I bought a front disc brake conversion kit for my 69 Charger with manual brakes from Stainless Steel. I've bled the system and the pedal is firm. The proportioning valve that came with the kit has been adjusted both ways which doesn't seem to help and it's located between the distribution block and rear brakes as per the instructions. I've cleaned the discs with brake cleaner. When I apply the brakes really hard the car just gradually slows down and eventually stops. The pedal only moves about and inch or so and is firm when I do this. At walking speed I stand on them hard and again is just barely works instead of stopping the car. My 10" drums worked way better! Any ideas or has anybody had this problem before?

What master and bore diameter?

John

Those calipers have very small pistons. You need to run a 15/16" bore master cylinder.

I had this same issue with them but i was trying their power brake set up. (which uses corvette master bylinder and booster) No matter how much i tried I could not get them working well. Are you using the ssbc master that comes with it? I ran their 4 wheel disc manual set for a while and their master is a 1 1/32 bore.

They worked well but i had to really really really stand on the brakes to get them to stop. I am currently running that same master with a dual diaphram booster and happy with it, but i am thinking of going to the 15/16 bore like dr diff indicated.

partial blockage somewhere. in my case I had a dented line & I had the exact same symptoms as you.

I have had all kinds of problems with my 4 wheel SSBC brakes over the years and have switched out masters, brake lines, and distribution blocks all with just mild success. They did call for like 500 miles of break in and that did help some. I have pretty much just written them off as an average setup just slightly better than well set up drums. I even have their slotted rotor force 10 aluminum caliper setup that was advertsised as being so great. I do get better repeatablitiy out of them but once again not nearly as good as I thought. Will be going to some type of 13" disk set up like from a Viper before too long. Good luck with yours and hopefully the switch to a 15/16" master will be you answer.
Todd

All the lines are new and no dents there. I am using the master cylinder that came with the kit. Can somebody recommend a master cylinder to use? (i.e. where to get one, what size or for what application car?) Is the 15/16th master cylinder bigger than what I have from the kit and if so, where can I buy one?

This is a common problem. SSBC doesn't even know about the 15/16" master.

Get a NEW 15/16" unit for a '73-'75 A-body POWER disc brake application.

We have the same problem on our 64. The 1-1/32" master cylinder didn't stop the car hardly at all. Put a 1" on it and no difference. Went to a 15/16" and the car stops, but pedal effort is very high. My dad had manual drum cars that stopped better than this setup. Thinking of experimenting with different pads or going to the larger rotor (we have caliper brackets). Is there a larger piston caliper that might work better than the 70's A body?

I have this 7/8" piston master cylinder with 4 piston calipers on the front and single piston calipers on the rear. No booster, manual 4 wheel disc brakes.

Brake pedal feel is firm but not too stiff.

http://store.summitracing.com/partdetail...mp;autoview=sku

They sell rear wheel cylinders for disc brake conversions on e bay. Call them problem solvers, but these are to alleviate air in the line or "spongy pedal" which is caused by moderen master cylinders lacking a residual pressure valve. Do a search on mopar rear wheel cylinders. Mo out

I just had the car out around the block and it's flat out dangerous. I stand on the pedal and it slowly comes to a stop. I don't suspect I'll get much help from the tech line. I'm going to try the 15/16 master cylinder and see what happens. If not, I'm just going to chuck the SSBC kit and put the 10" drums back on so I can drive the dang thing! Why couldn't I have just left it alone?

Yeah, there tech line was awesome when I was first having my problems!!! Guy told me well that car is heavy, if it is stopping from 60mph in anything short of 200' then that should be considered good. My drum brakes were stopping from 60 at around 150'. Boy good thing I spent nearly $2K on their awesome brakes so that my way heavier Explorer and my wife's fat minivan could stop better than my way lighter(3650 lb) roadrunner.
Todd

I think part of the problem is also that most folks go from a "power" drumbrake system to a new "non-power" disc/drum system. I think here's where they (ssbc) don't hold in account that original power-assisted cars have a shorter brakepedal-ratio, causing a firmer pedal and less force to the MC to begin with.

Sure sounds like Pedal ratio. I just went thru this too. Hard pedal & no way I could lock up anything.

Read through this....

http://www.hotrodheaven.com/tech/brakes/brakes6.htm

Mine is a c-body & there's 2 different pedals for the Power & manual setups. Also 2 different hinge points for each Pedal.

Doc diff sent me that link & sure enough my Pedal ratio was 3:1 & I needed 6:1. Modified the pedal & it's much better now. Working on other issues with the Brakes right now.

Butch

yikes

this is not what a guy wants to hear that was considering a manual to power brake upgrade

please keep us posted

My car originally was a manual drum car so I'm guessing the ratio of the pedal is correct for the manual disc brakes.