disc brake drag

[old timer]

I converted from drum to disc and they work good.
When you spin the tire with drum brakes it spins; but with disc brakes it just turns a little bit. Is there some trick so there is less drag on the rotor when brakes are released?

[mcarlson11]

that is normal, discs are supposed to drag somewhat. Drums are supposed to as well, when you put new shoes in on.

[Jake11]

Did you change your master cyl.?
The drum brake one has a ck. valve in it. It will make the disks drag.
If not, you can take it out pretty easy.

[old timer]

Yes when I put the brakes on i went with new rotors,rebuilt calipers, and new master cylinder that matched year of discs. I thought there was some trick to make the calipers back off more so they wouldn't drag.
If they would release another 1/4 inch there wouldn't be any drag.

[FORDification]

But then you wouldn't have enough pedal travel to engage them. Don't worry, it really IS how they were designed....that is, to have a slight drag.

[1968flareside]

Somewhat of a hijack here...

I'm getting ready to pick up the disc brake assembly to put in my 68. I already have factory power brakes. My question? Do I need the booster from the donor truck or can I use mine? And then I'll need the year, model of master cylinder that matches the donor truck?

[fordman]

yes you need the mc from the donor truck

[FORDification]

Right. Master cylinders are the same for power or non-power setups. It's when you change to disc brakes that they need upgraded.

[dragtruck]

I've done 6 disc brake swaps,I reuse the drum brake MC(if its the large small resivor type).I first swap the brake lines so the rear brakes are operated off the front of the MC(small resivor),I pull out the check valve on the rear part of the MC and run the front brakes off the rear,and bleed.I use the same power booster weather disc or drum,the brake pedals are the same,I have tried using a combo valve or just leaving the splitter in,the splitter works better,and all the coversions I have done have stopped hard.My last conversion,I redrilled the F250 discs to 5 lug,turned the face of the hub down from 1" to 1/2" and used all my drum brake hard ware except for all the parts and flex lines on the beams and installed it on my 72 F100,it stoppes my truck from 135mph extremely quick,this using all factory parts.