Rear Wheel Cylinder Question

[mcdougald7824]

Please forgive me I have never ventured into the rear axle so I’m entering virgin territory…

I just returned after being away taking care of family for the last two months to find out that the brake master cylinder on my `92 D250 had taken a dump. After replacing the master cylinder I started bleeding the brake system and found that the passenger’s rear wheel cylinder had also blown out since I was gone. Since I live in the wonderfully humid south Alabama, I was wondering what the possibility of water collecting in my brake system and freezing as a cause of the two failures at the same time?

Next question(s) I just finished reading the Chilton’s repair manual and have decided that its 9 steps to removing/installing the brake drum are about as useful as toilet paper. What steps do I need to do to remove the axle and the brake drum to gain access to the Wheel cylinder?

Does anyone have an idea on what size wheel cylinder that I need to get? I looked on the part store’s website and they are showing 3 different sizes: 15/16”, 7/8” or 1”?

I think that I have gotten the parts that I need to order down to the following, If `yall notice anything different or that I need to add please let me know…

1) Wheel cylinder
2) Gasket for axle hub
3) Brake shoes
4) (any misc. hardware that needs replacing)

[oldestof11]

Get everything for a 1ton truck. 1" cylinder, 3" shoes, resurface/new drums for the 3" shoes, associated hardware. The difference between the 3/4 and 1 ton brakes are the shoes and cylinders.

[ellis93]

I'd convert to one ton brakes and get rid of the ABS at the same time. Parts for the shoe swap w/ wheel cylinders Raybestos 314PG - 3" rear shoesRaybestos WC36057/WC36058 - wheel cylinders for conversion to 3" brakes _________________
Also check out this treads post. http://www.dieseltruckresource.com/dev/ ... l?t=102027

[slow_90firebird]

ive never changed the axle flange gasket on either floating axle truck ive owned both my 78 chevy and 93 cummins. As long as someone before you didnt mess with it like putting RTV in there or something, it should be a thin steel gasket.

Make sure you get the socket for the axle nut before you get into the project. IIRC dont quote me on this i think it was a 2 9/16" 6-point axle socket with rounded corners. I couldnt find the one with rounded corners so i got the sharp corner one and it worked just had a loose fit.

[mcdougald7824]

Hello all, Well here is an update on my wheel cylinder delima… I removed all the necessary parts and removed the wheel cylinder. One of the outer rubber boots was partially off the cylinder and when I removed the other one I found that the cylinder was rusted and full of nothing but water.

I took the old shoes and the cylinder to the part store and was informed that using the numbers off of my old parts that the vehicle already had 1 ton brake parts on it. The bearings and seals appeared to be recently replaced ( (NGK bearings) those part numbers also were also from a 1 ton rear-end)

I was wondering… under the hood of my truck is the line ticket from when the truck was manufactured. How can I tell from the mass if numbers listed if a 1 ton axle was placed under this D250?

The part store did not have a socket to fit the axle so I fabricated one out of 1/16th in. steel bar stock. Hard part was cutting the hole for the ratchet J. everything went together too smoothly, even the axle slid right into the splines on the first time.

Thanks for the link to http://www.dieseltruckresource.com I found some of the stickys to be very beneficial. And I think in the future that a disk brake conversion might be in store but now I have a question:

When would disk brakes benefit over the factory Drums? I do on occasion haul a trailer loaded with a tractor and implements from my house to my father’s and want to know that my truck will be able to stop on the hills.

[dunes450r]

disc brakes offer better stopping power than drums, that's the benefit. doesn't the trailer have brakes as well?

[mcdougald7824]

disc brakes offer better stopping power than drums, that's the benefit. doesn't the trailer have brakes as well?

yup trailer has brakes but i believe in redundancy if one system fails i want to be sure that the other system will work. (call me paranoid) I know that disk brakes will stop but if stopped on a hill (either up or down) do they have the same holding power as the drum brakes do? Im not worried about high speed stopping since my truck rarely sees speeds over 75mph

[ellis93]

This is what I've been told. Disc brakes offer more stopping power because of its ability multiply hydraulic force also they cool way better than drums do offering less brake fade from heat. What sucks about disc brakes is the way that E-brake set up on some. Some use the tail shaft of the trans. Where a drum brake is mounted (old ford superdutys) others use small brake shoes inside the rotors(very few work well) offering little stopping or holding power.

[mcdougald7824]

Yeah I've seen the drum on the tranny.... i believe that it was on an allison out of a school bus that somone swapped into a 1st gen. but not too fond of the "what if my drive shaft breaks. thought ?" any who....

ellis93... i just realised that you live up the road from me. I live in south mobile but spend a good bit of my day up near citronelle. I reach radio repeaters in Lucedale with my ham radio... nice to know someone near by!

[ellis93]

Yep 30 miles from mobile. I'm in and out of that city all the time. Doctor app and hitting salvage yards. if helps needed pm me.

[ahale2772]

wohhh... whooo.. whoooo...mcdougald7824 . alison from a school buss in a first gen?? ive been wanting to do that...infact ive got the cummins with the alison sitting waiting for me to do it, have any info on that truck??

dont mean to jack the thread

[Hansen01]

so i got a wheel cylinder out on my truck replaced it last year and its leaking again, i cant remember the 3quarter ton size, anyone know it?

[collegekid]

why do tractor trailers use drums if the stopping power of discs is superior?

[ellis93]

why do tractor trailers use drums if the stopping power of discs is superior?

Some have disc brakes,but its rarely seen.
I think that the semi builders industry still use drum brakes is because of they're reliability and maybe the thought "well its worked for 50 yrs so why change it now".