what do i need to know about hydro boost brakes?

[Soundguy]

how is the vehicle stopping?

 

[aczlan]

so the only thing that seems odd is that I can push the pedal to what feels like to the floor...with what I estimate to be much less than 100 lb effort (of course maybe I'm pushing harder than I think!) It does not feel like it is firming up with brakes applied. I bled brakes 3 times and pads are good, so it shouldn't be air in the lines, although I have no way to bleed the ABS valves.

On the '05 Suburban and the F350 with Hydroboost that was normal, all the brake pedal is is a hydraulic valve. As Soundguy asked how is the actual braking force? Does ABS kick in if you stomp on the brakes while moving?

Thanks

Aaron Z

 

[BrentB]

The truck seems to stop just fine. I took it out last week to try out the ABS on a country road, but result was inconclusive...only had time for one try due to traffic, and the truck stopped so quickly I'm not sure the ABS really triggered. will try again today. Aaron's comment about it just being a hyd valve makes a lot of sense to me, but it doesn't jive with the earlier post of a member whose rv feels normal.

I didn't want to muddy up the issue, but besides this, sometimes the rear brakes get much hotter than the fronts when I get out I can smell them. temp gauge showed front rotors at 150F and rears at 450F. I have to go down a steep highway (12%) to turn into my drive, so it is a significant braking event. seems unlikely that both rear discs would be dragging, so I thought maybe the brake booster or master cylinder were related. sorry I'm turning the tractor board forum into a truck brake forum!

 

[aczlan]

The truck seems to stop just fine. I took it out last week to try out the ABS on a country road, but result was inconclusive...only had time for one try due to traffic, and the truck stopped so quickly I'm not sure the ABS really triggered. will try again today. Aaron's comment about it just being a hyd valve makes a lot of sense to me, but it doesn't jive with the earlier post of a member whose rv feels normal.

I have only run 2-3 trucks with hydroboost, but I could put the pedal to the floor in all of them without a whole lot of "extra" effort.

I didn't want to muddy up the issue, but besides this, sometimes the rear brakes get much hotter than the fronts when I get out I can smell them. temp gauge showed front rotors at 150F and rears at 450F. I have to go down a steep highway (12%) to turn into my drive, so it is a significant braking event. seems unlikely that both rear discs would be dragging, so I thought maybe the brake booster or master cylinder were related.

That is odd, have you pulled the brakes to take a look? Its possible that the sliders are sticking a little on both sides and not letting go as they should.

sorry I'm turning the tractor board forum into a truck brake forum!

This is the "Trailers and Transportation" section, so no worries .

Aaron Z

 

[Gem99ultra]

One thing that you'll find out is that a hydra boost cylinder is a LOT more expensive than a vacuum booster :-(

They do support larger pads and drums than a vacuum booster built vehicle though. They're considered the premium brake systems.

Regarding some of the other comments already posted, the rear brakes should not reach 450 degrees with just a small amount of braking. I'd suspect a bad proportioning valve causing the back brakes to drag. That, of course, will wear them out in short order and will allow brake fade very quickly.

My suggestion - check out the booster, or have it checked, pronto.

On the other side of the coin though, my Chevy C1500 has vacuum brakes. I can "make" the pedal hit the floor, but I discovered that I was actually bending the firewall when doing so. On My C2500 with hydro booster brakes, I can not make it hit the floor. Same firewall - so I'm still confused on the Why's of it all.

 

[Diamondpilot]

The truck seems to stop just fine. I took it out last week to try out the ABS on a country road, but result was inconclusive...only had time for one try due to traffic, and the truck stopped so quickly I'm not sure the ABS really triggered. will try again today. Aaron's comment about it just being a hyd valve makes a lot of sense to me, but it doesn't jive with the earlier post of a member whose rv feels normal. I didn't want to muddy up the issue, but besides this, sometimes the rear brakes get much hotter than the fronts when I get out I can smell them. temp gauge showed front rotors at 150F and rears at 450F. I have to go down a steep highway (12%) to turn into my drive, so it is a significant braking event. seems unlikely that both rear discs would be dragging, so I thought maybe the brake booster or master cylinder were related. sorry I'm turning the tractor board forum into a truck brake forum!

Sounds like a bad proportioning valve.

Chris

 

[Soundguy]

do check them slides though. might need cleaning and a lil lube..

 

[BrentB]

last week I twisted a bleeder screw off the left front caliper, so I googled how to get the broken one out. The funny answer I found was:
1. drill out bleeder screw as large as possible without hitting threads
2. insert easy out
3. twist off the easy out in the bleeder hole.
4. go buy a reman caliper!

so I just jumped to step 4...only $50 which I thought amazingly reasonable. Anyway, I now know how to remove the caliper slide bolts, so I'll do that next and clean and lubricate the rear ones, to see if this solves the hot rear brake issue. the nice thing about working on pickups is I might not even have to remove the tire to get to the back bolts....there is so much room to work in.

Regarding the brake booster, thanks to all who shared their experiences...some say they can easily push to the floor and some can't. I've sure learned a lot about truck brakes! Since there is no leaking, and truck stops good, I'm just going to monitor it for a while.

Brent

 

[dodge man]

I've dealt with a sticky rear brake on my Dodge. It has hydro boost but I don't think that has anything to do with it. With mine I just think it was a sticky rear caliper. I also had problems with one reman caliper.

I'd say your calipers are sticking in back and without a doubt the pedal should not go to the floor. Maybe want to flush the old fluid out while your at it.

 

[Highbeam]

My 2000 F350 diesel has hydroboost brakes and the pedal does not go to the floor nomatter what. That is a failure. Unsafe to drive.

The hydroboost system acts like and feels like regular vacuum brakes in my experience.