Brake experts please read....

[boXXer]

Fitted some Capri V6 rear drum brakes today and have a bit of a problem...

i dont know whether its air in the system (i bled it a million times), or the wrong size M/C's, but i have a serious amount of pedal and hydro handbrake travel....

after having a quick read on 'tinterweb, i think it could be 2 things.

1, Do i need to use one of these residual valves inline? iv'e read they keep the pistons 'pumped' out a bit, thus reducing travel in the system? right?

2. Im running .625 m/c's in both the pedal box and h/brake. Could the volume be too small from these? i really dont fancy taking the pedal box out to change the cylinder tbh. i've read that a bigger m/c would reduce lever/pedal travel, at expense of power.

also, one thing, instead of running the line into 1 slave cylinder, through it, then out the otherside to the other slave cylinder, i have added in a T piece and split the lines to both rear cylinders, so both have a bleed nipple now. dont think that would make any difference but could be wrong....

[exboyracer]

Probably due to the larger bore rear wheel cylinders but they can be a pig to get the air out of sometimes.
Won't be the t-piece as that's the way mine is done, and it's fine. I actually think it's a better way of plumbing the system TBH.

Have you fitted the bleed nipples to the top of the cylinders?

[Pushrod King]

Have you made sure the self adjusters are working? How easily do the drums go on and off?

[Graham]

as i said in pm, 0.625 is small for a rear cylinder, but i dont think thats a major issue if it was ok on the old brakes, my betting is one or both your bleed nipples are not at the highest point of the system, or the shoes are way way out of adjustment.

[jagojon]

can try just gravity bleeding it too, crack the nipple off, leave them open and let it drip through, dont let it run out of fluid though obviously! this helps if you have a pocket of air thats been pushed backwards and forwards.

does the pedal pump up at all? if it does pump it up , hold the pressure on and then crack each pipe off.
did you adjust the shoes up manually too? as what graham said can make a crap pedal


agree with the t peice , better way of doing it

good luck mate


jon

[boXXer]

right, after a few pm's with Graham, i think the problem MAY have been solved

for better routing of the hose, i used the HIGHER take off on the slave for my brake lines, and the LOWER hole for the bleed nipples..... also, as im running capri v6 brakes now, you have to rotate the backplates backwards 45degrees so the holes line up with the axle, making the bleed nipple sit at about 3 o'clock, and the hosing sit at 1 o'clock. thinking this could be my problem.....

the pedal and hydro handbrake do get a bit better when pumped up too..... air!

also, they are self adjusting drums. I did clean and grease up all the linkages as i rebuilt the brakes with new cylinders, shoes, fitting kit etc. i manually 'pumped' the mechanical h/brake lever on the back then took the drum off and the 'cam' on the self adjuster had swung around a bit.

[jimmy2006]

back bleed it and it will take all the air out

[boXXer]

i was gunna try reverse bleeding it with a syringe or something but i think i may just swap over the lines with the nipples.

[Graham]

with cylinders plumbed that way round you would have to pump a hell of a lot of fluid backwards through the system to force all the air out,

far better to just swap the pipes and nipples, then it will bleed naturally, no pumping needed just open the nipples!

[exboyracer]

I think you've definitely found the problem there... it's the idiot holding the spanners

[alladdin]

good points as above - get the cylinders plumbed correctly, gravity bleeding can work well, and one more - self adjusters DONT work. you need to tweak them up a notch at a time untill drum is a little stiff to turn. as i mentioned before when i used 3.0 capri rear brakes i needed a pressure reducer to stop rear locking but you may be ok as you can adjust pedal box bias.

[boXXer]

Most definitely. Gunna swap it around tomorrow evening so will let you know.

[boXXer]

Yeah I had a go at manually tweaking the drums but when I fitted the drum it felt a little too tight to me. They seemed to work ok on my old 8" drums I have to say