Is there a difference in the brake booster and master cylinder between disc brakes and drum?

Most of the parts stores asked which I had in the front, discs or drums, when calling for prices on a new booster and master cylinder. The one with the best price and quickest availability didn't have the difference listed. Is there one? Thanks.

 

There is a difference in 4x4 vs 4x2 in certain years.

What year is your truck ?

 

Shouldn't be any difference for 2WD anyway, I think.
I bet they wanted to know because they were looking it up in the computer. They cannot step outside the computer's program, and don't know how to really find parts without it.

 

IRRC the disc brake master cylinder has a bigger piston. The drum brakes have a tendency to bind even tighter when they are applied. That's why you can have the parking brake set and back up unaware until you try to go forward. You don't get any such mechanical advantage with discs. A bigger piston in the master provides that advantage.

I never looked at converting to disc fronts, don't know if the proportioning valve is different.

 

The disc brakes are from a 1973 F100, 2wd. They are on my 67 F100 2wd.

 

My bad!
I did a few quick searches at napaonline, the masters have the same size pistons. There were some minor differences in the wheel cylinders: 1/16" diff in the rear cylinder diameters between '67 and '73 listings.

Maybe you should just go to a store that has both versions on the shelf, do a side by side.

 

I need to correct myself.
There is a difference between master cylinders; and there are several types of boosters.
For the 2WD boosters, they should all be the same '73 - '79.
There were a variety of boosters prior to '73.
The disc and drum master cylinders are not the same. One (I never can remember, but I think it is the disc type) has a restrictor to keep the pads close to the discs.

Yes, there is a difference in the proportioning valves as well, between disc and drum type.

 

I noted there was a difference right from the start

Right from the horse's mouth.

http://www.precisionrebuilders.com/p...ogPHB-0398.pdf

 

No parts stores around here have both on the shelf to compare them. In fact, none of them seem to even have ONE on the shelf. All of them need to be ordered.

Here I've always been told that larger cities had more to offer. I can't seem to find any of my parts in stock here. Where-as in my former home, a small town, they were usually right on hand. Go figure.

 

Time to say it again.

There are several methods to get brake upgrades on older trucks. The way that causes the least amount of issues, is to buy a donor 73-79 or 73-76 if you have a FE under the hood, and move the I-beams and power steering parts to your chassis.

Once complete, (If your donor was a 74F100) You go to the parts house and ask for 74 F100 replacement parts. It's that simple.

You can go to the yard and start pulling this and that and find your crying because some cat at the parts counter cant help you figure it out.

JD, I aint wanting to pee on your shoe laces, but the facts speak for themselves.

John

 

The booster for disc front is different than the booster for drum front. I think it has something to do with the throw.

 

Listen to our Moderator guys, THINK SYSTEM.

Otherwise you're just creating what we call a "Mulligan: as in Mulligan stew, where whatever we have gets thrown in & served up. It's OK with trim, paint, upholstery & other incidental stuff. With Brakes, wheels, tires and steering, it's not healty to either guess or mix & match.

FWIW Disc Brake Systems req' greater pressure while drum brake systems req greater fluid volume to expand shoes outward by filling wheel cyls w/ fluid. thus M-Cyls & the boosters are different. Do not count on the large franchise parts stores to have correct specifications for 30+ year old trucks. They only care about interchangability factors . Not "functional interchangability" either.

Consider this, some parts function right but & don't fit. Some parts fit right but don't function. Some parts don't fit or function right. Correct parts should always fit & function correctly so a vehicle performs at least the way it was designed to by engineers who built it. It can be improved on or be degraded depending on what is done to it. I prefer to always improve upon designs.

If shoe type systems are over pressured by using Disc type booster a risk of damage to drums and/or shoes thru' overheating when too much application pressure occurs.

Conversely, using drum type booster in disc systems produces less pressure in calipers (the reason disc systems require equalization valves) so the disc brakes become less effective although rear drum brakes in system do not, so then rear wheels are doing more "stopping" than front wheels do working with underpressured calipers/ discs.

In closing, think SYSTEMs!

When upgrading or retro fitting between model years my main objective is to improve upon whatever I start with. It is where notion of system integration applies. System integration is much more than adding random parts. I believe net end result of brake work should improve overall balance of performance, not reduce it.

But what do I know about braking/ performance anyway? Just my $.02 on this matter.

FBp

 

You'd think as long as I've been around here I'd get a little credit and or respect.

I bought the truck with the manual disc brakes from a 1973 already installed. If I were doing it, I would have gotten the whole setup together. But that's out of my hands at this point.

Beyond that, I don't have any room at my place in the Houston suburbs to park a parts truck if I were so inclined. I have a couple sitting at my family's place, but that's about 3 hours from here, and none of them have the parts I need.

Also, being that I intend on driving this truck for a considerable amount of time and much of that will be driving in Houston traffic, I prefer to go with new parts when possible. As opposed to scrap yard finds that have a higher likely-hood of failing when least opportune.

I'm working with what I have and trying to make sure I get the correct part that is going to work and fit right. I asked for the master cylinder and brake booster for a 1973 F100, as I was told my disc brakes came from. And as I said in my first post, one store didn't have separate listings for drum versus manual brakes, whereas the others did. Thus I wanted to be sure there was a difference, as I know many times, those questions really will have nothing to do with what part you need.

I do appreciate all the helpful insight. And please pee somewhere else.

 

jdbanks
I see you know what you're doing. . . . So the short answer is yes there is a difference between Disc & Drum type Boosters and M-Cyls.
IMHO avoid the guy who says they're the same. . .

FBp

 

In all fairness JD, you didn't mention it being a 73 in the original post.

That's why I never answered exactly which booster you needed,.

The year wasn't mentioned

The booster for the 73 is listed on that page I linked to.
These are the guys that rebuild them.