What Disc Brakes to Use

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4spdhemidart

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Yeah just when you thought all disc brake questions had been answered (LOL).

I need some help. I have just completed a Hemi Dart clone and it screams but it does not stop. Stopping is important. I was in a rush to put the car together and used a kit from ECI not becuase they were cheap, which they were, but becuase it was available quickly . Bolted right on to my 10 inch spindles and looked like it would do the job. Anyway...it uses Chevy calipers and to be honest the 10 inch drum system worked better than this disc setup. Called ECI and asked for their opinion on probemls and all I got was a run around...it's this and it's that...ect. I have replaced the master 3x times with new ones not rebuilt parts...the rear brakes are 11 inch off a b body, new lines and all new brake parts...installed a SSB prop valve in the rear line, new hoses...basicaly new everything and the car just will not stop.
I used the 11 inch rear drum brakes becuase bigger is always better right? or did I miss soemthing?

I am going to trash the ECI kit. My question is before I spend more money chasing problems and parts that do not work together I want to spend the money on something that will work. Throwing gobs of money at a problem does not always solve it.

I have a complete disc setup from a 75 Dart sport, upper and lower control arms...calipers rotors, ect...basiclly everything. Will this setup stop the car? What else do I have to change to make this work? I know I have to replace the UCA (big ball joint) what about the LCA? If I change the LCA what ball joints do I use the ones for a 68 Dart or the ones for a 75 Dart Sport? The 75 Dart parts also place the caliper on the front of the rotor...good or bad?

Would it be better to use a Wilwood or SSB kit as opposed to the 75 Dart parts? Should I trash the 11 inch rear brakes and replace with 10 inch drums?

The car is a blast to drive with a 680 HP Hemi but when it comes time to apply the whooooaaa pedal...life gets interesting...

I work in Iraq and Afghanistan so I only get a few months at home each year and would rather spend my time grabbing gears and listening to the sweet sound of a high RPM Hemi rather than chasing brake parts that do not work.

There are a lot of smart Mopar folks on this site and I am sure someone has the answer. Thanks guys.
 
guess it depends what your looking for... the stock style 73-up disc have always stopped my small and big block a-bodies just fine. a hemi weight quite a bit more i believe but i would think they would be ok.. i would think the disc you bought should do tyhe job also but you say it doesn't.. not sure if there is a problem with your system or they just aren't enough to stop the car.. kinda hard without seeing in person.... i'm running a drag style wilwood set up on the from of my dart now and it definatley seems to stop better then the stock 73-up set up that i had on the car. had to believe looking at the small caliber and small *** brake pads (must be the materials) but who knows if they would be what you are looking for.

the 11 inch drums should be fine. sure they are adjusted right?


71&
 
Since you already have the factory disc brakes I'd say use that.
Those aftermarket kits from eci and scarebird are meant to improve stopping versus OEM 9 X3 slant 6 drums at best.
You dont need to change the lower arms but you will ruin the lower joint boots in seperating. Replacement joint boots are hard to find.
Now I have questions for you... this power brake setup ? Is the pedal low or mushy ? You should have a high and hard pedal even if no power assist and using 2 feet to stop it today.
 
Could'nt tell if your brakes are power or not.
If manual,Your not using semi metallic pads are you?
They will NOT stop untill VERY hot!! and then not very well!!
Ford actually had a service bulliten on this in th 80's on escorts,rangers and mustangs saying not to put mettallics on manual brake cars.
I had to special order organics when I converted my 66 Cuda as no one locally stocked anything but mettalics for '73 up Mopar disks.
Hope this helps.
 
are the rears adjusted properly? did you break in the pads and rotors? what bore master are you using? did you bench bleed the master? did you wash the anti corrosive coating off the rotors?
 
To all that have responded...thank you.

Few more details. These are manula brakes. New 1 1/32 master for a 73 dart with disc/drum. My pedal is hard as a rock but when I dpress it it just does not stop the car like you would expect a disc brake to stop it. Yes it is a Hemi but I have fiverglass fenders, hood, keater delete, no back seat so I am thinking that th weight is much less that would otherwise be the case.

I have done all the usual things like bench bleed, check the lines, adjust the rears and so on...more than once and sometimes three times. Everything seems to be in working order.

Maybe I missed something? I know about making sure the bleeders are at 12oclock. Adjusted the rears and even sanded the rear brake pads to insure ful contcat with the drum. Burnished the front pads with 10x hard stops
and made sure all the cosmoline was off the rotors.

It seems as though everyone is very happy with the Wilwood kit so I may go there for a solution unless anyone thinks I missed something basic.
 
4spdhemidart said:
To all that have responded...thank you.

Few more details. These are manula brakes. New 1 1/32 master for a 73 dart with disc/drum. My pedal is hard as a rock but when I dpress it it just does not stop the car like you would expect a disc brake to stop it. Yes it is a Hemi but I have fiverglass fenders, hood, keater delete, no back seat so I am thinking that th weight is much less that would otherwise be the case.

I have done all the usual things like bench bleed, check the lines, adjust the rears and so on...more than once and sometimes three times. Everything seems to be in working order.

Maybe I missed something? I know about making sure the bleeders are at 12oclock. Adjusted the rears and even sanded the rear brake pads to insure ful contcat with the drum. Burnished the front pads with 10x hard stops
and made sure all the cosmoline was off the rotors.

It seems as though everyone is very happy with the Wilwood kit so I may go there for a solution unless anyone thinks I missed something basic.
Click to expand...

YOU MUST POST PICTURES FOR US OF YOUR CAR BEFORE YOU LEAVE!!!(if you havnt yet) Will it be a street hemi, if that's possible...I have a 68 dart gt I wouldn't mind saving money for a hemi, maybe one of these days I'll get lucky and find one lol
 
IF your 10" drum brake system worked better than your new disc system, something basic is wrong.

Did you run those 10" drums with your current hemi setup?

Does the car just not stop when you stomp on the brakes. Or does it just take a extra ordinary amount of pedal force to stop it?

What master clyinder diameters have you tried allready?
 
If you think about it... theres a lot more pad to drum surface than pad to disc. The main advantage of disc brakes is straight line stopping.
The first fluid pressure goes to the front brakes to create a nose down attitude. The rear brakes should lock down first. All this leads me to wonder about those rear brakes. Conditions I've seen were clogged fluid lines, lines switched at mater cylinder, and one guy who put adjusters in reversed meaning more he used the brakes worse they were. Then there was maladjusted park brake cables that threw everyting out of whack when the brakes were installed.
 
I got to vote for the stock Mopar disks. Granted I only have a slant in the front of my Dart, but stock 73 and up front disks stop it very well. I use the cheapest pads I can find. You can run the slightly bigger rotors from a Diplomat, you just need the caliper bracket and rotors, and 15" wheels. I like the stock stuff because you can buy parts for it anywhere, usually in stock at most auto stores.

A few things to check on your setup.

Are the rear wheel cylinders working?
WC pistons not frozen in the bores?
Are you getting good fluid flow when bleeding?
Rubber hoses can look fine on the outside but be shot inside.
Are any of your hard lines kinked or crushed?

Just a few things to check.

Good luck, sounds like it will be a fun ride once it is stopping well.

TopHat
 
i just read about the 8 hard stops. you may have boiled the binder to the top of the pads. the 30 30 30 test is better. 30 stops from 30 mph to about 10mph with 30 seconds in between each brake session. this helps temper the pads/rotors.
 
When you put on larger drums, did you change the backing plates & shoes, too.
I put a full 75 Valiant front end (K-frame, too.) under my 72 Demon which gave me manual LBP disks & a factory engineered sway bar that don't interfere with each other. I'm happy with it.
I may get razzed for this, but you may want to consider a softer brake pad for the front (organic vs. carbon). The carbon metallic brake pads are harder and work better with a little heat in them. I don't see that as an issue for you since you're adding mileage ¼ at a time.
 
1 sure way to decrease pedal effort is to put in a M/C with a smaller bore. The down side is more pedal travel.
I would keep the brakes u have and try a M/C with a smaller bore and then look thru the catalogs for some decent pads. The big advantage to the GM calipers is there are tons of "performance pads" avalable. The performance friction #83 compound comes to mind Its got great cold torque and dosent fade with heat.
 
Try a smaller bore master cylinder. More pedal travel and higher pressure at the pads. I have one on the shelf ready to put into my cuda, if I ever get my @&^%$*##*^% pontiac running right!
 
motorpirate said:
Could'nt tell if your brakes are power or not.
If manual,Your not using semi metallic pads are you?
They will NOT stop untill VERY hot!! and then not very well!!
Ford actually had a service bulliten on this in th 80's on escorts,rangers and mustangs saying not to put mettallics on manual brake cars.
I had to special order organics when I converted my 66 Cuda as no one locally stocked anything but mettalics for '73 up Mopar disks.
Hope this helps.
Click to expand...

Semi metallic pads are not an issue with manual disk brakes, technology has come a long way since the 80's. I have over 30k miles on 73+ disk brakes on my 68 Barracuda with a manual master cylinder. Takes a little more foot pressure but not excessive than it did to get the initial bite compared to the 9" drums (drum brakes by design give more initial bit due to their self energizing design) that were on the car but stops with the same level of confidence as either my late model pick-up or my wifes PT Cruiser. I would stay away from organic pads; they may have more initial bite at a lower foot pressure but they will fade much faster when they get hot reducing your ultimate stopping power compared to semi-metallic.

When I did the conversion the local parts store only had loaded calipers in stock so I went with the pads that came with the calipers . I was more than happy with the braking but they squeaked at low speeds. I replaced the pads with Raybestos PG+ pads which are a premium replacement pad. Besides getting rid of the squeak there was a marked improvement in the stopping power.

My recommendation before you go taring the front end apart to change the brakes try a premium pad. If this was a cheap kit they likely came with cheap pads. Something from EBC, Hawk or the like will likely make a big difference. TireRack.com sells a wide assortment of high performance pads. If the kit uses GM calipers you should have a large choice. I always get pads for my daily drivers from these guys and have never been disappointed with the performance improvement.
 
I like the idea of a set up from a Diplomat. My '75 Swinger has the SBP which I would like to change to a BBP when I do the brake upgrade. What's the best way to do this? I don't know yet if I have 9" or 10" drums, will that make any difference when I make my swap? Especially if I go the Diplomat route? (My car has the /6 so megga big block stopping is not the issue, just better than the non power drums I have now before I give the car back to my daughter).
 
I disagree with Redfish. The main advantage of disk brakes is their superior heat dissipation and resulting lack of fade.

I agree with the person who said that if you did the 10 hard stops back to back, you may have glazed the brake pads. Did this once on a drum brake car and got the same experience. Lo-Tech solution is to get a file to remove the glaze, Hi-Tech is to take to machine shop to have it removed by milling machine. The latter method assures a uniform thickness across the pad.
 
I almost wonder if the issue is front to rear ballance. You've got discs that are smaller up front than what Mopar ran, with some pretty decent rear brakes. When you give the brakes a huge stomp, which end locks up first?
 
RedFish said:
Since you already have the factory disc brakes I'd say use that.
Those aftermarket kits from eci and scarebird are meant to improve stopping versus OEM 9 X3 slant 6 drums at best.
You dont need to change the lower arms but you will ruin the lower joint boots in seperating. Replacement joint boots are hard to find.
Now I have questions for you... this power brake setup ? Is the pedal low or mushy ? You should have a high and hard pedal even if no power assist and using 2 feet to stop it today.
Click to expand...
For replacement boots check out http://www.suspension.com/bjb.htm
 
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