Not sure if this has been mentioned but a common cause of brake lockup is grease on the shoes from a leaking wheel bearing seal. It does just the opposite of what you might think. Also the rubber cups in the cylinder can swell and fail to release particularly if silicone brake fluid is used. I had that happen in a master cylinder.
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Sent: Monday, April 13, 2015 9:26 AM
To: 'Ron Waters'; Chrysler300@xxxxxxxxxxxxxxx
Subject: RE: [Chrysler300] 300F Brakes
Hi Ron,
I never understood that failure—have you ever REALLY seen it? brakes run at over 1000 psi, no way can an inwardly collapsed hose not open right up at 1000 psi? Opposite issue, burst is the failure mode? Yet I see this listed “as a possibility” a lot? How can that collapse happen? ( think “collapsed” garden hose—that is at 50 psi, water flow opens it) As an engineer, I cannot believe it can stay blocked at 1000 psi.. And brake hose wall is very stiff, does not just fall in? . My .02. If partially blocked, by junk?, maybe shoes cannot pull back, but that would not lock brakes up, only drag them . Even that I have trouble with ?
That being said, very real problems with these brakes are at times really hard to solve. Cams turned the wrong way are #1 on my experience. They will adjust that way, but all wrong. And new standard arc shoes into oversize turned drums that do not touch all the way around for 3000 miles, aggravated by overwinter rust as Bob says. But really hard to trust it is OK, if it locks once or 5 times, and then sort of stops locking.. Hate that.
I do not claim to know answer,--- but to illustrate: I have been into RF wheel (only) of 67 dart convert( not same brakes) at least 6 times now. Locks “once in a while” , new drum shoes , small parts, even spindle( ?bent) . It has been ok for a while. I suspect a small wheel cylinder leak once in great while, dampens shoe? changed that too.
Thinking about it, if one wheel, something is causing it, if 2 or 3, probably rust/self energizing too much. 3 wheel cylinders will not spring leak at once?
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'Ron Waters' ronbo97@xxxxxxxxxxx [Chrysler300]
Sent: Monday, April 06, 2015 2:37 PM
To: Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] 300F Brakes
How old are your brake hoses ? Sounds like they are collapsing internally, causing fluid not to return to the master cylinder.
Ron
On Mon, Apr 6, 2015 at 11:06 AM, Terry Mctaggart terrymct999@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:
First nice day here in Dayton OH, so I fired up the 300F to get it out of winter storage. Engine started up just fine, but the brakes didn't. When I apply the brakes normally, they totally lock up. Backing up, by only a few inches, releases them, but normal stops again result in lock up. Before I tear into the brakes, any suggestions about I might be looking for? Terry McTaggart
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