Struggling with this one. Any ideas?

[dixiebabes]

Changed the callipers and discs last year to vented and Princess 4 pots. Now I keep getting air in the system spongy pedal now and then. I have bled the system 3 times now and even changed the master cylinder to rule that out. Just been out for a quick run and it's gone spongy again. No visible signs of leaking and the resevoir is full. Pretty much at a loss now any ideas lads?

Dix

[mrzigazaga]

Hi Mate...Just a thought...Have they been bled properly, As i recall there are three bleed nipples..(ooo missus) on each calliper and if I'm right in saying that you bleed the lowest first..Another thought...Whats the condition of your servo like...Ziga

[dixiebabes]

Servo was ok before zig. There are 2 nipples on each caliper and just 1 on tge rear set up. We bleed the drivers bottom then top, the passenger bottom then top and the rear after that. We get air mainly out of the passenger side and the rear. The servo even if damaged wouldn't put air into the system though would it?

Dix

[Jack Valiant]

If you cannot use a powerful vacuum system to bleed the princess calipers then make up a couple of tubes going into the same container and on all the nipples and with a assistant working the brake pedal work the bleed nipples one at a time to get all the air out! You will b surprised on the amount of air that gets stuck in the caliper. Works for me and the pedal is very firm.

[dixiebabes]

Its mental chris, after each time we bled them the pedal seemed rock solid. Take it out on the road there it starts again spongy. I heard they were a bugger to bleed but this is getting ridiculous. We are getting quite a bit of air out each time especially at the rear.

Dix

[jon haines]

I had similar thing years ago but not with princess calipers though and I was adviced to start bleeding the rears first then passenger side front then drivers side and it worked a treat!

[dixiebabes]

jon haines said:

I had similar thing years ago but not with princess calipers though and I was adviced to start bleeding the rears first then passenger side front then drivers side and it worked a treat!

Cheers lads ill try both of them ways fingers crosses.

dix

[NTEL]

Just a thought. You say the problem arose since you installed the Princess Calipers? When I installed 4 pot Calipers to the Taz racer years ago,(Willwood super light copies) I found that the pedal felt terrible. Spongy and long travel. We figured that the master cylinder wasn't delivering enough volume of fluid to serve the extra, and larger, slave cylinders in the calipers. I ended up fitting a 1 and a 16th inch master cylider and that sorted it.

[ElvisWedgely]

The way I know it, is to start bleeding from the furthest caliper from the master cylinder, working your way nearer and nearer and bleed the nearest to the master cylinder last. Make sure the brake pedal is flat on the floor on it's down stroke before tightening each nipple.

Edited by ElvisWedgely on Tuesday 8th April 21:03

[adam quantrill]

How often do you drive the car?

[KKson]

Doubt it will make any difference but I always use an Easibleed kit so I can bleed the clutch/brakes without bothering the wife. The higher continual pressure also means a higher fluid velocity which may help shift any trapped air.

[dixiebabes]

adam quantrill said:

How often do you drive the car?

not as much as it should be driven adam. But this problem only started since the change of calipers and discs. The Rears have all been rebuilt 2 years earlier.

Dix

[dixiebabes]

ElvisWedgely said:

The way I know it, is to start bleeding from the furthest caliper from the master cylinder, working your way nearer and nearer and bleed the nearest to the master cylinder last. Make sure the brake pedal is flat on the floor on it's down stroke before tightening each nipple.

Edited by ElvisWedgely on Tuesday 8th April 21:03

I think this is where I am going wrong Tony as I have always done it in reverse of this. But we get air out every time and its ok for a bit then it starts again.

There is no way air can be introduced into the system that I dont know about is there? Cause that is what seems to be happening? ?????

Dix

[Yatesy350i]

Easy bleed worked really well for me on the Wedge. But even the easy bleed couldn't get the air out of the Midget clutch system last year! That was a right #@#t

[adam quantrill]

I find if the car isn't being used much the brakes go a little spongey, so I give them a hard poke when I come home - 60 to 30 in 3 metres - that sorts them out nicely in a few days.

Use them and use them hard!

[mrzigazaga]

NTEL said:

Just a thought. You say the problem arose since you installed the Princess Calipers? When I installed 4 pot Calipers to the Taz racer years ago,(Willwood super light copies) I found that the pedal felt terrible. Spongy and long travel. We figured that the master cylinder wasn't delivering enough volume of fluid to serve the extra, and larger, slave cylinders in the calipers. I ended up fitting a 1 and a 16th inch master cylider and that sorted it.

A very good point...I was reading about brake upgrades a while back and this is something that a lot of people don't consider when upgrading the system but its a big link in the chain so to speak...Ziga

[dixiebabes]

This is definetly air though lads due to when its pumped the pedal feels good. Adam.... tried that a couple of times and nearly had a nice blonde driving a ford ka sat next to me when they did work properly. Convinced the air is getting introduced not already in there as we have bled the buggers 3 times and got a load of air out every time, Physics say i am wrong and i usually am. Great brake upgrade if i eventually sort the air problem out.

Dix

[ElvisWedgely]

There are two things that spring to mind. Either, the air is not being expelled completely and so the pedal feels good initially. Then, once in use, the remaining air disperses and causes the pedal to go spongey, and hence more air is expelled on the next bleed, or, the servo is failing after some use, giving the spongy feeling.

Have you done the servo test by pressing the brake pedal and keeping it pressed, then starting the engine with the pedal still being pressed to see if the pedal gives a short distance under your foot. This is normal operation. I would do this test both when the engine is cold on startup and when the sponginess returns.

Whatever the problem is you will solve it eventually by trial and error. The only other thing that comes to mind, as already suggested is that the existing master cylinder is insufficient for the new setup.

Tony.TCB.

[dixiebabes]

Aye Tony servo is working and tested like you said. I tried that after fitting the new master cylinder.

Dix

[Wedg1e]

You sure one or other of the rear calipers isn't dragging and boiling the fluid? I guess the test would be to let the car stand once the sponginess appears and see if the pedal firms up again once the fluid cools down.