GMT 400 Hydroboost swap

I am in the process of doing this swap on my 93, so far I have a used booster from a 1990 k3500, all new lines, a ps pump from a 94 k2500 454 w/ hyddroboost, a gmt800 master, (had to grind down the outside to make it fit into the booster), and just finished modifying my stock 1500 pedal (moved the rod pivot up about an inch). so now once I get the cab back on the frame it should be a pretty quick install!

Guys- great info.. New to the forum with my 96 2dr... Can someone tell me the year "range" of truck I can look for to get these parts from that will be the bolt in for my 96? Thanks, any other advice appraised as well.

I found a 2002 3500 box truck that has the L31 in it but is nbs. Does anyone know if this brake pedal will work for doing the swap into my 97 k2500


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So you can use nbs gmt800 mastercylinder with hydro boost as long as you turn it down some? I see posts about just the master cylinder swap alone and good benefits due to the smaller plungers. And I see hydro boost with awesome benefits. If both used could that cause brakes to lock up easily?

91GMCK1500 said:

So you can use nbs gmt800 mastercylinder with hydro boost as long as you turn it down some? I see posts about just the master cylinder swap alone and good benefits due to the smaller plungers. And I see hydro boost with awesome benefits. If both used could that cause brakes to lock up easily?

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Just two weeks ago I installed hydroboost from an '02 2500HD/6.0L on my 99 K2500/5.7L. I swapped the booster, master cylinder, lines, and p/s pump. It was not a bolt on installation. I had to modify my brake pedal to make up for the shorter pushrod, drill a new hole in the firewall and fab up some brake lines. The difference in pedal feel and effort is 100% better though.

I want to do this on my 1991 Chevy Silverado C1500.

I've read the post, and still have a little confusion.

1. Are the parts list mentioned apply to the 88-94 model trucks? Like mine?
2. do i need to change out my power steering pump that is specific to the hydro boost. I just replace my factory one.
3. Seems there is mixed reviews on adding a cooler or not.
4. Has anyone done this on a 88-94 model and have any documentation? Parts list?
5. i would also like to add rear wheel disc brake conversion kit to the 91 Chevy. I saw one mention of needing a different master cylinder? true?
6. Anything else you wish to add to help this project along?

Thanks!!

Phillip Buessing said:

Just two weeks ago I installed hydroboost from an '02 2500HD/6.0L on my 99 K2500/5.7L. I swapped the booster, master cylinder, lines, and p/s pump. It was not a bolt on installation. I had to modify my brake pedal to make up for the shorter pushrod, drill a new hole in the firewall and fab up some brake lines. The difference in pedal feel and effort is 100% better though.

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Did the power steering pump bolt up or did it require modification since it was from an LS motor?


Edit: Read further back in the post that the GMT800 pump will bolt up.

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monstar_est87 said:

Finally a REAL Hydro boost write up..! Might I suggest adding part #s... And STICKY this thread..!


I wonder why ur 3500 isnt already equipped with hydro boost brakes..?



Would a diesel 1500 power steering unit work in this swap..? Or a 3500 power steering unit wit hyrdo work..? I have heard it might not bolt on but I'm not sure here...

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I did this swap on a 81 sq/b 3/4 ton 4x4. I used a hydo boost off similar yr 1ton. I kind of cheated by using my original m/c. O. D is a bit to big to fit into the hyd/b but very little grinding and it fit. Just bolted right on in place of the booster, no other mods. Works fantastic as i have little vacuum because of cam. I highly recommend this upgrade. As far as the pump goes if you use the proper one with two return lines you need the brackets that go with it because it has a bigger tank. I didnt have those brackets and had to modify the originals but other than that it bolted right on.

Cokeman95 said:

Did the power steering pump bolt up or did it require modification since it was from an LS motor?


Edit: Read further back in the post that the GMT800 pump will bolt up.

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You dont have to have a different pump. The proper pump has a bit bigger tank ( reservoir) and two return line connections but you don't HAVE to have that, you can just t into the existing return line. The reason for two return lines is because both the hydro boost & the steerimg box have one. You dont need to get to worked up over which pump....its just a pwr steering pump and you do already have one already mounted. It will work just fine.

DRAGGIN95 said:

I have owned a couple of factory 1 ton's with hydroboost that had no cooler from the factory, and I have not had a problem with them, but I am sure a cooler would keep the fluid cooler, and I have also tee'd in to the return line on at least a dozen 1/2 ton truck's with the regular vacume pump and had no problem, in fact I have 15K miles on my personal DD that is done the same way.

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Me too