Why & how to install a Hydraulic Handbrake in a rally car

Answering our most common questions about why & how to install a hydraulic handbrake in a rally car.
Two previous episodes covering hydraulic handbrake install and plumbing:
• Building a WRX rally c...
• Building a WRX rally c...
For all things rally, check out our website: rallyaction.co...

[@TheLoamRanger]

Thanks for this info! So with my 1995 GC8 Impreza L 5-speed rally car, I’m guessing that system won’t be ideal for a handbrake hey?

[@rallyactionwa]

@@TheLoamRanger depends on whether the car is 2wd or 4wd and whether it has disc or drum rear brakes. We've fitted plenty of these set ups to WRX models. Drum brake models can have a hydraulic handbrake fitted, however the rear brakes should be converted to disc.

[@060racing8]

I'm considering doing this kharnaCross car it is still road registered at the moment, considering swapping rear callipers for late model ones with electronic handbrake for parking. Hydro with dccd for turning electro for parking

[@rallyactionwa]

That may work if the brakes will fit. Depends on the model(s) you planning to do the swap on. Some hub/rotor/caliper combinations are not easily interchangeable.

[@060racing8]

@rallyactionwa late model Subaru to 2007 outback from what I've seen a lot of late model cars use TRW electro e brake callipers with different brackets for different models.

[@raycadbury]

What would happen if you forgo the biased proportioning valve? Would pulling the hydro at that point fully lock up the rear??

[@rallyactionwa]

Without a bias valve, pressing the brake pedal even under normal braking conditions may result in locked up rear wheels. The hydraulic handbrake should lock the rear wheels regardless of a bias valve.

[@raycadbury]

@@rallyactionwa I see! so the proportioning valve you have fitted in the cabin works independently of the hydraulic handbrake?

[@rallyactionwa]

@@raycadbury yes correct.

[@turistah]

I have a pump like yours and i Will mount it whith hard lines do you know if i can mount it upsidedown? The hardline passes under the car and it Will Be easy to make less curves in the hard lines.

[@rallyactionwa]

The handbrake master cylinders are not designed to be mounted upside down. It's likely you will have trouble with bleeding and/or correct operation of the brakes.

[@rz406]

Hai, can i install the hydraulic handbrake in my 2004 5mt wrx?

[@rallyactionwa]

@@rz406 the reality is it can be installed in most cars. We've had no problems installing a hydraulic handbrake in a GD WRX like yours.

[@rz406]

Thank you for the reply 👍👍👍​@@rallyactionwa

[@adamward1008]

Interesting, I did pretty much the same on mine although I put the proportioning valve on the front lines not the rear, because mine is disc front and drum rear it wouldn’t work otherwise.

[@adamward1008]

I have a load of video’s from a tripod of me locking up the brakes to see what locks first when on the pedal

[@adamward1008]

Ahh now ive got to the end of the video i see you’ve covered it ;)

[@rallyactionwa]

If you have fitted a proportioning valve on the front brake circuit it is incorrectly fitted and should be removed. It does not matter whether the brakes are drum/drum, disc/drum or disc/disc. With some cars the factory bias valve is inside the master cylinder, other cars it is fitted at the rear of the car. It needs a thorough investigation before any modification is made to the braking system. In all cases fluid should not be restricted to the front brakes.

[@adamward1008]

@@rallyactionwa its fitted to the front brake circuit because I had to remove the factory proportioning valve as it tied the front left to the rear right as one circuit and the front right to the rear left as a seperate circuit. Had i not put the aftermarket proportioning valve in to the front brakes after removing the factory one, only the fronts would lock up when stabbing the pedal…

[@rallyactionwa]

@@adamward1008 Your valve is still fitted incorrectly. Yes in modern cars the braking works on a diagonal system with a diagonal proportioning valve or sometimes the proportioning is controlled by an ABS unit if fitted. If fitting an after market brake bias valve, the correct way to do it is to remove all the factory plumbing from the car and run new brake lines to the front and rear. With a two port master cylinder generally one port from the master cylinder is used for the front brakes and the other port is used for the rear circuit which has the brake bias valve and hydraulic hand brake inline (we used this exact set up in the Subaru in the video). It is irrelavant whether the car has disc front/drum rear the same plumbing is used for both. In comparison to disc brakes, drum brakes need a check valve to keep the wheel cylinders correctly adjusted. Sounds like with your car further investigation is required. It may have a factory bias/check valve tucked up somewhere under the car. The other possibility is that if you have removed the bias/check valve, the rear wheel cylinders are not actuating correctly as there is nothing to hold the wheel cylinders in adjustment. Either way, the brake bias valve should not be fitted on the front brake circuit.

[@wonkylommiter6364]

So do cars fitted with this set up pass the relevant ministry of transport tests, or whatever is the equivalent in each country? here in the UK, rally cars are driven on public roads between stages and are therefore required to be road legal so would this set up still need a totally independant parking brake as well?

[@rallyactionwa]

That is an impossible question to answer! Each country and/or state/county may have different rules and allowances in regards to rally cars. Where we are, there are no major issues with this handbrake set up and many cars use it. All rally cars must pass scrutiny for each event and the scrutineers are also responsible to check safety for road use. As we mention in the video, we have seen some cars where the mechanical handbrake is retained in parallel with a hydraulic hand brake. Perhaps in some places this may be needed to comply with public road transport regulations.

[@wonkylommiter6364]

@@rallyactionwa Thanks for the reply.

[@michiel5160]

Where I live all cars have to undergo technical inspection. But they have other requirements for rally cars.
If you put a hydraulic handbrake on your road car and they notice it, you won't pass. However, they test brake performance on front axle and rear axle, so there is a change they won't notice - if you manage to keep the standard handbrake lever

[@rallyactionwa]

@@michiel5160 where we are, fitting a hydraulic handbrake (or any other form of brake modification) is illegal on road cars. Hydraulic handbrakes are only for dedicated competition vehicles.

[@bigbothoee8617]

What if you have 2x hydraulic systems ?

[@rallyactionwa]

What do you mean by 2 x hydraulic system?

[@colinmann6199]

try this