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Brakes in Reverse
https://slantsix.org/forum/viewtopic.php?t=18288		 Page 1 of 2
Author:  vynn3 [ Thu Jun 29, 2006 6:23 am ]
Post subject:  Brakes in Reverse
'67 Dart GT, 10" Power Drums all around. All of a sudden, whenever backing up, it's like the power assist is gone (it stops, but requires a LOT more effort). Going forward, everything's fine. I replaced the master cylinder on Sunday with no issues, and as said, it brakes fine straight ahead. Any ideas? Thanks in advance!

VM
Author:  SlantSixDan [ Thu Jun 29, 2006 7:16 am ]
Post subject: 
This problem started happening before you replaced the master cylinder? Or immediately after?

What did you replace the master cylinder with? A brand new one? A bench rebuilt unit? A "remanufactured" one from the parts store?

Did you bench-bleed the master cylinder?

Sounds like you have power brakes. Are you getting any abnormal noises (hissing, tooting) from the booster, or does the engine run roughly when you step on the brakes?

How long since the brakes themselves were inspected and/or rebuilt?
Author:  vynn3 [ Thu Jun 29, 2006 9:20 am ]
Post subject: 
Quote:
This problem started happening before you replaced the master cylinder? Or immediately after?
Immediately after.
Quote:
What did you replace the master cylinder with? A brand new one? A bench rebuilt unit? A "remanufactured" one from the parts store?
Remanufactured from the parts store.
Quote:
Did you bench-bleed the master cylinder?
Yep, and installed per the included instructions AND the service manual. Normal, forward braking is now great.
Quote:
Sounds like you have power brakes. Are you getting any abnormal noises (hissing, tooting) from the booster, or does the engine run roughly when you step on the brakes?
Yes, power. No abnormal noises from the booster, but now that you mention it, the idle is slightly rough of late... would a vacuum leak affect the boost only in reverse?
Quote:
How long since the brakes themselves were inspected and/or rebuilt?
Haven't had the car long, so this is step one of the inspection, so that I might know what to look for. My drum brake knowledge is a little rusty...

Thanks!

VM
Author:  SlantSixDan [ Thu Jun 29, 2006 9:23 am ]
Post subject: 
Quote:
Quote:
This problem started happening before you replaced the master cylinder? Or immediately after?
Immediately after.
Quote:
What did you replace the master cylinder with? A brand new one? A bench rebuilt unit? A "remanufactured" one from the parts store?
Remanufactured from the parts store.
Voila, there's your answer. "Remanufactured" parts are garbage. You are probably not getting much braking effect from the rear brakes at all, in either direction.
Author:  vynn3 [ Thu Jun 29, 2006 10:04 am ]
Post subject: 
How does the master cylinder know if I'm going forwards or backwards? Any other suggestions besides the "it's a rebuilt, so that MUST be the problem" approach?

I realize that rebuilt parts have a troubled reliability record. I would've purchased a new MC if A) I knew where to find one, and B) I didn't need the brakes to operate so that I could get to work the next morning. My decision to replace the MC came at 7pm Sunday night, when, while checking the brake fluid, the old retaining bolt for the cover snapped off in the MC. For me at least, circumstances often dictate the repair approach.

So, who sells brand-new master cylinders?

VM
Author:  SlantSixDan [ Thu Jun 29, 2006 10:31 am ]
Post subject: 
Quote:
How does the master cylinder know if I'm going forwards or backwards?
It doesn't. When you are going forward, the front brakes do most of the work. When you are going rearward, the rear brakes do most of the work.
Quote:
Any other suggestions besides the "it's a rebuilt, so that MUST be the problem" approach?
Hey, man, you installed a replacement master cylinder, immediately this problem began, and now you want to point a finger somewhere other than the master cylinder...? If I could wave a magic wand and make "remanufactured" parts not suck, I'd do it, but my magic wand lost its ballast resistor the other day and replacements are NS1.
Quote:
So, who sells brand-new master cylinders?
Raybestos, Bendix, Wagner, NAPA-United. I'll have some appropriate P/Ns for you later today.
Author:  vynn3 [ Thu Jun 29, 2006 12:59 pm ]
Post subject: 
Quote:
but my magic wand lost its ballast resistor the other day and replacements are NS1.
Then please search Ebay thoroughly and often, Dan. SOMEONE has to have one. Your exhaustive lists of part numbers and references just aren't enough anymore. :)
Quote:
Raybestos, Bendix, Wagner, NAPA-United. I'll have some appropriate P/Ns for you later today.
Thanks as always, Dan. <sigh> Okay, okay. I'll cave in and replace the shiny MC that's on the car with a brand new one, and pray that's the problem. But I'll probably cuss your name the whole time, just so y'know...

VM
Author:  SlantSixDan [ Thu Jun 29, 2006 2:39 pm ]
Post subject:  M/C part numbers
Raybestos MC36308 or MC36439
NAPA United 36308 or 36439
Bendix 11574
Author:  vynn3 [ Fri Jun 30, 2006 6:32 am ]
Post subject: 
Thanks, Dan.

VM
Author:  SlantSixDan [ Fri Jun 30, 2006 6:58 am ]
Post subject: 
No problem. You'll want to do a full system bleed (new master on the bench plus all four corners) to make sure the previous master didn't spit some piece of rubber or goo into the lines...and, as previously mentioned, you may want to do a more thorough inspection of the brake system in total when you get a chance. Flex lines front and rear, wheel cylinders, shoes, hardware, self-adjustors...
Author:  vynn3 [ Fri Jun 30, 2006 8:03 am ]
Post subject: 
Aaaaafirmative. NEW MC is on it's way from NAPA Online ($95.87!!!<grumble>).

VM
Author:  Rick Covalt [ Fri Jun 30, 2006 9:07 am ]
Post subject:  Rebuilt Junk!
I replaced a bad M/C on my sons Dart with a "rebuilt" from Advance. And after replacing that one 2 times in 6 months , I told them to put that money towards a "new" not remanufactured unit. The sad thing is the "new" one had a 12 warranty and the remanufactured one had a lifetime warranty. Go Figure. The thought of saving $30-40 on a remanufactured unit is not worth the hassle of doing the job over 2 more times.

Your "new" one will probably work great!

Rick
Author:  vynn3 [ Fri Jun 30, 2006 10:52 am ]
Post subject: 
I agree, and I obviously want to do the job right. But in this case, it turned out to be almost $70 more, not $30-40. Plus, a week's wait for shipping (despite my efforts, I couldn't find a new one in the Dallas area).

So, in retrospect, I still think spending $16 for a rebuilt and making the car driveable with an hour's worth of work was the right thing to do in my situation. Next week I'll spend another hour switching them out and return the $16 MC for a refund, rather than miss a week's worth of work waiting for the new one to arrive.

Thanks to both Dan and Rick for the comments. I'm just reiterating that circumstances sometimes dictate the repair. I can't always do things the way I'd like to.

VM
Author:  vynn3 [ Thu Jul 06, 2006 8:05 pm ]
Post subject:  Update: Brakes in Reverse
So, after waiting a week on a NEW master cylinder from NAPA online (which, it turns out, was delivered from a store 30 minutes away, I might add), it arrived today. Bench bled it, installed it, and BLAM!

Same, exact problem. Brakes okay (but not great) going forward, no braking power going backwards. So, one week and $100 later, all I've learned is what common sense told me: rebuilt parts may have a less-than-stellar track record, but snap judgements based on rebuilt parts are DUMB.

I'm not upset because of a misdiagnosis — Dan and the other board members have been of temendous help over the years. What I'm mad about is the fact that I begged for other options, other possibilities BESIDES the MC, just in case I did something wrong during the install. Dan even asked about the idle, to which I answered, "Yeah, come to think of it, the idle HAS gotten slightly rough". No comments in answer to that.

A similar situation came about a couple of months ago when I asked about a rough idle on my other Dart, the Swinger, a super six conversion car. During the conversion in January, I DARED to install a rebuilt BBD, so that was AUTOMATICALLY determined to be the problem. Well, I pulled the cylinder head two weeks ago, and guess what? Two burned valves! Replaced the head with a rebuilt (was that okay?), crank it up, and it runs fine, even with that crappy rebuilt carb. I'm sure it's just a matter of time, though...

I can do most of the work on my cars, but diagnosis is my weakest area. I guess I'm just not very smart. So I rely on OTHER people smarter than me to help figure things out BEFORE I just throw money at the problem. Also, I TRY to buy new parts, rather than rebuilt, whenever possible. But sometimes there are extenuating circumstances, so I'm forced to gamble. I can't believe I'm the only slanter who's done this, and that every rebuilt part is guaranteed to fail. In fact, I now have a leftover $16 master cylinder that seems to work as well as the $87 NEW one I ordered.

Back to the braking problem. I've pinched off the brake booster vacuum line, and after doing so noticed the idle doesn't roughen when I hit the brakes. I also switched the check valve from the one in my Swinger, and there was no change, so I've determined that the problem is probably the power brake booster itself. Next I'm either having mine rebuilt or buying a (gasp!) rebuilt one. From past experience, I figure this will cost around $200 and at least several days' wait. Before I proceed, does anyone concur?

Sorry for the rant. I'm hot, tired, broke, and hating old cars at the moment. Despite the huge payments, my wife's '05 Accord is looking very attractive right now. Maybe I'm just not cut out for old car ownership after all.

VM
Author:  SlantSixDan [ Thu Jul 06, 2006 8:20 pm ]
Post subject: 
Oy. How'd I miss your affirmative answer to the rough-idle question? Well, however it happened, it happened. Sorry 'bout that.

Sounds like you do have a dead booster. Booster Dewey is a reputable rebuilder. Or, y'know, you could just delete the booster and go to nonpower brakes...
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