a proper application of the handbrake is only a split second. It's not the classic harry highschool pull it and hold it for 3 seconds while the car is sliding. If you move the car around correctly all it needs is a little lock of the wheel to lose grip and initiate a slide. That being said you cannot do this with a locked center diff because it would stall on the moment of lockup. With an Audi of your era (lockable center / pre torsen) you can either dip the clutch momentarily or learn how to drive without using the handbrake. Most top drivers rarely use tnem. In the US there are very few corners on any stages where it would be neccessary. it's not San Remo! Everyone sees Gille P. give it a little at the hairpin but here I wouldn't build a car around it. My 80 performs admirably with a little lift of the throttle, quick tug, steering, throttle and brake input and away we go!
The earler idea of a dual master would not work on our diffs as the vacuum solenoid is way too slow. It's a nifty idea but completely unworkable. The Subaru uses a plate type electronic center diff that uses a variable voltage to determine lock up. When you tug the handbrake the diff loses all voltage and goes to full open. As soon as the handbrake is released and throttle fully decked the diff goes to full lock up, also locks fully under braking if set up that way. This is aclever boy and works very well. However an Audi will ALWAYS whip a Subaru in the really slippy stuff. Our diffs are simply better.


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## 4Wdrift (Dec 16, 2001)

*Re: hydraulic handbrake, anyone done it? (VTRally)*

I've driven many stage miles and can attest to the fact that there are many corners where having a handbrake in the equation would be extremely beneficial.
The whole principal of the dual master cylinder set-up would be to eliminate the vaccum actuated diff locks altogether. I'm just not sure if even a hydralic slave cylinder would disengage the diff soon enough. ( Maybe a question for Bilzcat1) In other words, would the diff require that torque is removed from the system before letting go? If so, it would require a bit of free-wheeling before it releases.
This could possibly be worked around by having a 2-stage handbrake. One click (say 1/4 lift and lock) could be engaged slightly before the corner (when your co-driver states the corner in the notes) giving 1/10th of a mile for the diff to dis-engage. the 2nd stage could initiate the locking of the rear brakes. After releasing the handbrake, it could be designed to return to it's home position, thereby re-engaging the diff and releasing braking pressure from the rear wheels.

_Quote, originally posted by *VTRally* »_The earler idea of a dual master would not work on our diffs as the vacuum solenoid is way too slow. It's a nifty idea but completely unworkable. 

Come on, where's your sense of good old American ingenuity and thinking. You know, develop something killer, decide it's not feasible, sell it to the Japanese, and watch them make millions off of it.

I love the negative feedback. It just gets me thinking harder. Keep it coming.
T.
"soon to attempt this and find out for myself"


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