1973 10" x 2" original rear drum brakes vs. 1970 11" x 2.5" rear drums??

[Road_Runner]

Simple question, is there that big an advantage to swapping the original 10" rear drum brakes on my 73 Barracuda with the larger 11" rear drum brakes from a 70?  I am probably going to swap the front rotors out for the larger 11.75 ones from a late 70's Mopar but if I stay with drums on the back is more stopping power necessarily good on an E Body?  The one time I had to emergency stop the Barracuda the back tires instantly locked up with the back of the car wanting to come around even though I was driving in a straight line.  Anybody done this and can share their experience, whether it was a big difference, worth it, etc.?

Thanks in advance, Jim

[RCCDrew]

Bump.  Anyone?? I was wondering the same thing.

[Chryco Psycho]

Most of the time the rear has too much bite & will lock up first thus the proportioning valve to balance the system so having more rear braking power would offset the balance more to the rear requiring the prop valve to limit the rear brakes even more to keep the balance . So IMO no advantage . Brad used different wheel cylinders to get a better balance without the prop valve limiting the rear . Most of the braking is provided by the front brakes as the weight will shift forward as the brakes are applied & the front will have the most traction .

[4 speed fish]

I used the 11's on the rear because the finned drums look better thru the rally wheel.I have power front and never had issues with the backs locking up.

[Mopar Mitch]

The smaller drums and related parts are considerably lighter than the larger finned brake setup.... I have both for the rear... been using the lighter brakes for reduced overall weight on the car.... may someday swap to the Dr. Diff 10.75" rear disc setup.  My stock brakes are pretty good (use old semi-metallic asbestos Wagner brake pads up front and Wagner asbestos/organic rear shoes... they haven't made the better asbestos material in roughly 25 years.. and when I'm done using those pads/shoes, then I'll re-consider my entire brake setup... pylon autocross and hi-speed road course lapping events/HSAX events...

[Katfish]

I used the 11's on the rear because the finned drums look better thru the rally wheel.I have power front and never had issues with the backs locking up.

I like the larger finned look too, but my rear still locks up even with the smaller WC.
Next step is to put 2" linings instead of 2.5" for less surface area.
Not interested in adding he adjustable deal.

So other than looks, which are important with larger rims, I have 18s in the back, no advantage.

[dutch]

Mine has 11"rear drums.  I`m not sure about other parts of the planet, but overhere those over happy rear brakes are a no-go for tech inspection. I installed an adjustable prop valve. works like a charm. The only pro for 11" I can think of is less heat build up, but the front brakes will probably glow up before the rears do, so.... 

[brads70]

As Neil said I used the truck wheel cylinders (Raybestos rear wheel cylinders WC37236)  and the smaller brake drums  I removed the stock valve/manifold thingy and replaced it with the adjustable Wilwood one. I never had to adjust it ever always left it wide open. At that time I was also using the stock 11.75 "big brake" set up.

Good reading here....
http://www.moparaction.com/tech/archive/disc-main.html

[RCCDrew]

Next question, would a big drum setup that was on a junkyard 8 1/4 or 9 1/4 bolt onto my 8 3/4?

[bc3j]

I also use smaller rear wheel cylinders, 13/16", with no prop valve and no lock up. I still use the original drum distribution valve with no issues. My rear brakes are 11 x 2.5 drums. My WCs are from a Dakota pickup with 10" rear drums. The Dakota with 9" drums uses a 7/8" WC.

[ntstlgl1970]

Next question, would a big drum setup that was on a junkyard 8 1/4 or 9 1/4 bolt onto my 8 3/4?

I took my 11" drum setup off a 74 Satellite with an 8 1/4, bolted right on my 8 3/4

[Chryco Psycho]

Next question, would a big drum setup that was on a junkyard 8 1/4 or 9 1/4 bolt onto my 8 3/4?

Yes the backing plate is the same for 7 1/4 - 9 3/4 diffs so it will bolt up the only issue would be drums from an A body with the smaller 4" bolt pattern or the 80 & newer Dodge trucks with 5" bolt pattern

[RCCDrew]

Sweet!  Saw some in the junkyard the other day so may be going to pick them up.