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Installing Hydroboost and bigger brakes in a 1970 Charger

Well, THIS came with zero instructions. I was completely on my own with every aspect of the installation.
 
**UPDATE**

Since I abandoned the Hydroboost aspect of this project, I installed a 4th power steering pump. This one was a used but functioning unit I had in the shed. It started off like the others. Steering assist worked at all engine speeds but then started to fail at idle. Ultimately, I had to rev the engine to get it to make any boost at all which made low speed steering very difficult.
I was blaming the hydroboost unit for killing these power steering pumps but now I had the same exact thing happen to the 4th pump and THIS one was installed with no hydroboost in the car.
Today while I was replacing the pump yet again, I found a kink in a hard line of the inline cooler. The return line from the steering box attached to the kinked line on the cooler. Flow was restricted on the return side as a result. I can only guess but flow was probably restricted by half. It may be hard to see but the kinked line is the top one and the kink is near the bend.

843 R.JPG
844 R.JPG


After straightening the kink and changing the pump, the steering assist seems fine. It started me wondering if the other pumps are still okay.
It also got me wondering if this Hydroboost unit is actually okay and is not defective.
Since I know very little about hydraulic function, I'm curious if a flow restriction in the return side could cause the HB to fail to work. The pump never made any sounds like it was struggling. No grinding sounds, no belt squealing, no chatter and the fluid wasn't foamy.
I'll do an internet search on fluid flow and see what I find out. In the meantime, I sent an email to Dr Diff about this. I hope that he responds soon.
When I pulled the hydroboost unit off, I installed a 15/16" manual master cylinder. The system isn't fully bled out yet but I have driven the car. The pedal does firm up and the car does stop but it isn't confidence inspiring. Oddly, it rips to a stop at slow speeds but doesn't feel as good over 20 mph.
I'm willing to admit that my efforts of a manual brake setup are another failure and that I need some type of power assist. I have the option of using the old '75 Dart vacuum booster again but with 7" of idle vacuum, I'll also need to dust off the vacuum booster and wire it in.
The other option is to take another stab at this hydroboost unit from Dr Diff.
Either way, I have the stuff here to make either work.
 
Any thoughts of trying a 7/8" bore MC with your current rotors/ calipers?
 
Kern Dog said:
**UPDATE**

Since I abandoned the Hydroboost aspect of this project, I installed a 4th power steering pump. This one was a used but functioning unit I had in the shed. It started off like the others. Steering assist worked at all engine speeds but then started to fail at idle. Ultimately, I had to rev the engine to get it to make any boost at all which made low speed steering very difficult.
I was blaming the hydroboost unit for killing these power steering pumps but now I had the same exact thing happen to the 4th pump and THIS one was installed with no hydroboost in the car.
Today while I was replacing the pump yet again, I found a kink in a hard line of the inline cooler. The return line from the steering box attached to the kinked line on the cooler. Flow was restricted on the return side as a result. I can only guess but flow was probably restricted by half. It may be hard to see but the kinked line is the top one and the kink is near the bend.

View attachment 1374770View attachment 1374771

After straightening the kink and changing the pump, the steering assist seems fine. It started me wondering if the other pumps are still okay.
It also got me wondering if this Hydroboost unit is actually okay and is not defective.
Since I know very little about hydraulic function, I'm curious if a flow restriction in the return side could cause the HB to fail to work. The pump never made any sounds like it was struggling. No grinding sounds, no belt squealing, no chatter and the fluid wasn't foamy.
I'll do an internet search on fluid flow and see what I find out. In the meantime, I sent an email to Dr Diff about this. I hope that he responds soon.
When I pulled the hydroboost unit off, I installed a 15/16" manual master cylinder. The system isn't fully bled out yet but I have driven the car. The pedal does firm up and the car does stop but it isn't confidence inspiring. Oddly, it rips to a stop at slow speeds but doesn't feel as good over 20 mph.
I'm willing to admit that my efforts of a manual brake setup are another failure and that I need some type of power assist. I have the option of using the old '75 Dart vacuum booster again but with 7" of idle vacuum, I'll also need to dust off the vacuum booster and wire it in.
The other option is to take another stab at this hydroboost unit from Dr Diff.
Either way, I have the stuff here to make either work.
Click to expand...
Just install a quiet new vacuum pump from Leed Brakes or another company and be done.

 
I am hoping the discovery of the kink will inspire you to revisit the hydroboost project. You were so close and have time and money tied up in it. I have owned vehicles equipped with hydroboost and it works really well. Would be a nice option to have on the list of brake mods for Mopars.
 
I was going to install the Leeds vacuum pump on my car, but I made the mistake of installing a CPP hydro boost instead. I ended up having to buy a new power steering pump to get the hydro boost to work properly. I really regretted not buying the Leeds unit.
 
Last edited:
Cass (Dr Diff) responded. He is looking into the possibility that the restricted line may have been an issue. He also mentioned that another customer had trouble with the Saginaw pump not being adequate. More to follow.
 
In order to get my CPP hydro boost system to work properly on my '56 Chevy, I had to purchase a Borgeson 800323 PS pump. It is a hi flow unit designed specifically for hydro boost systems. It has 2 return lines and requires a pressed on pulley. My system has worked fine ever since putting it on. I bought it from Summit for $157.19 at the time.
 
Aftermarket steering pumps....With as much of a mystery as it can be to find proper pulleys that line up where you want, how much worse is it to find something for a NON stock application??
Holy crap....This isn't a full custom build here. This is a fairly stock based car with some aftermarket parts.
If it comes down to having to put another pump in place, that would sway me back to the vacuum booster and pump. I already have that stuff here. Sometimes a man just gets tired of throwing money and time at a project.
 
Kern Dog said:
Aftermarket steering pumps....With as much of a mystery as it can be to find proper pulleys that line up where you want, how much worse is it to find something for a NON stock application??
Holy crap....This isn't a full custom build here. This is a fairly stock based car with some aftermarket parts.
If it comes down to having to put another pump in place, that would sway me back to the vacuum booster and pump. I already have that stuff here. Sometimes a man just gets tired of throwing money and time at a project.
Click to expand...
Yup, the aftermarket pump probably bolts right up to a small block chebby, but last I checked you don't have a small block chebby....
 
According to their site it's a universal pump for hydro boost systems. If a Mopar owner is contemplating switching to a hydro boost system, it's probably worth checking out the pump.
 
My apology guys. I just checked and Borgeson doesn't make a hi volume hydro boost pump for Mopar products.
 
This is strange.
When I first was gathering knowledge and parts, a member here suggested an aftermarket reservoir for the Saginaw pump, one with 2 return nipples.
I ended up getting one from a wrecked Chevy truck. It was a Saginaw model.
If the Saginaw pump was good enough to work in a 6000-7000 lb Chevy truck, why wouldn't it be enough for a system in a car under 4000 lbs?
Regardless, I can look at this as a learning experience.
 
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