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Old 11-11-2014, 04:09 PM
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Default Hydraboost install & review

I bought the kit from Hydratech. I decided that for the price it was the best way to go rather than try to piece it all together. I also have their knowledge & support if there are any problems.

As an aside, the Hydraboost unit weighs twice as much as the vacuum canister--15 lbs for the HB and 8 lbs for the vac booster.

Installation was pretty easy. For all the horror stories of changing out the booster, it wasn't that hard at all. No need to remove the steering column. I used a 1/2" drive socket which was deeper than a regular 3/8" drive socket but only about half the length of a deep 3/8 drive socket. A full deep socket would have been much harder to fit in there. Socket, u-joint, 1/2 to 3/8 drive adapter, 18" of extensions, all duct taped together. No problem. As far as problematic bolts on a C3, I give this one a 3 out of 10, mainly for the working position.

Removed the steering column bottom trim piece, headlight override vacuum switch & the heater duct. And the seat of course. It really wasn't that hard, quite simple and straightforward actually. The brake clevis pin came out and went back in easily too. Some prying & fiddling with a screwdriver & long needlenose pliers. Have patience. The only real pisser was when the door swung shut and latched while I was wedged under there. I had to do some real contortions to open it to get out. A bungee cord from the mirror to the fender fixed that problem.

In the engine bay I had to dremmel the fiberglass where the mount holes were mismatched between the firewall and the interior mount plate. I had to pry the old booster off and the new one didn't want to go back in. Took longer for the air compressor to build pressure than to clearance the holes. The Hydraboost did not come with a firewall gasket, I was going to smear a little silicone around it but when I got it test fitted I bolted it up and forgot. Oh well.

The new HB came with a brake pedal clevis & pin. I measured from the back of the vacuum unit to the clevis eye and matched the distance on the HB unit. Cinched the locknut, figuring if it was good it was done, if I needed to adjust I'd deal with it then. It was fine, brake pedal was exactly where it had been. Didn't need to readjust the brake light switch or anything. The HB clevis pin used a cotter pin rather than a snap washer into a groove, so I used the cotter pin one because it was a lot easier to put that in than replacing the snap washer on the OEM clevis pin.

Replacing the booster only took a couple hours actual working time.

Routing the hydraulic lines took the most time. I got the kit with the pre-cut & fabbed lines. The high pressure feed from the pump to the HB cylinder was no problem, but the high pressure return from the cylinder to the steering control valve I just could not get routed to my satisfaction. I spent several hours going through every possible way I could think of. My main concern was that the stiff braided line was one piece from the HB unit to the steering control valve and it moved back and forth with the tie rod, rubbing on the block, brackets, other lines, etc. all the way up into the engine bay.

I finally decided to go to a hydraulic hose & fitting shop and have a piece made up from the OEM high pressure pump to control valve line utilizing a flexible rubber U-bend to take the movement of the tie rod while securing the braided line at the pump. Just like the OEM line but with a 90* AN fitting to adapt to the braided HB line. (See photos a couple posts down.)

After that it was just bleeding the lines. My only screw up there was I forgot to tighten one fitting underneath and when I did I was loosening it instead and got a pint of PS fluid down my arm into my armpit. Oops.

Two things I still need to sort out: Pedal return is slow, which means restriction in the low pressure return line. I may have to get a new pump with a dedicated return for the HB. That brings me to ask: Does anyone have a part number or ID for an equivalent pressure pump to fit? I haven't yet looked into it.

More importantly, when I stomp hard on it, the pedal goes way down, then the cylinder (not the belts!) has a momentary high pitched groan and it starts pushing back. Pushing the pedal "firmly", it feels fine.

I haven't road tested it yet. I want to get these two things sorted out first. I have a call into Hydratech but they may have the day off since it's Veterans Day. I do too. Plus, it's winter here now. Yesterday morning at 8:30, it was 64* and sunny blue skies. By 11:00 it was 35* and dark overcast. By noon it was snowing. This morning it is 17* with snow still drifting down. No road test to try out new brakes this week!

Edit: 2 hours later--Jim from Hydratech just returned my call. He says the symptoms I have are normal for a new installation. They are from microbubbles in the fluid and I need to do is drive the car for 25-30 miles at a time for a couple hundred miles, carefully, and it will all sort out. All I need is some better weather now.....

I will post more as things develop.
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Last edited by JPhil; 12-07-2014 at 09:55 PM..
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Old 11-11-2014, 05:56 PM
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I have an '88-91 Serp drive setup, and so the fluid tank mounted on the frame under the master cylinder to save complicated crap due to other things....I have a 3/8 T in the return to that plastic tank....and bubbles in the fluid have not been an issue....I am most curious to hear if your pedal travel is a whole lot less like mine is.....and Like I say, I can lock em up so easy....

but there are other mods to my foot well, surely I have told of them.....

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Last edited by mrvette; 11-12-2014 at 01:27 PM..
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Old 11-12-2014, 04:16 AM
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I have the F-body serp setup, which puts everything where it was in the C3. After fiddling with the low pressure return system, I finally gave up and got a rebuilt P/S pump (needed one anyway, the old one wasn't healthy), and when I ordered the new one, I made sure the reservoir was the two-inlet type.

The groaning and slow pedal return indicate, in my experience, that the system hasn't fully bled out yet. Give it some time, it takes a while to get all of the air out of there.
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Old 11-12-2014, 01:29 PM
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Quote:
Originally Posted by Sam Cogley View Post
I have the F-body serp setup, which puts everything where it was in the C3. After fiddling with the low pressure return system, I finally gave up and got a rebuilt P/S pump (needed one anyway, the old one wasn't healthy), and when I ordered the new one, I made sure the reservoir was the two-inlet type.

The groaning and slow pedal return indicate, in my experience, that the system hasn't fully bled out yet. Give it some time, it takes a while to get all of the air out of there.
All I have ever done is turn the wheels back and forth lock to lock several times, and step on the brakes a few times, leave over night...same in morning, done.....

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Old 11-14-2014, 01:44 PM
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Here is the line I had fabbed up for the high pressure from the HB cylinder back to the steering control valve. I had them use the steel end and make a new flexible rubber piece for the "u" bend with an AN fitting to attach to the Hydratech braided line.





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Old 11-22-2014, 02:01 AM
68/70Vette 68/70Vette is offline
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There were GM vehicles sold with the hydrobeast brake system. One of the problems with hydrobeast (hydroboost) is that the low pressure return line cannot have any backpressure. Saginaw power brake cars that were equipped with the hydroboost, had a power steering pressure pump with a dedicated low pressure input (return flow)...the specialized low pressure return line had been laboratory tested such that the return hydraulic flow would not have any backpressure. I have one of these PS pumps in my garage. I've already posted the part number to a vettemod'r.

The hydroboost that I bought just shows a T junction for returning low pressure hydraulic hydroboost output with the low pressure hydraulic from the PS hydraulic ram. I've read to not do this. Return the low pressure output from the hydraulic ram to the stock PS input. Return the low pressure output from the hydroboost to a to a low pressure input for a PS pump explicitedly designed for the hydrobost
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Old 11-22-2014, 02:38 AM
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Tomorrow (Saturday) I will take it out for its first test drive. The roads have been icy & snowpacked for two weeks up till just a couple days ago, beginning literally 1/2 hour before I got it road ready. I'm not expecting it to be perfect tomorrow but I want to get an idea of how it feels.

Then Sunday it gets pulled in to get ready for pulling the engine for a rebuild.

So it will be next spring before I can give it extensive road testing. But perhaps while I have it apart I should just go ahead and get a new PS pump. That's the only remaining part of the whole steering system that's still original.

Last edited by JPhil; 11-23-2014 at 05:02 AM..
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Old 11-22-2014, 02:01 PM
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Quote:
Originally Posted by 68/70Vette View Post
There were GM vehicles sold with the hydrobeast brake system. One of the problems with hydrobeast (hydroboost) is that the low pressure return line cannot have any backpressure. Saginaw power brake cars that were equipped with the hydroboost, had a power steering pressure pump with a dedicated low pressure input (return flow)...the specialized low pressure return line had been laboratory tested such that the return hydraulic flow would not have any backpressure. I have one of these PS pumps in my garage. I've already posted the part number to a vettemod'r.

The hydroboost that I bought just shows a T junction for returning low pressure hydraulic hydroboost output with the low pressure hydraulic from the PS hydraulic ram. I've read to not do this. Return the low pressure output from the hydraulic ram to the stock PS input. Return the low pressure output from the hydroboost to a to a low pressure input for a PS pump explicitedly designed for the hydrobost
INteresting information, in that on my '72 I have a serp drive and a frame mounted fluid tank, not on the pump itself.....and a 3/8 T fitting for the two hoses, one from rack other from HB....and it works fine....I put on in a motor home project....and same thing, but this time it's of course a more typical p/s pump and box, I put the same T in the return line, and am getting vastly less in assistance.....I wrote it off as a heavy vehicle, never thought much about it.....
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Old 11-22-2014, 06:58 PM
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Default Road Test I

Just back from first road test, it's still tink-tink-tinking as it cools off.

But first, background before this ride: Installed it 2 weeks ago, had it ready for road testing when a cold storm blew in. Let it sit for a week. Checked fluid level then fired it up for a while till engine up to operating temperature last weekend to circulate fluid and hopefully remove any air bubbles, idling and revving, working steering and brake. Pedal feel same as before. Added fluid as needed, perfect level at both 'hot full' and 'cold full'. Let it sit again till today.

This morning before starting it I checked fluid again. Cold all week, ambient temp about 35* F this morning, 40* in garage. Fluid was up above 'hot full' level. Hmm. Hopefully air bubbles coalescing and pushing level up. Nonetheless I sucked some out to about halfway between 'hot full' and 'cold full'.

Took it for a ride, starting carefully around the neighborhood, left and right turns, testing brakes. Gradually expanded my route to longer faster roads, harder braking, ending up on a county highway for a few miles. 1 hour, probably about 20-25 miles.

I would describe the feel of the pedal as 'more concentrated' than the vacuum brakes. Not so much 'stiffer' but the same amount and feel of braking except with less pedal throw. At slower speeds, or rather with light application, perhaps 1/4 of the pedal throw for same braking 'feel'. At higher speeds, moderate application, 1/3 of vacuum throw. Less 'squishy' feeling than the vacuum brakes, and less effort as well as shorter throw. But really, just more like more modern cars brakes feel. Not hard to get used to at all.

First time I stomped on it fairly hard, from about 45 MPH, it slowed quick enough that all the stuff I have in back--jumper cables, tool bag, a box with oil & stuff, fire extinguisher--all came crashing up against the seats. That had never happened before. They had slid but never been thrown. I will have to secure that stuff better now!

Out on a stretch of highway with no traffic around I was able to stomp the pedal from 70 MPH. Oh yeah it slowed damn quick, I could probably have locked the tires if I wanted, but was in no danger of doing so uncontrollably.
I think why it felt so much 'stronger' braking quick at that speed was because the system could apply more pressure to the pads with less effort and pedal movement. But again, completely controllably. However, the pedal did travel much farther than I expected, probably 3/4 of the vacuum travel. But no squeal or groan that I could hear and no 'kickback' like it had done when I stomped on it while parked in the garage.

I still have slow pedal return. I could feel it holding back the car for a few seconds after releasing the brakes at all speeds. But especially so on the highway test where I stomped the brake then stomped the gas.

When I got back I checked the fluid again, it's down toward 'full cold' which was less than when I had left when it was stone cold. I added back what I had sucked out.

I definitely think I still have air in the system, but I'm not surprised. It'll work out. I will now let it sit and cool a couple hours and take it out again, and then again.

Very first impression: I'm pleased!

Last edited by JPhil; 01-04-2015 at 05:51 PM..
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Old 11-22-2014, 11:38 PM
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Excellent! I would never go back to the original vacuum can on my car.
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