Ok my 49 F1 has a volare front clip and brakes. I have put a disc conversion on the rear. Its a POL disc kit. I have replaced the master cylinder Prop valve and Booster. 4 disc prop valve fitted.All new pads. GM style 1" master cylinder. *2 booster.Have bled the master cyinder,bled the prop valve, bled all the lines and brakes.
Pedal goes hard and goes nearly to floor with out engine running.Wont pump up to real hard pedal. Start engine and pedal goes to floor. Have disconnected the master cylinder and tested by blanking off out lets and pressing pedal. ITS hard and only goes about half way down and stops. Have not done this test with engine running but assuming master cylinder is sound. Brakes are working but very poor. Certainly will not lock wheels up when moving. But will stop them quickly when up on stands and running in the air.I am out of ideas..Please help..

 

The first thing for me is to always re bench bleed the master and make sure there are no bubbles in both the front rear reservoirs. Since it is bolted up I would block off the outlets like you already have and then have someone push the pedal hard and watch for bubbles in the master and make sure it is thoroughly bled and full of fluid. Push the pedal real hard to make sure all the bubbles are out and the piston is fully compressed. Reconnect the lines.

i am not sure what you mean by bled the proportioning valve. Once the proportioning valve is hooked up to the master cylinder and brake lines hooked up then bleed your brakes starting at the right rear. The easiest way I have found is to fill a container about 1/3 with brake fluid and run a very tight fitting hose from the bleeder screw to the container with the end in the fluid. You need to be sure the hose is tight around the nipple so no air comes back in when you pump the brakes. Have someone Pump the brakes slowly and watch to be sure all the air is out. Or just let it gravity bleed by refilling the master as it slowly drains and the air rises to the top of the caliper and out......

Are all your bleeder valves at the top of the calipers/facing up?!

Others might be able to help about whether you have the right size bore for your brake set up....

 

I'n no expert, but have done a few of these. The adjustment between the booster unit and master cylinder must be adjusted properly to eliminate any slack there. The adjustment on the pedal also needs to be adjusted to remove all but a quarter inch of free pedal movement. What you are describing would indicate the rod between the booster and master cylinder is out of adjustment (too short). A one inch bore master cylinder should work fine in you application. Bleed the brakes with the engine off.

 

If you find it is not the rod length as per above Another thing to try to rile out any issues related to your brake lines. First be sure all your rubber brake lines are not swollen or bulging visually.

Next use vice grips and crimp each line blocking it off and then check the pedal. If it solves the problem you know you have a bad hose or still air in that caliper.

 

Thanks for the replies. I was thinking last night about the possibility of the adjusting rod being too short as the pedal does go a long way before it starts to work and another friend suggested the bulging flexi pipes. Guess I will be trying these today. Will re-post findings, Thanks again

 

Ok this morning i crimped off all the hoses and hey presto I had a hard brake pedal from about 1" down so I am assuming the hoses are duff. Will get new hoses tomorrow and hopefully that will sort it. Will re-post out come. Thanks

 

I took a look at your kit and before you go replacing all the brake lines verify one More item. If it does not have the ratcheting e brake calipers then it probably is one of the hoses....BUT, you need to clamp them off one at a time to figure out which ones. If it does have the set up I think I will bet anything that is your problem...read on...

It looks like those calipers are the ratcheting ebrake style? Cadillac D154 calipers?..They are Basically the same as the ‘79 Trans Am brakes and were used on various Chevy models of that era. Many of the rear disc conversions use them. The piston needs to be seated against the pads before you will get a good pedal. Clamping off the lines will take that out of the equation and may give you a false diagnosis.

Is the ebrake hooked up yet? If not you will not be able to get a pedal until it is hooked up and adjusted. The easiest way to adjust them is to depress And release the ebrake fully 30x. This seats the piston fully against the pad. THe piston moves in based on a ratcheting mechanism and can only be done with the cable and cab lever or foot pedal attached. When the piston isn’t fully seated it can’t move in far enough to get a good pedal as the ratcheting system holds the piston back from moving far enough to get the right clamping force.

Also What you will find is as the pads wear the the ebrake will become less and less effective. Just fully depress and release 30x and it will go back to working perfectly

This is the same issue as someone is having over on the NastyZ site. You will find if you skip to the end the brakes he is using are from the Right Stuff Detailing but also use that same caliper....

https://www.nastyz28.com/threads/rea....324421/page-3

Pics of ebrake set up.









very interested in your answer...

 

SSBC Drum to Disc Brake Conversion Kits A118 Is the rear conversion kit.There has been mixed feed back on these kits some people get the hand brake to work some don't and give up. I have never had it working off the cab lever. Sorry the master cylnder ,booster and prop valve are POL.. When we 1st installed the kit we manually actuated the hand brake actuators to bring the pads onto the discs. I did notice this morning that the NSR pad is not making complete contact with the disc I can see where it has not been making contact.fully. I now have all the flexi hoses off so will get them pressure tested tomorrow before I order new stainless braided ones. I do suspect the front flexis as they are old. The rear caliper ones were new when kit was fitted but the single one down to the T was old also. Will re-post when I know more..

 

So the story continues..Had some stainless braided hoses made up yesterday and came home and fitted them. A little better but still not a safe braking system. So the push rod from the pedal to the booster was on its max adjustment. I made a new push rod with an extra inch longer and hey presto the brakes are sorted. So The mupppet who fitted the brake pedal kit and new booster and master cylinder had wound the adjuster out to its maximum and assumed it was working. When he did it the rear disc conversion was not fitted and he blamed the poor braking on worn shoes, Even when i replaced the shoes it was no better. Any way i think the fault was not enough adjustment on the rod and possibly a weak front hose..Just glad its all sorted now...Thanks for the input guys..

 

Glad to be of some help to you in getting this sorted out.