Behold, Frankenbooster!

We4ever

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Aug 13, 2019
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The back half is from a 79 cutlass diesel reman from auto zone.
The front half and piston is from a 1995 Chevy 3500 dually found in junk yard full of water.

The benefits of this rig: It fits gn firewall, It fits the stock pedal, and 84 regal power steering hoses fit.

Larger truck piston for SUPER brakes.

waiting on master cylinder to test.
 

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We4ever

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Aug 13, 2019
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I've got a parallel thread on a gm truck forum. Trying to determine if I can fit a weaker master cylinder on this booster. Im worried the Jb8 will be a lockup monster or blow up my wheel cylinders. Also the truck I got the booster from had a proportioning valve that I didn't grab. Think I need one?
 

turbo87regal

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Nov 12, 2005
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I'm using a hydroboost from a 1998 Astro van witch I'm pretty sure has the same bigger piston as your truck unit, a master cylinder from the same 98 Astro van but with a fluid reservoir off of a 95 Saturn SL (if I remember correctly), S-10 Blazer dual piston front brakes and a stock proportioning valve for the Buick and it all works together awesome! Wheel cylinders won't blow out simply from swapping to hydroboost unless you have a pre existing problem before the swap. Not sure if I'm understanding you correctly but there is really no such thing as a "weaker" master cylinder just different bore sizes that will affect the amount of pedal effort needed to get the same affect at the wheels.
 

We4ever

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Aug 13, 2019
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Wheel cylinders won't blow out simply from swapping to hydroboost unless you have a pre existing problem before the swap. Not sure if I'm understanding you correctly but there is really no such thing as a "weaker" master cylinder just different bore sizes that will affect the amount of pedal effort needed to get the same affect at the wheels.
Thats why I asked. I used the word weaker because I figured the master from a 1 ton truck would generate more pressure in the line. I assumed a brake system designed to stop a huge truck and trailer would cause near instant lockup on a light car. Am I wrong? Im more than happy to be educated on this topic.

Im not sure about what master cylinders fit what boosters, i'm trying the 3500 at first just to guarantee proper fit (and its cheaper). I'll be happy to switch to something else after testing.
 

Chuck Leeper

8/10's of a century!
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May 28, 2001
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I've used the smaller version of the HB on a few cars. The last being a 55 Chevy, with the Metric discs on the ft, Ford drums rear.
This was done as the 8" dual vac system would not stop the car.
I invested in a brake press gauge and found out why.
Less than 900 psi at the ft wheels.
The HB was installed, same mc, Wilwood adj prop, 2 psi residual check in rear.
The brake psi was then over 2000 psi Certainly didn't require much pedal pressure.
The aftermkt guys say there should be 1200psi, to work....NP here.

FWIW, the bucket list project 55:
13" Vette brakes in ft, 11.25" Ford discs rear, 15/16" mc, Wilwood adj prop, no booster.;)
 

We4ever

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Aug 13, 2019
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Got it all bolted in yesterday and no surprise the piston seal on the junkyard half was weeping. Got a seal kit from pirate jack on the way, should be able to do a road test by Tuesday.

I think this might actually work!
 

We4ever

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Aug 13, 2019
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Ran into a slight hiccup, the 3500 master cylinder is so huge that it hits the power steering reservoir. Looks like I'm gonna drill holes in the bracket and scoot it forward about an inch.
 

No disintegrations

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Dec 27, 2015
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All else being equal a smaller master cylinder piston will increase braking force. It moves less fluid at a higher force. Sort of how first gear gives more torque at a lower speed than higher gears.
 

We4ever

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Aug 13, 2019
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So, this setup will likely make my brakes require more pedal travel to get the same brake force as the powermaster? If that's the case i'm cool with it, I found the powermaster to be really grabby.

I'm really dumb, somebody take a guess how this is gonna work.

Thanks for the vid Mr Brown :)
 

We4ever

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Aug 13, 2019
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I'll try it out in the church parking lot down the road.

Technical question: all the diagrams I've looked at for the hydroboost show a ball bearing component to the accumulator check valve. Both boosters I took apart didn't have a ball, and the pirate jack kit doesn't have a ball either. Is it safe to assume the ball is internal to the yellow plastic part? I've shined a bright light through it and it looks like there might be a ball in there but I want to be sure. Info online seems to be contradictory.
 

KC87

Active Member
Feb 11, 2009
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^Yup.


That's why we put bigger cylinders on the rear brakes to hold more boost.

Can I get a set of brakes like that to replace the rear ones on my GMC p/u? With all the tech they have now how does GM screw up something as simple as drum brakes.
 

earlbrown

runs with scissors
May 26, 2001
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I'm guessing because they don't have Jam Handy making their propaganda videos anymore. :)


All jokes aside, those old ass 'technical videos' are awesome. I love how they talk about latest/greatest cutting edge shit using gangster cars from 80+ years ago.

AND it still applies today.
 

We4ever

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Aug 13, 2019
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Well I am happy to report with new seals the brakes work! Looks quite handsome in the engine bay as well.

Sadly the new system seems to be too much for my 32 year old power steering pump to handle. Application of brakes is met with squeals and groans of protest. Can somebody point me to a high quality pump that can handle the extra demand?

Side note, during the test I noticed the car getting quite hot despite the install of new water pump and 160 thermostat. Removal of rad cap revealed acres of nasty brown sludge. A full road test will have to wait until nov when I can get new aluminum radiator.
 

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KC87

Active Member
Feb 11, 2009
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I'm guessing because they don't have Jam Handy making their propaganda videos anymore. :)


All jokes aside, those old ass 'technical videos' are awesome. I love how they talk about latest/greatest cutting edge shit using gangster cars from 80+ years ago.

AND it still applies today.
Talk about cutting edge back in the day, how about those radial engines for genius. There were some pretty smart cookies back then. Old farmall A and super A, mostly cast iron and all the different attachments that could be bolted all over the unit to do different jobs. Tons of engineering to do all that.
Sure does apply today only the gangsters are politicians and they drive armored up SUVs.
 

1KWIKSIX

Well-Known Member
Sep 29, 2007
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Mississauga, Ontario, Canada
Send your PS pump to a specialist like Sweet Mfg (Kalamazoo Michigan) or Jones Racing . Your pump needs to be modified to increase pressure to 1350 psi output and flow rate adjusted to 2.7 gal/min to work well with the extra demands of a HydroBoost system.
 

1KWIKSIX

Well-Known Member
Sep 29, 2007
2,283
223
63
Mississauga, Ontario, Canada
Send your PS pump to a specialist like Sweet Mfg (Kalamazoo Michigan) or Jones Racing . Your pump needs to be modified to increase pressure to 1350 psi output and flow rate adjusted to 2.7 gal/min to work well with the extra demands of a HydroBoost system.
In addition to the above, Lee Power Steering Pumps (California) is another place highly recommended for hydroboost PS pumps.