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Re: New disc brake conversion doesn't work [Re: timinator] #58211
05/13/08 11:54 AM
05/13/08 11:54 AM
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dogdays Offline
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Simple - you need more line pressure. it is not difficult. Put in a master cylinder with a smaller bore and you will CREATE more line pressure with the same amount of pedal effort. The other post gave you the blueprint, get a 15/16 master cylinder so you can get on with your life. It is indeed unfortunate that an otherwise responsible company would supply the wrong size master cylinder. They probably have a bad assumption going about the pedal ratio.

R.

Re: New disc brake conversion doesn't work [Re: dogdays] #58212
05/13/08 12:20 PM
05/13/08 12:20 PM
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Omaha Ne
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Ideally you need gauges to test the pressures the system is generating. IE: what pressure is the master actually putting out.
Lot's of variables here but a general rule is 1500 PSI in a panic stop should be a good starting point. The next thing to checkt is what's the caliper seeing???? The same pressure ( it should be. Next is putting a gauge between the pads and mashing the pedal.
Short of having the gauges one can look for deflection of the hoses and cailper brackets as the pressure is applied. If you see no movement then you probably have a master issue.
if you are getting good deflection then you probably have adequate pressure. Next thing to look at is whetehr the pads/rotors are glazed. ANd lastly you might try a set of pads with a more agressive compound. I had a 68 Olds cutlass with SSBS setup on it that did pretty much what your describing. After much hair pulling we installed a set of aftermarket "ROTOR EATERS" and the problem was solved. hope this helps

TIm

Re: New disc brake conversion doesn't work [Re: Dads426] #58213
05/13/08 01:33 PM
05/13/08 01:33 PM
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Central Ky, area
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CHRYCOFAN Offline
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Yeah, the bracket under the dash has the 2 pivot points, 1 lower than the other. Basically shortened the Pedal the distance between those 2 pivot points . Cut & re-welded it so that the lower pivot & pushrod lined up, sectioned between the pushrod & the pivot.

The distance between the 2 pivots was about 3.25" & we took that out between the old pivot & pushrod hole. The pedal might just be about an Inch overall shorter than a correct manual pedal (comparing to a friends Manual brake Fury ) but I still got the 6:1 I was looking for.

Yes I had a really good welder do it!

If I can locate a manual pedal later I'll just swap it. harder than hens teeth to find since most of the Barges got power brakes.

Butch

Re: New disc brake conversion doesn't work [Re: Dads426] #58214
05/13/08 01:44 PM
05/13/08 01:44 PM
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Irving, TX
feets Offline
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It's a combination of pedal ratio and MC size.

I went through the no-stoppy thing when I dropped a truck MC on the "big" Dippy rotors. Stopping the car required both feet on the pedal and my butt in the air. It was pretty hard on the steering column too. That MC was WAY too big and caused a super-hard pedal.
When I went to the larger calipers, the MC was the perfect size and the pedal effort dropped to normal.

Dropping the bore of the MC will reduce the pedal effort.
Maybe one of the K-car MCs would work?


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Re: New disc brake conversion doesn't work [Re: feets] #58215
05/13/08 01:54 PM
05/13/08 01:54 PM
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timinator Offline OP
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So the power pedal has the bracket and pivot points and the manual pedal has none, is this correct? I finally called SSBC and the tech said to check if the car came with manual brakes. I checked the pedal and brake rod connects directly to the master cylinder. My 68 Charger has power brakes and there's a bracket assembly with pivot points. Since the pedal connects directly to the master cylinder on my 69 with just the rod and no brackets or pivots, I'm guessing this was originally a manual brake car, right?

Re: New disc brake conversion doesn't work [Re: timinator] #58216
05/13/08 03:04 PM
05/13/08 03:04 PM
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Polson, MT
DoctorDiff Offline
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A, B and E bodies used the same pedal assembly regardless of brake type. The master cylinder push rod just bolted directly to the pedal if the car was equipped with manual brakes. The pedal ratio is around 6.25:1 stock.

Re: New disc brake conversion doesn't work [Re: DoctorDiff] #58217
05/13/08 03:45 PM
05/13/08 03:45 PM
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dogdays Offline
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Listen to the Doctor!

R.

Re: New disc brake conversion doesn't work [Re: dogdays] #58218
05/13/08 10:39 PM
05/13/08 10:39 PM
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NH
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Sorry to hear that you have been having so much trouble with your conversion, but as others have already stated, you are not alone.

I used the ECI disc conversion on mine... they work like a champ... Almost to good.

Re: New disc brake conversion doesn't work [Re: timinator] #58219
05/13/08 11:49 PM
05/13/08 11:49 PM
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Hatfield,Pa.
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I'll just throw this out there... would a wilwood residual valve(2 lb.?)in the front line from the master make a difference? This would keep some pressure on the pads and not allow them to retract into the calipers. ,D.


2015 Chrysler200s,2008 Charger R/T R&T,1999 Dakota R/T,1999 Viper ACR,1968 Charger R/T.
Re: New disc brake conversion doesn't work [Re: DoctorDiff] #58220
05/14/08 08:39 AM
05/14/08 08:39 AM
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Maryland
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Dads426 Offline
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Quote:

A, B and E bodies used the same pedal assembly regardless of brake type. The master cylinder push rod just bolted directly to the pedal if the car was equipped with manual brakes. The pedal ratio is around 6.25:1 stock.




It finally stopped raining here so I could check the 64 Plymouth. The ratio is about 3-1. No wonder that thing is so hard to stop! Good thing the boy is working out on the leg press...

There is a lower pivot hole in the brake pedal hanger. The way the pedal is configured, there must be a different pedal for manual brake cars. But if the distance between the pivots is the only change (about an inch), the ratio doesn't improve that much (to only about 3.5-1), so I don't think we will gain much.

Getting back to Doc Diff's statement, is the 64-65 B-Body brake pedal the same as 66 and up? Was there a different pedal for manual brake cars on early B-Bodies? The distance between the pivot and brake push rod on ours is 6" and the distance between the pivot and bottom of the brake pedal is 18". Does someone have a original manual brake early B-Body that they can check the measurements of the pedal and location of the pivot on the hanger (lower or higher point)?



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Re: New disc brake conversion doesn't work [Re: Dads426] #58221
05/14/08 01:14 PM
05/14/08 01:14 PM
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Central Ky, area
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At least you've found the issue. Now hopefully somebody with either a 64-65 car to look at or maybe a factory parts book can check it out for ya.

Maybe there's a whole different under dash bracket & Pedal for the Manual cars?

Butch

Re: New disc brake conversion doesn't work [Re: CHRYCOFAN] #58222
05/22/08 08:26 AM
05/22/08 08:26 AM
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timinator Offline OP
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I installed a 15/16ths master cylinder and the new rear wheel brake cylinders with the residual pressure check valves. There was a "little" improvement but the car still is too dangerous to drive. My 68 Charger with power drums will lock the wheels. Even the manual drums on this car were better. I'm about ready to give up and go back to stock drums. I have a power brake pedal assembly I'm considering installing with a new booster and master cylinder for a disc car. I really need to get this thing to stop. Where can I buy some "rotor eater" disc pads? I'm willing to try anything at this point. I checked the installation sheet and it doesn't list an FMSI# for these pads like it does for most the other kits. I'm hoping these pads aren't specific to SSBC. My kit was the A156 which is calling for an SSBC pad of A1033.

Re: New disc brake conversion doesn't work [Re: timinator] #58223
05/22/08 08:46 AM
05/22/08 08:46 AM
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Maryland
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I just bought a new brake pedal. It should be coming today or tomorrow. I posted a question about 62-65 brake pedals and a member measured thiers and it was about 3" shorter, so I found a manual brake car and got that pedal. If we get it on the car this weekend I'll post the results.

If your car had power brakes, measure the brake pedal from the pivot to the bottom of the footrest, and the pivot to the brake pushrod attachment point. Divide that number into the first measurement and that is your pedal ratio. Find someone that has a true manual brake car and ask them to measure their pedal and compare. From the measurements that I got, on the early B-bodies the pedals are different.

The smaller master cylinder will help, but not solve the problem if the pedal ratio is incorrect. Been there, done that.



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Re: New disc brake conversion doesn't work [Re: Dads426] #58224
05/22/08 08:52 AM
05/22/08 08:52 AM
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timinator Offline OP
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Ok, been doing some research and it appears the pads I have cross reference to an FMSI Part # of D-11. That's like a 67 Ford Falcon or Fairlane pad. Can anybody recommend an aggressive pad like EBC or something where they've had good success? Thanks

Re: New disc brake conversion doesn't work [Re: timinator] #58225
05/22/08 06:49 PM
05/22/08 06:49 PM
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Santa Cruz, California
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Lefty Offline
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I would think for the high price of their kits SSBC would be helping you more.

What's the piston size/sizes in the SSBC calipers?

Re: New disc brake conversion doesn't work [Re: Lefty] #58226
05/23/08 11:40 PM
05/23/08 11:40 PM
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timinator Offline OP
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They're twin piston 43 mm.

Re: New disc brake conversion doesn't work [Re: timinator] #58227
05/24/08 12:28 AM
05/24/08 12:28 AM
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Oregon
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Those are pretty small pistons. If you compare that caliper to the factory A body caliper with a single 2.75 inch piston you'll see that the SSBC caliper has only 75% of the braking force of a stock system.

That means the rest of the system needs to be re-calibrated with smaller components to match. First thing would be to put the smallest rear wheel cylinders that you can find in there and the smallest master cylinder. That might get you back to a properly balanced system.

Re: New disc brake conversion doesn't work [Re: AndyF] #58228
05/24/08 09:08 PM
05/24/08 09:08 PM
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Maryland
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I picked up a brake pedal for a manual brake car. Noticeably different. The ratio is closer to 6-1 versus 3-1 for the power brake pedal. There are two pivot holes in the hanger for the pedal, but we had to drop the steering column and remove the hanger to get the pedal out. The brake pushrod mounts higher than on the power brake pedal; luckily the firewall had holes and a cutout for a higher mount. But, I had to remake the brake lines to the proportioning valve and line lock. I put the 1-1/32" master cylinder back in and brake effort is noticeably better. Not nearly as good as a power brake car, but much better. I'm sure the 15/16 master cylinder would reduce effort further, but I like the lightweight master cylinder better.

4449186-Pedals.JPG (290 downloads)


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Re: New disc brake conversion doesn't work [Re: Dads426] #58229
05/24/08 10:21 PM
05/24/08 10:21 PM
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connecticut
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A residual vlave in the front will keep the brakes applied and not release...not a good idea! Have you all checked to make sure the rears are working? increase the rear line pressure it sounds like the fronts are not getting help from the rear...also are the rears adjusted correctly? I know sounds simple but you never know! Ive done a few conversion with no troubles im about to put a set of ford cobra brakes on my early mustang 4 wheel disc 13 in front rotors 11.65 rear fronts dual piston 38 mm 15/16 master is whats recomended...im thinking a hydro boost setup will be the way to go. its basically the same system on late model cobra mustangs and that car stops on a dime and gives u back 8 cents!


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Re: New disc brake conversion doesn't work [Re: timinator] #58230
05/24/08 10:23 PM
05/24/08 10:23 PM
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The Swamp
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If it were me I'd box up that SSBC stuff and send it back, and convert it over to factory Mopar stuff, using either 73 A body disc spindles (or the later F M J spindles) 11 3/4" rotors, calipers and caliper adapters from a Cordoba, a manual disc master from a 73 A body disc brake car and either an adjustable prop valve or a 73 A body disc brake prop valve. That swap has been done hundreds of times by lots of people - the 'hard' part is scrounging up the parts, and they really aren't that hard to find if you look. Only point in buying a kit like SSBC's is the 'convenience' of it being all in one box, but if it works like trash, why bother? My

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