Brake master cylinder swap help
 

Hello everyone! The other day I spent a good couple hours in the junk yard and scored a front crossmember off of a 78 c20 to upgrade my 65 c20 brakes. At the junkyard an oldtimer came around was enthralled to say the least of me doing this and was telling me that I needed a dual master cylinder set up and not a single like the old chevys have. In telling me that we went over to a 1984 c20 6 lug van and grabbed the brake master cylinder off of that, he was saying as long as this bolted up, had the proper stroke and the proportioning valve it would work. So I grabbed it up and payed only 50 bucks for everything. My question is does this part need the vaccum booster to work properly or will just the manual force make me stop? "If all the parts from the junkyard line up and work" Thank you everyone for your help, I did do a search but could only find troubleshooting help. :chevy:

Re: Brake master cylinder swap help
 

The short answer is no. Now for the long version. Your best bet would be to get one for the truck you pulled the front end off of. You need to try and match the master to the brakes and a 6 lug c20 van may have different calipers from an 8 lug truck. You also need a manual master if you don’t want to use a booster. Manual brake trucks use smaller pistons to create more pressure and power brake trucks use bigger pistons so if you use a power master cylinder without a booster it will work but will require more force to stop.

Re: Brake master cylinder swap help
 

If it had a booster on it from the 84 which I think it did you probably have a 1-1/8 or so bore master, making it more difficult to push with the pedal if it fits at all. Did you get Captainfabs master cylinder firewall adapter yet? http://www.67-72chevytrucks.com/vboa...=1#post3257836

Re: Brake master cylinder swap help
 

I would have loved too, but... That poor truck was stripped down to just the frame and body. I'm a greenhorn when it comes to mixing and matching brake components. That was my plan was to support the fourm and its members and purchase captinsfabs products, but this truck is a very slow moving project as I have way too many in my garage. I just wanted to get all my ducks in a row so when it comes down to it ill be able to controll what I can and let the truck throw the curve balls! :D :D :D
But thank you guys for your help!

Re: Brake master cylinder swap help
 

The brake booster on the '84 G20 van will bolt right up to one of my booster brackets. You can use either the '84 master cylinder or go to the parts store and pick up a '78 C20 master cylinder and bolt it to the '84 booster.