71 C30 Vacuum to Hydraulic Brake Booster Conversion

[71Dually]

Greetings,

Looking into converting the brakes on my 71 C30 Dually to later RPO JB8 with hydraboost.

With the exception of the out of round rear drums on my Eaton HO72 my brakes work fine. I picked up some JB8 13 X 3-1/2 rear brakes to convert to the 14BFF type. So now I want to upgrade the entire system to the larger JB8 brakes for a little bit more stopping power. Funny how one thing leads to another sometimes.

Currently scouring part catalogues for acceptable interchanges and parts info.

I read several threads regarding spindle, rear brake, hydraboost swaps etc...

I'm a tech kind of guy and looking at the parts books has helped but also brings up more questions. One question is about the size of the pistons in the hydraboost units and what would be best for my application. The catalogues hint that there are different diameter pistons (example .78 & .60) The light truck catalogues show the hydraboost came on everything from C10's with disc/drum to Motorhomes and P30's with Disc/Disc and GVW's up to 14,000 lbs. I got it figured I'm looking for a booster from a comparable GVW vehicle as mine rather than a C10.

In one of the catalogues it says refer to a hydraulic booster chart for additional information. It also mentions service pedal rods and to check this chart for those applications also.

My question is does anyone know where to find the Hydraulic Power Booster Chart the catalogue refers to. I think it may be in the catalogue but the "browse" feature on GMpartswiki requires I page thru way to much to see if its there. If it is in the catalogue does anyone know where about it may be to help narrow my search so I don't have to page browse the entire book.

Here's a pic of that reference in the catalogue to the booster chart.


Any input on this conversion is greatly appreciated. I'm mostly wondering about mounting brackets and such as I really don't want to do a lot of modifying to get this stuff all installed. I understand I may need to do a little but I just don't want to start chopping stuff up, modifying every thing I buy and cutting holes in my cab etc... if it isn't necessary.

Ideally I can do this conversion as a bolt in with all factory parts. I once installed a C6 transmission behind a 351C-4V in my 1970 Mercury Cougar. Everything was bone stock parts, no welding, cutting, drilling or modifying at all, everything bolted right in. The only exception was a custom length speedo cable as the C6 was never originally installed behind this engine in 1970. But that was real easy to have made at the speedometer shop. Meanwhile I didn't do anything to my rare Cougar Eliminator that can not be undone with the original parts I've saved. Hopefully I can do the same with my C30.

Thank you for your input and assistance.