Opinions on 7” brake booster?
- Thread starter Ken47
- Start date
When I get around to putting a camaro subframe in my '57 short step, I am going to retain the underfloor brake location to keep the firewall clean. My plan is to use a hydraulic brake booster from an old 6.2 L diesel truck, A, because it's more compact to fit under the floor and B, I don't have to run a vacuum hose to it. I DON'T like the cluttered look of excess wiring and hoses on the engine. Will have to use the power steering box and or pump (don't recall which atm) from the diesel also of course. Just another option.
Just a thought. Are you using residual valves in your brake lines?
They are necessary for m/c lower than the wheel cylinders.
Yes they are there. Correctly installed-I checked. I wonder if the brake MC is too large in diameter for the force provided by the booster? The force exerted is a result of the vacuum and area of the diaphragm. I believe the MC is 1 1/8” dia which is typical for power brakes. But also the boosters on a tropical power brake system are much larger than 7” and therefor exert more force on the MC. Then again I could be totally wrong 
. If I were doing this again I’d probably put in a double diaphragm 7”.
. If I were doing this again I’d probably put in a double diaphragm 7”.
To whoever it might concern: (worth nothing)
Because I am a klutz, my two finished projects with floor mount master cylinder were terrible and never could get them right (pilot error). All my installs with firewall crap boosters worked just great from the get go. Messy firewalls or not I will never use a floor mount gain!
Because I am a klutz, my two finished projects with floor mount master cylinder were terrible and never could get them right (pilot error). All my installs with firewall crap boosters worked just great from the get go. Messy firewalls or not I will never use a floor mount gain!
Never had luck with the floor mount either...just didn’t work right . Best thing that happened to me was the day I had my air ride down all the way and I tore off the booster on a small curb. Put it on the firewall and have never had a problem since...having said that I had a single 7 on my old truck and never had a problem...but it was firewall mounted...
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I wish I could move mine but I’m pretty well stuck with it where it is. There must be a way to get them to work better. I just haven’t figured it out yet
On our T bucket we run an underfloor MC with standard brakes (no booster). It has disc/drum brakes. I used an MC out of a 78 gmc 1/2 ton truck. It’s I believe 7/8” dia. They work just fine. I don’t understand why the one in the 47 isn’t.
On our T bucket we run an underfloor MC with standard brakes (no booster). It has disc/drum brakes. I used an MC out of a 78 gmc 1/2 ton truck. It’s I believe 7/8” dia. They work just fine. I don’t understand why the one in the 47 isn’t.
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The only difference in the pump is the cover has two return lines. You can install a second return yourself, or just use the cover from a diesel pump. In my case I "T" the pressure line at the steering box, and use a 3/8" hard line along the frame to a short rubber line to the Hydroboost. I also use hard line for most of the return line with rubber on each end. You can use 3/8" Bundyflex for the return line, but the pressure line has to be hydraulic rated.
A double diaphragm 7" booster gives nearly double the assist, and fits in the same place moving the master cylinder back about 3"
My go to for under the floor is a double diaphragm Fox Mustang booster, with a 90s F150 master cylinder. They bolt together, and are easy to make remote fill. I mount them so the booster is under the seat with a small bubble in the floor so I can raise it above the bottom of the frame.