Brake Pressure / Bleeding

[luke_mcmahon85]

I recently installed Hilux front calipers, r31 rears and a 1" master cylinder.

But for the life of me I cannot get them working.

I have bled the brakes 4 times now, each time bleeding the master cylinder first.

I do not get any air bubbles from the master cylinder bleed nipples or from any of the calipers.

However, when I go to drive i can press the pedal all the way to the floor with minimal braking. If i press it again quickly then i get good pressure and the car stops very well.

If i'm not wrong this means there is air in the lines right? Does anyone have any suggestions on how to get it out?

on the last bleed i followed this guide to the letter - http://www.zcar.com/forums/read/1/187540/187540#msg-187540

help please! i've been putting this off for month, i want my zed back on the road!

 

also, it's a 1976 260z 2+2 and I'm located in south eastern suburbs melboure, if anyone has any suggestions on a shop that will do a power flush/anyone wants to help me out let me know!

[Scoota G]

So did you install the MC at the same time as the front calipers? If so did you bleed the brakes from the furthest point away from the master cylinder first?

[sco_aus]

Also, check your booster, i have a small leak and it will go to the floor without pumping

[Zedman240®]

At what "o'clock" are your R31 rear calipers mounted? To bleed mine properly, I have to remove my calipers and the disc so when I bleed the system I can hold the caliper in a way that the bleed nipple is at the highest point (with the disc between the pads so they don't fall out). As it is now my calipers are at the 9 o'clock position on the rear left (rear passenger side) so if I was to bleed them still bolted in, air will always be trapped in the caliper unless I do all the above.

[luke_mcmahon85]

i installed everything at the same time and did the bleed from furthest to closest.

i haven't checked the booster? could this be the issue? the pedal is easy to push all the way down but gets firm if pumped? how would i check the booster?

yeah mine are mounted in the 9 o'clock passenger rear and 3 o'clock drivers rear - i thought the bleed nipple was in the highest point this way? what angle do you hold the calipers on to get them to bleed correctly?

 

thanks for the responses guys.

[Huw]

I have the R31 rears with stock front, upgraded to the 280 master and a better booster (cannot for the life of me remember which one). I had a similar problem with the R31's and it may be that I was not so familiar with the cars at the time but as sco_aus notes.......you may need to take them off to bleed....took me about 2 weeks (and multiple bottles of fluid) to figure out.

 

I really need to hunt down the hilux calipers....

[luke_mcmahon85]

Huw, you have no idea how much better it makes me feel that others have had the same problems, what finally got it right for you? do you have photos of your rear brake set up?

[Riceburner]

I have to remove my calipers and discs, hold the caliper horizontal so bleed nipple is pointing straight up,then bleed..... otherwise air stays in caliper piston bores.

[Ben]

You haven't got the 'lux callipers on back-to-front have you?

 

If so, you'll be trapping air in them too.

 

FWIW, my bias was up the creek after the same install, so I fitted an adjustable prop valve. Since then I've upgraded from the 7/8" to 1" and am now fitting 4Runner vented brakes.

[MaygZ]

If your booster is leaking (or the hose is leaking) you should have a roughness to the idle.  I have seen bloke who have put big boosters on who can stall there motor by pumping the brakes.

 

The bleed nipple must be right at the top.  Ensure that you have the nipple and the brake line the right way around, ie nipple at top and brake line at bottom.

 

Is the master new?  Did you put a kit in it, hone it?  You may have an internal leak in the master, where fluid is pushing past the cups and then seeping back over time or leaking into your booster or just sitting at the back of the actuating rod.

 

I have heard of people putting the cups in back to front, which would cause the problems you have.

 

Just some things to check.  Good Luck.

[Huw]

Just took them off and gave it a bleed (after speaking to a friend).

Still was not 100% confident had right so sent to the mechanic, Brakes are one area not to mess with.

 

Still haven't got the bias quite right and really need bigger brakes on the front but most importantly the brakes work and have been working for 3 years now.

 

[Zedman240®]

yeah mine are mounted in the 9 o'clock passenger rear and 3 o'clock drivers rear - i thought the bleed nipple was in the highest point this way? what angle do you hold the calipers on to get them to bleed correctly?

 

thanks for the responses guys.

Just as Gareth has answered...

Hold them in such a way that the nipple is at the highest point compared to the brake line going into the caliper. That way, any air trapped in there will get out rather than acting like a sponge in the system. Dont forget to remove the disc also and place it back in the caliper; so when you pump the brakes again, piston doesn't fall out..

[sco_aus]

Also check the rod length and that it may need adjusting to suit the different MC.  I just remembered this was my original problem, it made a big difference and now its just the booster.

[luke_mcmahon85]

yeah, i originally thought the rod length was the problem, but it was hard to adjust, so i took the spacer off... this made the pedal only go halfway down but still no brakes! hahah.

 

the master cylinder is new, and shouldn't have any issues.. when bleeding it it has never had any air bubbles.

 

i will try the horizontal bleeding method this week (fingers crossed).

 

 

[sco_aus]

To adjust the rod, I use a small pair of vice grips to hold the booster end in place on the little star shaped bit (lots of teeth sticking out part) and then used the appropriate sized spanner to adjust the outer hex part.  It is a very sensitive area and maybe worth looking into it again.

[luke_mcmahon85]

Thanks for all the help guys!

this reply is a little late, but i fixed the problem a week or so ago by following the bleeding advice, and moving the caliper to the 12 o'clock position, with the bleeder pointing straight up, and the air bled out straight away. it stops great now, no pumping or spongy pedal.

the pedal stops after only a couple of inches of travel, so i will follow sco_aus's advice and adjust the rod length accordingly, i will also look into a bias valve in the future as the rear is definately locking up early.

 

once again guys, thank you all for the help

[sco_aus]

Good to hear you sorted it.  No worries at all.

[Riceburner]

No worries Luke  Just wait till you have to change the pads  bahahaha it's a pain in the A... trust me! Theres a tool you can get from any auto store to wind piston back in, but i find an old socket with a bit of flat bar welded on the end works better. Gotta be better than drums.... Enjoy.

[53-681]

I'm experiencing an identical issue...

 

Is it the same deal with the hilux brakes? (caliper being in a horizontal position whereby the bleed nozzle is looking up)

 

Will give the horizontal method a go in the morning