Nbs hydroboost on an obs?
 

Will it work? I want to use the booster and master cylinder.

By NBS you mean 99-07 classic and by OBS you mean 88-00? If so then yes it will but without a little work.

I put both the booster and master cylinder from a 06 1 ton dually on my 95. The backing plate of the NBS booster has one stud thats offset from the rest and doesn't directly bolt up to the OBS firewall. I believe all that would need to be done is drill one hole but I'm not sure if thats doable or not do to potential brackets, braces, and what not that may be in the way. What I did was build my own backing plate out of 1/4 inch plate. After extensive google searching I found links to CAD drawings with the proper dimensions for building an OBS backing plate.

http://img.photobucket.com/albums/v6...5/HBoffset.jpg
http://img.photobucket.com/albums/v6...HBcentered.jpg
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I like it a lot. I got hoses for a 5.7 3/4 ton truck with hydroboost and they fit good even with a 3 inch body lift, still plenty of slack. The return hose is just bulk power steering return hose and to get the hook at the hydrobooster without kicking I bent a piece of 5/16 inch tubing in a 90 and shoved it up inside the hose. There isn't really enough return flow there to cause a restriction and its been working great for 3 years. I was going to get the factory NBS return hose but it was something like 60 bucks or more from GM.

Also keep in mind you will need a brake pedal for hydroboost. The pin is actually positioned higher up on the pedal.

One last thing. One of the fittings on my stock master cylinder was bigger than on the NBS master cylinder. I believe on the NBS master cylinder both fittings were 1/2 x 20 and I want to say the front fitting on my stock master cylinder was slightly larger, I think 9/16 thread. I ended up cutting the flare off, sliding on a new nut and reflaring rather then trying to find an adapter.

Thank you, this is great info. I just picked up the booster and master cylinder today. I'm a little confused about the whole offset or centered mounting plate. Which one do I need to use. I think I'm just gonna try to drill a hole though. I still have to track down a pedal and hoses, then make some time to swap it out.

I didn't understand it either but some OBS trucks had an offset backing plate and some were centered. I made mine centered as you can see. There is one last thing I forgot to mention and that is that you most likely will have to cut the rod off the old vacuum booster and put it on the hydrobooster. The eyelet on the rods are different for an OBS pedal vs an NBS pedal. It wasn't hard to do, just took some careful measuring then cutting some threads and using a 3/8 coarse thread coupler to connect the two pieces together. Like I said its been working great for years now. I got all my parts for free minus the hoses so I could justify the extra bit of fab work I had to do.

Can't I just use a brake pedal from a nbs and not have to change the rod? Or will that pedal not work in an obs?

Never held them side by side but I can't imagine it fitting. I think when I originally put mine on I wasn't aware of the difference in the pedals and used the hydroboost and stock pedal together but I did of course have to change out the pedal rod end. This worked but it gave me a really high hard pedal. Then I changed out the pedal and having already had the rod threaded and what not I just had to shorten it up a hair and it all fit just fine. Like I said there is some fab work involved. Its nothing too difficult but its not going to be a direct bolt on swap. If you get the OBS hydroboost parts then of course its pretty much going to be but either way you need to change out the pedal.

Ok, thank you. I'm gonna try to get both pedals so I can compare them.