The author describes himself as an engineering supervisor. I have no idea if he is a chemical or any other type of engineer. What he wrote has been written by many before him. Nothing he wrote sheds new light except for those unfamiliar with this matter. I’ve had Dot 5 in my 61 Plymouth since 2007 and in my 65 Corvette since 2012. My opinion is that there is no good reason whatsoever to use anything but Dot 5 in an occasionally driven mostly stored antique automobile. You will find this subject as divisive as religion, politics, oil type, weight & frequency of change, points vs. Pertronix and a host of others. There will always be those who claim to know better!
Danny Plotkin
From: 'James Douglas' via Chrysler 300 Club International [mailto:chrysler-300-club-international@xxxxxxxxxxxxxxxx]
Sent: Tuesday, July 2, 2024 11:08 AM
To: Dan Plotkin <dplotkin@xxxxxxxxxxxxxxxxxxx>; 'Chrysler list server' <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: RE: Re[2]: {Chrysler 300} Brake master cylinders for 56-61 Chryslers - heads up
Dan,
I am one of the first people to sniff out then businesses are just covering their ass or trying to plan in obsolescence to sell more product…
That said, are you saying that what the man in the article who proports to be a brake engineer is talking BS?
I know several people who are using DOT 5 without any known issues, and I know people that have had all kinds of issues.
I think one of the problems is a lack of control over the many variables involved.
If I was starting with a system from scratch that never had a drop of any fluid in it, I may think about using DOT 5. But with older parts and lines and the ability to properly clean everything of on those cars if some wants to run DOT 5 I feel that sticking with non-silicon is a better idea.
If you flush your system every 5 years with fresh fluid, then non silicone should work just as well. If one is pushing the temperature limits, then there are other problems that should be addressed.
James
Folks- This subject is fodder on the Corvette Forum I visit as many Corvette owners use DOT 5. Lately people have said that some aftermarket brake makers, Lone Star among them now void their warranty if DOT 5 is used. Some say that a new rubber formulation is used that is incompatible with DOT 5.
Others say that DOT 5 chemistry has been changed by its makers. As long as I’ve been in the hobby there have been warnings on brake products against the use of DOT 5.
I believe this is unadulterated BS. I think brake part makers have found that DOT 5 filled brake systems will likely never again need hydraulic service. Using DOT 5 pitted wheel and master cylinder bores are a thing of the past. That is a problem for aftermarket sellers of brake parts. Also likely operative is that DOT 5 can be harder to bleed and likely results in many more technical service calls and returns, so makers can just as easily say don’t use DOT 5.
The DOT 5 problem is not a incompatibility problem. It’s a business problem.
Danny Plotkin
I asked WhitePost about this and they responded with:
“DOT 5 does not affect the sleeves, but it can affect the seals. Article attached.”
I am attaching their document.
James
Thanks for the suggestion James but White Post does not guarantee their resleeve work when the part is used with DOT5. I have no idea why that matters, maybe you know.
This was a conversion on a 300G to DOT5 from unknown fluid use (most likely a mix of DOT3 and DOT5, as the P.O had dementia and could not remember what he had been using over the years)
Hence the use of a new master (along with new wheel cylinders, alcohol flush of lines etc.)
------ Original Message ------
Subject RE: {Chrysler 300} Brake master cylinders for 56-61 Chryslers - heads up
Send and old one to White Post and have it sleeved. Put in new guts.
James
Hi Carl,
Could you stuff a paper towel in the master, have a magnet or vacuum handy, and fine flat file the mating surface? Going all the way across the master reservoir to keep the file flat… Maybe it’s a little rough? Final finishing costs money so I wouldn’t be surprised…
I know filings aren’t desired in the reservoir ; maybe there’s a way to keep them out. I have had to do this on rocker cover mating surfaces (heads) to stop stubborn leaks…
I hesitate to write a post that sounds like whining, but I think it is a valid heads up and a statement about the current availability/quality of master cylinders for 56-61 300s (and other Mopars).
After much searching, and much to my delight, I found a listing on ebay that offered a "made in USA" brand new master cylinder for the above mentioned cars:
Turns out that the seller is Andy Bernbaum, with whom historically I have had good experiences.
So I ordered the part, and when it arrived, much to my disappointment, the part did not match the photo in the listing, as it does not say "made in USA" on the boot or anywhere else on the part.
No manufacturer box or instruction sheet was included either indicating country of origin. The part was absolutely IDENTICAL to the Chinese made master cylinder that I had recently bouight at O'Reilly Auto Parts for $10 less! It will fit of course, but will be no better quality than the part I already have. So I am returning the part.
The problem I'm having with the new Chinese made master cytlinders (all of them) is that they leak from the cap! No matter how tight, or how full or not the reservior is with fluid (I'm using DOT5 silicone), the cap/gasket will not seal well. I do not have this issue with my older American made masters cylinders or even the Chinese master cylinders from a few years ago. The casting looks ok as does the gasket material. I chalk it up to poor quality. I may try doubling up the gasket? Running out of ideas. The cap bolt is also metric spec now (10mm hex head) - all of them - rather than the familiar 7/16" that was used even just a few years ago. And yes, I bench bled the master per instructions, and actually, the Raybestos master (Chinese) says to not bench bleed or you will destroy the piston seal; so you bleed on the car (and waste fluid).
The plug in the bottom port will tend to leak some as well, despite using thread sealer, but that's not a new issue and some of the older American made units will do that as well.
Other than leaking, the Chinese made masters seem to function well.
Anyone else having this issue? Solutions?
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