I've been struggling for the last 3 months with a brake problem on my '70 Roadrunner. Two shops & 2 Dodge dealer master mechanics can't figure it out. Can anyone recommend a shop near Chicago that's an expert at old Mopars?

What is it doing?

agreed, the guys here can figure it out. complete details please

Chicagoland is a big place, I know several shops but mostly in the northwest suburbs.

The car was in storage for 20yrs. & the brakes didn't feel "just right" then they went out completely and suddenly without a brake warning light coming on & no obvious fluid loss.

I've replaced the master cylinder (three times), the metering valve (twice), the brake booster, the proportioning valve, new stainless brake lines front-to-back, new calipers, rotors, pads, drums, shoes, hardware front & back, brake warning switch (3 times), rear brake hose & passenger's brake hose. Only older part is left is the driver front brake hose & I wasn't getting fluid out of the passenger caliper, so the driver's hose isn't it. Master cylinder was bench bled + later bled on the car with the hoses (when I questioned my bench bleed).

Last night my wife pumped the brakes and I found a leak near the proportioning valve where the line between the proportioning valve & metering valve connect to each other at the end, so I have at least one more thing to try. The last leak(s) I fixed two days ago were this line & the one that comes down from the back of the master cylinder to the metering valve. It "seems" like with these stainless lines they start to leak at the ends if you connect/disconnect them a few times. I've also been unable to double flare the SS line with my flare tool (too hard & line slips out of grips). Since it doesn't look like Inline Tubes sells partial SS kits, I resorted to compression unions & mild steel line to fix the leaking half of the line(s). Now the "good SS half" of the line I mentioned is leaking too, so I will see if I can replace the whole line with mild steel. I have one more new proportioning valve I guess I could try too if it's the female half of that connection that's causing the leak.

That's a decent description of what you have done but really tells us nothing about what is wrong.

What does the car do that it shouldn't?

What doesn't the car do that it should?

Your description implies a front disc rear drum setup as opposed to all drum brakes, is that correct?

The leak which you have a handle on will cause an issue. Stainless lines can be a pain to get seated properly because they are too hard. Does the car have a brake booster? Using DOT5 fluid? That stuff causes a weird pedal feel. Brake shoes are on the on the correct side? Many years ago I got 1 wrong brake shoe in a new box. It was arc'd for a different size drum.

I'd plumb the lines with regular parts house prefabbed lines if you are amenable to that or what ever you want/need to have a sealed system (there are brands that bend easier) then have a block of wood under the pedal to limit the travel to normal height. set the Ebrake to lock the rear shoes (we'll adj em later). set the booster rounded pushrod nub clearance to .020". then we can bench bleed the MC on the car & then bleed the fronts then the rears. Holler back when you can.

Quote:

I resorted to compression unions & mild steel line to fix the leaking half of the line(s).

Compression fittings are not rated for the pressure a brake system produces!! get that line replaced immediately.

I will try to address several questions at once. Keep in mind that 20 yrs. ago it was my daily driver & the brakes worked fine from what I remember. I only put in the stainless lines because the originals looked rusty & I was basically re-doing the whole car mechanically.

1. This is a factory power front disc, rear 11" drum car.
2. What's it doing? At first, push the brake pedal, it didn't go to the floor, but the car had NO brakes & I rear-ended a Lexus. I replaced MC (3 times) & booster after that (already had done the other stuff about a year ago). Now, I have the brake warning light on, the pedal has limited resistance & goes to the floor. The brake warning light only comes on when I push the brake pedal.... and it has a leak now.
3. I am running DOT3
4. Pretty sure I have the right shoes....the wear pattern looks normal & even across the entire shoe when I pulled the drums to check the back brakes.
5. Rod/booster clearance - I think a previous comment Rapid made was why I switched to a different style MC the last time. I had been running the C-body/Hemi type narrow MC w/lines exiting towards fender which has the MC piston extending out of the MC. Because I couldn't figure out how to get a dial indicator on it to measure 0.020" clearance, on my third MC I switched to the wider one for 383/440 cars which has an inset piston. If I understood correctly, I don't need to check the clearance on that one.
6. Bleeding - I've done gravity (per factory service manual with the pin pulled out on the proportioning valve), vacuum bled & pedal bled... each method 3-4 times.
7. Compression Unions - you're right, but I'm desperate. I've had a bunch of issues that have prevented me from driving this car all summer long....I've waited 20yrs. to drive it.... I'm desperate.

Tonight I plan to buy a piece of mild steel tubing from AutoZone & bend it to replace the 1/2 mild-1/2 stainless piece that's leaking between prop/meter valves. If they have the right tube, I may go ahead and replace the other one I Frankensteined too.

Question #1 - Rapid - why do you put the block under the brake pedal? Why do you bleed front calipers before the rear drums?

#1 is to fix the leak which you are on top of. "limited resistance/goes to floor" sounds like air. warning light comes on cuz one half was opened or had a leak & the normal high psi side kicked the switch over which it just tells you that there WAS a problem (once we get the leak fixed), then we can recenter the switch. I put a block under the pedal to limit the piston travel to its normal "worn in" bore section as going past it can hasten the demise of the seals over time, definitely not a deal breaker but it DOES let your helper have perfect control of the pedal position while you are manning the bleeders. on the front discs first, again not a dealbreaker but since the piston pressurizes the back close to the firewall port for the front discs first I just habitually do them first plus they can be the hardest to bleed & I like to get the hardest jobs dealt with first then I have less on the back of my mind for the rest of the (easier) jobs. I have the helper pump the pedal several times to agitate the fluid then hold it down & you with perfect timing at that very moment crack a bleeder which helps on tough bleeding cases which calipers can be. EDIT I would stick something in the piston recess to measure the clearance out to the flange to set the nub clearance to ~.020"

Mc pushrod clearance needs checked and adjusted any time the master or booster is changed. Excess clearance makes fr too much pedal travel and the booster can run out of assist.

I'd replace the lf hose just because at this point.

When bleeding, do you get a nice strong stream of fluid at each bleeder?

Front bleeder at the top of the caliper right?

Fwiw, I didn't think 11" rear drums came with front disc. 10" is what I believe you should have.

When measuring to verify drum size do you measure the friction material or the backing plate?

Thank you for all your help Rapid, but I'm giving up. I'm going to see if I can find a Mopar specialist in Chicago. I mean, I missed the whole summer & I desperately need the garage space to work on my daily driver before Winter hits (any day now in Chicago).

On a side note, maybe I'm wrong about the rear drums? I recall that there are two sizes of shoes.... maybe 2-1/2" wide & 3" wide or something like that. Anyway, my car has the larger shoes. Maybe there are 2 widths of 10" drums????

And for Roe, I believe the drum size is the inside diameter of the drum itself. Someone correct me if I'm wrong.

Make sure you let us know if you find someone.I live in a south suburb and the guy I go to is in Roselle which is not close for me.It be nice to find someone closer you can trust.

when the time comes holler how it turned out

Well, I took the old runner to Nuts & Volts in Lombard, IL. On the plus side, they got the brake working though the pedal is really low/soft. They put in a Power Master proportioning valve (I'd replaced the prop/metering valve combo twice already with Inline) and re-plumbed some brake lines. Jerry did find that my rear axle end-play lock-washer was bent & the axles were creeping outwards (I'm happy he fixed this) but he also got confused about my left-handed lug nuts & replaced all the studs/nuts with right hand & also lubed the car.

I only asked to have the brakes worked on & the bill was DOUBLE what I was loosely quoted. I'd be pissed, but at least I could drive the car home. Overall, I'd rate him 3-stars out of 5. It'd be 4-star if the bill wasn't double. He knows the brakes aren't "just right" since he was showing me the fluid reservoir and asked me to check the level in a couple days. I can't be too angry since it'd already been to another shop + a Dodge dealer and two master mechanics (& me) not finding the problem.

If the brake fluid level stays OK, then I think I might have the brake booster rod too short vs. the master cylinder main piston hole so the pedal moves quite a bit before the brakes start to engage. Someone here or at FBBO told me that the clearance is like .020" or something (?) but I can't figure out how to measure that. I've got a dial indicator, but not sure how to check that. Any ideas?

(1) its no wonder we mechanics have reps for being crooks (there was a comedy routine on TV one time that cracked me up & the guy was comparing it to if he was in a restaurant & the waiter arrived with the bill saying that the steak took three times as long to cook so the bill is gonna be triple)! and dont forget the tip. (2) with a thick rod like a spare pushrod measure the depth of the piston "thimble recess" in the back of the MC out to the flat flange and adj the protruding round nub pushrod so that its distance from the booster flange is .020" less