Hydro boost units, who's got 'em?
03-20-2008, 10:57 PM
#31
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With this setup, what happens if your engine kills and you need to hit the brakes? (assuming no exhaust brake) The International bus I drive has hydroboost, but it also has "electric assist" - eBay link. That thing starts running if you kill the engine (with the ignition still on) and touch the brake pedal. It's not terribly responsive but it stops it.
03-21-2008, 12:39 AM
#32
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When I do my W250 I'm going to see if I can rig up a master and booster off of a bigger truck like your International bus or my GMC 7000 because they have about a 1.5" master and they have the electric back up in case your lose your power steering.
Doesn't save you in all cases (like when your cab ground strap burns, don't ask how I know) but if your engine dies or your power steering pump craps, it does.
JP.
Doesn't save you in all cases (like when your cab ground strap burns, don't ask how I know) but if your engine dies or your power steering pump craps, it does.
JP.
03-21-2008, 01:08 AM
#33
DTR's Night Watchman & Poet Laureate
Would one of you describe how you bled the system after install? and what type of fluid are you using?how much?
thanks!
BTW Excellent write up JD and Kizka!!!
RonA, $145??? post a lis tof the parts you used and prices please?
thanks!
BTW Excellent write up JD and Kizka!!!
RonA, $145??? post a lis tof the parts you used and prices please?
03-21-2008, 02:15 AM
#34
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With this setup, what happens if your engine kills and you need to hit the brakes? (assuming no exhaust brake) The International bus I drive has hydroboost, but it also has "electric assist" - eBay link. That thing starts running if you kill the engine (with the ignition still on) and touch the brake pedal. It's not terribly responsive but it stops it.
Back-Up
Similar to the vacuum booster, the hydro-boost is equipped with a backup or reserve in case the source of pressurized fluid is lost. A failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering gear. The hydro-boost uses a high-pressure accumulator to store power steering fluid under pressure in the event of a failure. There are two types of accumulators used, some hydro-boost units use an external accumulator, while others incorporate the accumulator in the power piston. The accumulator could be either of the spring-loaded variety or nitrogen-gas type.
In the event of a loss of pressurized fluid, the accumulator will provide two to three power assisted stops. Upon the first application of the brakes after an engine stall or loss of power steering, you would find approximately 60 to 75% of the normal assist available. If you were to release and apply the brakes again, you would find approximately 30% to 40% assist, then again approximately 10% to 20%, until you have depleted all stored reserve assist. Once you have depleted all of the stored pressure, the brakes will no longer have power assist and will be manual in their operations.
During normal operation, the accumulator is charged by pump pressure though a check valve assembly (See Figure 11). The check valve allows fluid into the accumulator, but prevents it from escaping. When the pressure in the power chamber is lost due to a failure, the input rod linkage will override the power piston linkage and cause the check valve to be opened. The open check valve will release the stored fluid in the accumulator into the power chamber which will provide the power assist.
Similar to the vacuum booster, the hydro-boost is equipped with a backup or reserve in case the source of pressurized fluid is lost. A failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering gear. The hydro-boost uses a high-pressure accumulator to store power steering fluid under pressure in the event of a failure. There are two types of accumulators used, some hydro-boost units use an external accumulator, while others incorporate the accumulator in the power piston. The accumulator could be either of the spring-loaded variety or nitrogen-gas type.
In the event of a loss of pressurized fluid, the accumulator will provide two to three power assisted stops. Upon the first application of the brakes after an engine stall or loss of power steering, you would find approximately 60 to 75% of the normal assist available. If you were to release and apply the brakes again, you would find approximately 30% to 40% assist, then again approximately 10% to 20%, until you have depleted all stored reserve assist. Once you have depleted all of the stored pressure, the brakes will no longer have power assist and will be manual in their operations.
During normal operation, the accumulator is charged by pump pressure though a check valve assembly (See Figure 11). The check valve allows fluid into the accumulator, but prevents it from escaping. When the pressure in the power chamber is lost due to a failure, the input rod linkage will override the power piston linkage and cause the check valve to be opened. The open check valve will release the stored fluid in the accumulator into the power chamber which will provide the power assist.
edit: Chrisreyn, bleed proceure is towards the bottom of the linked page.
03-21-2008, 02:51 AM
#35
DTR's Night Watchman & Poet Laureate
http://babcox.com/editorial/bf/bf030542.htm is a pretty good reference for hydroboost info.
edit: Chrisreyn, bleed proceure is towards the bottom of the linked page.
edit: Chrisreyn, bleed proceure is towards the bottom of the linked page.
10charactors
03-22-2008, 11:50 AM
#36
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Napa hose 7-2245 pump to hydroboost. $28
Napa hose 7-2246
Napa hose 7-2662
I used only 1 of the other 2 hoses. It was the pressure hose from the hydroboost to the power steering. I used 3/8" hose for the returns. It was $27.
I had to make a plate for the hydroboost to bolt to the firewall, and swap rod ends & adjust length.
03-26-2008, 01:42 PM
#38
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Ron,
Looks like good work. I went little more expensive becasue the only donor booster was in such poor condition, I used it for a core at napa.
Was the master cylinder similar to mine? or shorter from a van? I decided that I wasn't putting in some old crappy master cylinder with all this new brake stuff. I also wanted a aluminum master as they don't fail as often as the cast ones.
I also ended up returning some the OEM hoses and making mine as the hydraulic winch came with all the required fittings.
My next mission is to fully remove the vaccum pump and replace it with an aluminum ZF pump from 6b cummins the flow 5GPH with variable pressure. Since I have hydroboost, powersteering, and hydraulic winch I need a little more volumn.
I plan on using and electric vaccum pump from a new powerstroke to run the heater vents and cruise control.
Looks like good work. I went little more expensive becasue the only donor booster was in such poor condition, I used it for a core at napa.
Was the master cylinder similar to mine? or shorter from a van? I decided that I wasn't putting in some old crappy master cylinder with all this new brake stuff. I also wanted a aluminum master as they don't fail as often as the cast ones.
I also ended up returning some the OEM hoses and making mine as the hydraulic winch came with all the required fittings.
My next mission is to fully remove the vaccum pump and replace it with an aluminum ZF pump from 6b cummins the flow 5GPH with variable pressure. Since I have hydroboost, powersteering, and hydraulic winch I need a little more volumn.
I plan on using and electric vaccum pump from a new powerstroke to run the heater vents and cruise control.
03-30-2008, 09:35 PM
#39
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I have access to a hydroboost unit with Master cylinder from a 2003 Chevrolet 1 ton truck. The reason I am wanting to use this unit is because these trucks have 4 wheel disc brakes, and my truck also has 4 wheel disc brakes. Since I will get the hydroboost and master cylinder assy, I was assuming it would all be compatable. For those of you guys that have done this conversion, what else will I need to do other than fabricating a mounting bracket/plate to mount it to the firewall at the correct spacing distance and clocking? Do I also just need to T into the pressure line coming from the power steering pump, and also T into the return line?
03-31-2008, 05:47 AM
#40
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Thread Starter
I have access to a hydroboost unit with Master cylinder from a 2003 Chevrolet 1 ton truck. The reason I am wanting to use this unit is because these trucks have 4 wheel disc brakes, and my truck also has 4 wheel disc brakes. Since I will get the hydroboost and master cylinder assy, I was assuming it would all be compatable. For those of you guys that have done this conversion, what else will I need to do other than fabricating a mounting bracket/plate to mount it to the firewall at the correct spacing distance and clocking? Do I also just need to T into the pressure line coming from the power steering pump, and also T into the return line?
You can't T the pressure side, the hydroboost needs to get pressure first, then theres a pressure line that runs the powersteering unit. There's a priority valve in the hydroboost unit that sends pressure to the powersteering unit while your braking. A T in the return line will work just fine.
03-31-2008, 10:06 PM
#41
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i second this question...which years work?
i have a 79 gmc with a 91 cummins and using the stock cummins pump with the gm hydroboost doesnt flow enough for the pedal to return completely and the braking leaves alot to be desired. With an upgraded pump im sure it would work awesome.
i have a 79 gmc with a 91 cummins and using the stock cummins pump with the gm hydroboost doesnt flow enough for the pedal to return completely and the braking leaves alot to be desired. With an upgraded pump im sure it would work awesome.
03-31-2008, 10:19 PM
#42
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I'm sorry, I didn't mean T into the pressure line...typo....I meant T into the return line since the 93 p/s pump does not have return line fittings. Sorry...Thanks for the help guys
04-07-2008, 07:14 PM
#43
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i second this question...which years work?
i have a 79 gmc with a 91 cummins and using the stock cummins pump with the gm hydroboost doesnt flow enough for the pedal to return completely and the braking leaves alot to be desired. With an upgraded pump im sure it would work awesome.
i have a 79 gmc with a 91 cummins and using the stock cummins pump with the gm hydroboost doesnt flow enough for the pedal to return completely and the braking leaves alot to be desired. With an upgraded pump im sure it would work awesome.
anyone know which power steering pumps can be used??
04-08-2008, 08:41 AM
#44
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You want to look for a pump from a GMC 3500 HD that came with the hydroboost from the factory. It will have the correct output pressure plus the reservior with the double return. Press the pulley off and press the Cummins adaptor on and you're off and running. Bolts right up.