Vacuum brake questions

[ttypewhite]

I just finished installing my vacuum brake setup in my car. That's the master cylinder, proper brake pedal and dual booster. I bled all 4 corners and the pedal feels stiff when at idle. I took it for a ride and when I am in 3rd gear the brakes feel decent. My car idles at 16 inches of vacuum. Is that enough? Do I need a vacuum pump? Any recommendations on improving them let me know. I am no longer using the factory brass valve on the body for portioning. I am using a Summit portioning valve near my Master cylinder. Brakes are still all stock on the car with the exception of S10 wheel cylinders in the back. I want to get this sorted out first, then move on to my S10 brakes up front and Wilwoods in the rear.

My vacuum set up I installed


Installed

 

[kidglok]

16" should be enough, what master/booster/pedal are you using?


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[ttypewhite]

Complete Vacuum brake setup from 87 Monte SS, double D booster, pedal, bracket and Master

 

[kidglok]

Complete Vacuum brake setup from 87 Monte SS, double D booster, pedal, bracket and Master

Have you tried giving more pressure to the front and less to the rear thru the adjustable prop valve?


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[ttypewhite]

I have dicked with it a bit, but didn't feel any real noticeable difference.

 

[kidglok]

the only thing different with mine, i have a bigger hose running to the booster, but im not sure it would help more vacuum get to the booster?

 

[pacecarta]

its possible you have a bad booster , has happened to me on a couple pulls which is no biggie as they then become a core toward a new . just blows to get it all together to find it has no assist and have to do it again .
ive also had better luck with used original masters than some of the current cheap remaned masters .

make sure the check valve is holding, if its leaking your brakes will come and go with engine vac
i dont like that clear check valve as ive had them pop under boost ..not fun trying to stop at the big end with no assist.
there is a better all black smooth check valve available with 1/2" inlet (or get the summit billet valve)

also what is your vac source
ive tried the billet tta style and connecting to pcv line with a tee
i dont like either
the billet has a very small hole for the vac supply (1/8npt) , and teeing the pcv you have a vac supply teed to a vac leak so its not the best as vac signal will be lower.

what i do is tap the plenum ( or manifold ) for a 3/8npt fitting and run a 3/8npt to 3/8 hose barb (or 1/2" if check valve has larger inlet like the all black )
for higher performance use i run a 3/8npt to 6AN fitting and use a summit 6AN billet check valve at the booster with braided hose connecting it

if you run the rubber hose (use vac brake specific hose) there are inline check valves used on import vac brake system (some are black and white plastic but they also used a steel valve) that can be used inline of the booster check for added protection with high boost applications, and use breeze clamps on all the hose ends .

 

[ttypewhite]

I run my vacuum source from a vacuum block that I have in the back of the intake. Pic below. But I have other stuff T'd into that aswell (ie:map,hobb switch, fuel pressure reg etc)


I am going to drill a hole in my Champion spacer to supply it independently using a 1/2"NPT/AN#6 to that billet #6 check valve you have suggested from Summit.

 

[GNGAL]

This is my project for the rest of the week.... How long did it take you to install ?

 

[ttypewhite]

The install was done in under a hour. Bleeding all 4 corners was another 20min.

 

[ttypewhite]

It was my vacuum source that caused the stiff pedal. I took off my 1" Champion spacer and drill and taped it for 2 #6 fittings. My check valve has not came in as yet from Summit, so I ran a high pressure hose in it's place and the brakes are awesome.

My taped spacer. Pic sucks cause I had to pee, but i get the deal........

 

[kidglok]

It was my vacuum source that caused the stiff pedal. I took off my 1" Champion spacer and drill and taped it for 2 #6 fittings. My check valve has not came in as yet from Summit, so I ran a high pressure hose in it's place and the brakes are awesome.

My taped spacer. Pic sucks cause I had to pee, but i get the deal........

Sweet, workin good now?


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[ttypewhite]

Ya, it works great. Now I am going to install my S10 front brakes with cross drilled rotors. Once that's done, its on to the final chapter with my rear Wilwoods.

 

[trixdout]

Definitely bookmarking this thread. Its got alot of good information, at least for me.

 

[ttypewhite]

Parts from Summit came in. Very nice design and workmanship. Part # is also on the box for guys looking to do the same. I will install it tonight.

 

[ttypewhite]

Got my #6 line made up


Installed my check valve and hooked up my line to it. Very clean install

 

[trixdout]

Super clean. Looks really good. I'm gonna have to figure out how to connect it to the aluminum vacuum block the vendors sell with the vacuum port on the drivers side.


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[SCOOBY DOO]

Mike...if you haven't already done it...swap out the rubber flex hoses for the 3 Russel braided stainless steel ones. Made a huge difference with my car.

 

[ttypewhite]

Mike...if you haven't already done it...swap out the rubber flex hoses for the 3 Russel braided stainless steel ones. Made a huge difference with my car.

Brad, I bought them a couple years ago, just never installed them. I will install them with my new brakes tho. thx for the heads up.

 

[DavidM]

Super clean. Looks really good. I'm gonna have to figure out how to connect it to the aluminum vacuum block the vendors sell with the vacuum port on the drivers side.


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Mike this a great write up and alot of valuable information for anyone thinking of doing the vacuum conversion.

Trixdout, I am too going to order the check valve but need to figure out a way to hook it up to the driver side vacuum port using a braided line. Trying to stay away from rubber lines on this. Especially since my brake vacuum line is tied into my PCV line.