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Old 12-29-2012, 08:57 PM   #1
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Hydra-boost brake install issues in C3 vette

I installed a hydra-boost brake booster in my car a while back and have had issues with it since the install. I get a good bit of groaning form the pump and the booster gets hot, Ive tried a few things to resolve it.

Ive done a good bit of research on the internet and actually stumbled across a tech write up by who I believe is someone from Hydra-tech brake systems. He described a couple issues in detail that Im experiencing, groaning and push back on the brake peddle when depressed and heat buildup in the booster.

He explains that to much pressure on the return hose will cause the booster to build a lot of heat and will cause a slow peddle return once depressed.

He recommended staying with the 2.0 to 2.4 gpm from the pump as GM did.

He recommends -6 AN (3/8) lines for the supply and return lines and (minimum) for the line from the remote reservoir to the pump and that if anything smaller was used for the line between the pump and reservoir the pump will cavitate and always run noisy.

I decided since I had my system apart due to line rupture I would try and address as many of his recommendations as I could.

I took my remote reservoir apart and took a close look at all the fittings and lines. The outlet of the reservoir is a 3/8 NPT to -10 AN fitting, first issue. The 3/8 NPT fitting is too small for the supply to the pump per his recommendations of no smaller than . Ive checked and have room to drill and tap to pipe to gain the recommended size and will install a -10 AN to NPT adapter.



Reservoir Return line fitting size (drill bit inserted into fitting) and the reservoir to pump fitting (-10 AN to 3/8" NPT);



The pump discharge is -6 AN PTFE SS lines with an internal diameter of .293 (a little below the recommended 3/8). The returns form the R&P unit and the Hydra-Boost unit is also -6 AN line and is tied together with a Tee at the reservoir, not exactly what he recommends but close.



Distribution fitting in reservoir;


On the internal of the reservoir is a distribution fitting with an internal diameter of .247 well below the recommended 3/8. I believe this fitting is one of the main causes of the pump groaning, the reason for the heat build up in the booster and the slow return of the brake peddle which is caused by to much pressure in the return line to the reservoir from the booster. To resolve the issues with the return line I plan to remove the OEM distribution fitting and fab my own distribution nozzle for the reservoir. If the restriction was closer to the steering gear and away from the reservoir (Tee) it would not effect the booster operation.



Reservoir Return line fitting size (drill bit inserted into fitting);



He also recommends using a remote reservoir with a separate return for the Hydra-boost to eliminate the issue of to much pressure in the return line along with a reservoir with an internal filter for correct de-gassing of the steering fluid.
Im going to weld a bung on the side of the reservoir or drill and tap a 3/8" NPT hole for a separate fitting in case the new distribution header dont resolve my issues I can move the return from the booster to its own rout.

He explains that the booster is an open center hydraulic device meaning the fluid flows freely to the booster and own to the steering gear until the brakes are applied.

From what I can find on the net the steering gear is also an open center device meaning the fluid form the pump flows through the gear and back to the reservoir without obstruction until the steering wheel is turned and force is applied to the torsion lever in the gear. This being the case than the return line will need to be sized to flow the pump output flow without restriction. So if the fittings at the reservoir cause restriction than there will be pressure on the return line causing issues with the booster. This would support having a dedicated return fitting at the reservoir for the booster.

One other issue he explains is that the reservoir has to be vented at the cap. If the reservoir is allowed to build pressure from thermal expansion enough pressure can build in the return line and cause the brakes to self apply.

I may have to replace the reservoir if I can't work these issues out. The reservoir I have came with the Zoops serpentine drive unit I have on my engine.

Anyone else have this type of issues with their Hydra-boost install?

Neal

Last edited by 496BBC; 01-02-2013 at 09:14 PM.
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Old 12-29-2012, 09:15 PM   #2
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I use a GM pump and have two return line to the on pump reservoir. I have had no trouble with the system. All lines are 3/8".
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Old 12-29-2012, 09:24 PM   #3
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I need to include that I run a serpentine set up form Zoops an it came with the small GM pump as used in newer cars with a remote reservoir.

This system will work it just has to be set up right,

Neal
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Old 12-29-2012, 09:26 PM   #4
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Quote:
Originally Posted by iburke View Post
I use a GM pump and have two return line to the on pump reservoir. I have had no trouble with the system. All lines are 3/8".
You more than likely have the ideal set up for the addition of the Hydra-boost to the vette.

Neal
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Old 12-29-2012, 10:40 PM   #5
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Does your booster get hot as well? In the big aeroplane world, a hydraulic actuator that gets hot has an internal leak. But we're playing with 3000 PSI too.
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Old 12-30-2012, 03:40 AM   #6
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Quote:
Originally Posted by TimAT View Post
Does your booster get hot as well? In the big aeroplane world, a hydraulic actuator that gets hot has an internal leak. But we're playing with 3000 PSI too.
Yep, it does get hot but its really hard to tell if its heat from the engine and headers or generated from within.

Neal
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Old 12-30-2012, 08:03 PM   #7
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I had more time tonight to look at a few more things with my steering system.

I pulled the fitting out of the pump inlet to see what the internal diam of this fitting was. Turns out they used a fitting with a reduced internal diam of .390as seen below (fitting to the far left).



The below pic is of the fittings used in the plumbing between the reservoir and the pump inlet. Ill be drilling and tapping the outlet of the reservoir (middle) from 3/8 NPT to 1/2 NPT to achieve the required .



The pic below is of the reduced internal diam in the current fitting (-10AN to 3/8 NPT) at the outlet of the reservoir (see the shoulder).



The internal passage of the pump at the inlet is also reduced in size .383, not much I can do here until I see if the upgrades will resolve my pump issues. If I still have issues Ill remove the pump and port the inlet to increase the port size. The reduced inlet can be seen in the pic below. I had to use a mirror to get the pic so its a little hard to see.




The pump is a GM Type II pump with remote reservoir used on a number of OEM cars today; Zoops fits it to their serpentine setup. Ill be pulling the outlet flow orifice to check the size per the tech article. It should be in the .125 area to supply the required 2.0 to 2.4 gpm flow.


Neal
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Old 12-30-2012, 10:41 PM   #8
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The guy you thought was from Hydra-tech was pretty much right on.
Zoops, apparently might do some nice machining, but know squat about hydraulics. Your biggest problems were from restricted flow causing lots of extra heat eventually causing pump failure.

If you use less 1/2" from the reservoir to the pump, you will get the problems you're having. Bigger is always better, as the return hose can double as a reservoir too.
Most times when changes are made from tube to jic/an there will always be a restriction. Nothing wrong with a nice clamped, non pressure hose.
As an example, my wifes car, without hydraboost uses 1" or 1-1/4 suction hose.

The hydra boost and steering gear used 3/8" tubing/hose for the returns to the reservoir and that should still be used.

You can't compare the size of the suction ports of a P pump (type1) to your pump. That pump sucks from an internal reservoir, yours doesn't.

Run each return, from hydrabooster and from steering gear into separate ports on the reservoir, making sure that the port/fittings don't restrict the id. then return to the pump out the bottom, vented on top. Big a can as you can fit.
All your problems will be solved.

Here is a pic of the proper inlet tube for a Type2 pump. 1/2" ID.


Forgot to mention, you can't mix closed and open center hydraulic components, if one is open center, they all are, and this is open center.
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Old 12-31-2012, 08:41 AM   #9
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010752; thanks for your input

Hopefully I can get a true 1/2" on the whole supply line from the reservoir to the pump or at least that's my goal.

I'm still a little concerned about the return fittings with the ID a little smaller than the full 3/8" ID but we'll see how they work.

The return lines are I think one of my main issues with the system the way the peddle kicks back it has to be restricted or pressured up for this to happen.

We'll see when I get everything worked out,

I need to find an aluminum coupling so I can weld it to my reservoir for the return form the Hydra-boost.

Neal
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4:10 rear
2002 Z06 wheels
Dewitt's Radiator and Spal fans
Holley 1000 cfm HP series carb
Tuned with Innovate LM-1
Old 12-31-2012, 12:03 PM   #10
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Quote:
Originally Posted by 496BBC View Post
010752; thanks for your input

Hopefully I can get a true 1/2" on the whole supply line from the reservoir to the pump or at least that's my goal.

I'm still a little concerned about the return fittings with the ID a little smaller than the full 3/8" ID but we'll see how they work.

The return lines are I think one of my main issues with the system the way the peddle kicks back it has to be restricted or pressured up for this to happen.

We'll see when I get everything worked out,

I need to find an aluminum coupling so I can weld it to my reservoir for the return form the Hydra-boost.

Neal
Most people get hung up on the pretty an fittings and those adapters as you have found are where the restrictions usually are because those ports were originally not designed for proper an/jic adapters.

Your hydraboost should be either sae inverted flare or metric bubble. To maintain the largest opening, it's best to stay with the factory fittings, good hydraulic supplies or even some NAPA stores can crimp those tubes ends even with ss braided hose. You can still use an/jic on the other end at the reservoir. The 37 flare end is commonly hose id size, so an easy way to make your ports at the reservoir is to just cut the adapter part off and tig the flare side to the tank wihout any restricting bungs and adapters.
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Old 12-31-2012, 01:03 PM   #11
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Had not thought of cutting the AN adapter and welding that to the reservoir, thanks

I'm guessing you just buff the anodized coating off, I haven't dealt with this coating before and am not familiar with the process, is it just a surface coating?

The fittings at the booster itself are adapters to convert form the OEM port to AN style hoses. I'll pull them out and check them also (didn't think of even checking them, glad you mentioned them).

Yea at the time I plumbed all the circuits I really thought the SS hose would be more durable than the rubber. I've had more ruptures from the SS hose rubbing on something and cutting the SS braid and than the PTFE liner ruptures (PTFE hose was used on the high pressure side).

I think from this point on I may start replacing the hoses with hoses made at the local Hydraulic shop with the OEM fittings.

The AN fittings and SS hose do look sharp though.

thanks

Neal
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4:10 rear
2002 Z06 wheels
Dewitt's Radiator and Spal fans
Holley 1000 cfm HP series carb
Tuned with Innovate LM-1
Old 12-31-2012, 07:37 PM   #12
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Here are some stainless fittings you can polish. They take all kinds of hoses up to 3000psi which is twice what is needed.
http://www.hoseandfittingsetc.com/pr...ittings/#12843
I'm sure you can get these in stainless too. Search the site.
For hoses, links at top
http://www.hoseandfittingsetc.com/pr...ttings/43-ser/
If you looking for abrasion protection, look for hose armor
http://www.discounthydraulichose.com...ction_s/81.htm
Probably find it in ss wire too.

Anodized coating is a very thin, very very hard coating put on like plating. It must be removed to weld. Use oven cleaner, drain cleaner or lye (alkaline) or just grind/buff. If you want pretty, once all done and tested, you could get the whole tank anodized whatever color, not that expensive.

Your past hose problems probably were heat and pressure related as much as abrasion. In hydraulics, you have what are called spike pressures, only occur for split seconds, too fast for almost all normal gauges to show, but these can easily go to 10,000psi and slowly degrade the hose and crimps. The extra heat created by too restrictive a circuit just promotes hose and pump failure.

Don't forget that oem plumbed properly, GM just used simple fabric braid pressure hose rated at about 1800psi. I've got an old truck with original hydraboost/steering hoses that are 30 years old.
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Old 01-01-2013, 10:24 AM   #13
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Well Ive decided to go ahead and plumb the booster return to its own fitting. I was going to keep the returns from the steering gear and the booster together to see if that was an issue before I move it to its own fitting on the reservoir for verification but don't want to remove the steering fluid just to move it if it don't work out.

I built the new distribution header for the reservoir and bored the pump inlet fitting to a full .500 internal diarm.



The pump and fittings;



The new distribution header installed in the reservoir



Im waiting on the new hose ends for the line between the reservoir and pump to come in so I can finish plumbing that side of the system.

Im still trying to decide if I want to weld the new fitting for the booster return onto the reservoir or it I want to drill and tap a hole for the fitting.

I dont have the drill bit for the NPT tap or the drill bit for the 3/8 NPT tap so Ill need to locate and purchase them to finish.

Everyone is closed for New Years today so itll be tomorrow before I can proceed,

010752; Thanks for the links, I've purchased form discounthydraulichose a few times already.

Neal
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GM 454 stroked to 496
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Lunati solid roller 260* .701 lift
4:10 rear
2002 Z06 wheels
Dewitt's Radiator and Spal fans
Holley 1000 cfm HP series carb
Tuned with Innovate LM-1
Old 01-05-2013, 05:22 PM   #14
496BBC
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Not much to update on here,

Been waiting on Summit to send new -10 AN fittings, when they did arrive they were two different colors so I sent them back.

Ill purchase a hose from a different vendor and install it when it arrives.

The below pic is of the new dedicated return fitting for the hydra-boost installed in the reservoir.



Neal
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77 vette
GM 454 stroked to 496
10: to 1 comp
Lunati solid roller 260* .701 lift
4:10 rear
2002 Z06 wheels
Dewitt's Radiator and Spal fans
Holley 1000 cfm HP series carb
Tuned with Innovate LM-1
Old 01-05-2013, 11:44 PM   #15
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I'll be very interested in hearing the outcome. I ended up removing my Hydroboost and replacing it with a stock vacuum booster because the unit would heat up and self apply the brakes. I did improve on the return line flow restrictions but never set up a remote reservoire and certainly dint have a dedicated return line.
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