So, after having one of my rear wheels fall off yesterday on the freeway, I ordered a new drum and studs for my rear hub from the local NAPA. The drum came in today and it wasn't even close! The parts guy and I did some more digging around and when we cross-checked the seal number in my hub, it told us that I have a VERY heavy dana 70 (rated at 9000#, the book said!?) with 12x3 inch brakes. The shoes that are in it are only 2 1/2, but the drum is clearly 3" wide and very big and heavy. The door plate says the gross axle weight rating (GAWR) is 6084#. To make things even more confusing, the parts books all say that the 3" brakes are only on dual wheel 1-ton axles! The differential cover is a big 10 bolt pattern. There are part numbers all over the place on the axle and it's tag, but nothing in the NAPA guy's book used any of those part numbers.

Can anyone clue me in to what kind of axle I might have, or where I might go to reference the part numbers on the tag? If it is a dually 1 ton axle, what would it take to put dual wheels on it?

I guess the good news is that it is nice a big and beefy, but finding the right parts is becoming a PITA.

Thanks!

 

There should be a decal under the hood stating what rear axle you have. My dad's 93, 2WD has the 12x3 drums and it is a 250 SRW.

 

I noticed something similar when buying brake rotors. there was a normal and a heavy duty set in stock. I think if your GVWR is 8800lb on the door jamb sticker its likely you have the heavy duty axles.

 

Unfortunately, the decal under the hood is all faded out. I wish they would put those things somewhere sensible where they would remain readable! Is there someway to get that info from the VIN?

The door plate says GVWR is 8510#.

 

The drums on the W250s are ALL 12x3, and they came from the factory with 12x2.5 shoes. It is a worthwhile improvement to install 12x3 shoes, and I install these on all W250s I service. It only involves making sure the friction surface on the drum is completely machined. I haven't had much problem sourcing the proper drums- I believe they're all the same.

 

The napa catalog listed three different drums for the truck, two different 12x2.5 (for 5500# and 6200# axles) and a 12x3 which was supposedly for duallies. I initially ordered the drum for the 6200# axle, since that what the doorplate said the rear axle was, and that drum was nothing like the one I took off. not even in the same weight class...

I was wondering if it is possible to put the 3" brakes on, not that mine need changing yet. It's probably been 80,000 since the last brake job and the shoes look like they have at least 35% thickness left. I'm pretty broke so I will save that for later when I do the fronts at the same time. I know I have a warped rotor or two up there, but the pads look great there too.