testing a brake booster

Ed ke6bnl · October 14, 2004, 06:27:05 PM

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

Bob Paulin · October 14, 2004, 06:31:33 PM

The quick, down & dirty check has always been to.....

pump the brake pedal with the engine off to exhaust any vacuum.....

hold your foot on the pedal.....

start the engine........

and, the pedal should fall away slightly under light foot pressure.

B.P.

Ed ke6bnl · October 14, 2004, 06:41:18 PM

Quote from: "Bob Paulin"The quick, down & dirty check has always been to.....

pump the brake pedal with the engine off to exhaust any vacuum.....

hold your foot on the pedal.....

start the engine........

and, the pedal should fall away slightly under light foot pressure.

B.P.

I just went out and tried what you suggested and the pedal has no change at startup with it pumped prior to starting and the pedal held down.
thanks for the suggestion maybe do for a new one

? Ed

paul2748 · October 14, 2004, 11:23:55 PM

Do you have to really stomp on the brakes to make it stop. If you don't, the unit should be ok.

Ed ke6bnl · October 15, 2004, 12:34:41 AM

Quote from: "paul2748"Do you have to really stomp on the brakes to make it stop. If you don't, the unit should be ok.

No I don't have to stomp on to stop but as I compare it to my Jeep Cherokee if takes a lot more effort. but it may not have as large of a vacuum canister. would be nice if there was a test for the canister. I will have the truck down for paint and body and I will have easy access to the system so that would be a good time to check it out. Ed

MrMopar64 · October 15, 2004, 01:22:54 AM

Quote from: "Ed ke6bnl"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

I found this on another board....... Never tried it myself but it's worth a shot

>larry derouin
>Best way I know of checking a brake booster is to run the engine for a
>couple of minutes.....DON'T TOUCH THE BRAKES......shut down engine
>and wait about 10 minutes then just pull the 1 way check valve off the booster.

>If you hear a sucking sound with a *sigh* then it's ok.

MM64

Ed ke6bnl · October 15, 2004, 02:59:29 AM

Quote from: "MrMopar64"
Quote from: "Ed ke6bnl"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

I found this on another board....... Never tried it myself but it's worth a shot

>larry derouin
>Best way I know of checking a brake booster is to run the engine for a
>couple of minutes.....DON'T TOUCH THE BRAKES......shut down engine
>and wait about 10 minutes then just pull the 1 way check valve off the booster.

>If you hear a sucking sound with a *sigh* then it's ok.

I will try this proceedure tomarrow, this is a little like I suggested to hook up the vacuum canister to a vacuum pump gage and valve off and watch the gages for loss of vac. I have the stuff to do this and will try both thanks for the input Ed ke6bnl

MM64