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I posted this on another board but still not sure of a positive test for my vacuum canester.

Hi, I purchased a dual master and booster for under my 50F1 pu. Well it is well past any warranty by the time I was at stage of installing the unit. Now I have doubts that it works. The truck has a mustang II with 11 rotors in front and drums in the rear 9". I have the 2 and 10 residual and a proportioning valve for the rear brakes. I do not think the vacuum booster is doing anything. I do have good vacuum and the check valve on the housing seem to be doing its job. I was thinging of hooking the hose to a vacuum pump and with a guage and a valve see if the booster holds a vacuum but not sure if that will tell me anything. The truck accually stops ok but I do not think it is up to its potential and using the vacuum assist.. Any help in a proceedure for checking it out would be great. thanks Ed ke6bnl

The pedal does not change if depressed when engine is started.

Thanks in advance Ed
 

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aka Duke of URL
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The pedal does not change if depressed when engine is started.
With vehicle off, depress brake pedal several times exhausting vacuum reserve. Hold brake pedal down and start engine. The brake pedal should slightly depress by itself. If not, defective booster, poor vacuum signal, binding linkage, etc.

What type of manifold vacuum are you holding?
 

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Glad To Be Here
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Ed ke6bnl said:
Hi, I purchased a dual master and booster for under my 50F1 pu.

I do not think the vacuum booster is doing anything. I do have good vacuum and the check valve on the housing seem to be doing its job.
From what I've been able to find out the single diaphram 7" booster does not have enough area to be very effective.

I am running a dual diaphram booster (also mounted under the floorboards) which is supposed to work correctly as it has twice the area. I haven't hooked it up yet, so can not post results. (See my post concerning bleeding the system)
 
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