Hydroboost brake pedal return issue

[barronj]

I installed HB in my '68 a long time ago, and there's always been this issue with the pedal not coming all the way off, returning back to zero pressure. I can sense it when I take off and after braking and rolling that if I use my foot to lift the pedal, it frees up the brakes. Shrug.

Recently, I decided to throw a spring at it and it fixed it, but the spring was so heavy that applying full brake was a little sketchy- the linear progression of brake wasn't really there, it jumped from 60% to 90% bc of how much pressure was needed to get the brakes all the way applied. I needed a softer spring. I found a much softer one. The benefit of the heavier spring is it wrapped around the pedal assembly and I could hook it to a hole under the dash. This softer spring required some engineering. Enter 3D printer. Proud that I got the design right on the first try!

3D part

Spring install & comparison

https://imgur.com/a/8FXWDaI

 

[ba123]

So I seem to have a similar problem but not quite the same...I think. Not 100% sure because my driving has been the length of my street, once!

But even when not driving, if the engine runs the pedal does not want to come back as quickly. It does come back, but it takes a few seconds. My brake lights stay on (I don't have the stock switch) and that affects a couple other circuits I have for brake off/on control.

Not sure if I'll need to add a spring or not, but time will tell.

 

[Wild horse 75]

In the past I’ve had problems with hydraboost not returning when using a tee in the return line. But I’ve also used tees and y’s without issue. Using a spring to return the pedal is a bandaid fix for the real problem. Make sure your pedal has good bushings and isn’t sticking. And make sure the adjustment is correct on the pushrod.

 

[toddz69]

In the past I’ve had problems with hydraboost not returning when using a tee in the return line. But I’ve also used tees and y’s without issue. Using a spring to return the pedal is a bandaid fix for the real problem. Make sure your pedal has good bushings and isn’t sticking. And make sure the adjustment is correct on the pushrod.

^This. A pedal not returning correctly usually means there's a restriction in the return line somewhere, i.e. a tee. Make sure all your plumbing is correct.

Todd Z.

 

[Mascasa]

If your hydra boost unit is like mine,(GM) check the brass return fitting on the hydraboost unit itself, take it out and look inside the fitting, mine had a smaller hole that created a restriction, make sure that little hole is not plugged or restricted in any way. Tees in the line are not the best way to go, and depending on what pump you use that can be an issue as well. I have a return style Saginaw pump. Assuming all of that has been considered I was told that you can enlarge the hole in the brass return fitting when I had the same issue, I did so and had awesome results. I apologize but I don’t remember what size I enlarged the fitting to. Hope this might help.

 

[toddz69]

Very good advice! Those return fittings, like axle vent fittings, tend to get clogged or partially obstructed sometimes.

Todd Z.

 

[Mascasa]

I have also found that a a couple of in-line rebuildable power steering filters can catch a lot of junk, I run one on the return and supply, even on a “new” system properly flushed I have found that it will have a small amount of fine debris in them from I’m assuming rebuilding and assembly of the pump, hydraboost unit and the steering box etc. Pedals, bushings and pushrod adjustment can cause problems with poor pedal return too... just take your time and be thorough and you may find something.

 

[Yeller]

Mine the pedal weight would apply the brakes going down steep hills by itself. Had to add a throttle return spring to the pedal.

As others have said, it’s probably a return line restriction and my guess is the fitting. If it is the tee often it sucks the pedal to the floor by itself with the engine running.

 

[Wild horse 75]

If you can’t run dedicated return lines for each return to the reservoir using a Y is a much better option than a T. How you hook up the tee and how close it is to the reservoir are very specific. And the filter is a good idea. CPP requires a filter on the return line or they won’t warranty their booster.

 

[Yeller]

I use These filters on every steering system except full hydraulic, those get an inline spin on filter.

 

[dmoses42]

Borgeson sells new dual return reservoirs now, not sure how long they have been doing this but I just saw it recently....

https://www.borgeson.com/power-steering-reservoir

 

[ba123]

Just confirmed that mine stick as well. I have ZERO T's or Y's, my pedal is bearings, not bushings and everything new and really only happens when engine running.

I need a spring somehwere

 

[Mascasa]

Just confirmed that mine stick as well. I have ZERO T's or Y's, my pedal is bearings, not bushings and everything new and really only happens when engine running.

I need a spring somehwere

Try to open up the hole in the return fitting on the hydraboost? Looks like I drilled it out to 1/8 inch. It helped on mine

 

[Mascasa]

I just noticed that my spelling of Hydro-boost keeps changing to hydra boost... my bad

 

[Speedrdr]

I just noticed that my spelling of Hydro-boost keeps changing to hydra boost... my bad

Got to love autocorrect, right?

Randy