All I had to hear was "I worked for the government" to convince me to stay with dot5. George Sent from my iPhone 4 On Oct 14, 2010, at 8:07 PM, Herb <zephyr9900@xxxxxxxxxxx> wrote: > With all the talk about brakes and fluids, All I can say is your looking for > trouble with DOT 5. Once you change over you cant go back unless you > replace EVERY rubber part in your brake system. Dot 4 does every thing DOT > 5 does except contaminate the system with silicone, unless you live on the > north or south pole, or are running a dedicated race car, DON'T DO IT. > Extreme and I mean Extreme heat or cold conditions are all that I can > justify the use of DOT 5. I worked for the government and converted > hundreds of vehicles over to DOT 5, that experience is the reason I wont do > it to my cars. We kept consistently busy fixing DOT 5 related brake > problems. The only reason they do change to DOT 5 is any vehicle can > potentially go to any place in the world at any time, or that is the logic > in the manual. I know, I know DOT 5 wont absorb moisture, that is correct > but were does the moisture go??? O ya water is heaver than DOT 5, down to > the bottom of the wheel cylinders and calipers to stay, and that is why they > start leaking from the corrosion on the sealing serfaces. If you completely > purge or bleed your brake system every 30,000 or 35,000 like your supposed > to, you will never have corrosion problems with DOT 3 or 4 because the > moisture that is absorbed by the DOT 3 is gone when you do a system bleed.. > Problem is no one ever purges the system, out of sight out of mind until you > have brake problems, Same with Transmissions, no one changes fluid & filter > or thinks about it till a problem arises and by then it's tooooo late. O,Ya > when you bleed DOT 5 were does the moisture go? OOps, it is still at the > bottom of the wheel cylinders and calipers because it is not absorbed and is > heaver than DOT 5!! That said this is not an overnight problem with any > brake fluid, most of our cars are forty five years old or older and the > brake problems are just showing up. Actually I think the moisture that is > absorbed, is really a good thing if you service your system on a regular > basis. That is why I invested in a power bleeder, about every five or six > years I purge the systems on my cars and never have any problems other than > replacing shoes or pads. Here is an article that is good information. This > is just my $00.02 worth from experience, and I know everyone has a > conflicting opinion, this is just mine. > > > Battle of the DOTs > DOT 3-4 Verses DOT 5. Which brake fluid should I use? > "With regards to the DOT 3-4 verses DOT 5 brake fluid controversy, here is > an article sent to me by Mr. Steve Wall. It is one of the most professional > treatments I have seen on the subject". > [I had to condense this article from 6 pages to 1 due to space limitations. > Brake Fluid Facts > By Steve Wall > As a former materials engineering supervisor at a major automotive brake > system supplier, I feel both qualified and obligated to inject some material > science facts into the murky debate about DOT 5 verses DOT 3-4 brake fluids. > The important technical issues governing the use of a particular > specification brake fluid are as follows: > 1. Fluid compatibility with the brake system rubber, plastic and metal > components. > 2. Water absorption and corrosion. > 3. Fluid boiling point and other physical characteristics. > 4. Brake system contamination and sludging. > Additionally, some technical comments will be made about the new brake fluid > formulations appearing on the scene. > First of all, it's important to understand the chemical nature of brake > fluid. DOT 3 brake fluids are mixtures of glycols and glycol ethers. DOT 4 > contains borate esters in addition to what is contained in DOT 3. These > brake fluids are somewhat similar to automotive anti-freeze (ethylene > glycol) and are not, as Dr. Curve implies, a petroleum fluid. DOT 5 is > silicone chemistry. > Fluid Compatibility > Brake system materials must be compatible with the system fluid. > Compatibility is determined by chemistry, and no amount of advertising, > wishful thinking or rationalizing can change the science of chemical > compatibility. Both DOT 3-4 and DOT 5 fluids are compatible with most brake > system materials except in the case some silicone rubber external components > such as caliper piston boots, which are attacked by silicon fluids and > greases. > Water absorption and corrosion > The big bugaboo with DOT 3-4 fluids always cited by silicone fluid advocates > is water absorption. DOT 3-4 glycol based fluids, just like ethylene glycol > antifreezes, are readily miscible with water. Long term brake system water > content tends to reach a maximum of about 3%, which is readily handled by > the corrosion inhibitors in the brake fluid formulation. Since the > inhibitors are gradually depleted as they do their job, glycol brake fluid, > just like anti-freeze, needs to be changed periodically. Follow BMW's > recommendations. DOT 5 fluids, not being water miscible, must rely on the > silicone (with some corrosion inhibitors) as a barrier film to control > corrosion. Water is not absorbed by silicone as in the case of DOT 3-4 > fluids, and will remain as a separate globule sinking to the lowest point in > the brake system, since it is more dense. > Fluid boiling point > DOT 4 glycol based fluid has a higher boiling point (446F) than DOT 3 (401F) > and both fluids will exhibit a reduced boiling point as water content > increases. DOT 5 in its pure state offers a higher boiling point (500F) > however if water got into the system, and a big globule found its way into a > caliper, the water would start to boil at 212F causing a vapor lock > condition [possible brake failure -Ed.]. By contrast, DOT 3 fluid with 3% > water content would still exhibit a boiling point of 300F. Silicone fluids > also exhibit a 3 times greater propensity to dissolve air and other gasses > which can lead to a "spongy pedal" and reduced braking at high altitudes. > DOT 3 and DOT 4 fluids are mutually compatible, the major disadvantage of > such a mix being a lowered boiling point. In an emergency, it'll do. > Silicone fluid will not mix, but will float on top. From a lubricity > standpoint, neither fluids are outstanding, though silicones will exhibit a > more stable viscosity index in extreme temperatures, which is why the US > Army likes silicone fluids. Since few of us ride at temperatures very much > below freezing, let alone at 40 below zero, silicone's low temperature > advantage won't be apparent. Neither fluids will reduce stopping distances. > With the advent of ABS systems, the limitations of existing brake fluids > have been recognized and the brake fluid manufacturers have been working on > formulations with enhanced properties. However, the chosen direction has not > been silicone. The only major user of silicone is the US Army. It has > recently asked the SAE about a procedure for converting from silicon back to > DOT 3-4. If they ever decide to switch, silicone brake fluid will go the way > of leaded gas. > Brake system contamination > The single most common brake system failure caused by a contaminant is > swelling of the rubber components (piston seals etc.) due to the > introduction of petroleum based products (motor oil, power steering fluid, > mineral oil etc.) A small amount is enough to do major damage. Flushing with > mineral spirits is enough to cause a complete system failure in a short time > I suspect this is what has happened when some BMW owners changed to DOT 5 > (and then assumed that silicone caused the problem). Flushing with alcohol > also causes problems. BMW brake systems should be flushed only with DOT 3 or > 4. > If silicone is introduced into an older brake system, the silicone will > latch unto the sludge generated by gradual component deterioration and > create a gelatin like goop which will attract more crud and eventually plug > up metering orifices or cause pistons to stick. If you have already changed > to DOT 5, don't compound your initial mistake and change back. Silicone is > very tenacious stuff and you will never get it all out of your system. Just > change the fluid regularly. For those who race using silicone fluid, I > recommend that you crack the bleed screws before each racing session to > insure that there is no water in the calipers. > New developments > Since DOT 4 fluids were developed, it was recognized that borate ester based > fluids offered the potential for boiling points beyond the 446F requirement, > thus came the Super DOT 4 fluids - some covered by the DOT 5.1 designation - > which exhibit a minimum dry boiling point of 500F (same as silicone, but > different chemistry). > Additionally, a new fluid type based on silicon ester chemistry (not the > same as silicon) has been developed that exhibits a minimum dry boiling > point of 590F. It is miscible with DOT 3-4 fluids but has yet to see > commercial usage. > > > > > Herb > > 1956 Plymouth Belvedere 361 4-Sale > 1959 Coronet 326 Poly > 1961 Belvedere Custom Suburban 318 Poly > 1962 Dodge Dart 225 Slant Six 4-Sale > 1963 Fury 2D/HT 6.1L > 1963 Sport Fury Convertible 361 > 1970 Chrysler 300 Hurst 440 > 1999 Durango SLT 5.9L > 2008 SRT-8 Magnum 6.1L > St. Louis, MO. > > [Non-text portions of this message have been removed] > > [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! 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