Hydro-boost with Disk/Disk Prop Valve

[Orange Crate]

My disk/disk hydro-boost conversion proportioning valve turns the "brake" light on when applying the brake. This is a new first installation/test in the garage. I had selected a disk/disk proportioning valve when putting it together but it is obviously not the correct combo. So anyone with hydro-boost have a part number for a proportioning valve that works? I used the search function above with lots of info but non with a hydro-boost added in. The system has been bled numerous times and the light can easily be reset. I'm not looking for trouble shooting info unless you have hydro-boost.

[Rust_never_sleeps]

I don't speak hydroboost, but the type of assist should have nothing to do with the combo valve, which only interacts with the MC. Boost only changes the amount of pedal pressure it takes

[HO455]

I'm in the same camp as Rust_never_sleeps. The valve is shifting off center due to a pressure difference on the piston, inside the valve. Whichever side the piston is moving to is the low pressure side. Whether the low pressure is from a leak, or trapped air in a caliper, or possibly low pressure from the master cylinder is what you need to figure out. A brake pressure guage should help locate the problem.

Some rear disc brake calipers can be notoriously hard to completely purge of air. Sometimes the caliper has to be removed from the mounting and a plate inserted to mimic the rotor and then while the caliper is held so the bleeder is in the absolute upper position the caliper is then bled.

Good luck.

[Orange Crate]

So I thought I would start with a known good part number for the prop valve from someone whose hydro system already works, and go from there. Like I said in the first post, I searched on here a lot and the nightmare stories of bleeding gallons of fluid set me on the part number first.

[KQQL IT]

Caddy park brake calipers? A friend has been fighting a similar issue.
Was told the re pop caddy calipers are not the best.
He's switching to a later model mustang caliper kit.

[Orange Crate]

OK so I need two new rear calipers because a friend was told they were the problem? Is the "friend" on this board? If so maybe you could convince that person to log in and give everyone the real scoop (with pictures please, because everybody likes the pics...) I'm asking for a friend....I'm going to go broke if you guys keep spending my money like that, oh wait I need a brake pressure gauge too! I wonder how much a known good part number will cost me....

[KQQL IT]

It's on a oldsmobile.
Was relaying his experience with repop cad style rear calipers.

Pv4 is the standard name for disc disc, as far as a oem pn sorry.

[KQQL IT]

3667810 gm

Try this..

[Orange Crate]

Originally Posted by KQQL IT

It's on a oldsmobile.
Was relaying his experience with repop cad style rear calipers.

Pv4 is the standard name for disc disc, as far as a oem pn sorry.

An Oldsmobile with hydro-boost? I guess I'm not too sure how re-mfg calipers are the cause of a brake light AND he decided to get rid of them for another style? Were they leaking? I get that some calipers are hard to bleed but to give up on a set, they must have been really messed up. What was wrong with them specifically?

[Orange Crate]

Originally Posted by KQQL IT

3667810 gm

Try this..

So that is the one your friend has on his disk/disk hydro-boost system that works?

[fun in dirt]

I just used a universal, manual adjust, valve in the rear brake line. Don't remember exact brand without looking at it, but similar to this https://www.summitracing.com/parts/leb-apv02 . But I did pair it also with a new master cylinder off '01 Chevy with disc front & back.
Been working for 10yrs now with zero problems.

[Orange Crate]

Originally Posted by fun in dirt

I just used a universal, manual adjust, valve in the rear brake line. Don't remember exact brand without looking at it, but similar to this https://www.summitracing.com/parts/leb-apv02 . But I did pair it also with a new master cylinder off '01 Chevy with disc front & back.
Been working for 10yrs now with zero problems.

Congratulations on being the first with hydro-boost to reply. I would have thought more people would have already converted seeing how easy it is. Ya, looking at manual adjust valves the last couple of days. I have the stock disks/ calipers on the front D60 so they are close to the stock D44 rotors. D60 at 12.7 diameter and D44 at 12.4. not a big change there, but could need pressure adjusted because of that. The major difference is the width, D60 at 1.625" and D44 at 1.25". Some nerd info, the rear disks are actually the front disks from the old D44. I'll put a cab over camper on this Camper Special so I think I'll like the extra heat dissipation, although the original set up seemed to work just fine for over 40 years. Here is the old camper and the old "guard" dog.

[KQQL IT]

After his brakes wouldn't bleed, he took to a shop.
They told him the re pop calipers are a pita to bleed/adjust.
And still won't be good.
So swap to a more modern system is his solution.


You ever think a metric non park brake caliper to see if it's a proportioning valve or caliper issue ?

[Orange Crate]

Originally Posted by KQQL IT

After his brakes wouldn't bleed, he took to a shop.
They told him the re pop calipers are a pita to bleed/adjust.
And still won't be good.
So swap to a more modern system is his solution.

Non of that makes any sense....

So now I need MORE calipers? Maybe it because they would be metric....ya, that's it.

[LS short box]

On my 66 Mustang project with a hydro boost unit I used a Wilwood adjustable prop valve in the rear brake line. I used C5 Corvette disc brakes all around so not apples to oranges but the Wilwood prop valve once adjusted worked perfect.
Not a great pic but hard to see underneath the master.
One thing I had to add after installing the hydro boost was add a fluid resisvoir with a filter to eliminate micro bubbles. This per the folks at Hydra-Tech.

[Orange Crate]

Originally Posted by LS short box

One thing I had to add after installing the hydro boost was add a fluid resisvoir with a filter to eliminate micro bubbles. This per the folks at Hydra-Tech.

Super excellent info, much appreciated. So where exactly did the extra reservoir go? Which system was it plumbed in to, the master cylinder sys, or the hydro sys? Gold star for the nice Stang!

[67 twins]

Originally Posted by Orange Crate

Congratulations on being the first with hydro-boost to reply. I would have thought more people would have already converted seeing how easy it is. Ya, looking at manual adjust valves the last couple of days. I have the stock disks/ calipers on the front D60 so they are close to the stock D44 rotors. D60 at 12.7 diameter and D44 at 12.4. not a big change there, but could need pressure adjusted because of that. The major difference is the width, D60 at 1.625" and D44 at 1.25". Some nerd info, the rear disks are actually the front disks from the old D44. I'll put a cab over camper on this Camper Special so I think I'll like the extra heat dissipation, although the original set up seemed to work just fine for over 40 years. Here is the old camper and the old "guard" dog.

Yeah tell me how easy the Hydroboost is again. You can't seem to get it to work. Then you seem to have an attitude towards those that have replied. Good luck. As said already the type of booster dhould have nothintg to do with what proportioning valve ypu would need.

[Orange Crate]

Originally Posted by 67 twins

Yeah tell me how easy the Hydroboost is again. You can't seem to get it to work. Then you seem to have an attitude towards those that have replied. Good luck. As said already the type of booster dhould have nothintg to do with what proportioning valve ypu would need.

Fair enough. Here is a quote I think may help....

"Super excellent info, much appreciated."

I will call out BS when I see it, just for future reference.

[jeffahart]

I would leave it alone until you drive the truck. See how it brakes and stops and if like the bias and all else is good in the stopping/braking arena; then chase the light problem. You could get the light working with a new valve and not like how it stops. It will be a good point of reference ,anyhow, if you need to move onto a different valve. I'm running a disc/drum so I won't post the part. Hydro-boost is a great upgrade.

Good luck... Have fun!

j

[Joyridin]

I have a hydro boost on my truck running for about 3 years now. I don't even have a proportioning valve. I have never had an issue with the brakes locking up or being off balance. I have an adjustable prop valve I originally planned on installing on the rear like fun in dirt has, but I never got around to it. All it would do is stop the rear from locking if that were an issue.

I do not have the parking brake in the caliper. My PB resides inside the rotor, so I am using Explorer calipers. I have never had a problem bleeding rear calipers with the PB in them. The trick is having to pump up the parking brake lever to get the pad adjusted correctly or you will never got a good pedal. The rear caliper has a ratchet mechanism which pushes out the piston reducing travel. Once you have that set, then the piston has only a very small amount of travel. Whether that small amount will mess with your prop valve, I am not sure.

[Orange Crate]

Originally Posted by jeffahart

I would leave it alone until you drive the truck. See how it brakes and stops and if like the bias and all else is good in the stopping/braking arena; then chase the light problem. You could get the light working with a new valve and not like how it stops. It will be a good point of reference ,anyhow, if you need to move onto a different valve. I'm running a disc/drum so I won't post the part. Hydro-boost is a great upgrade.

Good luck... Have fun!

j

Solid advice for sure, and my own thoughts too. What was happening during (mucho) bleeding was an inconsistent light. I could bleed, set up the pedal for the next caliper (without a light) and before I walk around the truck the light would come on. Other times I would have no light with the pedal all the way down to the floor. And every combination of that too. I have no light right now so your suggestion is my next step, get it going down the road and see just how "easy" this hydro is ahh, ha, ha. I haven't figured out how to attach a case of your favorite beverage to this thread yet.

[Orange Crate]

Originally Posted by Joyridin

I have a hydro boost on my truck running for about 3 years now. I don't even have a proportioning valve. I have never had an issue with the brakes locking up or being off balance. I have an adjustable prop valve I originally planned on installing on the rear like fun in dirt has, but I never got around to it. All it would do is stop the rear from locking if that were an issue.

I do not have the parking brake in the caliper. My PB resides inside the rotor, so I am using Explorer calipers. I have never had a problem bleeding rear calipers with the PB in them. The trick is having to pump up the parking brake lever to get the pad adjusted correctly or you will never got a good pedal. The rear caliper has a ratchet mechanism which pushes out the piston reducing travel. Once you have that set, then the piston has only a very small amount of travel. Whether that small amount will mess with your prop valve, I am not sure.

Yes these calipers can be rascally. I have them set up OFF the rotors with a block of wood the same thickness as my rotors between the pads. This way I have the bleeder at the top (which, when installed, the bleeder is not the high point). Also using a small brass hammer to help collect the bubbles. Ok, gold star faxed....

[jeffahart]

Originally Posted by Orange Crate

Yes these calipers can be rascally. I have them set up OFF the rotors with a block of wood the same thickness as my rotors between the pads. This way I have the bleeder at the top (which, when installed, the bleeder is not the high point). Also using a small brass hammer to help collect the bubbles. Ok, gold star faxed....

If you set your brakes up right, the rear brakes will lock up on panic stop. But if you do a panic stop at 34-40 mph with the weight of the camper on the rear... it will plant your face in windshield and catapult your camper over the cab(ok, a bit of an exaggeration) but it will stop better with more weight on rear axle and can put your face into the windshield. Keep that in mind when you dicker with the brakes and no camper. Your biggest concern is slowing down with the camper. But you already know that.

j

[Orange Crate]

Originally Posted by jeffahart

If you set your brakes up right, the rear brakes will lock up on panic stop. But if you do a panic stop at 34-40 mph with the weight of the camper on the rear... it will plant your face in windshield and catapult your camper over the cab(ok, a bit of an exaggeration) but it will stop better with more weight on rear axle and can put your face into the windshield. Keep that in mind when you dicker with the brakes and no camper. Your biggest concern is slowing down with the camper. But you already know that.

j

Yes, have already experienced the "launch" through the windshield the first time I got to drive it around the garage (big circular driveway). I have seen (I don't know where) a set up that has an extra bias valve attached between the rear axle and the bed floor with linkage. Added weight squats the bed some and through the linkage changes the bias more towards the rear. I was thinking about an adjustable valve just for ops with the camper installed.

[67 twins]

Originally Posted by Orange Crate

Yes, have already experienced the "launch" through the windshield the first time I got to drive it around the garage (big circular driveway). I have seen (I don't know where) a set up that has an extra bias valve attached between the rear axle and the bed floor with linkage. Added weight squats the bed some and through the linkage changes the bias more towards the rear. I was thinking about an adjustable valve just for ops with the camper installed.

If I remember correctly(and I may not) GM trucks from the 80s had this before they,went to ABS