Disc brake swap - master cylinder question.

[67 coronet]

Thanks, I'm going to pull the drums off this weekend and see if I can figure anything out. I really hate the fact that most shops around here won't touch anything older than 1980, and those that will won't touch the brakes because they aren't 100% stock. I need to find an old shop that works on REAL cars, not just cars that you can plug a module into to figure out what's wrong! lol

Maybe I'll just get a $400 rear disc kit from eBay and be done with all this drum brake crap!

What do you think of this kit?
http://www.ebay.com/itm/mopar-8-3-4...t=Vintage_Car_Truck_Parts_Accessories&vxp=mtr

lol.no doubt.take a look at the scarebird stuff on ebay.i have used it many times and it is great quality.save you some cash as well.

 

[tallhair]

Here is an in depth article on what you need. I feel you will get a straight answer and can make your conversion an ez task. I'm going this route with my 65 Dodge...

http://www.moparaction.com/tech/archive/disc-main.html

thanks for posting ebooger .. love reading his stuff

 

[Belvedere-II]

lol.no doubt.take a look at the scarebird stuff on ebay.i have used it many times and it is great quality.save you some cash as well.

I've looked at his stuff before and didn't see antything for the rear conversion. The kit I viewed on ebay is only $350 complete, plus $50 shipping, and all parts are new, so it's not a bad price at all.

 

[Belvedere-II]

Well, I'm at a total loss. Two different master cylinders, two different adjustable proportioning valves, same problem.
I removed the factory junction block thinking maybe that was it, same problem.
I removed the proportioning valve and it was ten times worse - I was facing down hill and came to a hard stop. Even in drive, facing downhilll, the car wouldn't roll at all until I started driving and tapped the brakes a couple times.
I removed the drums, not difficult but snug, then I opened a wheel cylinder bleeder screw - it was holding pressure because the fluid squirted out. The rear wheels are hot, the front wheels fairly cool... the rear brakes are definitely getting hotter.
I adjusted the valve for more rear pressure, the brakes were worse, adjusted it for less rear pressure and the brakes were better but still after a few stops the brakes are locked up.

I have no idea what the hell is going on here, I did notice that my brakes were acting funny before I did the swap and I felt unsafe driving the car, that's why I went with discs.
I guess it goes into a shop next week, I'm tired of crawling under it with a broken ankle and trying to work on it - everything takes three times longer! lol

 

[RustyRatRod]

You asked about caliper placement. I don't know about the b bodies, but the a bodies need the calipers on the rear, because they will interfere with the strut rods if they are installed on the front. I suspect the b bodies are the same, but I am not certain. I will find out myself soon enough.

 

[ga66mopar]

When I first started driving my 66 after I had put it together my rear brakes was also getting hot. I unbolted the master from the power booster and turned the adjuster nut on the push rod in a few turns and the rear didn't heat up anymore. I have a-body disc with the factory a body valve and a bendix power brake booster. I driven the car on several 200 mile road trips and so far they work great. This may not help but I thought I would mention what I did.

 

[Belvedere-II]

When I first started driving my 66 after I had put it together my rear brakes was also getting hot. I unbolted the master from the power booster and turned the adjuster nut on the push rod in a few turns and the rear didn't heat up anymore. I have a-body disc with the factory a body valve and a bendix power brake booster. I driven the car on several 200 mile road trips and so far they work great. This may not help but I thought I would mention what I did.

OMG... well you were posting this as I was out in the garage doing... guess what? I pulled the MC off and turned the nut on the pushrod in about three turns and went for a test drive and I couldn't get the brakes to hold, but I could get the fronts to lock up under hard braking. I did several hard stops and tried to get them to hold like before and they wouldn't, when I got back, the rear wheels were cold (unlike before) and I came here to post the good news and you beat me to it!!! LOL

 

[5.7 hemi]

Talk about coincedence??? So are the brakes working better? You might need to adjust the proportioning valve now that the rears are working.

 

[Belvedere-II]

haha, yeah, that was funny that I was out making that adjustment and went for a long test drive and came back to share the good news and the solution was right there!

I've adjusted the valve as they suggest: about mid-way and then adjust from there. But I went for a drive, freeway, side roads, hard braking, easy braking, and it's all good now. When I got back home after more than 30 minutes of driving the wheels (at center) were slightly warm, not hot like before. No matter what I tried, I could not get the brakes to drag or bind up like before.

It's interesting because I when I installed the master cylinder it didn't come in contact with the pushrod, so I figured it would be okay... and there was a little play in the pedal. I guess this means my brake booster was holding pretty good vacuum for it to hold the brakes like that. I mean, I only turned the nut in about 1/8 - 3/16 of an inch. Apparently that's all it needed.

Man, I'm so glad they're working now.

Thanks to everyone for their suggestions and thoughts on what could be the issue with this, for it to be something so simple like this is a relief. I guess we can chalk this one up one more thing to check when doing a disc brake conversion.