Lets talk Hydro boost vs vacuume boost

[HotRodPC]

We have another member who is working on putting an Olds 425 into a Square. I still don't have my A833 in my truck if that's what you're asking.

 

[usar17]

What trucks should I be looking at for the pedal? Any with hydro boost?

I pulled a unit from a yard months ago and forgot about the pedal differences. I got mine from a newer Chevy van 3500. I'll also note that I'm switching everything to a 1994 wiring harness. Heres pics of the booster and brake switch. I'm looking to put this in my '85

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[usar17]

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[MadOgre]

Any diesel has hydro boost. and most 1 tons such as crew cabs.

I drove pops old square with the vacuum boost the other day, and I thought I had no brakes for a moment, then I remembered he had vacuum boost and not hydro boost like mine.

I like the hydro boost when im working under the hood, just so much more room. Those hoses last a long time. I've been running ATF for 10 years with out any issues from my unit. Although the steering gear packed it in last year so I replaced the pump, steering gear and all three hoses just to be safe.

When I step on the brakes the peddle is firm as soon as I touch it and it doesn't take much foot pressure to bring it to a stop. In fact there are not to many new vehicles, that stop any better IMO.

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[usar17]

I mean more along the lines will any pedal from a hydroboost truck work on a 85 k10. I need a pedal with a pin large enough to be able to connect the hydro boost rod plus the brake switch

My thoughts being, can I take the pedal off a gmt400 with hydroboost and use it on my square body?

 

[skysurfer]

IMy thoughts being, can I take the pedal off a gmt400 with hydroboost and use it on my square body?

I think you're in uncharted waters there. I haven't heard of anyone using gmt400 hydroboost parts in a square other than the steering pump and hoses which bolt right in. Not really sure what you're going for by using the wiring and switch attached to the pedal pushrod, hydroboost works without that stuff so it seems like you're making it more difficult than it should be.

 

[usar17]

This is just one section in a much bigger plan. I'm currently putting the entire drivetrain and wiring harness from a 1994 in my truck

 

[MadOgre]

I thought the hose fittings were different between the old and the newer? metric vs SAE

 

[skysurfer]

I thought the hose fittings were different between the old and the newer? metric vs SAE

Now that you mention it, that's sounds right. Somehow I got lucky when I pulled the hoses from a mid-80's square and they fit the steering pump from a '94 Suburban.

 

[usar17]

Well seeing as I have a 1992 power steering pump that isn't an issue. The only place I'm worried is the pedal

 

[SlickGTP]

When I put the Hydroboost in my '73 I had to buy a bushing for the brake pedal pin. The only thing is that it pushed the pedal out about a 1/4" or so, but it works great.

 

[HotRodPC]

What trucks should I be looking at for the pedal? Any with hydro boost?

I pulled a unit from a yard months ago and forgot about the pedal differences. I got mine from a newer Chevy van 3500. I'll also note that I'm switching everything to a 1994 wiring harness. Heres pics of the booster and brake switch. I'm looking to put this in my '85

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In our year models, any with 6.2 Diesel or 1 tons. I think I've decided to go ahead and keep the hydroboost on my 85 K10 was originally a 6.2.

I'd probably have sold this K10 project of mine if it wasn't originally 6.2 Diesel. There are a few things that come on the Diesel trucks OEM that are nice to have even if running a gas motor. Like the HydroBoost, dual battery trays, 80PSI Oil Pressure Guage instead of 60 which my 454 pegs the 60PSI guage right off of idle cold or even hot. I guess it has a high pressure or high volume pump in it. The noise barrier plastic coating on the firewall should help keep the cab cooler and the interior noise down too. I think I have to use the smaller HEI distributor cap dizzy though because the big OEM HEI cap hits on the firewall plastic. And then of course, being exempt from smog in Cali is huge too. I don't think I'll ever move back to Cali, but if I do....

 

[MadOgre]

In our year models, any with 6.2 Diesel or 1 tons. I think I've decided to go ahead and keep the hydroboost on my 85 K10 was originally a 6.2.

I'd probably have sold this K10 project of mine if it wasn't originally 6.2 Diesel. There are a few things that come on the Diesel trucks OEM that are nice to have even if running a gas motor. Like the HydroBoost, dual battery trays, 80PSI Oil Pressure Guage instead of 60 which my 454 pegs the 60PSI guage right off of idle cold or even hot. I guess it has a high pressure or high volume pump in it. The noise barrier plastic coating on the firewall should help keep the cab cooler and the interior noise down too. I think I have to use the smaller HEI distributor cap dizzy though because the big OEM HEI cap hits on the firewall plastic. And then of course, being exempt from smog in Cali is huge too. I don't think I'll ever move back to Cali, but if I do....

Ya that smog exempt is pretty cool with the diesel vin.

I have the factory style dizzy cap and I have to reset the timing everytime I change the cap cause you cant get to the cap screws unless you turn the dizzy.

Im thinking im gonna ditch that whole firewall insulator pad. It makes for a tight fit with the electrical harness behind the heads.

I like that the diesels came with the low coolant sensor and are wired for the 3,4 lock up. They also have the dual horns.

 

[Smith]

So got an 84 k10, booster is shot. I want to go to Hydroboost. I know I need a Master, a Hydro unit, and a pedal and of course brake lines and likely a Cooler. Anyway what trucks should I look at for these for it to mount up. I know I want to look at a similiar year due to metric vs standard Lines but what is the cut off. Will any Hydro Unit from the 73-87's work? What about brake lines? Will they hold up to the added pressure?
Thanks

 

[chengny]

You might have trouble finding a 1/2 ton truck to use for an example. Hydroboost brakes were normally only supplied as OEM equipment on 1 ton trucks.

If you stay below 1987 the master should accept standard (SAE/"A") brake line fittings. You might not even have to change your current lines - but they may have to be reversed front to back. See the images below.

A cooler isn't necessary, but can easily be added later - if you find you need it.

As long as they are in good shape, your current brake lines will handle the pressure. The brake lines supplied with HB assist were identical to vacuum assist.


Couple of schematics:

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An 86 K20 with vacuum boost:

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And an 86 K30 with hydroboost:

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