Hydraulic handbrake

[Rallyace 3]

Has anyone any thoughts on why I’m struggling to get an effective hydraulic handbrake? I’m using a .625 cylinder on a bracket located behind the standard handbrake. I’ve used this set up to good effect on other cars in the past, but struggling with the 205. There is no limiting device between the handbrake and the rear brakes and I’m running drum brakes with new cylinders and standard linings. I decided to use standard linings, as I’m using the car for Targa rallying, so overheating is not a problem. Are there many larger brake cylinders available? Any other thoughts?

 

[SweetBadger 94]

I have the same setup on my race car (used to be a rally car) but with discs on the back, and there's no way I could lock the rear wheels with the handbrake! 

 

Wilwood do a 0.5 inch master cylinder. Might do the trick.

 

https://www.demon-tweeks.com/wilwood-gs-compact-remote-reservoir-master-cylinder-1241086/

 

If not then you might need to go for a separate vertical lever to increase the leverage you have on the cylinder. 

[welshpug 1,657]

is it a gti or a base model?

[Thijs_Rallye 87 4 Cars]

What type of drum brakes? AFAIK only the 1.6 GTi units have no limiters in the wheel cylinders. 

[Tom Fenton 1,542]

I have a similar setup and even with a 0.5” cylinder and a few iterations of bracket and lever geometry it’s still poor to the point that warm tyres it won’t lock them. I’ve a theory I’ve yet to try that with both the cables and hydraulics acting on the shoes they are in fact fighting each other. I need to back the cables right off then try again just on the hydraulics. What I can’t understand is that my other totally standard 1.6 GTI handbrake is really keen.

 

[Thijs_Rallye 87 4 Cars]

13 hours ago, Tom Fenton said:

I’ve a theory I’ve yet to try that with both the cables and hydraulics acting on the shoes they are in fact fighting each other.

The cables are a completely separate system which never should interfere with the hydraulic part imho. I would suspect the slack adjuster mechanism, you might be running out of travel in the handbrake cylinder.

Edited August 23, 2021 by Thijs_Rallye

[welshpug 1,657]

13 hours ago, Tom Fenton said:

I have a similar setup and even with a 0.5” cylinder and a few iterations of bracket and lever geometry it’s still poor to the point that warm tyres it won’t lock them. I’ve a theory I’ve yet to try that with both the cables and hydraulics acting on the shoes they are in fact fighting each other. I need to back the cables right off then try again just on the hydraulics. What I can’t understand is that my other totally standard 1.6 GTI handbrake is really keen.

 

I think you are close on that theory, evrry rally car ive been involved with that still had the original lever on the hydraulic had the cables really slack.

[Tom Fenton 1,542]

13 hours ago, Thijs_Rallye said:

The cables are a completely separate system which never should interfere with the hydraulic part imho. I would suspect the slack adjuster mechanism, you might be running out of travel in the handbrake cylinder.

Think about how the two mechanisms would work on the shoes inside the drum before you tell me I’m definitely wrong!

[Thijs_Rallye 87 4 Cars]

10 hours ago, Tom Fenton said:

Think about how the two mechanisms would work on the shoes inside the drum before you tell me I’m definitely wrong! 

I'm sorry, you are right. I had the calipers in my mind :(.