According to Rock Auto website, and my ' go to parts guy ', the wheel cylinder, shoes, hardware kit, drum, are available in either 2 1/4" or 2 1/2", so it appears all of those components need to match. It looks as if there is more than enough distance from backing plate to the inside of the drum (surface of axle hub) to accommodate the wider 2 1/2" setup, after further thought maybe the 2 1/2" is a slightly heavier duty set up, perhaps it dissipates heat better so it would be less likely to warp. A B3500 has a 13" x 3 1/2" setup.How would you make it fit? Do you have wider drums available?
Maybe the slightly wider setup would dissipate heat better so less likely to warp, I am not hard on the drive train as much as I can be heavy on brakes.You probably will not gain braking power much as the PSI applying the brake will not be changed. Just lower pressure per lining size. That will give you longer life.
Thinking is more along the lines if the 2 1/2" are slightly heavier duty and the other system components are compatible with either size, then just go with the 2 1/2". Not a huge size difference % wise between 2 1/4" and 2 1/2", thoughts were it could be the shoe width are interchangeable and the rest of the system components remain the same. Obviously no desire to alter something that should not be altered.Your van already has RWAL or possibly 4 wheel ABS. Don't alter the balance of braking front to rear. You shouldn't need to. If there is a braking problem, address the real problem first.
You mention heat and warping.
The front brakes do most of the stopping. If you are pulling a loaded van/trailer in hilly country, keep well within the margin of safety or look for a heavier-duty truck (2500/3500?). The suspension and steering is almost 24 years old on this 1/2-ton 1500 as it is.
If you are asking a lot from the brakes, use premium components and expect a more frequent need for service.
I suppose it is possible that the backing plates could be different, I would think that the backing plates would be the same for either the 11" x 2 1/4" or the 11" x 2 1/2" setup, but I could be wrong. Figure not only would the drum be wider but probably thicker as well, and of course it would be this wider thicker drum that would help dissipate heat better, and less likely to warp, as much as it would be the shoe, that goes without being said.That would be normal. Backing plates would be different too.
Possible rear axle swap?I suppose it is possible that the backing plates could be different, I would think that the backing plates would be the same for either the 11" x 2 1/4" or the 11" x 2 1/2" setup, but I could be wrong. Figure not only would the drum be wider but probably thicker as well, and of course it would be this wider thicker drum that would help dissipate heat better, and less likely to warp, as much as it would be the shoe, that goes without being said.
I made a mistake earlier when I said the B3500 has a 13 " setup, it is a 12.13" setup.
12.13 x 3 "
12.13" x 3.5"
There is also a listing for a 11" x 2.5" as a light duty setup for a B3500, but then this is the RockAuto listing for a 23 year old van, so who knows how accurate the listing is or if they even care that it is.
The reason I posted this thread is because I figured at some point down through the years somebody may have came across this exact same question, and the answer may have been " yeah, you can use either a 2 1/4" or 2 1./2" setup, the rest of the braking system is the same, so long as the wheel cylinder, shoe, hardware kit and drum are matched for either size. " Figured it could be possible that for inventory reasons the ABS, master cylinder, brake line are the same for either setup, and that Dodge figured they could save $1.00 with the lighter shoe and drum, but who knows, irrelevant now.
I plan on replacing everything, so now would be the time to make the change, if there was a change to be made.
Are you asking if it has been, or, if one can be done ?Possible rear axle swap?
That's the spirit! But speaking as someone who is also not yet done sinking money into an older Dodge van I would urge both of us not to lose sight of sanity with our respective projects. Lots of room for cubic dollars in these things, no matter how good our intentions.It has pretty much been one thing or another with this van since I got it and even before I got it, but for $2,250 + $1,000 shipping figured I would have to put about $1,250 or so into it anyhow (not counting undercoating or sealing the undercarriage or a paint job, if that ever happens), but if I do the work myself that is quite a bit of a newer parts (brakes, suspension, tune-up, whatever else) and hopefully she will be reliable as the day is long, needs to be, even if I put two big ones into the van it is still around what they are selling for, $ 4,000 to $5,000, and that is probably not with a lot of newer parts, plus doing the work myself I know a lot of it will be done right.
Seeing how I live up North it is well worth the extra thousand dollars to not have a rusted van. Driving a Chevy, or a Ford, or a GMC cargo van ain't going to happen, I will go out of business first.