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Guest DammitBeavis

Would like to move XT6 handbrake to rear.

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Guest DammitBeavis

Having a front handbrake seems kinda useless unless it's just to be used as a parking brake. Is there a relatively painless way to swap and make them work on the rear wheels? Maybe a hydraulic unit that could patch into the rear brake lines? Disengaging the rear drive system when you pull the handle wouldn't be a problem since most of the wiring is already done for that.

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Guest DammitBeavis

Link doesn't seem to work, says that it doesn't exist.

 

I did some searching over on specialstage.com and found a guy that plumbed his rear brake line through an old fiero master cylinder, welded up a bracket for it, and attached the actuator pin to his handbrake handle. Unfortunately it didn't include any more detail.

 

Hehe, could leave the booster attached in case of multiple hairpins!

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Guest UltimateRX

I'm working on it right now. I got a set of rear calipers, the same size and dimensions as the Subaru rear caliper, but they have a level for the e-brake, just like the fronts do now. I didn't get the backing plates, so I have to hunt for another car to get those off of. I will probably take the entire e-barke system from the car. The car is a Chrysler product, but looks like a rebadged Japanese car, so the brakes are probably Japanese in origin. My first idea was to just replace that exsisting calipers with these, but the pull angle on the lever would not work so I need the backing plates. Hopefully the backing plates will bolt uo, if not I'll just redrill them.

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Guest DammitBeavis

I'm going to dig up an old master cylinder and perform some experiments on it. I think I know where an old Datsun unit is. It would be SOOOO simple to just route the rear brake lines through it IF it works.

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Guest ShawnW

What would be wrong with using the hill holder system as a 4x4 trick somehow? Isolate the system from the clutch cable and then put a lever onto the hill holder system........

 

Just an idea.

 

As far as the rears on an xt6 I would imagine Legacy or Impreza stuff would work and thats rear e-brake. The legacy I had (90) had an inner drum for the e-brake and a outer rear disc brake. Was neat.

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Guest Sweet82

For off road,

 

With the EA81...

 

A front park brake is a good thing:p

 

You could force power away from a lifted front wheel! :evil:

 

I locked my rears and am considering spliting my front park brakes to more accurately control wheel slippage in the air (since I can't seem to keep them on the ground anyway).:lol:

 

My Hatch has "Dual Diagonal braking" Hill holder would hold one front wheel and the opposite rear. Might be hard to get around that for just the rears:mad:

 

My two cents,

Glenn,

82 Hatch-Rhino Buggy conversion

01 Forester

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Guest GlCraigGT

if I understand the hill holder correctly, it only activates the front right and rear left brake. activating that brake combination at speed would probably not be much fun.

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Guest DammitBeavis

The use I had in mind for the handbrake is off-road racing where a quick tug at the handbrake brings the rear around tight turns when you're going to slow, or haven't enough traction for a scandanavian flick. I see the benefit of using the front brakes for a poor-man's versitile LSD, but that would be tough to orchestrate at speed.

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Guest DammitBeavis

BTW, this car has the automatic and thus, no hill holder.

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Guest james hogan

This topic has been gone over before . Although it was for an EA81. Wouldn't work for the 4spd dual range. Transmission implosion.

The transmission on the rallycars are switched through the handbrake to unlock(?) the rear as not to throw the gears out the bottom.<span style="text-decoration:underline"> I could be wrong.</span>

Would look into how the transmission would handle the abrupt halt of the rear wheels at speed.

Not trying to dissuade you from trying it, let me know what you find out, I've got an RX that could benefit if it doesn't destroy the gearbox.

 

If you are looking at pendelum swings for tight hairpins, could I interest you in some left foot braking off throttle?

<img src="http://groups.msn.com/_Secure/0PwDVAm4RAQ2JSJr1QBaI0fA0stQyjEUFh0*58jBwyETQdxYlMnejyOZFxlvX7X4ZKn9C9ZzAtK*G7CNoQJdNjkM5jJtI!EZG/Cnv0040.jpg" style="border:0;"/>

 

Regards,

 

Jay

 

edit for token rallycross picture

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Guest DammitBeavis

Left foot braking and pendulum turns work fine if you have enough traction to work with. I have trouble with that technique on slippery mud or grassy surfaces. Not enough grip to transfer the weight or to swing the car back and forth. Since the WRX also resists use of the handbrake I've been going into turns slow and then nailing the throttle just after turn-in to bring the rear around the outside of the turn. This usually results in an undesired drift to the outside since I'm giving up traction at all 4 corners and using the front wheels as paddles to rotate with. If I could just use the handbrake to use up all the rear traction I feel the manuver would be a lot neater. I don't use the handbrake much at all on grippy surfaces as I feel it's bad form.

 

I THINK the rear drivetrain issue has been solved already. Normally the TCU feeds a 50Hz-ish 12v PWM signal to the hydraulic solenoid that controls the clutch that locks the rear driveshaft to the automatic transmission output shaft. This allows some slip. The more power that it wants to transfer, the smaller the pulse width. If I cut the signal entirely, I get full power to the rear wheels. And if I feed it pure 12v, it's completely disengaged if you don't count the small amount that get's transferred by the fluid between the plates. That's what the FWD fuse does is it just feeds it 12v directly.

 

I figure I could just use the switch that's already on the handbrake for the indicator to feed the clutch pack 12v as soon as it leaves it's rest position.

 

Pull Handbrake = FWD, release handbrake = 4WD

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Guest bushbasher

In center-locked 4wd you have to disconnect the rear axle when e-braking, or the ebrake would also brake the front wheels through the drivetrain. That would be bad news, because the fronts have alot of force on them and are hard to break loose, so there goes your gears. I think the reason why subaru's are front e-braked is so that when ysome idiot pulls the e-brake, the fronts are directly locked up, and the rears lock up through the drivetrain, but thats not as bad because the rears don't have as much force on them, and are easier to break loose when braking. See where I'm getting at?

Oh wait, I just finished reading Beavis' last post, which makes my post kind of useless, Oh well I'll post anyways :D

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Guest Meeky Moose

hmm, i thought xt6 e-brakes operated all four wheels... if i remember right mine did anyways.... i could be wrong tho....

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Guest DammitBeavis

Unless I've missed something it appears that the cables go directly from the handle to the front wheels. Nothing to the rear wheels but the hyd brake lines. When I pull the handle, only my front wheels stop. Although I won't rule out the possibility that something is missing from my car.

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Guest SOOBME

Get a "Line Lock" from Jegs or who ever, put it in the front brake line before it splits to the wheels, but plumb it backwards. Wire it to a switch on the shifter, and when U hit the button U can push on the brake pedal and all U will get is rear brakes. Let off the button, and it will go back to normal.

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Guest alpha0001

for those using a full time 4wd tranny, like out of an RX, heres my suggestion. First of all only use it when the car is in open center differential, but use a hydrualic clutch master cylinder off of some car, who cares what... since it only has the one line feed, you could use that to rig up to a splice in the rear brake lines, and have the cylinder attached to some lever.. maybe not even the parking brake, but a SECOND brake lever (oooooh, aaahhh) I guess the only problem with this is, and I dont know about this, but do subarus with 4 wheel disk brakes have the brake lines diagonal? if they are still front and rear separate then this would work great

 

-Mike

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Guest UltimateRX

For those who are suggesting tieing into the exsist brakes lines with another master cylinder, can you explain to me how you plan to keep the front brakes from actuating when you apply pressure to the brake lines feeding the rear brakes? My understanding of hydraulics would be that if you tee into the brake line and apply pressure via hydraulic fluid, that the whole brake line would be pressurized, there by activating the front brakes also. Just curious.

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