How your Chargers brakes compare to your late model car?

[Kern Dog]

I've been dealing with inadequate brakes on my Charger for a few months now. I've tried many things to improve the performance, but I just can't seem to get it right.
My brother in laws 72 Duster stops as if I threw a grappling hook out the window. It has stock 10" rear drums and rotors/knuckles and calipers from an '88 5th Avenue. The master cylinder is correct for a 75 Dart. This car flat out S T O P s! It brakes better than any other A body car I have driven. Now after driving it, I feel compelled to get the Charger to THAT level or better.
Here's the scene: 12" Cordoba rotors, slider calipers from a 75 Dart. NON power 15/16" aluminum master cylinder. 10.7" rear disc kit from Dr Diff. The car brakes okay, but the honest truth is that the brakes in the car do NOT inspire confidence. I am used to driving  with the confidence that the brakes are there to save me. My '07 Ram gives me confidence. So does the 67 Dart.
I read somewhere that there was a caliper change in the 76 A body cars, and the FMJ cars used the same ones. I understand that there is a correlation between caliper bore size and brake effectiveness. Any opinions?

[Cooter]

Rear disc is most likely the problem. Most use some form of GM style caliper and GM calipers SUCK for pedal feel when mixing and matching with Chrysler parts.

This is a MAJOR problem with the Foward Look croud. Bout the only Disc brake set up that doesn't require you to modify the car to fit the parts uses GM calipers. Stock Master Cylinders were NOT designed for Four pistons(Sometimes, as many as 12 total system), 4 wheel disc "Kits"....Most who Drive "Spiritedly" on the street don't even NEED 4 wheel disc brakes. It's only there for the wow factor at best. I have yet to see where 4 wheel disc is worth the extra hassle and money over a rear drum set up on the street. BOTH will lock if you are in a panic stop.

[Mike DC]

Caliper bore size (in proportion to MC bore size) affects the pedal travel/leverage ratio.  Bigger MC bore + smaller caliper bore = brakes get pushed harder with less pedal travel distance.  And Vice versa.

It's important to make sure you don't get the front & rear wheel cyliders (be it drums or discs) too mismatched in size.  With the MC bore size pushing the same amount of fluid (front and rear) it can leave the front and rear brakes too mismatched in pressure.  A proportioning valve affects the temporary pressure difference when you hit the pedal hard, but there is also a "baseline" pressure relationship between the front & rear brakes that you have to get at least ballpark correct.
 

[404NOTFOUND]

My brakes are far from adequate as well. I pretty much have to gear down my automatic every time I try to stop in the city. I think my big cam has much to do with it. Tuning the engine to run better has raised the vacuum a bit and has helped with the brakes.

[Kern Dog]

Caliper bore size (in proportion to MC bore size) affects the pedal travel/leverage ratio.  Bigger MC bore + smaller caliper bore = brakes get pushed harder with less pedal travel distance.  And Vice versa.

It's important to make sure you don't get the front & rear wheel cyliders (be it drums or discs) too mismatched in size.  With the MC bore size pushing the same amount of fluid (front and rear) it can leave the front and rear brakes too mismatched in pressure.  
 

Thanks for that.
Okay, on that note, what would be a good starting point?
The stock 75 A body disc/drum setup was a 2.60 piston front caliper with a drum brake wheel cylinder size of what...15/16"?  Now I have a rear disc caliper size of about 1 7/16". It worked fine with the power brake setup except at low speeds. It seems that in retrospect, I would have been better off just adding a vacuum pump!
Thats water under the bridge though. I want to make the NON power setup work. I KNOW it can be made to work, I'm just encountering a few unseen obstacles in the process.

[BrianShaughnessy]

What prop valves?


   I had a FMJ prop valve initially with 11 3/4 rotor fronts ( Volare slider caliper ) and 11" rear drums. ... and even after I went to Viper fronts.    I dunno... just something not awe inspiring about it.

   Went with rear disk kit and put back the original drum prop valve setup and installed a adjustable prop valve inline to the rear brakes...  after several panic stop adjustments I think they kick ass now....
even if the whole aerospace components rear disks aren't anything I'd recommend to begin with.

[resq302]

My 69 charger with the factory bendix disc brake option stops a hell of a lot better than my 07 F150 4x4.  Also the fact that I can lock up the brakes in the charger vs. the vibrating foot massage I get when I try to lock up my brakes and the ABS kicks in my F150, I don't like so much.  I grew up knowing how to control a skid.  Now with these damn ABS brakes, it feels like I can't stop  and have almost gotten into more accidents since the ABS is kicking in instead of coming to a screeching halt.

[Chryco Psycho]

I often un plug the ABS just for that reason , I hate ABS

[resq302]

Neal, if you unplug it, wont that make a light come on the dash?  If not, I'd certainly entertain on how I can do that to my truck!

[Kern Dog]

My 69 charger with the factory bendix disc brake option stops a hell of a lot better than my 07 F150 4x4.  Also the fact that I can lock up the brakes in the charger vs. the vibrating foot massage I get  in my F150,

THATs funny!
UPDATE:  I swapped in a pair of 2.75 piston front calipers with new pads. The brakes improved slightly, but they still suck.
I've posted elsewhere about this and there have been a few other points brought up. First was pedal ratio. A manual braking system needs MORE ratio than a power system. Another point is to  omit the combo valve in favor of a totally split system.
I'm MORE confused than before.

[chargerbr549]

On my 69 RT Charger I went from power drum brakes to manual disc brakes 11 3/4" fronts with 2.75 calipers and 11"drums on the rear I had to take out the cantilever setup that was part of the system for the powerbooster and install the complete manual setup I got off a charger parts car, it about doubles the amount your brake pedal travels compared to when it had power brakes. I don't remember if a person can even run the cantilever setup with a manual mastercylinder and pushrod.

[autodynamics]

Mine are awesome
No problems to report

[Kern Dog]

I gave up.
The power booster and master cylinder are back on the car. I usually don't give up on car stuff but I just got tired of fighting everything. EACH move that I have made with a manual M/C resulted in terrible performance. I swear, it was far worse than any stock drum arrangement.
I'm going to use a disc/drum prop valve. Since it is likely that I'll need a vacuum pump, I'll probably mount it in the left fenderwell, behind the headlight. It should be easy enough to plumb from there.

[Road Dog]

They don't compare. I run the stock 10" drums on the Charger. The Challenger has insane braking. Truth is I rarely brake on either car i just let the cars gear themselves down. Letting off the gas on either car is like braking. If I had to brake suddenly on the Charger I'd just bring the rear around into a controlled slide.  Been there and done that. 

[Dino]

I have power drums and since everything drivetrain related came out of a cop car it's all HD and I do believe I have the bigger drums.  They are what? A half inch bigger?  I honestly don't think that makes all that much difference but okay...

I'm upgrading to a small Wilwood kit for the front because it came with the car and I'm not running anything larger than a 15" rim for now.  If I ever go bigger then the rotors will get bigger as well.

The only problem I have is early morning when it's cold it takes a bit longer for the oil pressure to rise and the brake system light will come on once or twice when I brake.  Once I hit the open road it's usually okay.

The pedal feels nothing like my daily drivers' and I do have to push down a bit harder but the car stops fine.  Had to do a fast stop coming back from work yesterday because apparently a big white Charger is not easily visible and this douche turned onto the road right in front of me.  I smashed the pedal and the car stopped quicker than I thought.  (mental note to self, install shoulder belts)

The brake system light came on again though, I better not wait to long to install the disc kit.

[resq302]

Dino,

The brake warning light just means that you have unequal pressure at the distribution block.  Meaning you could have a small leak somewhere resulting in pressure loss like either a leaking line, leaking wheel cylinder, or even a leaking caliper if you have discs.  I ended up rebuilding mine cause of that occasional problem only to find out that it was an o ring going bad inside the distribution block.  In a nut shell, the distribution block that has the safety switch has an internal looking dumbell weight as I call it with o rings on them.  If either side of the pressure not be equal, it pushes the dumbell down and makes contact with the safety switch causing it to ground and light up on the dash.

[Kern Dog]

The car is back together with MOST of the previous equipment in place. I used a refreshened proportioning valve and bled the system. It actually stops better NOW than it did before I pulled the power stuff. Maybe the newer (slightly larger) 2.75 front calipers and more aggressive front pads helped?
Thanks for the suggestions, Greg

[autodynamics]

Can't go wrong with big brakes

[Dino]

Dino,

The brake warning light just means that you have unequal pressure at the distribution block.  Meaning you could have a small leak somewhere resulting in pressure loss like either a leaking line, leaking wheel cylinder, or even a leaking caliper if you have discs.  I ended up rebuilding mine cause of that occasional problem only to find out that it was an o ring going bad inside the distribution block.  In a nut shell, the distribution block that has the safety switch has an internal looking dumbell weight as I call it with o rings on them.  If either side of the pressure not be equal, it pushes the dumbell down and makes contact with the safety switch causing it to ground and light up on the dash.

Is this true even when the light comes on only when the engine's cold?  Once it's hot it brakes fine.  I thought it wads an oil pressure/vacuum deal.

You know I hadn't though about the rear brakes, I'm just focusing on the front disc swap but I better rebuild the rear breakes while I'm at it!

[WHITE AND RED 69]

Why not go to a hydroboost unit? I just swapped out my old booster for a hydroboost and the difference is amazing. Before I had no confidence in my brakes, now I just tap the pedal and it stops like a new car. It is pricey but it is well worth it.

[Dino]

Why not go to a hydroboost unit? I just swapped out my old booster for a hydroboost and the difference is amazing. Before I had no confidence in my brakes, now I just tap the pedal and it stops like a new car. It is pricey but it is well worth it.

Hydrowhatnow?  I never even heard of that!  I'll have to google it.

Is there a specific model you need for a 2nd gen?

[WHITE AND RED 69]

Why not go to a hydroboost unit? I just swapped out my old booster for a hydroboost and the difference is amazing. Before I had no confidence in my brakes, now I just tap the pedal and it stops like a new car. It is pricey but it is well worth it.

Hydrowhatnow?  I never even heard of that!  I'll have to google it.

Is there a specific model you need for a 2nd gen?

It runs off the steering box pressure rather than the engine vacuum. I got mine from Reilly Motorsports and couldnt be happier.

http://www.reillymotorsports.com/store/product.php?productid=16195&cat=273&page=1