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post #1 of (permalink) Old 05-07-2002, 07:40 AM
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Hydroboost donor vehicles?

I've searched through the archives and all I could find was MC's excellent write-up on installing a hydroboost setup from a '76 Fleetwood. I may go that route as well on my CJ-7, but I was also wondering if there are any other good choices for the hydroboost stuff. I'd like to find an old setup in a junkyard to use as a core for a rebuilt unit, and I haven't been able to find any old Cadillacs in any of the local yards. What other vehicles should I be looking for?

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post #2 of (permalink) Old 05-07-2002, 07:53 AM
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Re: Hydroboost donor vehicles?

I know our 1990 Chevy Astrovan has hydroboost power brakes.
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post #3 of (permalink) Old 05-07-2002, 10:53 AM
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Re: Hydroboost donor vehicles?

1 ton chevy trucks, and almost anything the military used for past 15 years. humvees have really nice units with a resivoir and everything.
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post #4 of (permalink) Old 05-07-2002, 01:28 PM
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Re: Hydroboost donor vehicles?

Along with 1 ton Chevys, look for motorhomes, cargo vans, box trucks, etc.
post #5 of (permalink) Old 05-07-2002, 07:38 PM
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Re: Hydroboost donor vehicles?

Ricks new superjeep has a hydroboost , here are the previous owners notes about it: (warning, it is LONG)

I first pulled a booster and proportioning valve from a G20 Chevy van(diesel, '83. I then found another booster from a Olds Custom Cruiser Brougham '80. I actually made a second trip just to get the hose off the
Olds but it was 1/2 price day so I pulled the booster too. I used the mc from the G20 van(got a reman, didn't want to chance a salvaged mc) and mated that to the Olds booster. The difference in the booster is
that the Olds uses an internal accumulator vs. external on the van. It's smaller profile and the Old's booster looked to be in better condition(hoses were still attached and all connections still sealed.) I also used the mount from the van as that has a more vertical firewall to keep
the unit level. It's not completely level but it's close enough not to
cause problems.

The hoses are the expensive part of the conversion. You can use a
stock gates hose(pn#35761) for the pump to booster. The other pressure
hose from the booster to the gearbox is custom made. I tried calling
Vanco for a hose but they would only sell me the complete package. If you
check their website the pictures are the same as FourXDoc. On the Olds they use a hardline from the booster to the gearbox, I grabbed that at the same time as the booster. You have 2 options, go all Earls(assm. yourself) like I did or take the stock CJ pressure line and the upper end of the Olds hardline to a hose shop and have them put a section of
hose in the middle.

I had 2 sockets that worked perfectly as a centering device(bolted through the middle) to hold the bracket into place for drilling the firewall. Mount, connect hoses, bleed brakes and add fluid to the ps system. Its a good time to flush the ps & brake systems btw, I also added a ps cooler so I have a few more hoses running around than I like, but it's
a trade off I'll take for the ability to stop.

Observations: forget the proportioning valve, the Jeep one works great. It's a tight fit for the hoses next to the clutch mc and the one that goes over had to be moved a bit as not to hit the hood. The brakes don't seem to let off quite as quick, booster may be going south(~$275 for reman)
You reverse the lines to the brake mc, so they need "customizing". I purchased 2 ss braided hoses from Earls to clean that up a bit. If I would have used the booster from the van I would have needed to shorten
the actuator rod as it was about 4" too long, 4.5" is the size of the stock and Olds booster I used. Also need to enlargen the eye in the actuator rod 1/16". Actually I only used the mounting bracket from the van and discarded everything else. It would be way easy to make one out of
1/4" plate. It's a total bitch to disconnect the boosters under the dash!

I'm having an interesting problem with my hydroboost system in my CJ7 and looking for opinions from those more familiar with the system. It brakes great but it doesn't release all the way. If I am stopped and turn the wheel to lock, it releases and the pedal raises. It appears as if my pump isn't up to the task of pressurizing the booster fully. Someone posted a note on how to increase the pressure of the stock pump,
how is that done? Or do I need to get a pump from the truck it came from?

Adding a washer or 2 to the stock pump did nothing. Combining this with my earlier observations about the handling led me to believe that it was more a back pressure problem. If you got a look at Al's(Jeepaholic) setup, the return from the booster is joined to the return from the
steering gearbox by a tee fitting which goes to the pump. The 2 returns mated to 1 tube cause the problem, backup. This backup I believe places pressure on the booster not allowing it to return after the pedal is released.

Today I swapped out the stock ps pump to a pump from an Olds w/hydroboost. These pumps have 2 return fittings on the reservoir. Doesn't exactly fit up and I'll probably revisit it but it works correctly now, pedal is returned to top and brake light is turned off. The brakes feel differently than before too. Takes more pedal travel to engage the brakes to the same point as before but still can lock them up.

I'm surmising that if an extra return fitting was added to the stock pump it would work fine to relieve the back pressure. Probably a 3/8" brass barb soldered or JB Welded into the pump would suffice. I may try this as my new pump sits at about a 40deg. angle. Not exactly the best
for sloshing around off road.

Cut the filler neck from an old ps pump and mated it to the Olds pump that sits at an angle so now it sit straight. Also corrected the plumbing w/ 3/8" hose throughout. I correctly did the washer trick(I did it wrong before) and I think I over pressurized the booster and caused a failure as there is fluid leaking out between the booster and the mc. I
have gone through a gallon of ps fluid to date. I will remove the washer trick and replace the booster. PS is good only and high(2k+ rpm) and brakes are almost non-existant which leads me to believe booster failure.

Removed the washer from the pump and refilled. I attempted to locate another salvaged booster from an Olds but no luck. All parts stores are in the $200. for reman. Took the orig. booster from the G20 van that I still had lying around and shortened the actuator rod, switched the mounting plate back and installed. Works like new again. Brakes are a
little firmer but work fine. So after all that, I'm back to the orig. setup that I pulled, MC and booster from an '83 Chevy G20 van.

Internal actuator rod in the booster is sticking and locking the brakes on. This happened a half dozen times on the Dusy trail. It has not happened since. I think this is due to "standing" on the brakes and over
extending the acutator rod. I have a reman. Olds booster on the bench but will hold on to it for a while as the van booster is working fine. I may try to remove 1 washer on the power valve just for fun.

It is working fine.

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post #6 of (permalink) Old 05-07-2002, 07:46 PM
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Re: Hydroboost donor vehicles?

Lots of diesel trucks. My buddy's Suburban (not sure, what year, '96 maybe) 3/4 ton diesel has hydroboost

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post #7 of (permalink) Old 05-07-2002, 09:49 PM
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Re: Hydroboost donor vehicles?

yeah look in 3/4ton and 1ton trucks. most diesel's use hydroboost because they do not make vacume like a gas motoro will. i say that but my 97 f350 with a power stroke uses a vacume brake booster but it uses a vacume pump.
post #8 of (permalink) Old 05-08-2002, 05:51 PM
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Re: Hydroboost donor vehicles?

Thanks for all the info folks. I spent half the day checking all the local yards, and all I was able to find were boosters from later model Ford trucks which have the holes in the MC for the brake lines on the passenger side. I couldn't find a single GM unit, or any other make for that matter, so I guess I'm going to bite the bullet and pay the core charge on a rebuilt Fleetwood booster and MC.

post #9 of (permalink) Old 05-08-2002, 06:43 PM
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Re: Hydroboost donor vehicles?

[img]images/icons/crazy.gif[/img] Dean, that's amazing! The yards that I used to visit when we lived in CA have A LOT of GM Diesel pickups with the hydroboosts in them. I imagine that it's even more so here in Iowa since the diesel pickups were always popular with farmers and they have a short lifespan due to rustosis.[img]images/icons/crazy.gif[/img]
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post #10 of (permalink) Old 05-08-2002, 06:53 PM
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Re: Hydroboost donor vehicles?

It sure surprised the crap out of me. I'm in Texas, THE pickup truck capitol of the universe, but I couldn't find a thing except for the Ford units. Even if the Ford setup would work for me, the yards wanted about $200 for one of the things.

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