Disc Brake Debugging: New SSBC Front Brake Kit, weak stopping power

[snicker]

I need some help debugging a problem in a 69 Charger with drum brakes in the rear and a new SSBC disc brake install in the front. I have done the front install, bench bled the new ssbc master cylinder and added new brake lines from Fine Lines. I have the proportioning valve from SSBC added into the system after the distribution block and I am not getting good stopping power from the new front brakes at all.

I have bled the system at home and then ran the car up to have them vacuum bled at a shop to make sure I have all the air out of the lines. To test I have opened the proportioning valve all the way up which decreases the pressure to the rear brake lines and does not activate them. So, driving with just front brakes I can't get the brakes to lock up or have very forceful stopping at all. I was figuring with just the disc brakes in the front that would be enough to lock up the front when I slam on the brakes.

That doesn't happen...the car will still stop but it takes a little bit and isn't very aggressive. Am I expecting too much from the disc brakes or are they not getting enough pressure and activating fully? If the later, how can I debug that? Pretty much everything is new except for the distribution block. It is allowing fluid to the front brakes but it could it not be providing enough pressure? Could it also be a leak in a brake line connection?

Any suggestions on what to try to identify the problem would be helpful! Thanks.

[bill440rt]

Have you tried contacting SSBC first?? That would be my plan of attack. I've called their tech support before, they were very helpful.

[Musicman]

You should contact the manufacturer first of course... However, according to your description, your system is NOT setup correctly. The funny part is, if your description of the system is correct, you should be doing nose dives every time you hit the brakes. If your system was put together correctly, then I would tell you that your metering (hold-off) valve assembly is not functioning properly... probable secondary low pressure valve frozen open, or a sticky primary metering valve not fully opening.

[Just 6T9 CHGR]

Manual or power?  Regardless I had to give mine about 250 miles of driving to seat the pads into the rotors.  My biggest complaint was the excessive pedal effort needed to work the discs (mine was originally manual) Got used to it after a while though
call SSBC

[snicker]

It's power brakes with a stock power brake booster.

[Musicman]

Seem like a lot of folks have been having problems with the SSBC systems... or maybe it's just because their the only ones posting 
I recently used an ECI disc conversion on the front of my 67... no problems, just bolted right onto the old orginal spindles, and the brakes work great. Of course, I had a power drum/drum system originally, so I had to change a few things. I threw away the original distribution block and replaced it with a combination valve. I also added a new disc/drum master and installed a 10 psi residual valve in the line for the rear drums.

[snicker]

A little more debugging and I took the lid off of the master cylinder and lightly hit the brakes. I could see a squirt of brake fluid come out of the rear brakes bowl but nothing coming out of the main bowl for the front brakes. If I hit the brakes hard I could get a stream of brake fluid to come out of both bowls but it was clearly coming out more stronger out of the rear bowl.

[BigBlackDodge]

A little more debugging and I took the lid off of the master cylinder and lightly hit the brakes. I could see a squirt of brake fluid come out of the rear brakes bowl but nothing coming out of the main bowl for the front brakes. If I hit the brakes hard I could get a stream of brake fluid to come out of both bowls but it was clearly coming out more stronger out of the rear bowl.

Isnt the rear bowl for your front brakes?


BBD

[snicker]

Yes, it is the larger bowl and for the front brakes.

[firefighter3931]

The problem with the SS brakes kit is that the master cylinder piston bore diameter is too large. What you need is a smaller bore piston...something in the 7/8- 15/16 range to increase pedal pressure. I had a good discussion with Dr Diff and he reported the same complaint with the SS brakes kit from several of his customers. He recommends the small bore master.



Ron

[snicker]

I solved the problem by buying a $20 rebuilt master cylinder from Autozone for a 73 A-Body (what came in the kit). I bench bled it and put it on the system and I now have rocking stopping power.

Next up, call SSBC and tell them about the bad MC and see how they handle it.

[Musicman]

I solved the problem by buying a $20 rebuilt master cylinder from Autozone for a 73 A-Body (what came in the kit). I bench bled it and put it on the system and I now have rocking stopping power.

Yup, that's what I used... $20 rebuilt from the local retailer.

[terrible one]

Anyone got the part number for that? And that's for a manual front disc/rear drum setup?

[NMike]

so what did SSBC say?

[RECHRGD]

I bought the ssbc front disc conversion (manual) a couple of years ago and have had the same problem.  If they have been providing the wrong MC's in these kits they should be responsible to make it right.   I have always just figured that the disc brakes take much more pressure to operate and that I would have to put a booster in the system.  But, I have heard enough now about the MC being the fix that I think I'll contact them and see what they say.  I wouldn't think they would want the liability envolved with providing faulty braking systems.  Bob