Anybody with experience of pedal boxs, I have a modded sierra pedal box on my sapphire, 6pot calipers and .70 front Girling cylinder, now when I press the pedal I cant get the front cyl to move in at all, the pedal locks out totally, I just removed it tonight and it slides fine without fluid in but when filled with fluid it wont budge AT ALL, any ideas as I have no useable front brakes the rears are doing all the work. on the other side I have a .75 for the rear and they work brilliantly- locking up the rear at 100MPH
Any ideas what could lock it out?

 

Wind the bias all the way to the front . alternatively the rod length is too long to the rears , try a shorter rod and see what happnes .

 

Modding your own pedal box is a bold move unless you really know what you are doing but presuming that is the case I would try using .625 on the front and .70 on the rear.

 

rod length wont change the fact that the rod wont slide into the cyl, but i do understand what you are saying once sorted to set it up- I just physically cant make it slide in even with my fat legs, but remove the fluid and it is sweet as a nut slide with my finger tips

Hi Martin, the box has been modded before I bought it, its in my sapphire rallycar shell so maybe Ford or other prep co. did it?? i will try a cyl swap see if I can get it sorted. Thanks for your help.

 

The bigger the cylinder size the more likely you will have the above issue, try what I said previously.

 

How is the balance bar set with no pressure - and then with pressure ?

But as Martin said .625 front .7 rear is more norm.

 

I had been unable to set it up Tony as the balance bar just levered off the front cyl. Should be sorted now thanks to the above advice. Du you set the box up without fluid in then or were you just asking?

P.S. Im yet to fit the pedal box from you due to no Hyd clutch yet cheeRs

 

the box must only be setup with fluid and bled.

 

I was just asking as it will be acting different when empty to full.

As Mark says they should only be set up under pressure when full.

Just making sure you wasnt trying to set it up empty then filling it

 

OK, cylinders swapped, filled and bled and they are shit, brakes bite really late and dont feel right, spongey but fully bled, does a bias box set up need pumping before every use of the brake or should there be power enough to stop you straight away? The reason I ask is because the more I pump the pedal the harder it feels under foot.
Also the handbrake doesnt really have the positive power I was expecting either, though it stops the car on an incline no problems- Im not sure what I was expecting but it wasnt this?

Anybody with experience of how the pedal box system feels in comparison to a std setup, thanks Mark

 

you still have air in the system mate, the pedal on a pukka bias setup should feel progressive and firm and not be too heavy to retard the car at any speed, same with the hyd handbrake, lever length dependant should just need a little nip to lock the rear no worries,

ive always found the only way to bleed these properly is with a vaccuum bleeder

 

Thankyou Markk, its looking like i have a weep on the lines so air will be in there yes, will sort it, thanks all. Can you recommend a vacum bleeder for a bias setup please?