66 chevy pu drum to disk ?

Just got my PU runing again and may have a break problem. When I bought the truck it had allready had the disk breaks put on the front and they said they put a new master cyl. on it. I know there is a diffrence in back presher on drums and disk with disk having less. What I dont know is if my tuuck still has the 66 boster and cyl and they just put on a new 66 cyl or if its updated to the boster a cyl I need. Here are some pics of whats on it. Can anyone tell me. Allso if this is the 66 boster and cyl why cant I just take out the residual out of the master cyl or valve

 

looks like the later model one. My old 66 had a 1 pot m/c with drums.

 

looks like the original booster, with a newer disk brake m/c

 

That looks like the drum/drum setup, or a disc drum from a 3/4 ton. I had that setup and it didn't work with my 1/2 ton stainless brake line kit. So i got a new master for a 72 c10 disc/drum, it has a larger resevoir in the front (for the discs) and a smaller one closest to the cab for the drums. Head over to www.67-72chevytrucks.com if you need to.

And you'll need a proportioning valve for the 71-72 truck as well. The valve closest to the master on the drum/drum setups is a distribution block which just directs the fluid.

I used a 71-72 booster so i couldn't tell you if its stock or not, if the bolts all go into threaded bosses then its most likely factory. You can run whatever booster you want, just match the master cylinder to the proportioning valve and you'll be good to go.

 

looks to me like the older Vette 4 wheel disk m/c

http://www.allstarperformance.com/product.htm?prod=372

the drum/drum m/c has a smaller top on it, smaller reservoirs

 

I agree....Vette master.

 

Steve.....mine is a 64 and has a single resevior cylinder with a wire bail holding the cap on..I think 66 was the same as 64.

 

yeah, 66 originally used a single m/c

 

Thanks for the info guys. The first time I drove the truck (about ten miles) I got break fade real bad but the truck had been setting for some years. They dont seem to be to bad now, you just have to aply a lil more presher then I think you should. I think ill drive it some more and see what they do.

 

i see that it has power brakes ...but you say that it takes more pedal pressure than you think it should

what is that line from the booster hooked up to?

 

you can get one from (ece) or you can swipe one from a "72" and rebuild it....(my picture was too big to process)

 

It goes to the back of the carb where it be longs. Im not shure it should have that boster or whatever it is in the line though.

 

If you are having alot of trouble check out www.earlyclassic.com. They have all the stuff you need and a good tech line.559.291.1611

 

Why don't you try bleeding them?
if they're bled already and don't have air in the lines they aren't going to get any better.

 

I had a '66 C20 3/4 ton about three years ago & did the complete swap from drum to disc, i used a complete front crossmember from an '82 truck which bolted right in place, with only two extra holes needed in the chassis! even the steering arms connected up ok.
As for the master yours is a later type with booster from a late model as the original had no booster & used two bolts to secure it to the firewall, i used a Camaro unit complete with residual valve & that was easy to fit too, as it used the two existing holes & only needed two more made plus extending the operating rod.

Kev.

 

power brakes were optional back then ,and they had a funky booster like that....notice the mount at the firewall, won't see that anywhere else

 

Yeah i just took a closer look at that linkage thru the firewall........would they have run the booster with drums or?

I remember the shop manual having a section on air brakes for the larger chassis trucks with the same body.

Kev.

 

all they had was drums, so yeah, they would have run the booster with a single m/c with drums.