Hydro boost units, who's got 'em?
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From: Belvidere, NJ
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From: Richmond, VA
Hopefully this will be a helpful summary:
The top figure is the lay-out for the mounting pattern on our cab. The bolt spacing is 3.4" wide and 3.5" tall. The center hole is offset toward the top by .1". The hydro-boost unit requires a hole that is ~ 1 5/8", with a tab (my unit is actually slotted for two tabs, but one seems to be enough). If you use a chevy hydroboost & master cylinder that are designed to be mounted with the hoses pointing up in a vee, then the tab should be on the driver's side of the plate. The mounting bolts through the firewall are 3/8 - 16.
The nut that holds the hydro-boost to the plate is 1 7/8 square.
The center of the stock pushrod eye is 6 1/2" from the mounting face of the booster at rest. The eye is 1/2" in diameter.
High pressure into the hydro-boost unit is via the 18mm fitting, pressure to the steering gear is the 16mm fitting, and the return is the 5/16 fitting (normally it has a barb).
I made my plate out of 3/16 steel, 6 x 6. Threaded the four holes for 3/8 16 so I can start four cap screws just flush with the mounting face, tighten the nut with an open end wrench, then run the screws down tight like the original studs to slide through the firewall. For the center hole, I drilled & tapped for a 1/4 set screw centered just outside the hole diameter to make the tab. Should have used a 5/16 set screw, as 1/4 is a little loose. I then cut the hole with a 1 5/8 hole saw.
My particular hydro-boost pushrod was too short, even with the close mounting, so I cut the eye off and threaded it 3/8 16. I cut the pushrod from the vacuum booster and threaded the end 1/2 13. An adapting coupling nut with two jamb nuts holds them together.
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Joined: Apr 2006
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From: granite falls washington
Hopefully this will be a helpful summary:
The top figure is the lay-out for the mounting pattern on our cab. The bolt spacing is 3.4" wide and 3.5" tall. The center hole is offset toward the top by .1". The hydro-boost unit requires a hole that is ~ 1 5/8", with a tab (my unit is actually slotted for two tabs, but one seems to be enough). If you use a chevy hydroboost & master cylinder that are designed to be mounted with the hoses pointing up in a vee, then the tab should be on the driver's side of the plate. The mounting bolts through the firewall are 3/8 - 16.
The nut that holds the hydro-boost to the plate is 1 7/8 square.
The center of the stock pushrod eye is 6 1/2" from the mounting face of the booster at rest. The eye is 1/2" in diameter.
High pressure into the hydro-boost unit is via the 18mm fitting, pressure to the steering gear is the 16mm fitting, and the return is the 5/16 fitting (normally it has a barb).
I made my plate out of 3/16 steel, 6 x 6. Threaded the four holes for 3/8 16 so I can start four cap screws just flush with the mounting face, tighten the nut with an open end wrench, then run the screws down tight like the original studs to slide through the firewall. For the center hole, I drilled & tapped for a 1/4 set screw centered just outside the hole diameter to make the tab. Should have used a 5/16 set screw, as 1/4 is a little loose. I then cut the hole with a 1 5/8 hole saw.
My particular hydro-boost pushrod was too short, even with the close mounting, so I cut the eye off and threaded it 3/8 16. I cut the pushrod from the vacuum booster and threaded the end 1/2 13. An adapting coupling nut with two jamb nuts holds them together.
eBay item number:
290794266979 sellers name is sterlingworth16
is the ticket
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From: Tulsa, OK
An easy swap option.
Hydroboost conversion - Dodge Cummins Diesel Forum
Hydroboost conversion - Dodge Cummins Diesel Forum
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Joined: Apr 2002
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From: Richmond, VA
That's a good write up you linked to, Mark. Although this conversion has taken a lot more time & PITA factor for me than he makes out, and my vacuum booster push rod was 1/2 in diameter, not 3/8.
Making JIC to OEM adapters is a good idea. I had thought about it, but I would have had to buy a new steering pressure hose to cut up -- I twisted the gear pressure line on the AZ truck taking it apart -- so I used JIC ends at the gear, pump & hydroboost. I'll post pics at some point, but both of my hoses have elbows at both ends. Getting the hoses made so that they fit (with the correct relative angle between the two ends) is almost impossible. Having hard tubing at the pump & gear, would be the ticket, IMO. Close adapters & JIC 90 elbow fittings at the booster work pretty well, and then you can have straight fittings attach to the brazed adapters at the gear & pump ends.
For the return, I cut the barb off the reservoir return and put a compression tee right on it (it is important that the booster return is the branch, not one of the trunk legs).
The plate that Bob found should fit just fine IF you are using a GM hydroboost & master cylinder. The Dodge boosters use an adapter plate for the master cylinder that requires the booster to be clocked at an acute angle.
Making JIC to OEM adapters is a good idea. I had thought about it, but I would have had to buy a new steering pressure hose to cut up -- I twisted the gear pressure line on the AZ truck taking it apart -- so I used JIC ends at the gear, pump & hydroboost. I'll post pics at some point, but both of my hoses have elbows at both ends. Getting the hoses made so that they fit (with the correct relative angle between the two ends) is almost impossible. Having hard tubing at the pump & gear, would be the ticket, IMO. Close adapters & JIC 90 elbow fittings at the booster work pretty well, and then you can have straight fittings attach to the brazed adapters at the gear & pump ends.
For the return, I cut the barb off the reservoir return and put a compression tee right on it (it is important that the booster return is the branch, not one of the trunk legs).
The plate that Bob found should fit just fine IF you are using a GM hydroboost & master cylinder. The Dodge boosters use an adapter plate for the master cylinder that requires the booster to be clocked at an acute angle.
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Joined: Aug 2013
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From: Tulsa, OK
That's a good write up you linked to, Mark. Although this conversion has taken a lot more time & PITA factor for me than he makes out, and my vacuum booster push rod was 1/2 in diameter, not 3/8.
Making JIC to OEM adapters is a good idea. I had thought about it, but I would have had to buy a bunch of new hoses & cut them up -- anything here in the junk yard is too rusty to disassemble, and I even twisted the gear pressure line on the AZ truck taking it apart -- so I used JIC ends at the gear, pump & hydroboost. I'll post pics at some point, but both of my hoses have elbows at both ends. Getting the hoses made so that they fit (with the correct relative angle between the two ends) is almost impossible. Having hard tubing at the pump & gear, would be the ticket, IMO. Close adapters & JIC 90 elbow fittings at the booster work pretty well, and then you would have straight fittings attach to the gear & pump custom lines.
For the return, I cut the barb off the reservoir return and put a compression tee right on it (it is important that the booster return is the branch, not one of the trunk legs).
And that plate that Bob found should fit just fine.
Making JIC to OEM adapters is a good idea. I had thought about it, but I would have had to buy a bunch of new hoses & cut them up -- anything here in the junk yard is too rusty to disassemble, and I even twisted the gear pressure line on the AZ truck taking it apart -- so I used JIC ends at the gear, pump & hydroboost. I'll post pics at some point, but both of my hoses have elbows at both ends. Getting the hoses made so that they fit (with the correct relative angle between the two ends) is almost impossible. Having hard tubing at the pump & gear, would be the ticket, IMO. Close adapters & JIC 90 elbow fittings at the booster work pretty well, and then you would have straight fittings attach to the gear & pump custom lines.
For the return, I cut the barb off the reservoir return and put a compression tee right on it (it is important that the booster return is the branch, not one of the trunk legs).
And that plate that Bob found should fit just fine.
Definitely worth it though. I love the one in my Jeep.
The reverse rotation steering gear is another case where a short hard line would be the ticket. that pressure port is a super tight fit.
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From: Richmond, VA
I waited too long to edit these into my last post.
Here are pictures of my install:
At the pump is an M16 x 1.5 x AN 6 adapter. The hose to the hydroboost has a 45 JIC 6 fitting at the pump end, a 90 JIC 6 fitting at the hydroboost end, and is 34 inches long (could have been 35 inches). The hydroboost inlet has an M18 x 1.5 x AN 6 adapter. The hydroboost power beyond has an M16 x 1.5 x AN 6 adapter. The hose from hydroboost to steering gear has a 90 JIC 6 fitting at each end, and is 54 inches long. The gear inlet has an M18 x 1.5 x AN 6 adapter. The hydroboost return line is just 3/8 low pressure power steering hose. As you can see in the picture at the pump, I used a compression tee on the reservoir return inlet and two short pieces of 3/8 tubing with bubble flares to adapt for the dual returns, and bring the hydroboost into the branch of the tee.
In the pictures it looks like the hydraulic hoses & the clutch line are rubbing on the steering column, but they are actually free of the column, and each other.
I would consider moving the pin in the brake pedal closer to the pivot, so that the pedal has more travel -- with the hydroboost you barely have to move the pedal to get braking, initial pedal resistance (at least with my unit) is greater, but effort for stopping, obviously, is much less. Since that is a pain, I may just shorten the push-rod to the booster to lower the pedal so that it feels more natural to me.
For what it is worth: while I was bleeding the air out of the power steering hydraulics, I managed to burst the LH caliper hose -- without even trying to apply the brakes at full pressure. So, be careful if you do the conversion, you might find an unexpected weak spot in the system.
Here are pictures of my install:
At the pump is an M16 x 1.5 x AN 6 adapter. The hose to the hydroboost has a 45 JIC 6 fitting at the pump end, a 90 JIC 6 fitting at the hydroboost end, and is 34 inches long (could have been 35 inches). The hydroboost inlet has an M18 x 1.5 x AN 6 adapter. The hydroboost power beyond has an M16 x 1.5 x AN 6 adapter. The hose from hydroboost to steering gear has a 90 JIC 6 fitting at each end, and is 54 inches long. The gear inlet has an M18 x 1.5 x AN 6 adapter. The hydroboost return line is just 3/8 low pressure power steering hose. As you can see in the picture at the pump, I used a compression tee on the reservoir return inlet and two short pieces of 3/8 tubing with bubble flares to adapt for the dual returns, and bring the hydroboost into the branch of the tee.
In the pictures it looks like the hydraulic hoses & the clutch line are rubbing on the steering column, but they are actually free of the column, and each other.
I would consider moving the pin in the brake pedal closer to the pivot, so that the pedal has more travel -- with the hydroboost you barely have to move the pedal to get braking, initial pedal resistance (at least with my unit) is greater, but effort for stopping, obviously, is much less. Since that is a pain, I may just shorten the push-rod to the booster to lower the pedal so that it feels more natural to me.
For what it is worth: while I was bleeding the air out of the power steering hydraulics, I managed to burst the LH caliper hose -- without even trying to apply the brakes at full pressure. So, be careful if you do the conversion, you might find an unexpected weak spot in the system.
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Joined: Apr 2006
Posts: 840
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From: granite falls washington
Nice install looks realy clean.
BLEW the line ouch.
If I were you I'd up date all your brake rubber parts.
that chevy MC has a 1 5/8 bore compared the 99 dodges 1 1/4 to the old stocker 1 1/8.
BLEW the line ouch.
If I were you I'd up date all your brake rubber parts.
that chevy MC has a 1 5/8 bore compared the 99 dodges 1 1/4 to the old stocker 1 1/8.
