Hub vs flange mounted brake drum

[rreegg]

Making the rounds looking at brake drums for '88 F250 w/ 3" shoes. I'm curious if anyone knows what the difference is between hub mounted and flange mounted brake drums? Looks like the flange mounted has a rectangular tab on the exterior but not sure what that's for, it kind of looks like a long wheel weight.

I have a hunch they're interchangeable but cannot find much anywhere explaining the differences - doesn't the drum just fit onto the lug studs?

 

[u2slow]

Sound like "backmounted" vs slide-off drums.

On older full-floaters, drums were nearly always backmounted. You had to punch the studs out to take drums off the hubs. In the mid-80's Ford changed that and the drums slide off; dont need to remove hubs.

Drums and hubs are cast to fit one way or the other - not interchangable.

 

[rreegg]

Glad to not need to punch off the studs this time! I think the mounting flange is to assist in getting the wheel back in place, seems like kind of a gimmick vut are cheaper at some stores. Probably nothing to see here

 

[u2slow]

No gimmick here.

88 F250 drums should slide off with either design. The version with a protruding hub that has 8 more axle bolts is significantly stronger.

Parts books are getting terrible for suggesting every possible brake part used in a body style; in this case, '80-97, so watch for that.
What you see as a "wheel weight" is essentially that. To balance the brake drum.

 

[rreegg]

Are the drums shown in the pic the same as you're mentioning @u2slow ? I'm genuinely curious

 

[u2slow]

On those 2 drums, the center hole size differs 137mm vs 127mm. Match what you have.

I suspect this is still the full-float vs semi-float difference.

edit: "flange mount" or "hub mount" is not traditional or intuitive verbage in this case.

 

[franklin2]

The older trucks with the Dana rearend usually had the drums that were behind the flange. The Ford/Sterling rearends had the slide off drums. Semi-float was a different animal, I would think the center hole would be too small on those and they would most likely have the narrow brake shoes.

 

[rreegg]

the center hole size differs 137mm vs 127mm.

Nice catch

 

[u2slow]

My experience is the Dana axle on a SRW F-series ended around 84-85.

 

[rreegg]

Drums are right at wear limit with a 5”/127mm center hole. Thanks for the help and ready to get this show back on the road with the proper new drums

 

[u2slow]

Fwiw, i keep running drums like that. Fresh shoes to take up the slack, knowing that i typically get 10+ years use out of a set. (check on them when you rotate tires.) YMMV.

 

[franklin2]

Just don't get them turned beyond the limit. Been there, done that. Some places will turn the drums because you paid them to, and do not even measure them.

Did a brake job on a old 66 GMC pickup. After that I never had a good solid pedal. I messed with that thing for months. I finally caught it, they had turned the rear drums too thin and they were flexing when I pushed on the brake pedal. Lesson learned, even when you take your stuff to a shop, be on your toes and know everything about what they are doing and get the specs yourself.

Now I try not to turn the drums unless they have a large ridge on the outside edge. If they have that big of a ridge where I can't them slid off, they are probably toast anyway.

 

[Old-Red]

Can I jump in and ask about my 1986 F-250 6.9L 4x4? I will be getting mine done soon and wanted to ask if the drums are easy to remove style that rreegg has on his 1988 F250? And if so are they the HUB or FLANGE mount? Then too, if the wear limit is also a 5”/127mm center hole?

 

[rreegg]

Can I jump in and ask about my 1986 F-250 6.9L 4x4? I will be getting mine done soon and wanted to ask if the drums are easy to remove style that rreegg has on his 1988 F250? And if so are they the HUB or FLANGE mount? Then too, if the wear limit is also a 5”/127mm center hole?

The drums should pull right off and it's very possible the parts are the same. You may have 2.5" wide brake shoes/drums but measuring will be the only way to know for sure--mine are 3". It's easy to tell the center hole diameter with a simple tape measure or ruler

Background on my truck:
- new rear brake shoes, brake cylinder, hardware kit and adjustment last year. did Not change the drums as they're a wait-n-see item
- brakes have been feeling OK but probably needed adjustment

I haven't yet purchased new drums. Have made multiple measurements with a tape measure/ruler but haven't trusted them. Purchased a "brake resetting gauge" from summit racing last night to get definitive measurements. The difference in diameter between new and Old is only like 2.5 mm so high precision measurements are important - I've measured about 12-1/16" with a tape measure which is about 1/32" to 1/16" short of wear limit.

Still trying to get the brakes dialed in with this truck but it's kind of a moving target. Currently the rear driver brake catches better than the rear passenger despite recent adjustment.

 

[u2slow]

And if so are they the HUB or FLANGE mount?

The difficulty is nobody knows which label means what exactly.

The drum slides right off whether its semifloat or fullfloat. In neither case is the drum mounted; its held on by the wheel.