[Chrysler300] Re: [Chrysler 300] brake cylinders , general

The short answers.

Late shoes do NOT interchange with early pre 59 shoes.

Lines should be flushed with brake clean and blown out. Brake fluid would be a big waste and unnecessary expense.

Wheel cylinders should be as smooth as possible. I wrap a piece of scotch brite pad around the hone and shine it up with that. I use PB Blaster for hone lube.

Don’t piece meal a brake job. Change all the wheel cylinders, brake hoses, shoes, and master. Inspect and cleanout all lines.

Wheel cylinders from Bernbaum’s are correct, those from Rock Auto are not.

Front shoe springs attach to the web on the shoe, and are a different style than the rears (one long leg). The rears attach to the outer retainer on the shoe.

Send me a picture of what you are working with.

Don

From: mailto:Chrysler300-noreply@xxxxxxxxxxxxxxx

Sent: Thursday, October 22, 2020 12:57 PM

To: bob@xxxxxxxxxxxxx ; Chouinard JY ; chrysler300@xxxxxxxxxxxxxxx ; john.begian@xxxxxxxxxxxx

Subject: [Chrysler300] brake cylinders , general

past few days have been after D front wheel cylinders / brakes . Today, we solicit any comments / knowledge , or share same !

So, after a small leak with silicone fluid ,the left front of car grabbed badly . i do not think you can really get any brake fluid out of linings no matter what you try , with silicone being probably 20x worse . so new shoes have to go in . however the two old shoes were made differently from each other , although both had the only one “ set” of V ‘s as is correct in early 58 ,57 . = mix of brands? Single pair of V ‘s in each shoe are different heights . more on this in a moment .
although we could find no obvious reason for small leak by piston , some obvious significant crud was piled in top cylinder right behind the inward ( new) piston travel , despite being thoroughly cleaned ( stuff at assembly was spotless)and new piston put in recently with almost no miles . This Crud may have gotten under piston lip ? so bleeding brakes may move significant long term crud on our now old cars from lines to wheel cylinder ! heads up .
That says bleed all lines aggressively into a cup before attaching new wheel cylinders? did not know — or do that ...
so , Ed , who has worked with me for many years , got a new piston , and honed brake cylinder “ just in case a scratch “ I get this , but question came up in my mind what is spec of final wall finish ? common KD brake hone. .. on line , there are talks of “cross hatch “ ( =mouth wag , taken from engine cylinder?) . .. to me as engineer for a seal you want a mirror finish ? like on construction equipment rod, not a hone finish ? although maybe hone is ok . ( not sure about that .. would expect seepage due to microscopic rough surface ?) .
so out of caution and indecision decided to just replace cylinder , but this question remains ?? and many “rebuild job” honed cylinders do seep a bit . anyone know factually about finish ?
another seep is another set of shoes ... and all this work . and breaking in shoes.
says to me very light pass with hone or just leave it alone if clean after bench cleanup .

now , —“new “ shoes seemed to have both sets of V,s .
confused me as that is for “three platform brakes (?)” , and the third point they count is apparently the two plates in the middle of shoe web that are part of cam adjuster etc —-with the 4 large bolts . no info on new shoes — riveted rebuild no box. on shelf for years. probably for an F .
Trying these, on D , the extra V’s do not hit anything , ( no matching platform on backing plate ) so maybe later shoes ( 59 up) fit the earlier cars , or some would. After careful examination , I can see no issues .
so ? some questions:
1) of correct wheel cylinder finish , ? 2) later shoe retro retrofit ,? 3) bleeding st high flow may flush harmful junk into upper wheel cylinder , —- and not out the drain .. never thought of that .

there are solvents for silicone oil , Dow , but could not find retail sale of it .Think it is DS 2025 .. another subject .
all FYI !
john grady
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