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Illustrated Hydroboost swap

ashman

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Yeah, they are available, just didn't want to spend the money on it.
 

greatwhitez71

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Does anyone know which springs you need for the clutch and brake pedal assembly in a hydro post setup? Or is there any sort of gm brake/clutch small parts “kit”?
I picked a pair up awhile back but there’s no springs with them.
 

Shawn

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Not sure on part # on the spring for the HB brake pedal. I wonder if dealer can still get it? Looks like this guy
20190117_175815.jpg
 

Shawn

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I cant get to mine yet but doesn't look like a spring is needed for the hydro clutch
9qe97o.jpg
 

Chevk587

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This question may have been answered already if so I apologize. I’m swapping a hydro boost from a 1989 3500 into my 87 blazer . The first issue I’m coming to is the the rod that attaches to the pedal seems to be to short to reach the pedal in its normal location I haft to depress the pedal almost to the floor to get them to Line up ? I’ve never done this swap before and hydroboost it’s self is foreign to me . It’s a new/remaned unit from Napa auto parts . I’ve tried pushing from the master side to make it longer but it doesn’t seem to want to move any further. Any advice/help is greatly appreciated thanks in advance .
 

Tnsejed

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You'll have to either modify the pedal, or the rod. You also want the actuator rod to move in as straight a line as possible. Remember now when you modify the pedal depending on where it hits the pedal heightwise (in the up and down direction on the pedal), will change how much pedal movement and power you must generate to operate the brakes as needed.

Also, you need to make sure the master your using and hydroboost match up (easiest way is just get the units for the same vehicle, if you haven't already.) If the throw there is too different it will either drag the brakes or give you weird power assist feel. You can also modify the actuating rod on a lathe.

I didn't read anything of this thread, just posted based on @Chevk587 DM to me. Bash away :haha:
 

Blue85

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I know there are multiple factory rod lengths, depending on years, etc. If all the other parts appear compatible with each other, you could measure how "short" yours is and shop for a longer one. I have no experience with this company, but they seem to sell parts: https://powerbrakes.com/hydroboost/. The other company that was suggested before is maybe only on Facebook now: https://www.facebook.com/Tallon-Hydraulics-377001262353060/. Because figuring out what make/model/year had the length you need may be difficult.

It also seems feasible to cut and weld to extend it, but some have balked at that idea. You'll want a little bit of slop to be sure it's not engaging a little all the time. There are guys making adjustable length ones here: http://67-72chevytrucks.com/vboard/showthread.php?t=448895.
 

Chevk587

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Thanks guys , so all my stuff is from an 89 all matching parts booster master etc . The pedal is the wild card here , I’m not positive what year it’s from but clearly not an 89 lol . I think I have an idea to make it work / extend the rod I also thought of cut/weld an extension but i think I’d rather make some sort of extension hole to hole gonna do a little more research too coming up with what length is good might be tricky. Are 89 pedals able to swap into a 87?
 

Chevk587

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So here’s a quick sketch of what I’m thinking on doing (not an artist lol) if I’m thinking right this should work . What do you guys think ?

7D9D4DDE-77F3-431B-9823-6563BC624304.jpeg
 

Chevk587

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The option is buy one for an 87 1ton probably what I should have done in the first place .
 

Tnsejed

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That should be fine. Make it .1875 thick, as there is some off angle stuff that could happen under panic stop, unless its freespan isn't very long. Check the throw as it might angle the rod too much under movement.
 

Chevk587

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6E0CB2C2-46D4-43A8-A8E3-6752D3C5B8DD.png 77D36A9C-4E6D-41AA-942E-128CE2BB76F0.png Top image is the 89 the bottom is the 87 . The 87 looks longer to me but hard to tell from the picture.
 

Blue85

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So here’s a quick sketch of what I’m thinking on doing (not an artist lol) if I’m thinking right this should work . What do you guys think ?

View attachment 368861
Welding at the booster end seems better than welding at the pedal end. That keeps it one solid rod, with pivot point at the pedal attachment, as designed.
 

Chevk587

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I see what your saying it would just lift the rod up
 
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Shawn

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I have an original hyrdroboost pedal for a square automatic if you want to buy one. $40 shipped and can have it off by tomorrow.
 
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