GM hydro boost brakes for newbies like me....

[underdrive]

Joe, thanks for pointing out the qualities of the Swagelok fittings and unions - with the pressures they're made to withstand they should indeed hold up just fine to the PS and brake lines pressures. That being said, their street-use legality is still an issue. The inspections technician won't know the difference between the high-quality unions and the hardware store stuff, they will see a compression fitting and they will fail the vehicle. Because even if they knew which is which and what can hold up and what's unsafe, the rulebook they have to go by does not differentiate between different compression unions - in there a compression union is a compression union regardless of who made it and to what standards and what torture testing it passes.

Chilli, go to your favorite parts store and order a hydroboost and pressure hoses for a Chevrolet C30 454 4bbl DRW from the same model year as your truck. This is a 10k GVW truck, the highest you could get back then, and consequently it has the strongest hydroboost. You can turn your CUCV hydroboost in as a core, the parts store can't tell the difference and A1 Cardone likely won't care one bit - half their junk is, well, junk anyways, what's one mislabeled hydroboost unit, a drop in the bucket. Make darn sure you remove the star-shaped retainer, the spring behind it, and the plunger that pushes on the master cylinder from the front of the CUCV hydroboost, and keep them, do NOT give those items to the parts store as part of the hydroboost core - reman hydroboost units usually lacks those parts when you open the box, there was a time where I used to raid the local salvage yards every weekend just to bail out fellow GM owners who got screwed like that.

 

[chilliwak]

Joe, thanks for pointing out the qualities of the Swagelok fittings and unions - with the pressures they're made to withstand they should indeed hold up just fine to the PS and brake lines pressures. That being said, their street-use legality is still an issue. The inspections technician won't know the difference between the high-quality unions and the hardware store stuff, they will see a compression fitting and they will fail the vehicle. Because even if they knew which is which and what can hold up and what's unsafe, the rulebook they have to go by does not differentiate between different compression unions - in there a compression union is a compression union regardless of who made it and to what standards and what torture testing it passes.

Chilli, go to your favorite parts store and order a hydroboost and pressure hoses for a Chevrolet C30 454 4bbl DRW from the same model year as your truck. This is a 10k GVW truck, the highest you could get back then, and consequently it has the strongest hydroboost. You can turn your CUCV hydroboost in as a core, the parts store can't tell the difference and A1 Cardone likely won't care one bit - half their junk is, well, junk anyways, what's one mislabeled hydroboost unit, a drop in the bucket. Make darn sure you remove the star-shaped retainer, the spring behind it, and the plunger that pushes on the master cylinder from the front of the CUCV hydroboost, and keep them, do NOT give those items to the parts store as part of the hydroboost core - reman hydroboost units usually lacks those parts when you open the box, there was a time where I used to raid the local salvage yards every weekend just to bail out fellow GM owners who got screwed like that.

Thank you Underdrive! :victory:This is exactly what I was thinking and was very curios why no one else had mentioned the things that you said. I was scratching my head and almost wanting to bang my head against the wall because I was repeatedly asking the same question in different ways to find out if your solution was not a possibility. Now if either the 79 hydro boost housing or the lines where no longer available then I would just have shut up and quit asking questions. By buying the 1979 hydro boost housing and lines new at a parts store I am now able to make the system work without having to re flare lines or otherwise modify the system other than make a t fitting for the return lines. This makes things so much easier.:wings:

 

[underdrive]

This is exactly what I was thinking and was very curios why no one else had mentioned the things that you said.

Well at least the way I understood your plan for the longest time was that you had a metric CUCV hydroboost that you wanted to use as is, and you just needed some lines to make it work with your SAE pump and box on a low budget. So that's what I kept trying to figure out a way for, lol

 

[Larry]

Thank you Underdrive! :victory:This is exactly what I was thinking and was very curios why no one else had mentioned the things that you said. I was scratching my head and almost wanting to bang my head against the wall because I was repeatedly asking the same question in different ways to find out if your solution was not a possibility. Now if either the 79 hydro boost housing or the lines where no longer available then I would just have shut up and quit asking questions. By buying the 1979 hydro boost housing and lines new at a parts store I am now able to make the system work without having to re flare lines or otherwise modify the system other than make a t fitting for the return lines. This makes things so much easier.:wings:

Sorry Chilli, I thought that option was obvious when you asked if the standard thread hoses and hydrooster were still available and I replied they were and even provided the Napa standard thread booster part number in post 47 of this thread. Then if I you think back to post 308 of my K10 thread where this topic started I mentioned the m/c to booster push rod, star retainer and booster to firewall bracket are nonexistent anywhere other than to buy a booster from a salvage yard. I can help lead a horse but can’t make it drink and to put 2 and 2 together

For what it is worth, the hydroooster core itself is only worth $40 but the m/c to booster push rod, star retainer (for the pushrod) and booster to firewall bracket are invaluable. A reman booster with standard threads will cost around $300 to $400. As a price example, Napa’s list price is actually $409.36 with a $43.02 core. They are not cheap, but they could be had for much less than what Napa wants. The price of a reman booster sure makes the idea of making hoses out of AN fittings, or reworking the hoses to make a metric booster work with your standard p/s pump and steering gear more appealing, no? It all depends how much you want to spend. I too would prefer to keep all of the parts factory off-the shelf as much as possible. Just makes getting replacement parts down the road much easier, especially if your sitting on the side of the road with a blown hose and need one now.

 

[chilliwak]

Sorry Chilli, I thought that option was obvious when you asked if the standard thread hoses and hydrooster were still available and I replied they were and even provided the Napa standard thread booster part number in post 47 of this thread. Then if I you think back to post 308 of my K10 thread where this topic started I mentioned the m/c to booster push rod, star retainer and booster to firewall bracket are nonexistent anywhere other than to buy a booster from a salvage yard. I can help lead a horse but can’t make it drink and to put 2 and 2 together

For what it is worth, the hydroooster core itself is only worth $40 but the m/c to booster push rod, star retainer (for the pushrod) and booster to firewall bracket are invaluable. A reman booster with standard threads will cost around $300 to $400. As a price example, Napa’s list price is actually $409.36 with a $43.02 core. They are not cheap, but they could be had for much less than what Napa wants. The price of a reman booster sure makes the idea of making hoses out of AN fittings, or reworking the hoses to make a metric booster work with your standard p/s pump and steering gear more appealing, no? It all depends how much you want to spend. I too would prefer to keep all of the parts factory off-the shelf as much as possible. Just makes getting replacement parts down the road much easier, especially if your sitting on the side of the road with a blown hose and need one now.

Thanks Larry, I guess I just misunderstood it all. Part of the problem is that I am in Denmark trying to get the parts for the truck which is in Canada. I could always use the excuse.. `I guess I was kind of drunk at the time´ Thanks everyone for their input and patience with an old man like me....:ylsmoke:

 

[underdrive]

For what it is worth, the hydroooster core itself is only worth $40 but the m/c to booster push rod, star retainer (for the pushrod) and booster to firewall bracket are invaluable.

I'm pretty sure at least the m/c pushrod and its spring and the star retainer are all the same starting from the '70s SAE boosters all the way into the '2000s metric ones with the more ABS-friendly internal valving. Last time I checked we had hoarded a '70s booster, a mid-'80s one, and one that's like '01 or '02, all came from 1-ton dually trucks and IIRC they all measured the same there. Opens up a few more options if one is in dire need of these parts. Now the bracket that bolts the hydro to the firewall is obviously different, but the reman unit should come with that already installed, at least the Cardone ones used to. What I never understood is why they always chucked the front parts away, it's not like they are much of wear items, or, alternatively, easily available in the aftermarket...

I too would prefer to keep all of the parts factory off-the shelf as much as possible. Just makes getting replacement parts down the road much easier, especially if your sitting on the side of the road with a blown hose and need one now.

When it comes to hoses that may not actually be the case. Many commercial-truck service shops can make AN- hoses in a matter of minutes, some of these outfits have mobile shops who will come to your location and either deliver the freshly-made hose to you or make you one on the spot. It won't be cheap, but neither is waiting on the local parts store to open just to realize that while they do carry the hose they have none in stock and it will be at least another day... So call for the tow and off to the hotel we go, add to that any ramifications that not arriving at your destinations fairly on time may have, and suddenly the expedient big-truck roadside service doesn't look so bad anymore.

Chilli, check Rockauto for a hydroboost unit - sometimes they get their hands on OEM units and prices are actually lower than aftermarket reman units. I'll take an OEM hydroboost over a reman any day, unless of course the aftermarket unit comes from someone like Vanco.

 

[Stinger]

Just found this site. What a great resource for a newbie like me.
Need some help with my current project. I found a wrecked 2012 Chevy HD 2500 with 6.o liter engine and 6L90 transmission. This vehicle had Hydroboost steering and brakes. All of those now reside in my 05 Jeep LJ (stretched TJ). Everything is great except the brakes. While they work they do not work well. In fact, in low gear, low ranges they will not hold the vehicle at an idle. Obviously not a good thing for a rock crawler. I have the truck booster and its master cylinder in the jeep. I understand that this MC has a 2.5 or so inch bore. The brake calipers are standard jeep. Is it possible that this combination is the cause of the lack of braking or should I look somewhere else? Is it possible to mount a standard Jeep master cylinder to the boost?
Thank for any help

 

[J.R.]

Just found this site. What a great resource for a newbie like me.
Need some help with my current project. I found a wrecked 2012 Chevy HD 2500 with 6.o liter engine and 6L90 transmission. This vehicle had Hydroboost steering and brakes. All of those now reside in my 05 Jeep LJ (stretched TJ). Everything is great except the brakes. While they work they do not work well. In fact, in low gear, low ranges they will not hold the vehicle at an idle. Obviously not a good thing for a rock crawler. I have the truck booster and its master cylinder in the jeep. I understand that this MC has a 2.5 or so inch bore. The brake calipers are standard jeep. Is it possible that this combination is the cause of the lack of braking or should I look somewhere else? Is it possible to mount a standard Jeep master cylinder to the boost?
Thank for any help

Im pretty sure I read somewhere (probably Stu-offroad ) that the stock jeep calipers are inadequite (somethin about surface area...yada...yada )and that after Stu switched from a single piston caliper to a dual piston caliper the stopping was MO Betta. Maby poke around on his blog / mods index for how he dealt with the hydroboost conversion.

Edit: yup it was Stu's site. Here is a direct quote from his site:

"We have to go back to the last brake project I did on my TJ, which was the Vanco Big Brake Kit. This kit, intended for 15" wheels, was the first major brake upgrade for a TJ owner. The flex prone 63mm single piston factory calipers with their 19.3" sq of surface area, were replaced with a new dual piston caliper. The pistons were 46mm in diameter and provided approximately 20.6" sq of surface area. The dual piston caliper provided a much more uniform pressure over a larger area of the brake pad which greatly improved braking performance. A greater area of the brake pad was in full contact with the swept area of the new high performance rotor. The result was awesome brakes compared to the factory setup. But hold on, we aren't there yet.

The history story continues..... Next on the scene are the later model TJs with their 16" wheels. Of course, a larger wheel means more space for a larger caliper/rotor. Blaine and Van responded by working out the details for a larger caliper for the new 16" kit. But hey....what about us 15" folks. I have a fair amount of money invested in my 15" aluminum bead lock wheels so swapping those out isn't really an option. Not to worry.....next comes the 16" Big Brake Kit for 15" Wheels. The caliper for the 16" kit with 48mm pistons, yielding 22.4" sq of surface area, will fit in my 15" wheel. It was a matter of finding a suitably sized caliper for a 12" rotor that would allow its use in both the 15" and 16" wheels. Nicely done!

Next came the 15" and 16" kits for the Warn Small Hub conversions. (These two kits require machined center-bores in the rotors, which is what I installed on my TJ several years ago.) A Big Brake Kit for the Warn 5.5" hub conversion kit was also brought to market. Finally, a 17" Big Brake Kit with 54mm dual piston calipers, a new master cylinder, and 13" rotors finished out the upgrade path.

Why the reference to the piston's surface area? It's all about the pressure being generated by the master cylinder. The increased piston size means a larger surface area on the piston. The pressure created by the master cylinder has a larger piston surface area upon which to act and so generate more clamping force on the rotor. Increased clamping force means better braking performance as long as the pads can withstand it. "

Hope it helps.

 

[toddz69]

Just found this site. What a great resource for a newbie like me.
Need some help with my current project. I found a wrecked 2012 Chevy HD 2500 with 6.o liter engine and 6L90 transmission. This vehicle had Hydroboost steering and brakes. All of those now reside in my 05 Jeep LJ (stretched TJ). Everything is great except the brakes. While they work they do not work well. In fact, in low gear, low ranges they will not hold the vehicle at an idle. Obviously not a good thing for a rock crawler. I have the truck booster and its master cylinder in the jeep. I understand that this MC has a 2.5 or so inch bore. The brake calipers are standard jeep. Is it possible that this combination is the cause of the lack of braking or should I look somewhere else? Is it possible to mount a standard Jeep master cylinder to the boost?
Thank for any help

I haven't looked at trucks as new as 2012 but I find it hard to believe that it has a 2.5" diameter bore master cylinder. The largest bores I've seen are 1 3/8" on my '01 Super Duty. Hydroboost should be able to hold your truck motionless at idle even in low range. For reference, I have a 4 speed Atlas in my Bronco and I can easily hold it motionless in the 2.7 and 3.8 low gears. When I put it in 'stupid low' (i.e. 10.xx:1), the brakes still hold but the suspension starts to load up and 'climb', if that makes any sense. An odd sensation to be sure.

Can you double check the master cylinder bore? It may be cast onto the side of the master cylinder body. Also, how large are your tires?

Todd Z.

 

[underdrive]

Stinger, according to various parts stores websites the factory LJ master cylinder has a bore of only 1", whereas the 2500HD master has a 1.5" bore. Surface area of the 3/4-ton master cylinder piston is therefore 2.25 times larger than what the LJ calls for (1.767in^2 vs 0.785in^2) - assuming input force from the booster is kept constant that means more than twice LOWER line pressure in the lines and the calipers. To offset that and go back even to stock line pressures you'll need a booster that pushes over TWICE as hard on the master cylinder - we all know the hydroboost is a powerful beast, but is it THAT powerful?

So my suggestion would be go down in size of the master cylinder. We ran into the very same issue when hydroboosting a S10 Blazer, its factory master has 1" bore but we thought 1-1/4" would give it better feel - well it didn't, at low engine speeds when the pump didn't make very high pressure the brake pedal felt quite hard and required significant force from the driver to stop the truck in a timely fashion. We dropped the master down to 1-1/8" bore as that was the smallest we could find that fits a hydroboost unit, and all has been great ever since. IIRC this second master cylinder we used was originally intended for a '79 Chevrolet C10 with the 350 engine and power brakes, an AutoZone part number would be NM1521 - this is your standard old-school-looking cast-iron master with the tin cap on top, looks way out of place on a modern vehicle but hey if it works it works! Anything that we found was hydroboost-compatible and of the more modern 2-piece design with an aluminum master cylinder and plastic reservoir on top of it was 1-1/4" bore, which was obviously no good for our application. One thing though, the C10 master we used has SAE flared ports (9/16" for the front brakes and 1/2" for the rears) while your Jeep calls for metric bubble flares (10mm for the front brakes and 12mm for the rears). You'll need a pair of SAE-to-metric adapters, not sure how easy it will be to locate them in the required 9/16"-M10 and 1/2"-M12 variety - you may have to stack a few together to get the right end sizes, or you may be better off reflaring your brake lines altogether.

All of the above is assuming you just found a way to line up the GM hydroboost with your factory Jeep brake pedal, and you haven't instead altered the pedal leverage by moving the pin for the booster pushrod up or down. If you have done some brake pedal work, tell us what exactly you did and we may be able to recommend a different master cylinder that will work for you.

 

[toddz69]

So my suggestion would be go down in size of the master cylinder. We ran into the very same issue when hydroboosting a S10 Blazer, its factory master has 1" bore but we thought 1-1/4" would give it better feel - well it didn't, at low engine speeds when the pump didn't make very high pressure the brake pedal felt quite hard and required significant force from the driver to stop the truck in a timely fashion. We dropped the master down to 1-1/8" bore as that was the smallest we could find that fits a hydroboost unit, and all has been great ever since. IIRC this second master cylinder we used was originally intended for a '79 Chevrolet C10 with the 350 engine and power brakes, an AutoZone part number would be NM1521 - this is your standard old-school-looking cast-iron master with the tin cap on top, looks way out of place on a modern vehicle but hey if it works it works! Anything that we found was hydroboost-compatible and of the more modern 2-piece design with an aluminum master cylinder and plastic reservoir on top of it was 1-1/4" bore, which was obviously no good for our application. One thing though, the C10 master we used has SAE flared ports (9/16" for the front brakes and 1/2" for the rears) while your Jeep calls for metric bubble flares (10mm for the front brakes and 12mm for the rears). You'll need a pair of SAE-to-metric adapters, not sure how easy it will be to locate them in the required 9/16"-M10 and 1/2"-M12 variety - you may have to stack a few together to get the right end sizes, or you may be better off reflaring your brake lines altogether.

All of the above is assuming you just found a way to line up the GM hydroboost with your factory Jeep brake pedal, and you haven't instead altered the pedal leverage by moving the pin for the booster pushrod up or down. If you have done some brake pedal work, tell us what exactly you did and we may be able to recommend a different master cylinder that will work for you.

Good advice - I'd be interested in any mods you may have done to alter the pedal ratio as well. 1 1/8" bore master cylinders usually work pretty well for most setups.

Todd Z.

 

[beags86]

Ok Larry, teach me. I have been quietly following along so I can do my own hydroboost conversion. But I still could use some guidance. I have never messed with this stuff before.


Out of a 82' c20 with the 6.2.

My truck is a 79' k10. Auto, not going to use the whole bucket just the brake pedal.

These followed me home from the yard tonight, where do I get new lines? Or do I go back and take the old lines for the hard line ends? What else do I need for the hydroboost conversion? PS pump?

 

[Larry]

Ok Larry, teach me. I have been quietly following along so I can do my own hydroboost conversion. But I still could use some guidance. I have never messed with this stuff before.

View attachment 276167
Out of a 82' c20 with the 6.2.

My truck is a 79' k10. Auto, not going to use the whole bucket just the brake pedal.

These followed me home from the yard tonight, where do I get new lines? Or do I go back and take the old lines for the hard line ends? What else do I need for the hydroboost conversion? PS pump?

Looks like a good collection of parts to start the swap. This install is now fresh in my mind again as I just installed hydroboost on my Polar Bear Suburban in the past few weeks. The install is a straight forward bolt for bolt install. The brake pedal is surprisingly easy to replace without even needing to drop the pedal box whereas on the K10 I had to replace the entire pedal box because I was also swapping to hydraulic clutch. One mod you will need to do is beat the two studs out of the booster bracket in your picture then hog out the holes so the studs in the firewall will pass through them. You’ll figure it out when you get there.

The biggest problem you are going to have is the same situation I was in on my ’78 K10 and what we’ve talked about with Chili with his ’79 where he has a standard thread steering gear, standard thread p/s pump but a metric thread hydrobooster (1982 C20 would be metric threads at the hydraulic hose connections at the hydrobooster). With that, you’ll need to figure out which way works best for you to create hoses; make custom hoses out of AN fittings and hose, buy new off the shelf hoses (yes, new hoses can be purchased from just about any parts house) and cut off the tube nut and install the correct tube nut and reflare, or replace your steering gear and p/s pump with ‘82 and newer metric pieces. You really don’t need to replace the p/s pump to add hydroboost as you can tie the return hoses together in a t-fitting as discussed above but if you choose to replace the pump, than buy a hydroboost pump with the dual return ports. I had to buy a new pump for the Suburban as the old pump reservoir from the 5.7L would not fit the 8.1L accessory bracket so I went ahead and got a hydroboost pump since I had to buy a new one anyway. Lastly, you will need to buy a master cylinder for whatever the truck was that donated it's booster to you so the m/c will match the push rod in the booster.

 

[beags86]

Looks like a good collection of parts to start the swap. This install is now fresh in my mind again as I just installed hydroboost on my Polar Bear Suburban in the past few weeks. The install is a straight forward bolt for bolt install. The brake pedal is surprisingly easy to replace without even needing to drop the pedal box whereas on the K10 I had to replace the entire pedal box because I was also swapping to hydraulic clutch. One mod you will need to do is beat the two studs out of the booster bracket in your picture then hog out the holes so the studs in the firewall will pass through them. You'll figure it out when you get there.

The biggest problem you are going to have is the same situation I was in on my '78 K10 and what we've talked about with Chili with his '79 where he has a standard thread steering gear, standard thread p/s pump but a metric thread hydrobooster (1982 C20 would be metric threads at the hydraulic hose connections at the hydrobooster). With that, you'll need to figure out which way works best for you to create hoses; make custom hoses out of AN fittings and hose, buy new off the shelf hoses (yes, new hoses can be purchased from just about any parts house) and cut off the tube nut and install the correct tube nut and reflare, or replace your steering gear and p/s pump with ‘82 and newer metric pieces. You really don't need to replace the p/s pump to add hydroboost as you can tie the return hoses together in a t-fitting as discussed above but if you choose to replace the pump, than buy a hydroboost pump with the dual return ports. I had to buy a new pump for the Suburban as the old pump reservoir from the 5.7L would not fit the 8.1L accessory bracket so I went ahead and got a hydroboost pump since I had to buy a new one anyway. Lastly, you will need to buy a master cylinder for whatever the truck was that donated it's booster to you so the m/c will match the push rod in the booster.

Crap! your telling me the steering gear for an 82 is metric huh? What year was the switchover?

I am also going to be doing a crossover set up as well, in fact I have just found (junkyard) a decent reman steering box out of an 80'(I think) I pulled awhile back. I don't remember if the wrenches I used were metric or not.
I wonder if should just pull the gear and the lines to get started.

I currently am running a serpentine belt setup from a 91' K5 so I am thinking I should be able to source a new pump with that. I do plan on a new pump just because. And of course a new MC for an 82 C-10.

 

[tgdoumit]

First of all, thanks for a great thread!
My question is about something I may have misunderstood:
Should I look for a hydroboost off a ONE TON rrig of same make and vintage as mine or does it matter?
I'm using a Dana 60 off a 78 ford 3/4 ton up front. It has dual piston calipers.
The rear is a Dana 80 off a 96 ram 2500.
All this goes into a 88 suburban with a 12 valve cummins. (Currently in pieces)
Thanks!

PS... It seems the original poster has things in hand so I figured it would be okay to invade and ask a somewhat related question on his thread.