My Daihatsu 2.8td has a vacuum pump on the rear of the alternator for brake boost connected directly to a D90 master and on to discs from a '89 classic. Generally the brakes are great but on the trail, particulary when making attempts at ledges, they are weak as I back off. I am adding a vacuum reservoir to solve this. Should I keep the check valve on the master as well as the one on the reservoir?

In theory I don't think you would need one between the new reservoir and the original brake servo, but I don't think it would do any harm either.

I'm making a reservoir for vacuum assisted fiddle brakes ( Rover Metro master cylinders ) out of a fire extinguisher. It's about 300mm x 120mm dia and made from aluminium.

Jeeze! That's high tech!! We used to solder a barb into an empty coffee can. The biggest PITA was getting the coffee out through that little hole..

Thats basically what Ford used too.

My 67 Cadillac Calais had two apple juice tins (factory) as vacuum reservoirs. That car had miles of vacuum line. No check valves IIRC...

yeah, but polished and laquered ally will look the bollix! :flipoff2:

And I've got an empty ally extinguisher....................

have you put a gauge on it to see if you are actually losing vacuum?

It could be that the brakes just suck and if that be the case having more suck at the pedal will not help much which will mean you just did a bunch of work for naught....which will really suck.