Long-time member. 1st Post.
Well, I finally finished my CPP Hydro boost install into my 454 in my 67” Chevelle Malibu. Like others, I went for this option because I could never reach the recommended fourteen inches of vacuum for my brake booster after I put in the big block (a big stick cam didn’t help either). I could get 9-10 inches driving but never ever reached fifteen inches (the rule of thumb to operate a vacuum brake booster safely). If I remember correctly, at idle it bounced around five inches—that was definitely a tipping point. Honestly, my trust in stopping, even with four-wheel disk brakes, really limited the amount I drove the car. In December 2017 I bought the Classic Performance Products (CPP) HydroStop™ kit. The initial install/modification went relatively fast and most everything went smooth and uneventful. Here's a copy of my line diagram:
![Image]()
However, after the initial operations checks it was evident something was amiss. Next thing you know I’d been away from the original install awhile and then life took a priority. You know, work, moving, house upgrades, remodeling, promotion, job changes, travel and kids. So, it goes. But I finally finished this project recently and I decided to finally put this writeup together to highlight my efforts and results and hopefully save someone a ton of time and head scratching after they’ve invested in a Hydro Boost or HydraStop™ setup. I’ll use those two names interchangeably.
I installed the CPP HYDRASTOP™ Hydraulic Assist Systems Show Stopper kit in 2018 but did not use their hoses or fittings (especially not the “T,” later they introduced the “Y”). The HydraStop™ required at least two gallons per minute (GPM) and a power steering pump capable of 1200 psi but they caveat that with “total assist available is dependent on the max pressure from the pump.” I also bought a Performance Steering Component (PSC) reservoir about the same time as my CPP kit. I mounted the PSC reservoir to the fender and routed the two -AN 6 return inputs to the reservoir and then plumbed one -AN 10 return to pump.
![Image]()
I built all my own stainless steel (SS) lines with -AN fittings vs the rubber hose in the kit. Based on all I read and my experience I did not trust adding the “T” to connect the low pressure return line from the steering gear and the pressure return line from the HydroStop™ to the power steering pump (PSP) reservoir return—not enough volume, line too small etc,. Not to mention, the return line input on my PSP faces down. NOTE: There are posts out there where you can heat up the PSP return line tube and rotate it 180 degrees – but that still limits the amount of fluid going back to the PSP.
The system I designed was totally different. Here are some of the differences. I modified the PSP by replacing the PSP flow control valve for more flow and I added a PSC reservoir tank with internal filter. And, I also used Banjo fittings at the HydraStop to ease the line bends and easily clear the obstructions.
![Image]()
I also used JIC or -AN fittings on everything (37-degree flares). I also bought adapters for the fittings on the steering box but again made all my own stainless steel (SS) lines and flares. Since I had the steering and hydro boost return to the new reservoir it was a much cleaner install but wasn’t prepared for the troubleshooting required to make this system sing.
![Image]()
Issues:
After my install, I accomplished the manufactures system bleed procedure – the front end was still on jacks. At the engine run after the bleed no matter what I tried I could never get the “air” out of the system. During the operational checks the pump would whine and it would get so bad hydraulic fluid would foam out of the new reservoir. The bubbling out the top of the reservoir was my first clue I had some flow/pressure/volume issues. Ultimately, I had to step back and access where/how the air was getting into the system or why it would bubble out at the PSC reservoir tank. Even more concerning, there were times fluid would slowly bubble oil out the top of the cap on the PSP tank– not consistently but on occasion. During any road test the brake setup worked but when the brakes were applied the pump would whine loudly. The brakes definitely responded ten times better than the vacuum brake booster even with the issues. All of these areas needed further investigation. As an airplane mechanic I knew this was about fluid dynamics but just had not been able to isolate the what/where/how. So began a slow and methodical troubleshooting effort. All AN fittings, hoses and line fittings were removed and pressure checked for leaks again – none. At the reservoir tank I had a -AN 10 fitting I connected to a -AN 10 SS line I fabricated that ran to the return tube of the Saginaw Type 1 power steering pump (PSP). It ran below the PSP then up into the back at the return line in the PSP, oh and I had reduced that line to an -AN 6 to get it to marry up with the PSP hose pipe line mentioned above in the second paragraph. All these issues would take some time to thoroughly investigate, resolve and then rectify. Ultimately, I got to a point I just had to walk away for a while to research solutions and rack my cranium. Think fluid!
Focused Steps for Remediation:
![Image]()
Once I removed the PSP again and took it apart to add the new bigger remote reservoir, I found some “sparklies.” Not good. I flushed the system as good as possible and I decided to just replace the PSP. It was back to square one but time to change it up for sure. Do I go with a Saginaw Type II pump, screw around with all the different mounts and pully options to match my March Pully setup or try for a close form, fit function pump to match up with all the lines and mounting hardware? I decided to keep the Type I pump but use the remote fill reservoir I already purchased above. You get to a point where you just have to remove as many variables as possible. PSC also makes a PSP (with press on pully) specifically for Hydro boost setups with the reservoir above – that might be your best solution.
![Image]()
![Image]()
I’ve read more posts across the inter-webs of issues folks have had after installing hydro boost setups vs seamless uneventful installs. As with any modification, there’s a ton of variables that inevitably raise their ugly craniums; and each setup seems to have its own character and head ache. Don’t be afraid to try something different. One thing that I might have to work in the future is a fluid cooler on the two -AN 6 return lines (steering and hydro stop return lines) or the -AN 10 line between the PSC reservoir and PSP….I’m actually really amazed at how warm the fluid gets after a real hard workout. Hope this helps!
Well, I finally finished my CPP Hydro boost install into my 454 in my 67” Chevelle Malibu. Like others, I went for this option because I could never reach the recommended fourteen inches of vacuum for my brake booster after I put in the big block (a big stick cam didn’t help either). I could get 9-10 inches driving but never ever reached fifteen inches (the rule of thumb to operate a vacuum brake booster safely). If I remember correctly, at idle it bounced around five inches—that was definitely a tipping point. Honestly, my trust in stopping, even with four-wheel disk brakes, really limited the amount I drove the car. In December 2017 I bought the Classic Performance Products (CPP) HydroStop™ kit. The initial install/modification went relatively fast and most everything went smooth and uneventful. Here's a copy of my line diagram:
However, after the initial operations checks it was evident something was amiss. Next thing you know I’d been away from the original install awhile and then life took a priority. You know, work, moving, house upgrades, remodeling, promotion, job changes, travel and kids. So, it goes. But I finally finished this project recently and I decided to finally put this writeup together to highlight my efforts and results and hopefully save someone a ton of time and head scratching after they’ve invested in a Hydro Boost or HydraStop™ setup. I’ll use those two names interchangeably.
I installed the CPP HYDRASTOP™ Hydraulic Assist Systems Show Stopper kit in 2018 but did not use their hoses or fittings (especially not the “T,” later they introduced the “Y”). The HydraStop™ required at least two gallons per minute (GPM) and a power steering pump capable of 1200 psi but they caveat that with “total assist available is dependent on the max pressure from the pump.” I also bought a Performance Steering Component (PSC) reservoir about the same time as my CPP kit. I mounted the PSC reservoir to the fender and routed the two -AN 6 return inputs to the reservoir and then plumbed one -AN 10 return to pump.
I built all my own stainless steel (SS) lines with -AN fittings vs the rubber hose in the kit. Based on all I read and my experience I did not trust adding the “T” to connect the low pressure return line from the steering gear and the pressure return line from the HydroStop™ to the power steering pump (PSP) reservoir return—not enough volume, line too small etc,. Not to mention, the return line input on my PSP faces down. NOTE: There are posts out there where you can heat up the PSP return line tube and rotate it 180 degrees – but that still limits the amount of fluid going back to the PSP.
The system I designed was totally different. Here are some of the differences. I modified the PSP by replacing the PSP flow control valve for more flow and I added a PSC reservoir tank with internal filter. And, I also used Banjo fittings at the HydraStop to ease the line bends and easily clear the obstructions.
I also used JIC or -AN fittings on everything (37-degree flares). I also bought adapters for the fittings on the steering box but again made all my own stainless steel (SS) lines and flares. Since I had the steering and hydro boost return to the new reservoir it was a much cleaner install but wasn’t prepared for the troubleshooting required to make this system sing.
Issues:
After my install, I accomplished the manufactures system bleed procedure – the front end was still on jacks. At the engine run after the bleed no matter what I tried I could never get the “air” out of the system. During the operational checks the pump would whine and it would get so bad hydraulic fluid would foam out of the new reservoir. The bubbling out the top of the reservoir was my first clue I had some flow/pressure/volume issues. Ultimately, I had to step back and access where/how the air was getting into the system or why it would bubble out at the PSC reservoir tank. Even more concerning, there were times fluid would slowly bubble oil out the top of the cap on the PSP tank– not consistently but on occasion. During any road test the brake setup worked but when the brakes were applied the pump would whine loudly. The brakes definitely responded ten times better than the vacuum brake booster even with the issues. All of these areas needed further investigation. As an airplane mechanic I knew this was about fluid dynamics but just had not been able to isolate the what/where/how. So began a slow and methodical troubleshooting effort. All AN fittings, hoses and line fittings were removed and pressure checked for leaks again – none. At the reservoir tank I had a -AN 10 fitting I connected to a -AN 10 SS line I fabricated that ran to the return tube of the Saginaw Type 1 power steering pump (PSP). It ran below the PSP then up into the back at the return line in the PSP, oh and I had reduced that line to an -AN 6 to get it to marry up with the PSP hose pipe line mentioned above in the second paragraph. All these issues would take some time to thoroughly investigate, resolve and then rectify. Ultimately, I got to a point I just had to walk away for a while to research solutions and rack my cranium. Think fluid!
Focused Steps for Remediation:
- All line connections were re-checked for tight seals and no leaks at the fitting. Earlier, I even took off each line and pressure checked the line. After all were checked and I had totally eliminated the possibility of the pump sucking in air at the pump or a line I moved on.
- Power Steering Pump (PSP). I took off the pump and replaced the PSP flow control valve with one that could accept more flow and volume. No change. None. Nada. This really got me focused on volume and the reductions of fluid flow in the closed loop system.
- The Saginaw Type I PSP is not a powerful “sucking” pump and the return is “low pressure.” The way my return line from the PSC reservoir (-AN 10 line) to the pump was routed it descended low and was also reduced (to -AN 6) to mate up with the hose fitting in back of the reservoir. This was definitely the biggest obstruction and impediment to normal PSP production. The return loop below the PSP is ok in many hydraulic systems but when you’re talking the low pressure return and volume required you need for the added hydro boost/hydra stop output it’s a show stopper – you have to have a big return line to keep the PSP tank with adequate fluid. Note: I could heat up the return tube on the back of the PSP and rotate it but it was still a reduction in flow of fluid -AN 6 vs -AN 10 and still too small. I almost drilled and tapped an -AN 10 fitting on my tank but I still had the existing return tube I’d need to deal with. I found a remote fill reservoir for a Saginaw Type I pump on the PS motorsports dot com website. It had the option of a -AN 12 or -AN 10 fitting on the top of the pump. I was all set up for the -AN 10 return line so I kept that. Based on experience, I would recommend bigger is always better. I have no affilation with PSC. (see pic below of reservoir that attaches to psp)
Once I removed the PSP again and took it apart to add the new bigger remote reservoir, I found some “sparklies.” Not good. I flushed the system as good as possible and I decided to just replace the PSP. It was back to square one but time to change it up for sure. Do I go with a Saginaw Type II pump, screw around with all the different mounts and pully options to match my March Pully setup or try for a close form, fit function pump to match up with all the lines and mounting hardware? I decided to keep the Type I pump but use the remote fill reservoir I already purchased above. You get to a point where you just have to remove as many variables as possible. PSC also makes a PSP (with press on pully) specifically for Hydro boost setups with the reservoir above – that might be your best solution.
- Reservoir Height. I had mounted my reservoir on the fender – driver’s side but in the same large area as the battery on the opposite side (see pic above). I had plenty of space but I needed to raise it up as high as I could to ensure I had a good drop from the PSC reservoir tank to the top of the PSP new -AN 10 fitting. It definitely was not the excessive line drop I wanted but all other options were exhausted. I have the AC compressor right above the PSP so moving the PSC reservoir next to the PSP was impossible. So, I ended up raising the PSC reservoir just enough so the hood would close and not touch the PSC reservoir tank. Next, I slightly turned it so the return line didn’t require a 45 degree and ran it toward the PSP -AN 10 fitting. Again, this allowed enough of a hose drop but the install issues kept on piercing progress.
- PSP Press ON vs Keyed. My only issue with the new PSP was it was a press on pully vs the “keyed” shaft on the old PSP for my serpentine March pully. March does not make a shaft cover for “keyed” type Pully - they do for the Press on type. Press on pullies have their own character. If anyone uses March press on pullies, they know they are almost impossible to remove easily. I probably didn’t spend as much time as I could have comparing “keyed” pumps and that was on me. Regardless, I bought a press on pump and new pully. In my opinion ‘keyed” pumps are so much easier to deal with if you have a big impact driver. Here’s the issue if you ever get into modifying pully sizes and PSPs (Type I vs Type II): you have to be absolutely correct on depth with spacers on the mounting brackets, pully sizes, etc,. Trust me it can be a total headache. I like the “keyed” pully as you can get in there (just barely) and take it on and off while trying to ensure alignment spacing is perfect before everything is installed and torqued down. Press fit – forget about it. The PSP has to come out and then you have to do monkey physic madness with a pully puller and harmonic balancer working in harmony – nuts! But March Performance suggests you, “use a three-prong pully puller to remove the pully.” No matter which route you take, be careful not to mar and torque it out of round. Pro Tip: When installing the press fit pully on the bench make sure you have the mounting bracket (under the pulley) bolted on and don’t drive the pully to the stop just in case you need a 1/8 of an inch out on the shaft for a good straight belt lineup.
- Belt Alignment! Ughh. Get ready to spend some time in the hardware bins. Correct Alignment is probably the most important step in alleviating belt or pully noise and/or subsequent failure. Whether it’s a small block or big block with a short or long water pump finding exact measurements on the interwebs based on your install is almost impossible especially if you’ve moved around components like alternators and air conditioner compressors. Next, add in an aftermarket Pully system like Concept One or March Performance and you have all the symptoms for cranium ache. Here’s a starting point I used – PSP bracket 2-9/16”; water pump 3.6” long. I started out by not bottoming out the new press on pully. After first engine run it was apparent it wasn’t in far enough. I removed the PSP and next, I bottomed the pully on the shaft. After install it was clearly in too far necessitating spacers. I had tried to TLAR (that looks about right) it but failed. You have a few options. Continue to mess with moving the pully on the shaft or start working shims on the PSP pump and water pump mounts – the preferred method. I went the preferred route. As for the shims, I used different width washers for a 3/16” spacer width I measured via a straight edge. The PSP mount bolt (bracket bolt just below the two long water pump bolts) was only 3” long. Once I added the spacers the 3” bolt was too short. I got a 18-8 Stainless Steel Socket Head Screw to match the other bolts but got one longer -- 3/8"-16 Thread Size, 3-1/2". That bolt I cut down to 3-3/8” so I had a few threads poking through the mount but not touching the block. A hex head bolt would not work as the PSP pully circumference is right at the mounting hole. Get ready to install, tighten the serpentine belt, verify alignment and adjust shims accordingly. My idler pully also needed a shim. Yes, I pushed in the bearing to be flush but the belt was still riding on the idler pully flange. I added a shim between the mount and idler pulley so I could ensure a slight gap and make sure it wasn’t riding on the flange but had a 1/16” gap. Be patient. Once you get it right there will be no noise. When it’s wrong you’ll hear a clicking sound typically. Watch for rubber deposits. That will also tell you things are not aligned correctly too. Here's a good pic of the shims (washers). You can't see the ones on the PSP bracket under the bottom water pump bolt.
- PSP -AN 10 return fitting on the remote fill reservoir. As you can readily see from the picture above a female -AN 10 flare will need to be attached. In my case a straight fitting to hose was impossible as there would be zero drop from the PSC reservoir tank. Nor would a 30 or 45 degree bend work. A short 90-degree fitting would have to do as the -AN 10 stainless steel return line will be short, as direct as possible, and it had to be elevated as mentioned in para 4.
- March Pully AC Bracket. The thick aluminum AC bracket was in the way of the return line (PSC reservoir to PSP) so I had to remove some meat on the bracket for the hose to pass through (see pic abvove--guess i could have polished it up a bit). Next, I had to find a short 90 degree -AN 10 fitting for the top of the PSP. After that was done, I measured the distance and fabricated the stainless-steel return line with -AN 10 hose fittings on both ends (other end attaches to reservoir pic above). If I ever have to go to a rigid tube instead of the SS flex line, I could easily make that work too.
- Leak test and Bleed Procedure. After everything was all hooked up and tightened it was time to fill the PSC reservoir. I used PSC Swepco 715 Power Steering Fluid as it has an anti-foam additive. Since the system had been “opened up” I started the entire bleed procedure (front end was still on jacks). As the reservoir tank decreased, I’d fill the PSC reservoir to maintain the level just above the filter. Bottom Line: Follow your own hydro boost manufactures bleeding procedures.
- Finally, it was time to crank er’ up and finish the bleed procedure. I purposely left the cover/lid off the PSC reservoir to witness the flow of fluid. WOW! There was plenty of fluid flowing and before long there was no trace of any bubbles. The tank level stayed constant. There was no pump “whining” when turning the wheel. Next, after everything was double checked and no leaks were observed it was time for a short road test. That went off uneventful as well. And, I could throw the wheel totally to one side and apply brakes and still there was no noise from the pump. Win Win.
- My setup will easily handle an autocross setup.
- Make sure you plug the vacuum line from the manifold that was used to for the original power booster setup.
- Get a new PSP that will accommodate your design. Don’t rely on two lines returning to one line the same size (regardless of a “Y”). Get a pump that will accept a larger return – you need volume back to the pump so it can generate pressure or, modify your existing pump reservoir case like the PSC one above. If you don’t, I guarantee you will get cavitation as the fluid turns to vapor at low pressure which causes air bubbles to permeate your closed system rendering your hydro boost ineffective. Bottom line here and my recommendation – buy a new PSP with the fittings/connections you need. In my case a new pump (with the right connections/fittings) right off the bat would probably have eliminated many issues I had to deal with later (volume, pressure, pump whine, inevitable cavitation and of course, “sparklies”).
- If using a reservoir, use a -AN 10 or -AN 12-return hose to the PSP pump. Look at it this way, if you have two -AN 6 return lines with a nominal OD tube size of .375 you need to at least double the size of the line (.750) going back to the PSP for superior performance. In my case the -AN 10 of .625 has been working fine but I have a large reservoir that can easily keep up.
- If you plan on doing autocross, you’ll definitely need a setup like mine – plenty of volume, pressure and flow.
- If using a reservoir, install it above the PSP and definitely above the fluid “return” point of the PSP. PSC has a great .pdf out there showing the desired mounting options to ensure your system works. That article has limitations you don’t want to exceed.
- Spend the time on the Master Cylinder to marry everything up correctly and bleed according to directions. I took my time “bench bleeding” it and it made the rest of the install – proportional valve, brake lines and pedal go easy.
- Do give up! I walked away from my install in what was supposed to be a temporary timeout for research when I hit a wall with it 4 years ago and then “life” got in the way. About a year ago I had to move the car in the garage. When I fired up the beast, I could hear the pump whine. Popping the hood, it was an immediate epiphany…the gravity fed return line was restricted and was lower than the pump—two major show stoppers.
I’ve read more posts across the inter-webs of issues folks have had after installing hydro boost setups vs seamless uneventful installs. As with any modification, there’s a ton of variables that inevitably raise their ugly craniums; and each setup seems to have its own character and head ache. Don’t be afraid to try something different. One thing that I might have to work in the future is a fluid cooler on the two -AN 6 return lines (steering and hydro stop return lines) or the -AN 10 line between the PSC reservoir and PSP….I’m actually really amazed at how warm the fluid gets after a real hard workout. Hope this helps!
