Does fitting a hydraulic handbrake increase pedal travel?

[Al Weyman]

I had to fit a hydralic handbrake assembly to comply with CTRC rules of a working handbrake (?) and what with putting bigger calipers alround my brake pedal travel is a bit marginal. Does anyone know if the handbrake fitment (a DT supplied one) would cause this because the pedal travel is reduced somewhat when I apply the handbrake although I realise this is applying the read calipers of course.

[graham bahr]

it shouldn't do, but if your real calipers have bigger pistons then they certainly would, failing that are the calipers mounted dead square (other wise you may be getting excessive pad knock back) have you driven the car with this set up yet? a bit of bedding in may well improve matters.

it may well be worth investing in a 2LB one way valve in the rear brake line, this could reduce the travel by holding just a tiny bet of pressure in the rear circuit although not enough to cause any binding

[graham bahr]

Originally Posted by Al Weyman

I had to fit a hydralic handbrake assembly to comply with CTRC rules of a working handbrake (?).

personally i can never understand why a race car should have to have a handbrake unless its also road legal

[Al Weyman]

Thanks Graham, I don't understand it either although if I have not cured the terminal understeer who knows it may be pressed into action around hairpins. :-).

I have driven the car with the big grand national six pots up front and the hydralic handbrake and is was marginal but usable but the rears were sticking anyhow which may have reduced travel. I have now fitted the Bremsports on the back and maybe phycological but felt as though the pedal had more travel. Never heard of the 2LB valve, it wont cause brake binding you say, where are these availible?

[graham bahr]

rally design from memory, they do two versions the one i mentioned and a higher poundage one for use with drum brakes

[retro_msport]

Personally i would go for the line lock... easy instal and you just push down the pedal, flick the lever and the circuit is locked.
Grahams right about the Residual Pressure valves ....

http://www.rallydesign.co.uk/catalog...448ac9c246ac32

they do adaptors etc to fit it too

[COLIN STUBBS]

al watch out your hyd. handbrake cylinder isnt either trying to burst when you pump the pedal [because its getting pressurised from the inside and bending the circlip each time you pump] or the mounting brackets straining. thgis will give you lots of movement. a spacer trapped between the bracket and the cyl will stop the first. like grahm says though get em all bedded in first!

[Al Weyman]

Yes I should have gone for a linelock I think but was not sure what they would or would not accept, as it turns out no one took a blind bit of notice! Thanks for the link and the other info, I may try and get it out somewhere and try it first as Graham said because it is still usable.

[Richy_Rich]

One of our guys was excluded from a meeting for not having a handbrake fitted.

I thought the reason was to do with having a secondary system incase your brakes failed, not sure how a hydraulic handbrake would help there anyway. Can't really remember now but I'm certain they pointed it out in the blue book to him.

[Al Weyman]

Depends what the failure was I guess, but that is the regs, I checked first and they told me it was acceptable so after a lot of agg and expensive I fitted it. The 'handbrake' on the old camaro was in fact a second foot brake and not particular practical to fit especially with a disc brake conversion.

[graham bahr]

i just had a read of the blue book, basically it states that there must be either a mechanical system applying brakes to two wheels or two seperate hydralic systems i.e dual circuit brakes.

so you need either a mechaninical handbrake or a twin master cylinder setup, although this doesn't take championship regs into account so they might require a handbrake.

but either way as far as the blue book is concerned either no handbrake or a hydralic handbrake isn't legal if you only have a single mastercylinder

[Al Weyman]

I have a single master cylinder but it is a tandem system i.e. different circuit for front and rear, presumably that is legal as I have submitted cars like this and with no handbrake for years and have never been questioned.

[graham bahr]

i guess so Al it all depends on where you draw the line, seperate circuits, cylinders, fluid reservoirs ultimatly you only have one brake pedal!

[zefarelly]

if your getting too much travel fit a larger bore master cylinder ? I did . . . . all of a sudden rather than pumping my pedal, I flat spotted my tyres

[retro_msport]

Its the same with MOT's .... Allthough the DOT book says " must have an effective means of locking 2 wheels on the same axle" you try getting some wheel chocks to pass...

Same as the second system in case of failure... a bias pedal box will pass here as it can only skew so far so if you do loose one circuit you'll still have the other. So effectivly you can have a piece of wood wedged against the pedal as the hand brake. But again, its hard to get an MOT'er to pass it. Wether the nice man in the bay would pass it too is another matter

[Al Weyman]

I know that is the ultimate solution Zef and may have to go that way eventually but it is a lot of work and money to do that and I have always got on very well with the stock tandam cylinder with power booster and wilwood bias valve to the rears. If I could find a stock cylinder with a bigger bore I would go for that but I think I have the biggest available fitted. I had also thought about removing the pedal and redrilling say a bit closer to the pivot to increase the leverage action, anyone done this?

[graham bahr]

Originally Posted by Al Weyman

I had also thought about removing the pedal and redrilling say a bit closer to the pivot to increase the leverage action, anyone done this?

i looked into it Al but conclued that the small amount you could move it would add very little to the leverage, but it might be a usefull trick to adjust the pedal travel, as i assume pedal pressures aren't an issue with your car seeing as your still using a servo

[graham bahr]

with a tandem master cyl such as Al's i can see you might get into a disgussion as to whether you needed a seperate handbrake or not, but with a bias twinmaster system as far as scruitineering goes that lack of a handbrake shouldn't come into it, well i hope not anyway, i've always raced/sprinted in cars with no handbrake no issues so far,

if rich's mates car was also a spitfire than i can see the possible problem there if it still has the orgional master cyl as they only single circuit.

having said that if i were to loose say the front brake circuit whilst racing i would end up in the armaco, as no way in a million years would the tiny little rear pads stop my car from racing speeds, handbrake or no handbrake!

[graham bahr]

personally i dont think you can beat a bias box and all round discs for that consistantly solid, exactly the same time every time pedal

[retro_msport]

Originally Posted by graham bahr

personally i dont think you can beat a bias box and all round discs for that consistantly solid, exactly the same time every time pedal

100% correct

[Al Weyman]

You are obviously right but lot of work and money.

[graham bahr]

not so sure on that one Al, i've now put mk2 escort pedal boxes in 3 different cars that weren't mk2 escorts and that actually made quite cheap and easy conversions particulary if you take the cost of replacing an OE master cylinder into account, just need to find one for my mk2 now....

[Al Weyman]

You have not bought a Camaro cylinder, they are under 50 quid! I am also concerned about loosing the power brakes. That Penske IROC thing has the twin set up, maybe if I cant get he travel right I will have another look. I would just need to work out cylinder sizes somehow.

[graham bahr]

Originally Posted by Al Weyman

. I would just need to work out cylinder sizes somehow.

almost every thing i've ever seen uses a 0.7 front cyl and 0.75 rear

[Al Weyman]

What about holding the rear brakes on, can this happen with these things fitted.