Hydroboost conversion 96 Z71 - help

[gabeancounter]

Have a 96 K1500 Z71 I am wanting to convert from vacuum to hydroboost to help with the crappy brakes. The power steering pump started leaking so I figured this is a great time to replace both with the hydraulic setup.

Trying to figure out which hydrobooster can be a direct swap or if I need to fab a plate or what Acdelco 178-578 or 178-579?

Also does anyone know if you have to swap the pedal out as well?

The engine is all original with no cam swaps etc. Is this the best way to fix the crappy brakes on this truck - for the $?

 

[pro-rallye]

It's a great inprovement over the stock vacuum boost. The only thing you should have to change is the length of the pushrod on the back of the hydroboost. This needs to match your existing pushrod length of the vacuum booster or your pedal will be in a different position. You can accomplish this by either doing a cut and weld (if you trust your life with your welding skills) on the pushrod or by simply spacing out the hydroboost the difference in length. And you will be able to use the stock pedal as well. I did this to my 71 IH and it worked amazingly well! The first time I hit the brakes my head hit the sunvisor!

Edit: the hydroboost from a chevy 6.2 diesel is the one you should be looking for. grab the master cylinder too!

 

[gabeancounter]

Pro-rallye,
No way I would trust my life to one of my welds. lol. I think instead of trying to space it out I will just swap the pedal as well. Thanks for the info.

Anbody know a website that I can actually look up GM part #'s?

 

[mastertech]

have you looked at a site called fullsizechevy.com, they seem to have a lot of participation and a good history of builds.

 

[Dmaxman]

You could try to see if you can find a master with a larger bore diameter that has the same mounting fit. That can help get rid of the crappy soft GM brake pedal in those years.

 

[gabeancounter]

have you looked at a site called fullsizechevy.com, they seem to have a lot of participation and a good history of builds.

That is the main site I found out about the swap. Most of the builds are 5-10 years old and the members don't seem active any longer. I think I might post over there as well and see if I have any luck.

You could try to see if you can find a master with a larger bore diameter that has the same mounting fit. That can help get rid of the crappy soft GM brake pedal in those years.

I assume you would have to change the vacuum booster for the larger size MC? I was thinking the bore size actually sits back into the booster? I had seen that mentioned on another site but it was an old post and figured I misunderstood.

 

[warmpancakes]

just get the Hydro boost and master from a 2000 C3500 direct bolt in need the rod too

 

[Lotek]

just get the Hydro boost and master from a 2000 C3500 direct bolt in need the rod too

+1, any year with the same body style. It also will work on the earlier R/V truck without modification. I used one on my 75, the only difference was the donor booster had metric hose fittings.

Your existing m/cyl will bolt up as well.

 

[gabeancounter]

just get the Hydro boost and master from a 2000 C3500 direct bolt in need the rod too

Need the rod too? I assume you mean the rod from the booster to the pedal? Can you take this out of the vac booster and install in the hydro booster? I assumed the rod came in the booster already - problem with all this lies in the length and placement of the rod. Notice the mounting position of the rod on the hydro vs the vac. My understanding is that this forces you to get a plate fabricated or swap the brake pedal with one from a hydroboost.

 

[gabeancounter]

Tim,
My understanding is the MC is a different size bore than the HB MC. Not sure...

 

[Lotek]

The rod should come with the hydroboost. If not, order one from the dealer. The factory used the same firewall and pedal for either application.

I have a buddy who adapted one into his 68, had to weld the pushrod on that one.

 

[warmpancakes]

I mean the rod between the booster and master, I know theres a fancy term for it but its basically a steel rod

 

[Lotek]

Tim,
My understanding is the MC is a different size bore than the HB MC. Not sure...

Hmmm, would have to bug the parts guys, I put mine on over 15 years ago and don't remember.

Warmpancakes, iirc the pushrod comes with the booster, but the important thing is to make sure the clearance is right. Had a truck come in once that had been mengineered, the pushrod had been adjusted so that it was slightly too long and when everything warmed up, caused the brakes to drag slightly. that was fun to diag.

 

[Busted_Knuckles]

A word of encouragement, my 05 Sub is a 2500 4x4, with quadrasteer and every option the truck was available with (it was ordered). Anyhow, the pig is heavy, never scaled it, but read it was over 7500lbs.

It has hydro-boost brakes, with ceramic pads, and it blows my mind how well it stops, considering its weight. Ive owned 3 other subs in the last 20 years, still have an old school 91. None of them had Hydro-boost, all where 3/4 4x4s. All stopped fine, but nothing like the 05. I know the ceramic pads help, but Ive also installed the same bendix ceramic pads on jeeps and my Ford F450. So I have some feel for the difference in pads as well.

The subs main duty is pulling trailers, and Ive got two that don't have brakes.. anyway, I love those brakes !

 

[gabeancounter]

The rod should come with the hydroboost. If not, order one from the dealer. The factory used the same firewall and pedal for either application.

I have a buddy who adapted one into his 68, had to weld the pushrod on that one.

I think the mounting holes may be the same but the pedal is different?

 

[gabeancounter]

Thanks busted knuckes for the encouragement.

Anybody know a website to view diagrams? only available @ dealers?

 

[Busted_Knuckles]

Thanks busted knuckes for the encouragement.

Anybody know a website to view diagrams? only available @ dealers?

But of course, all you have to do is ask !, oh thats right, you did....

Here is the GM Parts Catalog online http://www.compnine.com/index.php

You can find this there: http://www.compnine.com/index.php?u...1147577463&capuid=1&majorgroup=04&grouptype=B

Although Im not sure what youre looking for, if you cant find it, I have the 2009 GM parts catalog on my PC, I can look stuff up for you, might even be able to do screen shots, although Ive never tried doing that, but I have a program on my pc to do just that.

Good luck, BK.

 

[Abodyracer]

Here is what I found when changing the hydroboost booster on my 88 1 ton. The rod between the booster and the pedal is crimped onto the booster. I had a shop rebuild my booster so not sure if new boosters come with the rod. Something to keep an eye out for. Also keep in mind you will need all the proper hoses from pump to booster and back. The pump will also be different than your stock pump As it need to pump more fluid and pump it to two different uses. The stock pump will not pump enough volume and it does not have the proper hook ups.

 

[Lotek]

I think the mounting holes may be the same but the pedal is different?

The 68?, iirc we had to modify the adaptor plate, drill a hole, and change the length of the pushrod, on the 75, it was a drop in conversion except for the hoses, re-used the pump, had to run a tee fitting in the return line, worked perfectly until I put a vintageair frontrunner serpentine belt kit on it, then, with the newer style pump, I went with a remote reservoir and a cooler, because it areated the fluid when it got hot.

 

[gabeancounter]

After looking at all the diagrahms etc. It seems to me that the 178-578 AcDelco hydroboost is an exact match (use the same pedal, same MC, etc). I will need to replace the pump with a hydro power steering pump. Also I will need the hoses.

I hope I looked at the diagrams correctly. The hydro is $425 for a new acdelco.

 

[pro-rallye]

Why do you need to replace the pump? If the difference is just the extra ****** to hook the return of the hydroboost, you can just "t" into your original return line instead. Might save some money. And if you know what year they came on, try calling around salvage yards and you could probably get it for about 50 bucks or so. They may even throw in the lines for free. I got my hydroboost for 30 without lines but it was from an astrovan. Food for thought anyways.

 

[csmitty]

I'm pretty sure you should have a P series saginaw pump so that should have more than enough pressure.

I did the saw a few months ago on my 98 wrangler, I was swapping out the steering box so figured why not do it all. Its mainly a trail toy around town vehicle so went with mostly salvaged parts. P pump from 85 camaro. HB unit from 2000 Astro, MC was a new unit from a mid 70s chevy 3/4 ton. Which was only $25 or so at AZ. I think its 1-1/8". You should be able to find new lines at AZ as well that will fit well. I got some from 02 or something 2500 HD since they seemed to be a good length and just bent them the little bit I needed to. Added a filter as well from the same truck since it was pretty universal.

You can T for the return line but you want to make sure that the one from the HB goes straight into the res. or could cause some brake issues i've heard.

For my pedal I spaced out the HB from the firewall what was needed. You can also cut and thread the pedal rod for a turn buckle style hardware piece. Some of the HB you can remove the rod and swap but some you can not. I think the staked ones you can't. Like I had. Then just had a machinist cut me a brass bushing to adapt to my brake pedal.

Its pretty damn amazing how quick it stops my little 3500lb Jeep. I've got eldorado calipers on the back. stock jeep on the front and going to do the WJ dual pistons soon. Can you have too much brakes

 

[gabeancounter]

The reason for replacing the steering pump is that it is leaking. Figured it would be a good time to do both. The coupons for Advance Auto makes most of the new parts just a little more than used. The big item is the HB.
I look forward to having good brakes with this truck.

Anybody have experience with the rebuilt Cardone HB? They are a little less than half the price.

 

[csmitty]

From things I've read the reman HB units aren't done very well. Basically better off finding a low miles salvage yard one. Mine was from a 2000 and the newest in the yard, though the odometer was gone. So I have no idea. Pretty sure the accumulator is shot as I'm pretty much manual brakes the second I lose pressure. But my goal was better brakes on the cheap. I def. have less than $200 in it all. box/pump/HB/MC/lines. Fabricated my own pump mount since my Jeep had the smaller TC pump on it.

vancobrakes sells kits and individual HB units as well, or he can get you whatever you need. he seems to be the only one that can build them right. i'd check around over at pirate4x4.com if you haven't already. Lots of conversion info over there.

 

[Lotek]

I did mine with salvage parts, still going strong, just get one with no signs of a leak at the seam. Go with the synthetic power steering fluid, makes a difference.

 

[Astroman]

Hey all, I know this is reviving an old thread, but I wanted to know everything I will need to install HB in the same truck. When I bought it, I replaced the steering gear box and pump with regular ones. Do these need to be replaced with HB components? That would ****!

 

[sz0k30]

Also does anyone know if you have to swap the pedal out as well?

ABSOLUTELY no reason to swap brake pedals. Vacuum or hydro, they are still just power brakes. The only correct way is to make the pushrods the same length.

Guys, all you are doing is swapping a vacuum assist brake booster for a hydraulic assist brake booster. Don't overcomplicate things.

The photo is from my conversion on my 67 Impala.

 

[Astroman]

ABSOLUTELY no reason to swap brake pedals. Vacuum or hydro, they are still just power brakes. The only correct way is to make the pushrods the same length.

Guys, all you are doing is swapping a vacuum assist brake booster for a hydraulic assist brake booster. Don't overcomplicate things.

The photo is from my conversion on my 67 Impala.

Thanks for the reply. I understand how the conversion works now. The last question I have is, is it really necessary to replace the MC? Why would that be the case?

 

[e015475]

The only reason you should have to swap pedals is if you are putting a booster on a car/truck that didn't have any power assist. Non-assist brakes generally have more leverage than power assist brakes.

You might find that with a Hydroboost your brakes are a lot more sensitive that they were with a vacuum booster. It takes a little getting used to. Engagement is quicker than a vacuum booster and just varying the pressure on the pedal modulates the brakes - there's very little pedal travel, at least on mine.

If it is too sensitive you might try a larger master cylinder, but I'd try it a while and see if I could live with it.

For anybody contemplating a Hydroboost, I've done the last couple with junkyard units from Astrovans. If I have any problems, I rebuild them with a kit from Pirate Jacks. I buy the pre-fabbed mounting flanges on ebay

 

[Monza Harry]

The Power Steering pump reservoir will have two return lines which you can just switch the can or add the return to yours. Some vehicles have the same pedal manual or power, top hole: manual, bottom hole: power. Our old Safari [GMC version of the Astro] also had a hard line that ran in a "duct" in front of the rad, return side line as a cooler. Many don't believe it is necessary but the "General" must have seen some circumstances where this might be needed. Harry