what do i need to know about hydro boost brakes?

[Soundguy]

ok.. so dumb question.. does the brake system use the unitran fluid as well.. or does it still use dot 3 and have a seal between the assist side and the brake cyl?

soundguy

 

[rjkobbeman]

ok.. so dumb question.. does the brake system use the unitran fluid as well.. or does it still use dot 3 and have a seal between the assist side and the brake cyl?

soundguy

Unless something has changed, the actual brake system is independent of the "assist". Very similar to a vacuum assist. Two entirely different systems... just connected via a mechanical linkage.

As I recall, on our old Chevy, in place of the vacuum assist device connected to the master cylinder, there was a hydraulic assist device connected to the master cylinder. This device looked like a pump with hydralic lines going to it. Those hydraulic lines came from the power steering system. Had regular DOTx brake fluid in the brake system.

 

[aczlan]

When I say it sucked, I mean you couldn't steer at low RPMs. Either the power steering pump wasn't big enough or the pulley size was wrong. The pump obviously was not efficient enough at low RPMs (especially idle) to operate both the brakes and power steering. Navigating a parking space when you foot is on the brake while steering was difficult. (We had an automatic tranny.)
Often, we had to touch the gas to keep everything working.

Has that happen on a 2002ish F-350, the power steering pump became weak and you wouldn't brake and steer at the same time. The truck was MUCH easier to drive after I replaced the pump.

Aaron Z

 

[Soundguy]

ok.. good.. that was what I was thinking.. but heck.. had to ask.

soundguy

Unless something has changed, the actual brake system is independent of the "assist". Very similar to a vacuum assist. Two entirely different systems... just connected via a mechanical linkage.

As I recall, on our old Chevy, in place of the vacuum assist device connected to the master cylinder, there was a hydraulic assist device connected to the master cylinder. This device looked like a pump with hydralic lines going to it. Those hydraulic lines came from the power steering system. Had regular DOTx brake fluid in the brake system.

 

[Bird]

Had regular DOTx brake fluid in the brake system.

As did all the ones I've seen so far.

 

[Soundguy]

good to hear, thanx

soundguy

 

[wkpoor]

My 3500 Express van has the Hydroboost. Fantastic braking! Would have it over vacuum anyday.

 

[schmism]

ok.. so dumb question.. does the brake system use the unitran fluid as well.. or does it still use dot 3 and have a seal between the assist side and the brake cyl?

soundguy

I had the same question when i got mine. i popped the top off the master cylinder to see what was up. It was clear enough to me that the 2 fluids were different and that were was a simple diaphragm type setup between the 2 sides.

I kinda have to work at keeping mine running at "idle" when im trying to manuver but i think that has more to do with sucktastic carb tune in general and not so much a fault of the system.

 

[Soundguy]

was it rebuilt.. or just not generally good at idle in the first palce?

soundguy

 

[schmism]

its a $1500 farm truck.

I grew up wrenching on toyotas and BMW's. My first American V8 with a carb was this truck 2? years ago. In short i know nothing about them.

Dont get me wrong, I know my way around a wrench, i can set timming, do plugs, wires, troubleshoot electrical crap (hey i own bmw's) even rebuilt a motor or 2 from ground up....but messing with carbs... ah that one is over my head.

but when you give me a $1500 farm truck thats been patched together over the years.... linkage/springs arnt right... choke control is wonky, vacuum hookups... what are those?

if you let it set in the yard and idle it sound great, but its that low speed maneuvering especially under load (even with the granny low) that can be a challenge to operate. Its an unrefined 1985 one ton. not a new modern truck. YOu have to work at driveing it between feathering throttle when taking off from a dead stop, to rowing 2' long gear changes. Addtional engine load at idle from the hydrobreak in combination with stearing at the same time... your feet are busy between the break, gas, and clutch when maneuvering around in tight spaces (like trying to back up offroad to dump stuff)