View single post by Mark Rosenbaum
 Posted: 06-20-2007 04:44 pm
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Re tipping valve.

The tipping valve shuts off the connection between the brake fluid reservoir and the bore for the master cylinder's rear piston.  When the piston is all the way to the rear (i.e. brake pedal not pressed), the valve is tipped, and open, as shown in the drawing attached to my previous post.  The valve is supposed to seal when the brake pedal is pressed and the rear piston moves forward.  When the valve seals, pressure can build up in the rear piston's bore, and this pressure is applied to (a) the front brakes and (b) the rearward face of the front piston, which operates the rear brakes. 

However, if the tipping valve fails to seal, pressure can not build up in the rear piston's bore.  Under such a circumstance, the front brakes are inoperative, and the rear brakes don't activate until the rear piston comes into physical contact with the front one, which occurs only when the brake pedal is close to the car's floor.

The most common reason for a tipping valve to fail to seal is debris in the brake fluid.  Even barely-visible particles can prevent proper operation.

Re brake balance.

The JH has no native means to alter the balance between the front and rear brakes.  The easiest way to change the balance is probably to install rear wheel cylinders having pistons of a different diameter.  Since the rear brakes came from a Vauxhall, it's reasonable to think something suitable might exist, but you'd have to research the subject.  As an alternative, you could use two master cylinders along with an adjustable mechanical linkage.  Perhaps one of our racing members could offer advice on such an arrangement.

Last edited on 06-20-2007 04:48 pm by Mark Rosenbaum