Disc brakes still not stopping good

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71Demon

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Four wheel SSBC disc brakes on the car now with 4 piston fronts and single piston rears. Had a 1" bore wilwood master cylinder that just would not bleed after many attempts. So I put the disc/drum 1-1/32" master on that I was using when I had drums on the rear and disc fronts, and removed the residual valve. Have a in line proportioning valve on the rear brake line under the car near the center of the door. Got a good hard pedal but the car just does not stop good. Just kind of lazily comes to a stop with hard push on the pedal. Any ideas on what could be the problem now? Help???
 
line bulge and/or the rotors/pads need to be bedded in properly
 
Using braided stainless lines on the calipers and the ssbc kit came with braided stainless lines on the rear end housing. Can they bulge?
 
Are you using a booster or just manual brakes? The 1 1/32 bore master is too large for a 4-wheel manual disc setup. You'll get a hard pedal like you describe. Dr Diff recommends a 15/16 bore 2-bolt aluminum master in that application. He modifies the standard 15/16 bore masters to accept a manual brake pushrod. Then you use an adaptor to mount it in place of the stock 4-bolt unit. The stock length manual brake pushrod is retained...no need for an adjustable pushrod.
 
burdar said:
Are you using a booster or just manual brakes? The 1 1/32 bore master is too large for a 4-wheel manual disc setup. You'll get a hard pedal like you describe. Dr Diff recommends a 15/16 bore 2-bolt aluminum master in that application. He modifies the standard 15/16 bore masters to accept a manual brake pushrod. Then you use an adaptor to mount it in place of the stock 4-bolt unit. The stock length manual brake pushrod is retained...no need for an adjustable pushrod.
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Thanks. Was thinking it might be too large from what I have read too. Dr Diff have a website I can order from??
 
stay 1" or less if you can. The 4 wheel drum master is what some are using.
 
71Demon said:
Using braided stainless lines on the calipers and the ssbc kit came with braided stainless lines on the rear end housing. Can they bulge?
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old school lines bulge, but with stainless you have that covered. I would still give rebedding them a shot before I swapped hardware. This is what I have always followed with great results...
Bedding in Brakes, Zeckhausen Racing
 
Call Cass at Dr Diff. He's a very knowledgeable and helpful individual. Explain what you've got going on and listen to what he says. He will get you on the right track. Also agree on the bedding of the pads. Keep in mind some of the friction material is "race only" and requires heat before it operates at peak performance.
 
4mulas said:
Don't confuse BEDDING for bLEEDing
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oh sorry just did the bedding still can't lock up the brakes. Feels a little better but still uncomfortable due to slow stopping.
 
If you didn't follow the brake bedding procedure that IMO is most likely the issue.

It was my problem.
 
you followed the link I posted? Once the brakes fully cool, there should be a major change
 
If they are done well, the disc surface will have a grey hazy look like graphite and you'll definitely smell them burning before you are finished
 
Still battling this 4 wheel SSBC disc brake set up. Ive bled them so many times, I even pressure bled them. Tried 1 1/32 and 15/16 masters and still not stopping good. Im thinking I just don't have enough pressure at the calipers. How much pressure do I need? Would adding a power booster help? Thanks,
 
Adding a power booster will not help.

They make the pedal easier to push, that's really about it. Yes, on an A-body the bracketry for the power booster changes the pedal ratio slightly as well, but you've covered that and more by using 15/16" and 1-1/32" masters.
 
72bluNblu said:
Adding a power booster will not help.

They make the pedal easier to push, that's really about it. Yes, on an A-body the bracketry for the power booster changes the pedal ratio slightly as well, but you've covered that and more by using 15/16" and 1-1/32" masters.
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I have a small piston master cyl out of an 87 dodge diplomat on my 4 wheel disc set up. it will stop ok (so far) but still requires some leg. think I`m going to extend the brake pedal about an inch, and move it over -more like an auto. brake pedal. ---- thots on this ??-- anyone!
 
71Demon said:
Got a good hard pedal but the car just does not stop good. Just kind of lazily comes to a stop with hard push on the pedal..
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does the car have good initial bite, or does it feel almost like you are sliding when you press the pedal, like the brakes are wet, but then they come in more when you push harder?
in an attempt to lock the brakes up, when you stab the pedal, does the nose dive, or does the car come to an even, controlled stop, just not as soon as you'd like?

also, what PN SSBC kit is it? I ask because your issue may simply be the brake pads. Everything may be functioning 100% correctly, but you are just not getting the performance you want, under the conditions you are driving the car. A legit high performance racing or competition brake pad is going to perform very poorly in a daily driver, just like standard pads will perform poorly for racing. A standard pad is designed to give great initial bite and braking from fully cold through warm, conditions a daily driver sees, but get them hot through REALLY HOT, they can fade completely out. High performance pads will have that same vague "brake fade" feeling fully cold through warm, but will have great bite and braking hot through REALLY HOT. There are pads on the market that are great mid-range warm/hot performers, think street/strip pads. Looking at the SSBC kits online, I don't see much info on the brake pad material. If you are unsure of what kit you have, or what pads your calipers are loaded with, that is what I suggest trying next. Load a set of "basic" pads and see if they offer the performance you are looking for..

**edit- reading through the SSBC website, I am VERY surprised to read this in their tech section:

How should I bed in my new brak pads and rotors?
WITH EVERY NEW SET OF ROTORS AND PADS, YOU SHOULD GIVE YOUR VEHICLE 200 - 250 MILES OF EASY DRIVING TO PROPERLY SEAT THE PADS TO THE ROTORS. DO NOT TAKE THE VEHICLE UP TO 60 MPH AND JAM ON THE BRAKES BEFORE THE FIRST 200 - 250 MILE BREAK IN PERIOD IS OVER, OR YOU WILL GLAZE THE PADS AND ROTORS

this is the complete opposite of my personal experience with disc brake systems from standard equip to high performance, fixed to floating rotors. I guess it's like engine break-in. Some believe you need to baby it, keep the rpms low and build up to normal driving, others believe a "hard" brake-in is best..
 
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