11” to 11.75” disc upgrade?

[rikubot]

Got an easy one for ya. I bought a disc upgrade from classic a while back for the 11" disc, spindles, calipers, etc. I am considering doing the upgrade to 11.75". Will the rotors fit right on the the spindles and if so are the only parts I need the caliper bracket and rotors? Thanks guys/gals.

- Mike

[Nacho-RT74]

dunno which one you got, but if upgrading on stock parts setup ( laters Mopars ), yes, so simple like that

[rikubot]

My apologies I meant to include the link:

https://www.classicindustries.com/product/all-years/dodge/all-models/parts/mp500511.html

[b5blue]

Uses every bit inside of a 15" wheel. My Torque Trust 15X8's are so close they popped the balance weights off.

[Kern Dog]

I didn't click on the link but....
The OEM 11 and 11.75 brakes used the same caliper and knuckle. (People incorrectly call them spindles) The larger rotors use a longer caliper bracket.

[rikubot]

I hadn't considered that. I run Magnum 500s, 15x7. I bet those wheel weights would be history. I appreciate your input Kern. One more reason to pass on the "upgrade"

[Dano 1]

Somewhat related to the OP's original question, does anyone have opinions on how much better the 11.75" rotors actually are? I'll be converting my '69 from front drum to disc using all the oem parts and have both sets of caliper brackets. My original plan was to go straight for 11.75" rotors but now I'm hesitating due to wheel options down the road. Does anyone have first hand experience going from 11" to 11.75" rotors that can speak to any real improvement in performance?

[b5blue]

  My car is a daily driver and for that I went heavy duty. Think in terms of brakes are heat pumps so bigger mass = better. Calipers/pads the same yet placed outward more = better. If your not out in street traffic all the time, doing extended road trips or some kind of sport I don't think that edge is worth the weight.
25 years ago when I started looking for parts 11 3/4 setup was the cat's meow but now with drilled/slotted and better pads smaller could match but be more efficient.

[Nacho-RT74]

there are 11.75" drilled and slotted rotors at Rockauto.

I'm just waiting to find caliper brackets for pins calipers ON A DECENT PRICE ( or maybe if somebody find the accidentally at some JY up there and is so NICE to sell/send to me LOL ) to proceed with the upgrade

[Kern Dog]

A larger diameter rotor gives better "leverage" for better braking. Even if the same caliper and brake pads are used, the larger rotor will stop the car faster in shorter distances.

[b5blue]

Yea but the question was "How much better"?  12% better?

[mrob]

b5,
I did this swap on my 69 Coronet. Originally had 74 A-body 10.87 inch rotors and the A-body calipers with semi-metallic pads. Then went with the Dr. Diff 11.75 inch brake kit and kept the A-body calipers with semi-metallic pads.
In my opinion, it's not a "night and day" difference. The biggest difference I feel is when slowing down from highway speeds. I notice that now, the pedal effort is a little lower and I come to a stop in a shorter distance. Around town, I really don't feel much of a difference.
The bigger brakes would probably be better in emergency stop situations, but I haven't had any yet.
Hope this helps

[bc3j]

I did the 11.75" change on my E Body. Found a slight improvement and like it. My better change was using organic pads. The rotors are thick and don't heat up for me in ordinary driving for the semi metallic pads to work well for me. The organic pads, for me, are better. I don't race the car just cruising, but it will stop very well from highway speeds if needed (and it was on one occasion where a lane change in front of me caused a rather rapid stop). Edit: My mistake, my pads are FF friction coefficient and work well.

As far as wheel weights, I had them stuck as near as possible to the hub and told the installer to use low profile weights. They clear ok and don't interfere with the caliper, the higher profile weights will hit the calipers. My 15" wheels are steel and use the traditional rim mounted weights on the inside of the rim only, requiring stick-ons to be added near the hub. The outside of the wheel is clear of visible weights. I also use the slider type calipers.

For your consideration, I got rid of the Chinese steel races in my 11.75" rotors immediately.  I replaced them with Timken bearings and races.  

[Nacho-RT74]

b5,
I did this swap on my 69 Coronet. Originally had 74 A-body 10.87 inch rotors and the A-body calipers with semi-metallic pads.

They are actually not A body specific, but any Body regular equipment.

[Dano 1]

Thanks for the feedback guys, I understand the theory/science of larger rotors but was really looking for seat-of-the-pants feedback so this was great. Since I have both brackets and the calipers/pads are the same I may just give the 11" rotors a shot first and then I can always upgrade later for the price of rotors (cheap).

[Highbanked Hauler]

I have 11:75 on mine with 15 in. wheels and haven't had a problem.  I never had any complaint against 11 in. drums  and went to discs because of drop spindles only.  I can't see why you would be throwing wheel weights because of caliper position.

[Bronzedodge]

I'm about to do this exact change in a few weeks.  I'm figuring the steel rim is thinner than an alumunum, or Mag wheel.  The factory didn't have weight problems.  I'll post in a month or so.

[b5blue]

I have 11:75 on mine with 15 in. wheels and haven't had a problem.  I never had any complaint against 11 in. drums  and went to discs because of drop spindles only.  I can't see why you would be throwing wheel weights because of caliper position.

15X8 Torque Thrust rims with weights clipped on inside edge. They seared off with a little pop. What's the deal with the drop spindles, how low are they? 
Got any pics?

[b5blue]

I'm about to do this exact change in a few weeks.  I'm figuring the steel rim is thinner than an alumunum, or Mag wheel.  The factory didn't have weight problems.  I'll post in a month or so.

Running factory 15" junkyard rims (80's New Yorker I think.) was no problem with anything including weights. 

[c00nhunterjoe]

If you have big wheels and big tires that will hold through extra braking, you will notice more then with little wheels and little tires. What good are viper brakes if you have a 205 tire on the front? The stock 4 wheel drums will lock up the brakes on command without hesitation,  but slap on some corner hugging suspension and tires and they will fade under repeated heavy abuse. Same concept with 1 disc setup over another. Ive found with the majority of "disc upgrades" its more a matter of want then need. And that is perfectly fine.

[Highbanked Hauler]

I have 11:75 on mine with 15 in. wheels and haven't had a problem.  I never had any complaint against 11 in. drums  and went to discs because of drop spindles only.  I can't see why you would be throwing wheel weights because of caliper position.

15X8 Torque Thrust rims with weights clipped on inside edge. They seared off with a little pop. What's the deal with the drop spindles, how low are they? 
Got any pics?

No pictures yet.  My experience only..  They set the front end down 2 in. and  improve the handling some. You will need the adjustable upper control arms to get enough camber adjustment  to keep the tires flat on the road. Alignment specs are not a problem. I run such a tall tire you wouldn't see much of a difference compared to other Chargers. If you are considering doing this pm me and I can tell you the details if you are interested.

[b5blue]

Interesting for sure!  I'll PM not wanting to hijack topic. 

[Mike DC]

but slap on some corner hugging suspension and tires and they will fade under repeated heavy abuse.

It was called "repeated heavy abuse" 50 years ago.  Today it's called "normal driving."  

Many highways in urban areas are basically 75 mph traffic jams.  Everyone is going very fast but you can barely maintain 10 yards of space from the next car.  

And many other drivers carelessly slam on their brakes as a habit.  Why not?  Their car is liable to have 18" wheels, low-profile tires, hydroboosted multi-piston calipers, 13" rotors, maybe an automatic stop sensor system . . .  

[c00nhunterjoe]

but slap on some corner hugging suspension and tires and they will fade under repeated heavy abuse.

It was called "repeated heavy abuse" 50 years ago.  Today it's called "normal driving."  

Many highways in urban areas are basically 75 mph traffic jams.  Everyone is going very fast but you can barely maintain 10 yards of space from the next car.  

And many other drivers carelessly slam on their brakes as a habit.  Why not?  Their car is liable to have 18" wheels, low-profile tires, hydroboosted multi-piston calipers, 13" rotors, maybe an automatic stop sensor system . . .  

If we are comparing going from an 11" rotor to an 11.75, to a modern car with all of those gadgets, then we are barking up the wrong tree. A 50 year old charger cannot be compared to a modern car on the highway during rush hour

[b5blue]

My experience is we create a rolling distraction, I bought all my brake stuff well before anything else was available.

[Mike DC]

    

If we are comparing going from an 11" rotor to an 11.75, to a modern car with all of those gadgets, then we are barking up the wrong tree. A 50 year old charger cannot be compared to a modern car on the highway during rush hour

But that's my point - a 50yo Charger does have to share the road with modern cars.  

I'm not trying to gripe about the 11.75" rotors.  I'm just saying 9-10" front drums aren't enough.  Not if the car sees tight traffic over 40-50 mph, which is getting pretty common now. 

[b5blue]

I get ya, it depends on use mostly. Weekender/Daily/Show-Event/Race I drove my 70 for many years on 10 inch drums as my primary car. (Including 600 mile a day road trips.)

[c00nhunterjoe]

   

If we are comparing going from an 11" rotor to an 11.75, to a modern car with all of those gadgets, then we are barking up the wrong tree. A 50 year old charger cannot be compared to a modern car on the highway during rush hour

But that's my point - a 50yo Charger does have to share the road with modern cars.  

I'm not trying to gripe about the 11.75" rotors.  I'm just saying 9-10" front drums aren't enough.  Not if the car sees tight traffic over 40-50 mph, which is getting pretty common now. 

And my point was 99% of us with 50 year old cars are not using them as daily drivers and do not frequent the interstate during rush hour with them.... my comparison of tires to braking ability and drums to disc and then to the op of 11 to 11.75 rotors was for relevancy. I never argued drums were better then disc on these cars.
     As a side note. I dont think most of our insurance companies would be too thrilled about daily driving the interstates in rush hour. I know most classic insurance companies have restrictions and would fight you on an interstate wreck at those congested times of day. My state itself has rules for historic tags so god forbid something happens, you better have proof of why you were in that situation with that particular car.
   

[Mike DC]

   
That's true about the insurance company issues. 

But still.  I live in the outskirts of a medium size midwestern city.  It's not one of the big coastal urban centers.  In my area dense highway-speed traffic is normal for 2-3 hours out of the 24, five days out of the seven.  It's a very normal thing. 

[Brass]

I live within 2 miles of downtown Seattle, and congestion is almost always bad, day or night. My car has to keep up with the demands of modern traffic whenever I drive, and freeways are practically unavoidable entering or leaving town. So far, 11.75 discs, EBC pads, and a hydroboost unit seem capable enough.

With respect to insurance, I think insurance companies factor in your ZIP code when calculating rates. Also, I don't drive my car more than what I have indicated to them.

[c00nhunterjoe]

On that logic then , i drive mine in traffic, on c12 race gas, with skinny front tires and slicks, and never had a problem with stock brake setups.

[flyinlow]

I have upgraded from 11 to 11.75" brakes.  Hawk HPS pads and slotted rotors. 11 inch Right stuff kit on rear. I did this while I had 15 " BFG's. Some improvement with the 11.75, not a big change. When I went to 18 wheels and G Max  05's tires the larger brakes really started see an improvement .

[b5blue]

Being the caliper/pads are the same for both I think the largest gain is H.D. or repeated use. Even greater so with upgraded pads and rotors like flyinlow has. (I'd like a link to what you got?)

[flyinlow]

https://www.summitracing.com/parts/hwk-hb643f-595

front pads

[b5blue]

Thanks! I'm not boosted, stops well looking to upgrade, how much and where on the rotors if you don't mind? (My rotors used 1980 St. Regis as lookup.)

[Dano 1]

1978 Chrysler Cordoba is a reliable cross-reference for the 11.75" rotors. My go-to these days is rockauto.com and they have rotors starting at $37.79 + shipping.

https://www.rockauto.com/en/catalog/chrysler,1978,cordoba,6.6l+400cid+v8,1062717,brake+&+wheel+hub,rotor,1896

[b5blue]

I've got rotors bought long before slot/hole type were ever something you could buy. Looks like 140 is average now, surprised even Rock has them now! Thanks 

[Nacho-RT74]

I got my 10.90" drilled and slotted rotors for my Charger 8 years ago!!!!... Maybe around $40 each as far I recall from Rockauto. Centric brand. Can't recall the exact price but it was barelly around 25-30% more than the stock replacements. Really good priced. Of course I didn't go with 11.75" because I still don't have the caliper brackets... but some day!

Accomplished with Bendix ceramic pads and Raybestos metallic rear shoes

[flyinlow]

Thanks! I'm not boosted, stops well looking to upgrade, how much and where on the rotors if you don't mind? (My rotors used 1980 St. Regis as lookup.)

Zinc plated rotors with slots.(plain and drilled/slotted were options.) Forgot the vendor,  I think about $150 a pair 5-6 years ago.  


I did sand the zinc off the wear bands before I did the brake in ritual.

[b5blue]

Thanks for the info guys! 

[375instroke]

Here's my  Friction material is nothing to cheap out on, and run the biggest stock size drums or rotors you can, for everyday driving.  Here's why I think that.  I have a 273 Dart with 9" drums, and it stops great, at least once.  Probably has real asbestos shoes.  My 340 Dart with the "HD" 10 " drums stops like crap.  Both cars are untouched by me.  Have a '64 Dodge 880 that had the worst brakes of any car I've owned.  From 60 to 30 was ok, but then it acted like someone sprayed oil on the shoes, and started shaking violently.  Had the shoes relined at a local brake place that does mostly big trucks.  That car stops great now, with just the fronts redone.  My Charger R/T with the big drums could stop fine at freeway speeds one time, but after that, it had to cool off if you wanted to stop again.  From 80mph, it was a struggle at the end.  It has the 11.75" discs now, With Raybestos semi metallic pads, and it stops great.  Another Dart I had, with the 11" discs always stopped great till I drove around San Francisco.  With all the hills, they got hot, and stopping ability was greatly diminished.  Now for the race car. which is a Fox Mustang.  We're talking up to 36 hour road course endurance racing.  The brakes were off an SVO turbo Mustang, 11" discs front and rear.  Stock couldn't keep up.  Drilled and slotted rotors couldn't keep up.  Hawk Blue pads were really good, but those, with drilled and slotted rotors, and cooling ducts, it still needed improvement.  Those pads lasted 28 hours, and when they woke me up for my turn to drive, they told me "We had to put those parts store pads on.  Don't enter the first turn any faster than the speed you want to die at."  Going up to 13" Cobra rotors and calipers, which are $40 each, at any Schmuck Auto Parts, and Hawk Blue pads, could drop that car from 156mph into a hairpin, lap after lap, in 95deg ambient temps.  My take is run the largest rotor you can, and don't skimp on the pads.  I really think drums get such a bad rap because people put the cheapest piece of crap shoes they can find on there, and if you look up the coefficient of friction on them, it's less than steel on steel.