Hydraulic Hand Brakes

[badhairdave]

I don't use my handbrake on the track, just when parking the car and when it's on the trailer.

I've recently installed an incabin bias valve and have a braided line running through the cabin to the rear brakes.

This got me thinking that it'd be a pretty easy job to install a hydraulic handbrake and so reduce unsprung weight by getting rid of the factory drum assembly.

Wise or unwise?

Never having had a brake failure i have no idea how effective a hand brake would be at trying to knock off speed anyway so figure id ask.

[Tektrader69]

I was talking to JP at UAS a few weeks ago about the factory Hand Brake assembly.

John says rip it out and reduce the unsprung weight. Put back a hydraulic hand brake assembly and plumb it into the rear system

[wlspn]

So would you's be looking at running rear rotors made for a caliper handbrake or simply removing the drum brake components?

[badhairdave]

Just remove the factory handbrake and retain the caliper and rotor.

[GT-RZ]

What gives you guys the impression that the drum assembly weighs anything? It's fk all. Hydraulic handbrake is no good for parking your car either because the pressure drops off.

[boxheadmr]

if race car then yes go ahead but if a road car you need the cable brake. I would not trust it by itself though

[badhairdave]

What gives you guys the impression that the drum assembly weighs anything? It's fk all. Hydraulic handbrake is no good for parking your car either because the pressure drops off.

It's made of metal, it weighs something. By removing it the unsprung weight is reduced. Significantly cheaper than new lightweight wheels.

Pressure bleeding off is an interesting one i didn't know about. Not really critical for me as the car live on a flat floor, as long as it can hold presure over a few hours during towing i'd be happy.

Boxhead, when you say you wouldn't trust it on it's own do you mean in a brake fail on track scenario or just a car parked on hill scenario?

[GT-RZ]

if you have ever taken the drum assembly off and feel the weight in your hand you will understand...

You may as well put helium in your tires buddy, If you think that much weight will do any difference your dreaming. Besides it's different to wheels because the assembly, unlike wheels is not a rotating mass. You may as well fit plastic wheel nuts or take off your window mirrors and get the same effect.

What car is it? If your concerned you should just go and get the alloy rear hub assembly. 32 or 33 GTR or any R34 depending on what you have.

[boxheadmr]

i think you will find the weight of the rear drum assembly will like most things make a difference to performance. You are talking a few KG's with the drum, pads and cables probably 10kg.

Little bits all add up to make a larger difference.

BHD - The piston in the handbrake can leak, it is something that will probably never happen though

[badhairdave]

Pulled the brake assy off the knuckles and chucked them on the old bathroom scales.

They reckon 1.5kg each, not including cables, though the backing plates have been trimmed too so maybe a touch more for unmolested ones. Funnily the cable weighs almost 1kg on it's own!

the bare s13 knuckle is 5kg. Anyone know the weight of an alloy z32 one? Internet says up to 8pounds saving (3.6kg) but i can't see a lump of alloy weighing in at only 1.4kg.

Obviously analogue bathroom scales so weights are more indicative than anything.

[sav man]

don't do it unless you want to find your car parked at the bottom of every hill that you park it on. GT-R rear hubs are 1/2 the weight of Gtst ones, so you will get a total of 5kg savings with the alloy ones.

And the hydro will weigh more when you add the weight of the lines, master cylinder, and handle..etc

[badhairdave]

So based on every ones opinions of hydraulic handbrakes; They are useless as a handbrake...

So may as well not have one at all?

Or are they useful in an emergency, say like i blow a hose on the front circuit or boil the fluid (again most likely in the front circuit).

Line is already running through the cab, sav man, so the only extra weight will be the handbrake assy itself, offset somewhat by the removal of the factory one and bracket on the tunnel.

[GT-RZ]

they are only used because they give instant lock when using in drifting. nothing more.

[boxheadmr]

also useful in motorkhana's/skidpan days.

If there is issue with the brakes in an emergency then most likely it is to do with something that would affect the hydraulic handbrake so not much good there either.

[Luke_ENR34]

I went for a lockable hydro handbrake from the UK, weighs hardly anything.

Couldnt you just leave the car in gear also to prevent rolling?