Drum Brake Question

Hello, I believe my F100 originally came with manual brakes however there is a vacuum booster currently installed (not done by me). My F100 has 5x5.5 lug pattern and inside diameter of brake drum is 11". I found a crack next to one of the brake shoe rivets so I will be replacing shoes, wheel cylinders, and hardware.

My question is, are wheel cylinders specific to manual (11") or power (10") brakes? At the part stores all the brake parts options are designated for manual or power, because of the two different sizes, including the wheel cylinders. Should I order power or manual brake wheel cylinders or does it not matter?

Thank you for your time  

If you go to the page at Documentation/Driveline/Brakes and then go to the Rear Brakes and then the Rear Brake Parts List tabs you'll see that the manual brakes are 11" and the power brakes are 10".  And the manuals use Parts List #1 while the power uses Parts List #2, both of which are included on that page.

Here is a snippet of Parts List #1 showing the wheel cylinders being part # D30Z 2128-A.




And here is a snippet of Parts List #2 showing the wheel cylinders.  Note that there are two different part numbers.  The Year column says that D30Z-A is used "80/", which means 1980 to the end of the catalog, which is 1989.  And then it says D2SZ-A is to be used on 1984 vehicles.

So I think your truck with 11" drums should use Parts List 1, but that your wheel cylinders are the same as those in PL 2.

Thank you for your help Gary! That confirms my question. A semi related follow question for you. When replacing the brake combination valve, is it best practice to drain the master cylinder reservoir first OR try to plug the outlets to keep fluid in reservoir? I’d like to make the least amount of mess as possible.

I would suck the fluid out of the master cylinder with a turkey baster bulb.  That will minimize the mess.  And since I'd want all new fluid in my system that would be a good start.

Copy that, thank you!

FYI
My 81 F100 with the 5.5 wheel pattern was a manual brake truck but my parts truck had power with 4.5 pattern.
I wanted power so did a lot of checking and came to the same out come the for the F100 trucks power or non-power used the same wheel cly.

The only think I have to remember when getting brake parts is everything at the wheels are for a non-power system.

BTW front beams on out are different between 5.5 / non-power and 4.5 / power trucks but the calipers have the same piston dia. between the 2 trucks.

I also found the masters had the same piston dia. between power & non-power and that would make sense being the calipers piston dia. & wheel cly are the same.
Dave ----

Dave,

Thank you very much for your helpful insight. Regarding your comment about different beams, do you know what is different between power and non power trucks? is it something in addition to the spindles like forged vs. stamped beams? I guess if I ever had to replace beams in the future I would probably upgrade to a newer ball joint system but curious to know either way.

Kind regards,
Jesse

Jesse3877 wrote

Dave,

Thank you very much for your helpful insight. Regarding your comment about different beams, do you know what is different between power and non power trucks? is it something in addition to the spindles like forged vs. stamped beams? I guess if I ever had to replace beams in the future I would probably upgrade to a newer ball joint system but curious to know either way.

Kind regards,
Jesse

Both my trucks were 81's (late 80 mine / early 81 parts) and had forged beams.
The 2 bolted in to my truck, it is the kingpin size.
Because the pins are different sizes in the beams is why you cant swap the spindles.
Now if you have the large pins (in my searching large wheel pattern too) and wanted to go small pins guess you could find a machine shop to make bushings to fit the large pin beams and the small pins & spindles for the small wheel pattern.

My truck came with after market 5.5 wheels but frozen pins.
Parts truck came with 4.5 steel wheels that did not fit, used only to get it on my trailer.
I did not know of the wheel pattern at the time. Plan was to swap the full front suspension from parts truck to mine.

When I went to put my wheels on is when I found out about the pattern issue.
I then thought I would just swap hubs, nope the spindles are different.
When looking deeper into it is when I  found the kingpin size difference making the beams different also.

So you can unbolt the beams from the frame and swap as a whole but can not swap parts between the 2 wheel bolt patterns from beams on out.

Now based on that and how my trucks were built with different wheel patterns and how others were built is how I came to the power & non-power brake setup.
It seams for the F100 trucks, they were the only trucks with the different wheel patterns, the large pattern came with non-power brakes & large kingpins and the small pattern had power brakes and small kingpins.

Again it is what I have come a cross on the F100 trucks.
The F150 trucks all had the larger wheel pattern of 5.5 (and guessing larger kingpins?) and then in 84? went to ball joints.
Dave ----

ps both of my trucks were the same GVWR of 4700 and 300 six so that was not it on patterns.
Small pattern style side long bed, SROD transmission, AC, PS, PB.
Big pattern flare side short bed, T18 transmission, PS.

I beleive the beams up to early 90s I think it is will bolt into our trucks.

Great info Dave!

Thanks for your time.
Jesse