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Brake Fluid

Brake Shoe Dimensions

Brake Shoes




Richard Grover wrote: I was messing with my brakes a while ago. I spent a month researching the brake fluid question. I summarized my findings for the list (what list was I on back then?) but I don't know where it is now. So even though most of you know most of this, here goes from memory:DOT3 is hydroscopic (or hydrophilic whichever term you like) which means it absorbs water. As it absorbs water over time, it's characteristics change, most importantly it's boiling point is lowered. Under extreme conditions you have water vapor in the wheel cylinders and catastrophic brake failure. Also, water rusts steel and cast iron. (Rust in brake parts is bad, that' s why I was redoing my brakes!)So let's use something else! DOT4 is still hydrophilic, but better in some other ways.DOT5 is silicon based. Silicon doesn't absorb water. It is used in racing vehicles and other high performance applications. Problems are that it entrains air more than DOT3. You get bubbles in it just pouring it into the master cylinder, and it is hard to get these out. Air bubbles in the brake systems are almost as bad as water. Getting the air out of a Willys brake system is harder that many other newer vehicles. Also, all those high performance applications are serviced frequently -- daily for a race car! You can't mix the two, so you need to completely empty, rinse and dry your brake system before switch to DOT5. My conclusion: If I am willing to flush and replace DOT3 in my brake system just once a year, I can pretty much eliminate any problems with water from atmospheric absorption. (Remember we have vented master cylinders.) If I ever submerge my Willys above the hubs, I need to replace a bunch fluids immediately, including brake fluid. Not all DOT3 is the same, so I try to get the good stuff. (Sorry I can't remember all the brands - except Ford sells a decent one for about $6/pint; also I think Castrol makes one). Oh yeah, even top quality DOT3 costs a lot less than DOT5.Disclaimer:Your solution maybe different than mine. I live where it is quite dry.

Ronald L. Cook wrote: I completely agree with you, Richard. I just replaced everything except the master cylinder (have it, didn't need it)on my GPW. I elected to stay with heavy duty DOT 3 and change it once in a while. Moisture is a problem here in Iowa, but not near as large a problem as getting the brake fluids mixed. I hadn't thought about the air entrainment, but you are right there, also. These things are hard enough to get the air out of. I think it gets trapped above the rear axle. The steel line is higher than the master cylinder at that point.

Ben Page wrote: Yes. All the vehicles I restore (for other guys) are rebuilt with stainless steel sleeves on all the slave cylinders and the master cylinder. I then replace all the brake lines and the rubber hydraulic lines and fill the system with silicon brake fluid. It saves having to drain and change the brake fluid in your system every year. Its time efficient and cost saving. Does this help Art?

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Frank Wood wrote: My manual tells me my PU brake shoes should be: 12.25x2x.212 for the front shoes, front and rear and 10.03x2x.212 for the rear shoes, front and rear. All eight shoes Carl Walck sent me look exactly the same. I assume the largest dimension is the length along the outside radius. All have a length somewhere between 10 and 12". I guess I could compare to my old one but I thought I might ask WT first. Anybody bought brake shoes for their truck lately?

Ben Page wrote: Frank, The brakes shoes should be the same length but the linings (say again - the linings) should be a different lengths. You should have one short lining and one long lining (for each side). The long lining goes to the front. The short to the back. If you want to put them the other way around you'll find that your brakes work better in reverse<chuckle>

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Stephen J Perialas wrote: List, I received this note from a friend ,,, can any one help ? <<<<"I heard a noise in the right rear wheel of Blue. When I pulled the drum off I found a broken brake return spring. I caught it in time so there is no damage but I noticed something that struck me as odd. The short brake shoe is on the back and the long shoe is on the front. That is the opposite of what I was taught however I have never worked on a 47 Willys before either. When I looked in a parts book it also shows the short shoe on the back and the long shoe on the front. What is the reason for this.>>>>" Thanks for the help....

Reed Cary wrote: Steve, Don't know what to say. Is "Blue" a CJ? If so, my 3rd edition Parts List shows the short shoe in the front.

Ronald L. Cook wrote: This is a late reply, but my GPW has the long brake shoe on the front. Maybe it has something to do with non-servo brakes.

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This page last edited 18 September, 2000

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