Hi all,

After a bit of advice...

I've fitted a bolt on disc brake conversion to my baja and can't seem to get the brake pedal to come up even after extensive bleeding.

A mate said that I might have to get a different master cylinder when changing from drum to disc.

Thoughts and advice please...!

Thanks, Marc.

A bit more info wouldn't hurt, like what model car or master cylinder presently fitted and what disc kit did you fit. May want to check with the supplier of the kit.

Sorry Matt, yes I should've given more...

68 baja ball joint/disc brake front end
drum rear on swing axles
Empi kit from Classic VW
Current master cylinder is the one with two supply lines going into it with seperate tubes off to front and rear brakes

Hope this helps....

Thanks,Marc.

IMO all should work ok, I have had cars come in with that exact setup with no problems as far as I can recall. Doesn't help you except that there must be some other problem.There are recommendations that for disc's a higher pressure residual pressure valve is required but I havent used them yet, I have some coming from the states for a job so may help with supply if you need them. Does the master cyl push rod have the necessary play (about 1 mm) before it contacts the piston? If not it may not get the fluid replenished at zero stroke. Are the disc rotors and wheels fitted properly yet?

http://www.wilwood.com/MasterCylinders/MasterCylinderValves.aspx 


Residual Pressure Valve

Thanks Matt, I'll check the master cylinder push rod, that would definitely account for the issue if it's not right!

The wheels and calipers are all in place properly, yes.

I can see the benefit of a residual pressure valve for race use, but for the street, wouldn't it be like having your foot very lightly on the pedal all the time? i.e. wearing out brake pads more quickly?

Willing to give anything a try though to get it right. I'll check the push rod and bleed them a few more times and let you know if I'm up to trying the valve!

Cheers, Marc.

Hi

Is there a left and right calliper? As in the bleed nipples being at the top.

Steve

Hi Steve,

Yes there is a left and right and they're on the right way with bleed nipples at the top.

Marc

Are you bleeding the furthest caliper from the master cylinder first and then working back to the closest one last.

This is the way I was taught 25 years ago, not sure if it makes a difference.

Kev

Kev,

That's the way I was tought to do it too. Yes, started with the left rear and worked my way closer. Aparently I just haven't done it enough times yet!!

Bleed and bleed......

What condition are your rubber lines in? Have you moved them or are they cracked at all/ cruddy inside? a small leak perhaps where you have mated the new calipers...

sounds like it could be a dud master cylinder.

Not sure about the rubber lines, I might replace those before I do any more bleeding.

I'm hoping it's not the MC Ian, I only put a new one in about 12 months ago and it was working fine with the drums before the conversion....

Hi

I fitted a new master cylinder to a bug a few months ago, front bled very easily, the rear wouldn't get a pedal at all and no fluid came out of the nipples no matter how much we bled the system, I then used my vacuum bleeder and got a pedal straight away.

Are you getting a good rush of fluid out of the nipple when when you open it?

Steve

Well I thought I was getting good flow, but reading all the responses, I'm not so sure now!

Will check it tonight when I get home from work and see how we go....