Brake Booster

[KFH]

A few years ago I fitted a newly rebuilt VH44 from a southern firm on my 59 Fc with standard brakes.  I have never been happy with the hard pedal on hard braking  but assumed that is normal.  Today I checked the vacuum to the booster - all good. It is plumbed correctly.  Contacted the firm who suggested to drive it with the vacuum clamped off.  I removed the hose and blocked it off.  The braking on a hard stop was softer and a much better pedal feel. They will service it for me if I send it to them.   Is there something I have missed or is the unit faulty?  Just want to be sure that I have not missed anything.

One suggestion the firm made was that the diaphram is most likely faulty. This being caused by the petrol fumes being drawn off the vacuum feed at the base of the carby. To prevent the fume damage I should do like they do on the red motor and draw it from the inlet manifold near number 6 cylinder. Anybody heard about this?

[ardiesse]

Keith,

I ran HR discs on the ex-family EK for many years with the booster plumbed into the vacuum port in the middle of the inlet manifold.  Atomised petrol is everywhere inside the inlet manifold - that's its job.

No, I'd suspect that the non-return valve is leaking.

Diaphragms on the VH44s are quite easy to replace - you undo the big clamp, remove the back shell, lift the diaphragm off, put the new one on and reassemble.  Depending on your installation, you may even be able to do the work without disconnecting the hydraulics.

A quick way to determine if the diaphragm is leaking is to start the engine and apply the brakes.  If your diaphragm's leaking, the idle will speed up while the brakes are applied.

Rob

[KFH]

Thanks Rob.  I'm to blame, silly me   I have found the problem. Not enough vacuum. The reason is I made a rookies mistake when installing the booster. I fitted a T at the carby in the line that feeds the vacuum advance on the distributor. I should have connected the vacuum line to the inlet manifold where the vacuum wipers were originally connected. The brakes a now operating well with a much lighter pedal. Terry from Hydroboost was happy to check the unit out if needed.

Keith