Rally rear brakes

[stevorally]

I am still building this rally car and have come up against another little problem.

I am using the original brake servo and master cylinder, I was also going to retain the handbrake cable arrangement. (No hydraulic handbrake) What I need to do is join the two brake feed at the master cylinder then run a single line inside the car to the rear brakes, then split it into two feeds for the rear calipers. Will this work? Will I have to use a larger bore pipe for the single line to transmit the pressure and flow to the rear brakes or can I use the same bore piope over the full run?

Thanks

Stevo

[beatin u]

I think your idea will work, you should get away with using the same core size through out.
Why don't you just run 2 lines??

[nova_rally]

Road or Stage Rally?

Alan

[_JH_]

don't join two feeds from the master cylinder. fit a blanking plug in one and use the other as your line through the car.

Are you fitting a bias valve then?

Where are you thinkin of placing the T-piece?

I have a good article from a ford magazine about running one line through the car in a fiesta XR2 I could get scanned and send if you want.

[stevorally]

The car will be a stage rally car if it ever gets finished.

My idea was to join the two rear feeds as soon as the leave the master cylinder the run the singlr line down the center of the car to the seat base then put another T piece therethen run a line to each rear corner through bulkhead type fittings.

I'm not running two line because i'm using areoquip type hose and its bloody expencive.

No bias valve either.

If I only use one line from the master cylinder will i get enough pressure and flow of fluid at both rear brakes? Will the available pressure from the master cylinder be effectivly joined internally thus producing one line at higher pressure and flow?

Rally cars who'd have em................?

[nova_rally]

Your plan sees fine to me, but you may be running a reduced pressure at the rear corners. Without a Bias valve this might be a bonus as it wouldn't make locking up so much of a problem. I'm not a brakes expert so I wouldnt take that as gospel, I'm sure someone can tell you whether that was right or not!

Good luck with it, Mines for road rallying and must be finished in 2 weeks (ready for the LLeyn Rally).

Alan

[Aragorn]

do not join both rear feeds

the circuits are setup diagonally so that if u lose a brake line u still have brakes from the other circuit

if u join both rear feeds you will lose this redundancy and if something happens to ONE of your rear brakelines u will lose ALL braking

what i would suggest is to block one of the rear outlets and remove the restrictor from the other (drill right thru the middle of it) then run that single line to the t-piece

[2litreturbo]

if you drill out the restrictor will that not give him problems with over breaking at the back?

[rgv_stu]

well that wont work

you will have 3 calipers on one side of the m/c and 1 on the other.

you need to remove the diagonal split. you can do this by replumbing the lines so that the one part of the m/c does the fronts and the other the rears

[stevorally]

:idea:

If I drill out the restrictor to twice its area then use only one line would that not give me the correct braking effort at the back?

:?:

[stevorally]

:idea: :idea:

F**k it i think i'll just run two lines in copper brake pipe in the car!!

[2litreturbo]

well that wont work

you will have 3 calipers on one side of the m/c and 1 on the other.

you need to remove the diagonal split. you can do this by replumbing the lines so that the one part of the m/c does the fronts and the other the rears

so just swap the middle two lines on the m/c ( i presume when people say m/c they mean master cylinder and not motor cycle? lol )

[_JH_]

don't join two feeds from the master cylinder. fit a blanking plug in one and use the other as your line through the car.

sorry forgot to say this:


you need to remove the diagonal split. you can do this by replumbing the lines so that the one part of the m/c does the fronts and the other the rears

And I really would fit a bias valve if I were you. Whether you've got discs or drums. Think you need to remove the restrictor/proportioning valve whatever you want to call it. Don't just drill through it. You should be able to get a union to fit.

[Aragorn]

the only safe way to run a bias valve is to have one feed to the rear fed into 1 bias valve and then split off into 2

running 2 bias valves is dangerous as u wont be able to match them perfectly

[2litreturbo]

^^^^^^Agree

[_JH_]

the only safe way to run a bias valve is to have one feed to the rear fed into 1 bias valve and then split off into 2

running 2 bias valves is dangerous as u wont be able to match them perfectly

am i missing something? who said to fit 2 bias valves? was it deleted or something lol?

[2litreturbo]

if you have two lines running too the back, then you will need two valves. Otherwise one will will always be locking up

[_JH_]

no shit. he said he wasn't running any bias valve, and was gonna just run 2 copper lines. I said to run one line and a bias valve. I love the way everyone always want to add something purely to try and show off some knowledge. round here its referred to as having a mouthpiece about cars

[2litreturbo]

no s**t. he said he wasn't running any bias valve, and was gonna just run 2 copper lines. I said to run one line and a bias valve. I love the way everyone always want to add something purely to try and show off some knowledge. round here its referred to as having a mouthpiece about cars

calm down. I never said that you sugessted running two lines! Merely that if he did run two lines he would need to valves. Read the post properly next time please!

[brian]

pedal box from rally design - ?130 not that dear and solves all problems encountered with blanking off one of the rear lines causing a brake inbalance, because on the pedal box there is only one feed for the rear and one for the front.
Be careful that regs allow copper pipe inside the car. in Ireland you get away with it in a historic but its not 100% allowed in a newer car. i just collected my braided lines today for the rally car :D .

[stevorally]

Oh dear i hope nobody has fallen out over this post..... :D

I have spoken to some rally prep companies, they all said if i was giong to keep my original m/s i must run the two lines, i can't join them and run a single line.

Didn't know about the copper pipe in the car thing though, I'll have to check this in the blue book.

Thanks for all your help.....now shake hands and say sorry!

:wink: