RE: [Chrysler300] 300F Brakes

["'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

Understand your point..yes a checklist, but this exchange very good as many others apparently have had that happen..me too. All those people cannot develop a synchronous plugged hose or wheel cylinder leak in winter storage, but they all will get some rust inside drum. Says rust theory and self locking is probably right???? 

 

Any hydraulic thing would not keep hi psi on wheel cylinder, it would cause slow release or dragging.(assuming it was working right and put together right when put away..working right) .as opposed to almost violent locking and staying locked, until you back up, at which point it is then NOT locked till you try it again going forward .. I think shoe grabs drum rust and mechanically jams tight like a wedge. Both are self energizing going ahead after all. Backing up frees them obviously. 

 

This exchange really helps…..it says back up and jam on brakes pretty hard 4-5 times and then see about forward. You are right that incorrect assembly does this, I had one F front that locked up violently going slowly, (LUCKY!) after it had been working Ok for awhile , due to the adjusting cam flat spring (not return spring) being on wrong side of adjusting cam after rebuild….easy to do that ,and it does go together. Book is not clear at all on this either….no real images of it assembled right. …needs a “phantom view” of it assembled.  Draw that long flat spring into service manual on top of illustrations, as you take apart .

 

Wish I had seen this exchange many years ago. Now I feel I took them all apart a few times for nothing…..back then. 

 

Worth trying, in any event…

 

John Grady

 

From: Ron Waters [mailto:ronbo97@xxxxxxxxxxx] 
Sent: Monday, April 13, 2015 12:16 PM
To: John Grady; Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] 300F Brakes

 

John -

 

All anecdotal information. Lots of reports of folks that had problems similar to Terry's. When they replaced the hoses, the problem went away. Apparently, as the hoses deteriorate, the internals close up. Kind of act like a check valve, causing the fluid not to immediately return to the master cylinder. It's never happened to me. Just on the list of 'things to check'. 

 

Hoses are easy to replace. If shoes are locking against the drums, then something is causing them not to release. If all the brakes are locking up, it's likely a hydraulic issue instead of a mechanical one (for example...weak or incorrectly mounted return springs, etc). Piston jamming in the bore of the m/c is also worth considering. Create a checklist. Sort the list by either 'most likely' to 'least likely' or 'easiest to fix/replace' to 'hardest to fix/replace'. Eliminate the items one at a time until problem is solved.

 

Ron

----- Original Message ----- 

From: John Grady <mailto:jkg@xxxxxxxxxxxxxxxxx>  

To: 'Ron Waters' <mailto:ronbo97@xxxxxxxxxxx>  ; Chrysler300@xxxxxxxxxxxxxxx 

Sent: Monday, April 13, 2015 11:26 AM

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

 

 









[Non-text portions of this message have been removed]



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Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
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