jbooth35
Member
I'm getting the car back on the road. Going to replace the entire braking system and having trouble finding rear 11x3 drums that are on the 65 polara. Please advise.
Thanks
Thanks
Source for 11x3 rear drums
- Thread starter jbooth35
- Start date
Rockauto has 11x3 for the fronts, but I don't see any for the back.
jbooth35
Member
That was my first stop. I did find some in Canada, and I'll get those if I can't source them in the states. Thanks for looking.
70bigblockdodge
Old Man with a Hat
I would not put those back on unless this is a convertible. That is too much brake in the rear and will cause a lock up and car will come around on you trying to panic stop especially if keeping the single pot master (also a bad idea for anything other than museum).
D
Deleted member 220
Guest
Bought mine at car quest
Furyman
Active Member
Pretty sure the rear 11x 3 was discontinued 20 years or so ago. I have stock.....picked up 3 skids of obsolete Mopar drums a couple of years ago. I'm in Canada. All the boxes I have are mid 70's date codes and made in USA.
I believe the 11x3 linings are the same, f/r. Was thinking the drums were similar? Have to look in the parts book to make sure.
In looking about 11x3 brake shoes a while back, on RockAuto and in the individual manufacturers' websites, some listings for 11x3 are really 11x2.75. Kind of have to read between the lines and look at the specs to see what they really are, or are supposed to be.
CBODY67
In looking about 11x3 brake shoes a while back, on RockAuto and in the individual manufacturers' websites, some listings for 11x3 are really 11x2.75. Kind of have to read between the lines and look at the specs to see what they really are, or are supposed to be.
CBODY67
D
Deleted member 220
Guest
jbooth35
Member
It's always stopped fine with the factory 11x3s. It does have a single pot master cylinder, but I'm converting to disks in the front. Is there another year/make/model car I should cross reference to find these. Autozone, Carquest, Rock Auto don't even list the 11x3 rear drum. This is a 426 car.
Furyman
Active Member
They do not look like 11 x 3"s too shallow...pretty sure a correct one is 3.25" deep.....I will check tomorrow.
Furyman
Active Member
An 11 x 2.75 is a C body front drum.
My point was to cross-check the specs in the different websites. Brake items usually go by "industry numbers" (at least the core number for the particular parts), but what might claim to be 11x3 might not really be that.
CBODY67
CBODY67
Furyman is the guy to buy from - he posted above.
70bigblockdodge
Old Man with a Hat
Rears are usually 2.5 wide all depends on the backing plate/brake support. A 3"" surface is not for a 3" wide shoe.
Again for safety sake I would not put that powerful of a brake on the rear of a non convertible or wagon.
Again for safety sake I would not put that powerful of a brake on the rear of a non convertible or wagon.
jbooth35
Member
My actual shoe is 3” wide.
There was a police and taxi brake option with 3" drums all around. My car (66 Monaco 440 4 speed 2 door hardtop) had that option originally - but now has discs up front.
If one is concerned about too much rear brake in a front disc 3" rear drum setup, I would suggest they use an adjustable prop valve to reduce rear braking force in panic stops and potential lockup/control loss.
If one is concerned about too much rear brake in a front disc 3" rear drum setup, I would suggest they use an adjustable prop valve to reduce rear braking force in panic stops and potential lockup/control loss.
mikedrini
Well-Known Member
I think I found mine through NAPA actually..
mikedrini
Well-Known Member
Ask and ye shall receive..
70bigblockdodge
Old Man with a Hat
Those are some powerful rear brakes. Yes it will work but you are asking a awful lot out of the proportioning valve, especially in a panic situation. Since he needs new drums that are hard to find and getting brake supports for 11×2.5 is easier, even available brand new, all the hardware/wheel cylinders crosses over. They would be a better balance for the disc brakes he is putting on the front, which leads me to believe 100% correctness is not a driving force here. Why not correct the problem now instead of after the car scares the piss out of him when it swaps ends after that deer ran out in front of him. If 11×3 rear brakes were so great, why did the stop offering them in later model years? Bigger is almost always better but sometimes it is not.
Well, in a panic stop without ABS, you have to use your analog decal sensor to modulate the brake pedal pressure . . . like in the old days. F/R balance was handled not just by the width of the brake shoes, but also the diameter of the wheel cylinders. And many road tests talked about "Mopars" locking up one of the rear wheels in their panic stopping tests . . . in the middle 1960s time frame.
As long as the tire/road friction interface is overpowered by the brakes, tire slippage will happen, no matter what. Better tires (usually radials) can allow the brakes to work "more" and stop quicker.
On my '77 Camaro, I upgraded the rear brakes from 9.5x2 to 11x2. With the full-metallic COPO 9C-1 police spec front pads, it stops "like a Chrysler" with the pedal at the top, rather than like the typical GM car with the pedal 1/2 way down. More brake, less pedal, more confidence . . . it seems to me. That 11x2 rear brake was on the '81 Export Z/28s, but also fits '77 MonteCarlo and the middle 1980s Caprice police cars. No issue with early rear lockup.
From new, the car didn't stop nearly as well as it should have. Not particularly an issue with the size of the brakes, but the friction materials used on particular applications. Of course, the less comparative stress the brake frictions are under, the longer they should last.
As for the police/taxi factory brakes being 11x3s f/r, remember that law enforcement vehicles don't normally have "empty" luggage compartments. I somewhat doubt that the accountants at Chrysler would have allowed those more expensive rear brake sets IF they weren't needed for best performance in the important law enforcement market.
Personally, I would desire the "most brake" I could put on a vehicle (size and/or friction material), add better tires (if they weren't already there), and then learn how to drive/brake for best performance. Years ago, Chrysler determined (from instrumented testing on dragsters) that best acceleration happened with 10% slip of the rear tires. I suspect that similar would be true in deceleration, too?
Besides, if the tire locks-up in braking (and the driver maintains that), it's the rubber than controls the stopping distance rather than the size of the brakes. Check out some of the old "Car and Track" segments on YouTube to see that happen!
CBODY67
As long as the tire/road friction interface is overpowered by the brakes, tire slippage will happen, no matter what. Better tires (usually radials) can allow the brakes to work "more" and stop quicker.
On my '77 Camaro, I upgraded the rear brakes from 9.5x2 to 11x2. With the full-metallic COPO 9C-1 police spec front pads, it stops "like a Chrysler" with the pedal at the top, rather than like the typical GM car with the pedal 1/2 way down. More brake, less pedal, more confidence . . . it seems to me. That 11x2 rear brake was on the '81 Export Z/28s, but also fits '77 MonteCarlo and the middle 1980s Caprice police cars. No issue with early rear lockup.
From new, the car didn't stop nearly as well as it should have. Not particularly an issue with the size of the brakes, but the friction materials used on particular applications. Of course, the less comparative stress the brake frictions are under, the longer they should last.
As for the police/taxi factory brakes being 11x3s f/r, remember that law enforcement vehicles don't normally have "empty" luggage compartments. I somewhat doubt that the accountants at Chrysler would have allowed those more expensive rear brake sets IF they weren't needed for best performance in the important law enforcement market.
Personally, I would desire the "most brake" I could put on a vehicle (size and/or friction material), add better tires (if they weren't already there), and then learn how to drive/brake for best performance. Years ago, Chrysler determined (from instrumented testing on dragsters) that best acceleration happened with 10% slip of the rear tires. I suspect that similar would be true in deceleration, too?
Besides, if the tire locks-up in braking (and the driver maintains that), it's the rubber than controls the stopping distance rather than the size of the brakes. Check out some of the old "Car and Track" segments on YouTube to see that happen!
CBODY67
Similar threads
