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

toddz69

Explorer
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.

It shouldn't matter. Those Ford calipers (which I'm familiar with) have huge pistons. I'd still try a unit off a pickup/Suburban from the vintage of your rig. If the master cylinder bore is too small and the pedal is too low for your liking, you can always step up a size in master cylinder bore.

Todd Z.
 

eggman918

Adventurer
When I did my cummins swap I used the hydroboost off the bread van and the '77 Ford master cylinder IIRC I needed an adjustable rod from the booster to M/C.
swap069.jpg

100_1379.jpg

100_1115.jpg
 

legendaryandrew

Adventurer
I actually have a related question...well hydroboost related. I found a how to for installing the factory hydroboost on GMT800 trucks, but it involves replacing the brake pedal, because the hydro pedal has a different lever ratio. My 'burb has the adjustable pedals, does that effect which pedal I get?
 

chilliwak

Expedition Leader
This thread gives you all the info you need about GM hydroboost supplied by our helpfull members. Cheers, Chilli....:)
 
I'm coming late to this party but I just did this on my 1973 Suburban. This will work on any 73-91 burb or 73-87 squarebody Chev.

I was surprised how simple this conversion was.

Here is a summary of what I did, using a 1983 K30 as a donor (craigslist) however you can get all these parts "new" from rockauto for under $400.
Hydroboost
1983 K30 unit is a direct bolt in to the fire wall.
Pedal linage works ok, though the eye is a different size (HB is larger). No mods at all required. ( read somewhere that one is 1/2 and one is 9/16 )

Power steering Lines
*1983 K30 stock lines that came with the donor. No mods.

Pump Bracket
This one was tricky because I assumed they would all work.
Options were: 1973 original, 1983 K30 (broken), 1984 K20 (not the same!)
I tried the 84 but the pump would not mount up.
Pump Bracket: 1973 K10 original bracket
Notes:

Pump
1983 K30 from the donor.
Notes: This one has two return lines (from gearbox and from hydroboost); USE THIS, I have read that using a "T" for the return lines will give you issues.

Pulley:
Single pulley from the stock 73 K10

Gearbox
1984 Saginaw gear box.
I had this laying around and used it because all the lines are metric and bolt right in.
Notes: 73 K10 uses a different size input shaft (larger)
Mods required: The input shaft is a different size on my 73 K10 vs the 84 K20.
I bought a new rag joint that has the correct size. This was horrendously expensive! $46

My write up is here: http://67-72chevytrucks.com/vboard/showthread.php?t=701079

After driving it some, here are conclusions.

Pedal feel is very firm and "wooden". Some don't like that. The vacuum brake set up is more ... sensitive feeling. Hydroboost is like stepping on a 2x4, and you stop. Not delicate feeling.

This fixed my braking issues, which I believe are the result of low vacuum produced by my worn out 350. So I'm happy with that.
 

chilliwak

Expedition Leader
Looks like you have everything under control there Mr Swissarmy. I am glad that this thread is of use to someone. Cheers, Chilli..:)
 

superbuickguy

Explorer
two things:
1) wooden feel may be because you have the pedal adjusted too high, if the travel isn't enough, you'll never use your rear brakes - thus increasing stopping distances and potentially cooking the front brake pads
2) never use a T - it's pretty easy to take the pump housing off then weld/braze another nipple on. Alternatives to welding include getting a Franz oil pan adapter. Always put the return line below the fluid line.

extra - do consider a power steering cooler when you do this, you get a lot of extra heat in the system by adding a hydroboost - GM does, some it doesn't matter, but if you get growling/whining due to aeration you will need a cooler... it doesn't even have to be large. 4x8 works excellent for even up to 40" tires.
 

Larry

Bigassgas Explorer
2) never use a T - it's pretty easy to take the pump housing off then weld/braze another nipple on. Alternatives to welding include getting a Franz oil pan adapter. Always put the return line below the fluid line.

extra - do consider a power steering cooler when you do this, you get a lot of extra heat in the system by adding a hydroboost - GM does, some it doesn't matter, but if you get growling/whining due to aeration you will need a cooler... it doesn't even have to be large. 4x8 works excellent for even up to 40" tires.

Why? GM used T fittings in the return lines on Hyrdroboost G-vans & P-Chassis. International and others did the same. My K10 has a T on the return side while my Burb has a dual return pump reservoir. The everyday and off road difference in steering and brake power is 0% even in 100 degree temps off roading in the desert. There is nothing wrong with a T albiet they may be a little more work to bleed
 

superbuickguy

Explorer
Why? GM used T fittings in the return lines on Hyrdroboost G-vans & P-Chassis. International and others did the same. My K10 has a T on the return side while my Burb has a dual return pump reservoir. The everyday and off road difference in steering and brake power is 0% even in 100 degree temps off roading in the desert. There is nothing wrong with a T albiet they may be a little more work to bleed

because a T can create back-pressure in the system or worse, if there is a failure back pressure can result and a burst line - which, of course, could blow power steering fluid onto the exhaust and cause fires. It also would cause loss of brake boosting and power assist to steering.

it's awesome it works for you, but stop telling others it's okay because it isn't. I've had to fix far too issues for people who took advice, who aren't engineers, and didn't know better. Honestly I have a pretty poor view of people whose only experience is "it hasn't happened to me yet" experience. The latest one was another who thought a T was fine.... argued and argued and argued but complained and complained about whining from the steering. We put a Franz tap in his steering box and it fixed the issue.

don't use a T unless you're a hydraulics engineer. Need I be more clear?
 

Larry

Bigassgas Explorer
because a T can create back-pressure in the system or worse, if there is a failure back pressure can result and a burst line - which, of course, could blow power steering fluid onto the exhaust and cause fires. It also would cause loss of brake boosting and power assist to steering.

it's awesome it works for you, but stop telling others it's okay because it isn't. I've had to fix far too many people who took advice who aren't engineers and didn't know better to count and honestly I have a pretty poor view of people whose only experience is "it hasn't happened to me yet" experience.

Haha, that is truely funny. We'll just agree to disagree on this one. How many issues has GM had with the T fitting arrangement on G vans and P chassis? We still use T fittings on return lines with Hydromax on Internationals to this day.
 

tgdoumit

Adventurer
i don't know how many times I've been through this thread, lol! I'm finally getting to where i can do my own swap. lots of good info here!!!
 

chilliwak

Expedition Leader
Good to see people are getting use of the old hydro boost thread even if there is a few heated discussions going on here. Just remember people, we are here to help each other. Cheers, Chilli...:)
 

Forum statistics

Threads
185,424
Messages
2,874,295
Members
224,720
Latest member
Bad Taste
Top