Brake booster issues

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volaredon

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My son has a 72 fury wagon, not sure if he's a member here or not. I know he knows a few people that are members here...
I took the booster to have it rebuilt and I think it will have to go back in. The pedal is still Rock hard. And the plunger that goes in the back of the master is still floppy loose in the front face of the booster. Is there anything else we can swap in in place of the original one? I certainly can't get a day off of work to take it back, but I have some in the attic off of various years of Dodge truck and van in the attic
Would one of a "formal" C body work?
 
The hose to the booster might also be bad, check that first. Over time the rubber lining on the inside of the hose can come loose and collapse, blocking the vacuum to the booster. Also check the fitting that goes into the intake manifold as those sometimes carbon up and get blocked. The travel rod on the front of the booster will not usually cause the problem you are describing.

Dave
 
I know hose is new and not clogged as is fitting on engine side. Pulling it off with engine running and putting my thumb there , there's plenty of suction and no collapsing hose.
 
If you have vacuum to the booster, then most likely whoever rebuilt it messed something up and it will have to come back off. You should be able to move the travel rod, but it should not flop around. Can you hear any hissing or other vacuum related noise that would suggest a bad diaphragm in the booster?

Dave
 
The push rod coming out of the booster going into the rear of the master is adjustible - you'll see a small hex area - that can be turned while keeping the long part of the push rod stationary by gripping the knurled area with pliers, and it will thread out. Possibly it's adjusted all the way short...

See image below. If that doesn't solve the problem, then something may be messed up in the rebuilt booster. Try putting a space between the pushrod and the master's piston cup to see if that settles it down. The pushrod when properly adjusted should hold the master away from the booster about 1/16 of an inch before bolting it down, to add the necessary preload.

1745153643144.png
 
Ross Wooldridge said:
The push rod coming out of the booster going into the rear of the master is adjustible - you'll see a small hex area - that can be turned while keeping the long part of the push rod stationary by gripping the knurled area with pliers, and it will thread out. Possibly it's adjusted all the way short...

See image below. If that doesn't solve the problem, then something may be messed up in the rebuilt booster. Try putting a space between the pushrod and the master's piston cup to see if that settles it down. The pushrod when properly adjusted should hold the master away from the booster about 1/16 of an inch before bolting it down, to add the necessary preload.

View attachment 716354
Click to expand...
Yup. I know about that. Definitely not the problem.same booster same master same everything that was originally on the car when all as good before the booster crapped out.
That part shown flopped around when we pulled the booster (stop so I can delete the goddamn ad that just covered my screen so I couldn't see the reply box at all) and when my son initially drove it upon reinstalling it on the way to my house he called me from the side of the road and told me it was dragging and he smelled hot brake. That car has never had that problem before. I ended up loosening the master til it rolled free, it was like it was partly applying the brakes without touching the pedal. He put the original spacer that was between the master and booster back in (looks laminated much like a thick carb base gasket) but the foam had disinterested, I ordered new foam from DMT but I figured that would compress to a thickness that would make it irrelevant but now I guess it "pushes" thru the brakes like only one end is working. I moved the car from one side of the driveway to the other and not the garage and the pedal was rock hard and I didn't think I was gonna stop. Last time I drove that car (last year before the booster crapped out) it stopped great. High firm pedal like you'd expect from a power brake car. Not rock hard and barely stop...
 
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I'm a mechanic by trade and have worked on LOTS of brakes and brake problems and this one seemed pretty straightforward but it's not turning out that way. I've changed a handful of boosters over the years but have never run across anything like this. again what's the interchange on a booster for this car? I have a lead on a used one that looks alot like this one I'm thinking of going after for now til I get this one figured out.
I mean the "real" interchange, not just ebay's or the parts store's list.
I hate those as all they say is "will not fit such and such car" but don't tell you what it does fit. We've all used parts on our cars that worked fine even though the "catalog" said "it won't".
I had one, 88 lebaron that I worked on years ago and messed with that pushrod adjustment out of the booster and it took me A LOT to get that right again, this about 30 Years ago. Prior to this one that was the only other car I'd messed with that on and quickly wished I hadn't. That car had a different issue than this one and I don't remember what but the problem ended up having nothing to do with adjusting that pushrod.
 
Definitely sounds like a booster and/or master problem. If they're the original parts that were on the car to begin with, then something's off in the rebuilding process. I'd have the rebuilders check their work for sure.
 
It's normal for the pushrod to be loose in the booster. It just sits in place.

I just finished battling a hard brake pedal problem at work with a 1964 GTO. That turned out to be a combination of poorly designed aftermarket calipers and a defective proportioning valve.

Since your '72 wagon should be all stock parts, you probably just have a bad booster.

Any C body booster from 1965 to 1978 will bolt in, though it would not be wise to use one of the small diameter '65-'68 drum brake boosters. The disc brake wagons all came standard with dual diaphragm boosters, but a large single would work just fine, unless maybe you want to tow a 5000 lb trailer.

I don't think anyone here has taken the time to see if any of the truck or van boosters would fit in a C body. Maybe you should look into it, since you have sample boosters. The three factors that will determine fitment will be the dimensions between the mounting studs on the back, the length of the rod that goes to the pedal along with the hole diameter, and the number of studs for mounting the master cylinder. Chrysler switched to a 2 stud master in the late 70's/early 80's.

If you want to eliminate the rest of the brake system as a problem, try bleeding the brakes with the engine off. If you can easily pump fluid through the system, everything on the hydraulic side is fine. On the previously mentioned GTO, I could open both rear wheel cylinder bleeders and stand on the brake pedal, and it didn't budge an inch. The proportioning valve had failed and completely blocked off the rear circuit. You could barely stop the car because the caliper pistons in the aftermarket front calipers were too small and wouldn't apply enough force to the disc pads. Whoever designed the calipers thought that two 1-1/2" pistons equaled one 3" piston, which is not the case at all. Those crappy calipers are still available in a $1300 kit from Stainless Steel Brake Corp.

First off though, you should check the vacuum to the booster by pulling out the check valve with the engine running.


Jeff
 
Last year I rebuilt the calipers on that car, took em apart and glass beaded them, reassembled with new o rings and seals while Nick (my kid/car owner) replaced all the lines front to back with that NiCopp line, everything bled out great then. Not many miles since. All new rubber hoses too.and wheel cylinders . I'm 99% sure the problem is within the booster. Already checked the line to the booster with engine running, that's all good. It drove fine all summer after that ,(he drove it pretty much daily over the summer) the Booster showed issues the last week or so, when he parked it for the winter I had him pull the booster and I took it to a place like 2 blocks from midway airport to be rebuilt.
There's a year warranty, I'm gonna have to run it back up there and have them recheck their work.

What drives me crazy is that I helped him gut out another 72 wagon and I told him at that time to keep that master and booster even though his appeared fine then.
Instead he sold it as someone gave him (in his words/ opinion). "too much to say no to" and here we are.
 
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If the brakes were self-applying, without foot movement, might that mean the existing brake fluid had become contaminated? Which would be evident with expansion of the rubber diaphram on the bottom of the master cyl top.

Just a random thought as you mentioned "self-apply". No more, no less.

What might make a "van" booster out of a "car" booster can be the mounting brackert and such. Seems like Dodge Van boosters had a right-angle mechanism between the brake pedal and the booster/master cyl unit? Possibly same booster, just what mounts it is different.

The ONLY solid work-arounds would be the old Hollander Interchange Manual.

Please keep us posted on your progress,
CBODY67
 
No no contamination
That spacer between the master and booster I think may have become partly delaminated.
I've dealt with contamination in brake systems before. It's definitely got something to do with the booster.
 
I'd probably send the booster to someone else to rebuild. Apparently they don't know what they are doing. Remember, you get what you pay for!
 
As far as I know if you want a direct replacement it would have to come from a 72/73 station wagon, they used a Midland Ross booster, the other models used a Bendix.
 
Would it hurt to put a Bendix one on at least "for now"?
That one my kid sold which came off of another 72 fury wagon looked different from this one. I'm thinking that one may have been a Bendix.
I'm talking to someone who has one he knows is off a C body but that's all he knows about it, pix look like the one we took off the parts car. I dunno if it was a date thing, or this factory used Midland while the other factory used Bendix or what/ and I don't care as long as I can bolt it on and have it work. He's wanting to take it on power tour, he's paid and from the Ohio stop we basically would have to go past the exit for the town that Murray Park is in... I actually got the windshield from him that's in this car now. I'm hoping we won't have to wait and get one from him... I felt he choked me pretty good on that windshield....
 
Yup it's the booster. No doubt. Had tach and vacuum gauge on engine, pulled check valve with it running, it's good. Swapped in another check valve and it operates exactly the same. I stick a bolt in vacuum line from booster to engine and it slows down and smooths out, idle goes from 1175 with it hooked booster or line hanging free and open to 790-800 with booster vacuum line plugged with w bolt.
 
well I ran it back up there/// there was definitely problems within. He warrantied it, gotta get back up there to get it. My son is questioning his install (had father in law "helping") and the rebuilder is questioning on his end as to "what happened".... he was an azz when first called about it but was totally cool about it once he got his hands back on it and actually got inside...
Ive deal with this company before but not this guy... the guy I was used to, retired....
 
Just picked up the re rebuilt booster from the rebuilder.
He's had it done for a week but I made a deal for the used booster mentioned earlier in the post that my kid offered to the rebuilder as a core in "trade" to make the guy "feel better" about his end because nobody seems to know who's fault the rebuild going bad was. My son had doubts about his help on installing (wasn't me) possibly having something to do with the issues and the rebuilder guy wondering if he did something/missed something the first time...
The rebuilder was in alot better mood after we had the failed unit back in his hands and he had it back apart... When we originally called him about a potential problem he put up a wall of sorts and made it seem like he was the only one who knew anything about cars ans brakes... Once he seen the innards he changed his tune and was much easier to talk to...
I will be helping him reinstall it myself within the next day or two, not like there's much involved, you know, hold it in place til he gets under the dash and starts the nuts on the studs.
 
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