Brakes Lock up with hydro boost Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TurnNBurn · 10-12-2009, 10:12 PM

I am having trouble with my hydroboost brakes. I installed the unit, I hooked it up, fired it up bled the brakes and the work. My problem is they work WAY to good, or bad not sure yet. I did a few 5mph tests and when I push them soft they stop fast, Violently fast. I went to the road crusin about 25mph when I push the brakes they will lock up. I thought I might have the lines backwards. I switched them around, no diffrence. Has any one had this problem?? Please any Info would be great.

cableguy0 · 10-12-2009, 10:55 PM

hydroboost is a lot more sensitive than a normal vac booster and takes a little while to get used to. dont stab the pedal unless you plan on stopping in a hurry. light pedal pressure is all thats needed to stop. drive around for a while and just try to get used to it. i have been driving stuff with hydroboost for a few years and now and then i almost put myself through the windshield lol.

TurnNBurn · 10-12-2009, 11:06 PM

So that is just they way they are?? I suppose there is no way to tone it down a little.

cableguy0 · 10-12-2009, 11:13 PM

my tow truck didnt do it but it weighed 8000 lbs empty. the systems are designed for bigger heavier vehicles typically but after driving with vac assisted brakes and a cam too big to make any vac i really appreciate having the brakes be sensitive. it just takes a bit to get used to it. i would say drive it around for a bit and see how you feel in a couple weeks

James McClure · 10-13-2009, 07:38 AM

one thing no one mentions is was the truck you put the unit into manual brakes before? If it was the pedals are different in that the anchor and MC pin are closer togther giving you a higher mechanical advantage needed for manual brakes. I did this with an old Chevy wagon. Installed a vac booster but never changed the pedal and had the same thing happen to me as you are expirencing. let us know, jim

Storm Chaser · 10-13-2009, 12:14 PM

Are all 4 wheels locking up? Something is wrong here. True, hydroboost is more sensitive than vacuum, but it should not be as sensitive as you describe. I was a mechanic in the USMC, and 75% of the trucks in my fleet were HMMWV's and CUCV's (the CUCV is the chevy pickups and blazers). All of those trucks had hydroboost, and none of them locked up that violently. I've also owned many hydroboost trucks- again, no violent lockup.

Like I said, there is a little bit of difference between hydroboost and vacuum, but not so much of a difference that any schmuck shouldn't be able to get in one for the first time and get used to it after a stop or two. If the system is set up correctly and everything is working, the difference between hydroboost and vacuum shouldn't be greater than the difference between manual brakes and power brakes. Otherwise, y'all have something going on that is not quite right.

boatpuller · 10-14-2009, 12:58 PM

yea,what you describe isn't hydroboost.you got something going on.i had an old ford truck that i adjusted the rod from the pedal thru the booster into the back of the master cylinder.if that's adjusted wrong.your brakes can drag.not sure if hydroboost has that rod.iv'e never had mine apart in that area.

jondancer · 12-18-2016, 10:22 PM

Mine does this too , I need to fix it !

SCOTI · 12-19-2016, 08:45 AM

Quote:

Originally Posted by jondancer

Mine does this too , I need to fix it !

This....

Quote:

Originally Posted by James McClure

one thing no one mentions is was the truck you put the unit into manual brakes before? If it was the pedals are different in that the anchor and MC pin are closer togther giving you a higher mechanical advantage needed for manual brakes. I did this with an old Chevy wagon. Installed a vac booster but never changed the pedal and had the same thing happen to me as you are expirencing. let us know, jim

I changed from Hydraboost to Vac brakes on my dually & had to change the pedal for the correct ratio so the system worked properly.

jondancer · 12-19-2016, 10:17 PM

How can it be adjusted ?

10-12-2009, 10:12 PM	#1
TurnNBurn Registered User Join Date: Oct 2004 Location: North Dakota Posts: 103	Brakes Lock up with hydro boost Help I am having trouble with my hydroboost brakes. I installed the unit, I hooked it up, fired it up bled the brakes and the work. My problem is they work WAY to good, or bad not sure yet. I did a few 5mph tests and when I push them soft they stop fast, Violently fast. I went to the road crusin about 25mph when I push the brakes they will lock up. I thought I might have the lines backwards. I switched them around, no diffrence. Has any one had this problem?? Please any Info would be great.

10-12-2009, 10:55 PM	#2
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Brakes Lock up with hydro boost Help hydroboost is a lot more sensitive than a normal vac booster and takes a little while to get used to. dont stab the pedal unless you plan on stopping in a hurry. light pedal pressure is all thats needed to stop. drive around for a while and just try to get used to it. i have been driving stuff with hydroboost for a few years and now and then i almost put myself through the windshield lol. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

10-12-2009, 11:06 PM	#3
TurnNBurn Registered User Join Date: Oct 2004 Location: North Dakota Posts: 103	Re: Brakes Lock up with hydro boost Help So that is just they way they are?? I suppose there is no way to tone it down a little.

10-12-2009, 11:13 PM	#4
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Brakes Lock up with hydro boost Help my tow truck didnt do it but it weighed 8000 lbs empty. the systems are designed for bigger heavier vehicles typically but after driving with vac assisted brakes and a cam too big to make any vac i really appreciate having the brakes be sensitive. it just takes a bit to get used to it. i would say drive it around for a bit and see how you feel in a couple weeks __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

10-13-2009, 07:38 AM	#5
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Brakes Lock up with hydro boost Help one thing no one mentions is was the truck you put the unit into manual brakes before? If it was the pedals are different in that the anchor and MC pin are closer togther giving you a higher mechanical advantage needed for manual brakes. I did this with an old Chevy wagon. Installed a vac booster but never changed the pedal and had the same thing happen to me as you are expirencing. let us know, jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

10-13-2009, 12:14 PM	#6
Storm Chaser Registered User Join Date: Oct 2006 Location: In the Indiana Corn Posts: 449	Re: Brakes Lock up with hydro boost Help Are all 4 wheels locking up? Something is wrong here. True, hydroboost is more sensitive than vacuum, but it should not be as sensitive as you describe. I was a mechanic in the USMC, and 75% of the trucks in my fleet were HMMWV's and CUCV's (the CUCV is the chevy pickups and blazers). All of those trucks had hydroboost, and none of them locked up that violently. I've also owned many hydroboost trucks- again, no violent lockup. Like I said, there is a little bit of difference between hydroboost and vacuum, but not so much of a difference that any schmuck shouldn't be able to get in one for the first time and get used to it after a stop or two. If the system is set up correctly and everything is working, the difference between hydroboost and vacuum shouldn't be greater than the difference between manual brakes and power brakes. Otherwise, y'all have something going on that is not quite right. __________________ 1988 R2500 Crew Cab Immediate plans- get it running! Future plans- Rear disc swap & Hydroboost Dually conversion with shackle flip-n-switch 4x4 conversion with 52" springs Maybe some new body panels Who needs a car when they make crew cab trucks? Last edited by Storm Chaser; 10-13-2009 at 12:20 PM.

10-14-2009, 12:58 PM	#7
boatpuller Registered User Join Date: Sep 2005 Location: Sun City West, Az Posts: 3,822	Re: Brakes Lock up with hydro boost Help yea,what you describe isn't hydroboost.you got something going on.i had an old ford truck that i adjusted the rod from the pedal thru the booster into the back of the master cylinder.if that's adjusted wrong.your brakes can drag.not sure if hydroboost has that rod.iv'e never had mine apart in that area. __________________ " Never look up a dead dogs butt." Last edited by boatpuller; 10-14-2009 at 12:59 PM.

12-18-2016, 10:22 PM	#8
jondancer Registered User Join Date: Jul 2010 Location: central michigan Posts: 1,194	Re: Brakes Lock up with hydro boost Help Mine does this too , I need to fix it !

12-19-2016, 10:17 PM	#10
jondancer Registered User Join Date: Jul 2010 Location: central michigan Posts: 1,194	Re: Brakes Lock up with hydro boost Help How can it be adjusted ?

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