11" brake drum to 10" swap

[Brian in GA]

Alright, here it is.  I'm rebuilding the rear end on my junkyard rescue, and have gotten to the brakes.  The car had no drums on it when I bought it.  I tried to swap a set from my parts car, but naturally they were 10" and the ones I need are 11".   

I've checked around for 11" drums, and AC Delco makes them, at $130 each.   

I have also posted on the wanted section for anybody with a set lying around.  My question is this:  If the 11's are too scarce/pricey, wouldn't I be ok to swap to a 10" (which I already have) for the complete brake assembly on the back as I intend to do an upgrade to discs on the front?  As I understand it, if the R/T was ordered with discs on the front, they put 10" drums on the back as standard. 

Would I be looking at enough of a performance advantage to matter between a 10" and 11" rear drum with discs on the front?  I'm not real crazy about spending an extra $250 on this rear end project unless it will really be worth it.   

Thanks for the advice.

[lilwendal]

All Rts had the 11 inch drums in the rear iregardless of front brake configuration.  I responded to your requet for drums but now I see it looks like your needing backing plates and evrything else.   I could help there as well.  If you want to go 10 inch its a straight swap.

[Ghoste]

I thought discs came with 10's on the rear too?

[Brian in GA]

Yeah, I thought if there were discs on the front, 10" drums were on the back.  The only way 11" drums came on the back were if there were drums on all corners. 

Of course, the possibility I am wrong always exists.  THis is some info I picked up from research on this board. 

And lilwendall, I'm pm'ing you.  I only need 11'' drums if you have 'em.  I've got the backing plates and hardware for the 11". 

[resq302]

You are correct.  If you got the optional disc brakes up front (at least in 69 anyways) you got 10" drums in the rear.

[lilwendal]

Man I parted out 2  68 RTs that were disc brake cars and both had 11 inch drums. I still have the complete front and rear suspebsions for both.  Maybe in its 40 year life span they were swapped
I always put the 11 inch back on.  Learn something new every day.

[Chatt69chgr]

Consdering that 75% of your braking effort is in the front, if you swap to discs, I don't see the 11 inch drums really helping that much.  The C-bodys had big discs in the front and the 11 inch drums in the back but they weighed over 5000 pounds.  So you could get the bigger backing plates off a C-body.  All the brakes interchange between the different rear ends.  If you really need the 11 inch drums, Oreilly had them made by Wagner in USA for a good price.  I believe I would go with the 10 inch.  When I bought parts, nobody here had Raybestos.  Either Bendix (real expensive but good) or cheap store brand from who knows where.  I ended up ordering all my small stuff from Rock Auto.  Just make sure if you order from them that you build the order online, even if you cancel it and then call them for the actual order, to make sure all the stuff is coming from the same warehouse, as they charge a separate shipping charge from every warehouse that parts get shipped from.  I got bit on this.  A $5 part and $10 shipping charge.  But if you just understand how this works, you can avoid this problem.  Rock Auto has real good prices and good parts.  Good thing they are around since so many of the parts handled locally are of poor quality.