2.5" v.s. 3" drum brake difference

[Vern]

Hi there, can anyone help me out by explaining the differences between 2.3 and 3 inch drum brakes before I get in there this evening? Obviously the drum and shoes are different but what about hardware and backing plate?
Bought 3" shoes when i need 2.5 but the parts truxk has 3 and drums look good. Perhaps there's some parts compatability.
Thanks in advance.

 

[towcat]

2.5" SRW
3" DRW

 

[hce]

2.5" below 8500 gvw
3" above 8500 gvw
3.5" is for duallies.

 

[ifrythings]

2.5" SRW
3" DRW

You mean
2.5” semi floating
3.0” full floating srw
3.5” full floating drw

 

[Vern]

Apparently there are 3" on my parts truck srw with overload springs also. I'm wondering what needs swapping to upgrade to the 3".

 

[hce]

Apparently there are 3" on my parts truck srw with overload springs also. I'm wondering what needs swapping to upgrade to the 3".

I would imagine the only practical way would be to swap rearends.

 

[Vern]

I would imagine the only practical way would be to swap rearends.

You don't think the backing plates could be removed then?

 

[Vern]

I would imagine the only practical way would be to swap rearends.

o.k. I see the full floater wasn't offered with 2.5" brakes, and in my particular case somewhere along the line a PO put 2.5" shoes in a 3" drum. The 2.5" drum I bought would not fit over the axle flange. What a saga.

 

[Dirtleg]

Just to muddy it up some more. When replacing my rear wheel cylinders I was able to determine the F250, F350 SRW and F350 DRW wheel cylinders were all different.

 

[Macrobb]

Just curious, but did Ford ever put a semi-floating 10.25 behind an IDI? I've only seen full-floating 10.25s and Danas on the earlier models.

 

[compressionignitionrules]

I had a dana 70 behind an idi, but it was a 1984 F250 with a T19 . never seen a Fseries semifloat behind anything but a 4.9 or 5.0 in a an F250 light duty.

 

[subway]

i had a semifloat in my F350 crew but i think that was swapped in, i was under the impression that the semi floats were only a light F250 option.