Weak Hydroboost.
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
Weak Hydroboost.
I got the truck pulling pretty good...Now I need it to stop!
I just replaced rear calipers, pads, rotors and installed a reman master. The pedal is nice and hard and the brakes seem to work OK until I really mash the pedal. I can't get the brakes to lock at all and they don't soak up the speed very quick. I can feel the pedal pushing back up at me but I can stomp it almost to the floor and the wheels still wont lock.
Is there a way to diag this? My PS works fine, even with 3 tons in the back.
No ABS and I bypassed the rear proportioning valve.
I just replaced rear calipers, pads, rotors and installed a reman master. The pedal is nice and hard and the brakes seem to work OK until I really mash the pedal. I can't get the brakes to lock at all and they don't soak up the speed very quick. I can feel the pedal pushing back up at me but I can stomp it almost to the floor and the wheels still wont lock.
Is there a way to diag this? My PS works fine, even with 3 tons in the back.
No ABS and I bypassed the rear proportioning valve.
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
I haven't had the front wheels off but the rear brakes, including lines, are brand new. Is there a pressure valve in the pump? Like a ball and spring or something? I notice the pump whining when I hold the brake pedal down hard. Could the system be sucking air somewhere?
Fleet Owner
Joined: Jul 2006
Posts: 20,376
Likes: 843
From: Mi'kma'ki
i went through my brakes and replaced pretty much the whole system now.
it wasn't until my rear wheel cylinder started to leak,and let me know to change both,that i really noticed a HUGE difference.
they where shot before they leaked.now i have really nice brakes.
with hydroboost brakes,
im no expert,but if your hearing the power steering pump squeal when you press the pedal,i would kinda think the pump may not be good.
you'll need help from someone who has this setup though.
you may want to provide the year of your F-superduty (f450) too, while waiting.
it wasn't until my rear wheel cylinder started to leak,and let me know to change both,that i really noticed a HUGE difference.
they where shot before they leaked.now i have really nice brakes.
with hydroboost brakes,
im no expert,but if your hearing the power steering pump squeal when you press the pedal,i would kinda think the pump may not be good.
you'll need help from someone who has this setup though.
you may want to provide the year of your F-superduty (f450) too, while waiting.
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
My truck is a '94 450 Super with 4 wheel disks. Everything but the front CPRs', PS pump and hydroboost unit are new. I just took a load of wood over to the farm and the brakes feel nice but, like I say, if I mash it to test a panic, they don't lock or even stop that hard.
Getting the rear brakes working properly made a huge difference but the stopping power just aint there.
The PS pump does the Ford growling whining thing but only when the brakes or steering need a lot of flow. And not bad.
Getting the rear brakes working properly made a huge difference but the stopping power just aint there.
The PS pump does the Ford growling whining thing but only when the brakes or steering need a lot of flow. And not bad.
Posting Guru
Joined: Dec 2005
Posts: 1,528
Likes: 0
From: Peterborough, Ontario
So all the steel and rubber lines are also new?
I know there are a couple 'mods' that can be done to the power steering pumps to increase flow, but not sure what they are or where to find them at the moment. I suspect there should be tests to figure out whether it is the PS pump, or hydroboost unit too.
I know there are a couple 'mods' that can be done to the power steering pumps to increase flow, but not sure what they are or where to find them at the moment. I suspect there should be tests to figure out whether it is the PS pump, or hydroboost unit too.
Postmaster
Joined: Apr 2008
Posts: 4,802
Likes: 1
The brakes should be able to throw you into the windshield. I have hydro on mine, and while I do not have 3 tons of load in the bed I do often have at least 1 ton, and brakes perform great. Well, other than lately the hydroboost has been whining as if she's cavitating, yet the fluid is full and there are no leaks anywhere in the system and she stills tops great...
Power steering pumps do wear out tho, so maybe it's time to replace yours? How's your power steering, does it feel somewhat weaker lately? You can try running an "A" pressure relief valve and spring inside it from a Mustang Ford or a Mark VII Lincoln, this makes for higher line pressure in the regular F-series pumps, but I've been told that the F-Superduty pumps do run higher line pressure from the factory so for all I know you could already have the "A" valve and spring in there...
Power steering pumps do wear out tho, so maybe it's time to replace yours? How's your power steering, does it feel somewhat weaker lately? You can try running an "A" pressure relief valve and spring inside it from a Mustang Ford or a Mark VII Lincoln, this makes for higher line pressure in the regular F-series pumps, but I've been told that the F-Superduty pumps do run higher line pressure from the factory so for all I know you could already have the "A" valve and spring in there...
Trending Topics
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
So all the steel and rubber lines are also new?
I know there are a couple 'mods' that can be done to the power steering pumps to increase flow, but not sure what they are or where to find them at the moment. I suspect there should be tests to figure out whether it is the PS pump, or hydroboost unit too.
I know there are a couple 'mods' that can be done to the power steering pumps to increase flow, but not sure what they are or where to find them at the moment. I suspect there should be tests to figure out whether it is the PS pump, or hydroboost unit too.
I removed/bypassed the weight sensor/proportioning valve so I should be getting full pressure to the rear axle.
The truck weighs just under 8,000 Lb.
Before I replaced the rear brakes, they did almost nothing. The front axle was doing at least 90% of the work.
The brakes should be able to throw you into the windshield. I have hydro on mine, and while I do not have 3 tons of load in the bed I do often have at least 1 ton, and brakes perform great. Well, other than lately the hydroboost has been whining as if she's cavitating, yet the fluid is full and there are no leaks anywhere in the system and she stills tops great...
Power steering pumps do wear out tho, so maybe it's time to replace yours? How's your power steering, does it feel somewhat weaker lately? You can try running an "A" pressure relief valve and spring inside it from a Mustang Ford or a Mark VII Lincoln, this makes for higher line pressure in the regular F-series pumps, but I've been told that the F-Superduty pumps do run higher line pressure from the factory so for all I know you could already have the "A" valve and spring in there...
Power steering pumps do wear out tho, so maybe it's time to replace yours? How's your power steering, does it feel somewhat weaker lately? You can try running an "A" pressure relief valve and spring inside it from a Mustang Ford or a Mark VII Lincoln, this makes for higher line pressure in the regular F-series pumps, but I've been told that the F-Superduty pumps do run higher line pressure from the factory so for all I know you could already have the "A" valve and spring in there...
I can stand on the brake pedal with both feet and the brakes won't lock. Not even close.
The pedal is high.
I feel it's not safe. My other truck is a Mack CH612 with a 10 yard dump body so I'm used to keeping a safe distance.
If someone ever pulled out or stopped short right in front of me though, they'd be a gonner!
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Postmaster
Joined: Apr 2008
Posts: 4,802
Likes: 1
Hmm, something feels sketchy about the relief valve pull the pressure hose from the pump, then pull the large fitting it threaded into, valve will be right behind it with a spring behind the valve. Take a note of what letter is stamped on the valve...
As for the weak brakes, I dunno what to tell ya man, I got a 1-ton with drums so way different from the beast you're working on. I'm still thinking a new pump would not be a bad idea, especially if she's already moaning and groaning even when you don't touch the wheel or the brakes...
As for the weak brakes, I dunno what to tell ya man, I got a 1-ton with drums so way different from the beast you're working on. I'm still thinking a new pump would not be a bad idea, especially if she's already moaning and groaning even when you don't touch the wheel or the brakes...
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
I drove it again. I mashed the brake pedal to the floor (@ 0 mph) and the idle slowed 200rpm and the belt started squealing. I Mashed it as hard as I could a couple times rolling around 10mph. Brakes didn't lock and my face didn't bounce off the steering wheel. I don't like it.
I need more brake fluid pressure.
The pump sounds fine until the steering wheel is yanked over or the brake pedal is stomped on hard.
I say the brake pedal goes to the floor but it really doesn't. It comes close but never quite gets there. I'm standing on it to the point that the seat back is flexing at the frame.
I'm going to bleed the whole system again even though there is no free play in the pedal and the first pedal stroke feels the same as the 10nth.
The pedal grabs high. Right at the top actually. The brakes feel really good until I try a panic stop. Then...no good.
I need more brake fluid pressure.
The pump sounds fine until the steering wheel is yanked over or the brake pedal is stomped on hard.
I say the brake pedal goes to the floor but it really doesn't. It comes close but never quite gets there. I'm standing on it to the point that the seat back is flexing at the frame.
I'm going to bleed the whole system again even though there is no free play in the pedal and the first pedal stroke feels the same as the 10nth.
The pedal grabs high. Right at the top actually. The brakes feel really good until I try a panic stop. Then...no good.
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
Tomorrow, I'm going to take a look at the fire wall to make sure it's not flexing or cracked. Is there a way to tweak the hydroboost unit? I keep reading that a good system can bust a steel brake line.
Not mine!
Not mine!
Postmaster
Joined: Apr 2008
Posts: 4,802
Likes: 1
I can tweak the pump, but know no ways of doing anything to the hydroboost itself. I'm sure there are ways to do it, I just don't know them. But I gotta say something definitely ain't right with your system - I can stand on my brake pedal and the engine hardly slows down, the hydro whines like a pissed off banshee but the engine runs the same way as before and the belts don't squeal at all... Like I said, pull the pump relief valve and see what you find there, if it's a "B" valve try installing an "A" valve and spring - valves are actually identical from what I've seen, I think the letter designation refers to the spring behind the valve - longer and/or stiffer spring results in higher line pressure out the pump and into the hydro.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Something is not right, I did a panic stop with mine and split a new steel rear brake line like it was glass.
All four wheels also stopped instantly, even though the truck took a little longer.
All four wheels also stopped instantly, even though the truck took a little longer.
Thread Starter
|
Mountain Pass
Joined: Jun 2010
Posts: 105
Likes: 0
Not right for sure.
I need more stopping power.
I have a pressure transducer for my dvom. I don't know what kind of pressure it can handle and I don't know how much pressure my pump is capable of. I'm pretty sure the problem is in the actual booster though.
I need more stopping power.
I have a pressure transducer for my dvom. I don't know what kind of pressure it can handle and I don't know how much pressure my pump is capable of. I'm pretty sure the problem is in the actual booster though.
Postmaster
Joined: Apr 2008
Posts: 4,802
Likes: 1
As I said, pumps are cheaper than boosters, and chances are the pump could stand replacing by now. If that don't solve your issue, then it's booster time... I know it kinda sounds like throwing parts at it, but that's the more reasonable process of elimination. Pump puts out over 1400 psi by the way, this with the normal truck "B" spring and valve - the "A" spring and valve make for higher line pressure, and there's also an Explorer setup out there than can apparently easily blow the seals out of a steering box.
Thread
Thread Starter
Forum
Replies
Last Post
fasthauler
Brakes, Steering, Suspension, Tires, & Wheels
28
Sep 30, 2018 10:41 AM
IDIDieselJohn
1987 - 1996 F150 & Larger F-Series Trucks
28
Nov 14, 2016 01:01 PM
kincfu
1968-Present E-Series Van/Cutaway/Chassis
7
Mar 23, 2016 06:59 PM
dylancroghan
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
3
Oct 26, 2014 10:46 AM
Hotairjunkie
Brakes, Steering, Suspension, Tires, & Wheels
1
Jun 26, 2013 08:40 AM
