Hydroboost followup questions

[earl84]

I have successfully installed a HB out of a 2004 Chevrolet 3/4 ton truck in my '66 C20. The brakes work great, but I am having a few issues and have some questions.
The first and biggest issue is that the brake pedal is slow to return to the rest position, and I wonder if this slowness is causing what is really my larger issue, which is intermittent brake drag. Doesn't happen all the time, but it does happen. When I did the install, I put in a 90 degree fitting on the return side that I drilled out the orifice to be the same size as the stock straight fitting. Flow may be restricted there, but companies like Hydratech sell the same fitting, and apparently don't have issues. I run my return lines from the HB and the PS gearbox to a T fitting, and they are plumbed correctly, but there may be some restriction there as well.
Has anyone else experienced this? Could my HB unit require a rebuild? I can't remember the name of an internal part that I have read that may be a cause for the slow pedal return.
My second issue is that the steering is overly sensitive. It's freakin' awesome at slow speeds, but at highway speed I really have to be on my game, it is ultrasensitive. I think this valve http://www.summitracing.com/parts/hdt-ps-101 might help in this area, does anyone have experience with this?
Also, does anyone know if the brake line ports on the 2004 master cylinder are the same 1/2-20 (3/16 line) for the front brakes and 9/16-18 (1/4 line) for the rears? I would like to use the 2004 master to see if that has anything to do with brakes not releasing fully. Currently have a '79 C20 master cylinder mounted.
Oh, I also replaced the combination valve, thinking that may have had something to do with the brake drag, but it had no effect.

[BR3W CITY]

Ahhh yes, the first few days after an HB swap is nerve racking.

Steering sensitivity is an issue caused mostly by the fact that the steering gear your using wasn't designed for the pressures that the more modern HB's put out. People have a few different ways to quell this, from trying orifice restrictions to changing the gear load in the box. IMO the best solution would be to get a flow regulator or an orifice and lower the pressure to the box a little. I haven't completed this part yet either, but I was talking to the guys at Turn One about the adjustable unit they offer.

As for the brake pedal; I had this issue as well. While mine isn't "slow", it sure isn't fast and doesn't like the top 1/2" of travel. Many vehicles used a return-assist spring on the brake pedal to fix versions of this problem. I'll be doing the same to mine this spring. We temporarily hooked a small screen door spring to mine at it actually worked well as a proof of concept.

Are you disc/disc or disc/drum? There is a chance your running a disc/disc master on a disc/drum truck.

[earl84]

Thanks for the reply.
I knew the issue with the steering gearbox, but had to give it a try and see how it worked. That valve you are talking about is more expensive but a little cleaner install and has quite a few less connections, and therefore less areas for leaks. Might have to try that instead. Here's the valve you are speaking of, right? http://turnone-steering.3dcartstores...alve_p_33.html
The brake pedal has the stock spring on it, but I don't think a weak spring is the problem. Probably couldn't hurt to throw a stronger sprin on it while I fine tune and troubleshoot this, though. It's being held back due to a restriction or something. Ive done some research and culprits can be air in the system, foaming due to the type of fluid used, or an internal thing in the HB that I still can't recall the name of.
I am running disc/drum, and am sure I have the correct master for that setup.
Anyone have experience with either of the two variable valves or slow edal return, or know the size of the fittings on the 04 HB master?

[Captainfab]

Something I think would be worth trying as it may be causing the issues. Try eliminating the tee in the return line and run 2 return lines directly to the reservoir. That is how GM ran them in 99% of the vehicles with hydroboost.

[BR3W CITY]

FWIW mine is setup like Cap says, but I still have the light steering.

Yes Earl, thats the unit I'm talking about. I was going to talk to one of their techs to see if there was a cheaper static-pressure option for us, but haven't had a chance to yet. I actually rebuilt my unit internally, and I have pictures of what I did in my build. i"m not sure which internal part would cause any issues though, aside from the actual internal valving, there isn't much to them.

When we did my swap, I went from manual brakes and didn't have a return spring at all! Does your feel like it generates a lot of heat (mine does). If you apply the brakes and move the steering wheel around, the charge lines to the PS pump get HOT.

[earl84]

Thanks for the replies, guys. Captain, I think I might get the PS pump with 2 return lines, as I have read in various places that this fixed other peoples slow brake return issue.
BR3W City, I saw your HB rebuild, and that's actually what made me think of the rebuild kit. You do some really nice work, BTW, love your truck. I have never felt the lines so I don't really know if they are getting hot or not. I bought a PS cooler to install, but ran out of time before I moved from TX to CO, so it is sitting in a storage unit now.
I looked in the factory service manual I have for a '79 with HB, and it show the following for slow pedal return troubleshooting:
1. Excessive seal friction booster (Fix: Overhaul with new seal kit) 2. Faulty spool action (Fix: FLush steering system while pumping brake pedal) 3. Restirction in return line from booster to pump reservoir (Fix: Replace line) 4. Damaged input rod end (Fix: Replace input rod and piston assembly)

I think my plan of action will be to 1. Put back on the factory HB return line fitting. I installed a 90 degree fitting that I drilled out, and I sort o thought that orifice was too small, even though I drilled it out to the same as the factory fitting. I also think it is too tight of a bend and maybe a more gradual bend will do the trick. If that works, I can take my time with the rest of this, since my truck really works fine, except foe the slow pedal return, and it's ugly cousin, the dragging brakes. Following that experiment, 2. Install a PS Pump with 2 return lines. 3. At the same time, since I am getting into more work, install the PS variable pressure valve. 4. Put all new -6 AN fittings and lines on. Since the truck is basically working fine, I can do these clean up and make it pretty things, and I have always wanted to try my hand at making these lines. It will come in handy for later planned projects. This is my daily driver for now, so I have to keep the major projects to a minimum.
Still wondering if anyone knows the sizes for the '04 HB master cylinder ports for the front and rear brake lines, or has any experience with the PS Variable pressure valves.

[Captainfab]

I don't know the size of the ports on the '04 master cylinder, but they will be Metric.

[earl84]

Followup to the followup.
I talked with Turn-one steering, and the tech said their variable valve was more for guys that go to the track, then drive on the street, and probably would not be enough of a difference to fix the sensitivity problem. He suggested I order this: http://turnone-steering.3dcartstores...ting_p_29.html, so I did, and I installed it, as well as a two return port PS pump, and drilled out the 90 degree return fitting as large as I felt comfortable doing, from the HB to the PS pump. I apparently threw out the HB fitting. Oops.
Here's my results. The brake pedal is still slow to return, and the brakes still drag intermittently. The steering sensitivity is right where I want it now on the highway, but it has apparently brought to light another problem. When I first start the truck, it feels like I have manual steering, then when it gets warm and I cycle the steering a little bit (only a couple minutes) it acts like normal power steering. I thought maybe it was air in the system and would eventually work its way out, but so far no luck. I called Turn-one steering and talked to the tech about it. Super smart and very helpful guy, BTW. He said it sounds like my PS gearbox may have what they call "Morning sickness." Never heard of it. Apparently, as PS gearboxes age, internally the seals can shrink and/or the internal gears can wear out, and the fluid will essentially blowby and no pressure is built up to provide power steering. This is remedied as things warm up. The only fix appears to be live with it or replace the PS gearbox.
My next move will be to buy a freakin' stock fitting that is straight out and see if that fixes the slow pedal, and to rebuild the HB unit itself, like BR3Wcity did. I will also order a nice clean master cylinder and reservoir for a 2004 3/4 ton Silverado, maybe my slow return brake pedal and dragging brakes is due to the '79 C20 master cylinder being bad. I am fine with the way the HB works, great braking action, and the steering sensitivity, but I need my brakes to stop dragging.
Incidentally, when I spoke with the Turn-one tech, the flow restrictor fitting reduces the flow rate, not the pressure, so the HB brakes are not affected. The PS gearbox cares about flow rate, not pressure, so it works well with the reduced flow. My old physics brain says that if you reduce the flow, then the pressure should go up because the pump is still pumping the same amount of fluid at the same rate, right? So the pressure has to increase. Well, the flow restrictor basically is in the bypass position on the pump and so the excess fluid recirculates back into the PS Pump, and the pressure is not affected. I explain that poorly, but there are guys all over the Internet that use different shims to increase the pressure on the bypass spring to do similar things. I'll let you investigate that on your own to understand. I understand it enough to know it works for me.
I wish I had a pen and paper when talking with the tech, because he told me the flow rates and pressures of all of my particular PS pumps, and PS gearbox, but I didn't. I do remember that he said the above fitting that I posted the link to started at .093 inches. I don't know what my stock 2004 3/4 ton Silverado PS pump was, but a 9/64 drill bit fit very snugly in it.
Oh, and the fittings on the 2004 3/4 ton master cylinder are 1/2-20 flare fittings, which shocked me.
Sorry for the long-winded post, maybe some tidbits will help someone else. One too many beverages tonight, haha.
On a side note, I fabbed up some front shock relocators, cut off the front bump stops, and replaced all 4 50 year old shocks with KYB shocks from Carquest. Big difference.

[BigDan3131]

It seems like -6 lines are kind of small on the return side as less restriction equals great flow. I would have at least gone with a -8 for the return. I haven't seen anything in your posts about pedal location and rod length. Was the rod into the HB pushing it in slightly? Did you have more than one hole to install the rod in on the pedal?

[earl84]

I didn't use -6 line, used regular 3/8 rubber line, but -6 is used widely by almost every company that has anything to do with HB. Pis rod was double, triple and quadruple checked, and for grins I stacked a couple spacers between HB and master cylinder that made it impossible to be the problem. I had to push the pedal almost to the floor for brakes to engage. Pedal effort was never my problem, and it had power brakes before, so the other hole to increase pedal ratio is not the issue.

[66farmer]

I put HB on my truck and it worked great you can check it out on my thread.
I used 1978 master, steering box, steering pump W/two return lines the HB is off 95 astro van. The only mod I did was add a .060 spacer between master and HB. The only other thing I can add you have to get the air out before it fells right.

[earl84]

Thanks for all the replies, gents. I am away from my truck for two weeks, but will report back when I am able to execute my new plan of attack.
66farmer, I have driven over 1000 miles with the current setup. The air should be out by now.

[Modges'66]

So, you had (vacuum) power brakes before, and they worked great, and you had (fluid) power steering before, and it worked great, correct?
Now you are running your steering and brakes on the same (fluid) pump and they don't work that great together....
Is it possible that the pump is weak?...just sayin, I would think that the pump may not be able to supply the volume needed for both...I don't know how old it is.

[earl84]

Originally Posted by Modges'66

So, you had (vacuum) power brakes before, and they worked great, and you had (fluid) power steering before, and it worked great, correct?
Now you are running your steering and brakes on the same (fluid) pump and they don't work that great together....
Is it possible that the pump is weak?...just sayin, I would think that the pump may not be able to supply the volume needed for both...I don't know how old it is.

No, when I had the vaccuum booster, the brake pedal was extremely hard. I think the vacuum was 14 pounds, marginal at best. The brakes and power steering are great right now. The remaining issues are a slow to return brake pedal and intermitent dragging brakes.
I replaced the old PS pump that only had a single return so I could get rid of the T fitting on the return side from the HB and the PS gearbox, thinking it might be a source of restriction causing the slow brake pedal return and possible intermittent brake drag. It did not fix the issues. I also drilled out the 90 degree fitting on the HB return line that went to that T fitting. It did not fix either problem, either.
BTW, your truck build is amazing, very nice.

[Modges'66]

Sorry, I must have missed the part about replacing the pump!
Just trying to "stir the pot" and think outside the box.
I have an astro that I drive as a daily, and the hydro-boost works excellent.
I have also had a brand-new Buick Grand National that had hydro-boost that worked awesome.
Both vehicles you can notice when doing hard braking & hard cornering at the same time...You can feel it in the wheel, which made me think of the pump....
BTW, thanks for the comment!

[BR3W CITY]

Originally Posted by Modges'66

Both vehicles you can notice when doing hard braking & hard cornering at the same time...You can feel it in the wheel, which made me think of the pump....
BTW, thanks for the comment!

My '66 does this too. If your hard on the brakes on an off ramp, you can feel the steering get a bit heavy.

[BigDan3131]

Last questions, do you have both a 2lb and 10lb inline residual pressure valves installed? For some reason on a few of the vehicles we have done swaps on there was always some issue like yours. The valves made a huge difference. What are you using for fluid? ATF or actual power steering fluid?

[BR3W CITY]

Dan, where would that be? I didn't remove/add anything when doing my swap, just rebuilt it with a kit and put it into my truck like that.

[earl84]

Originally Posted by BigDan3131

Last questions, do you have both a 2lb and 10lb inline residual pressure valves installed? For some reason on a few of the vehicles we have done swaps on there was always some issue like yours. The valves made a huge difference. What are you using for fluid? ATF or actual power steering fluid?

I don't have residual valves installed. From my understanding, they are used in applications where the master cylinder is mounted down lower than the lines and allows fluid to drain back into the master cylinder, or something like that. I am using synthetic PS fluid.

[BigDan3131]

Even though they say to put those valves in when its low mounted we talked directly with the techs from Wilwood and in cases where the brakes seemed to drag putting in those valves helped. On the two brake swaps on 57 fords we put them in after the proportioning valves. Lately on the Chevy's we have been using the master cyl from cpp with the built it proportioning valve.

Link: http://www.classicperform.com/NewPro...V-1/MCPV-1.htm

Its so simple to adjust, you just use a allen wrench.

[earl84]

Originally Posted by BigDan3131

Even though they say to put those valves in when its low mounted we talked directly with the techs from Wilwood and in cases where the brakes seemed to drag putting in those valves helped. On the two brake swaps on 57 fords we put them in after the proportioning valves. Lately on the Chevy's we have been using the master cyl from cpp with the built it proportioning valve.

Link: http://www.classicperform.com/NewPro...V-1/MCPV-1.htm

Its so simple to adjust, you just use a allen wrench.

Hmm, interesting. I wonder why the residual valves help..... I'm guessing that with that master cylinder, I would not use my combination valve that is currently installed, correct?
Any idea if it comes non-chrome. I took a brief look, but the CPP website isn't very user friendly.

[yossarian19]

I am not sure but I think most dual piston master cylinders have residual valves built into them. I can say for sure I've never seen one on an OEM application, though I've mostly worked on mid-80s and newer stuff.

[BR3W CITY]

I"m using the 97 master from an Astro (same place I got the HB unit from). I'm combining that with a 2006 HB pump. I also got the high-mount resevoir as well, but I was under the impression I didn't need to use it since the 2006 pump has the resevoir.

I'll need to look at those valves. Are they universal? I've never seen them in when browsing Jegs.

[BR3W CITY]

I just wanted to bump this up, I'm still curious about those valves.

[earl84]

I'm curious about the answer as well. I am still out of town and won't be doing anything for another week at least, and when I do, I will save the residual valves until later, but I really appreciate the replies.