Just wondering why you're changing from DOT3 to DOT4 fluid. Not sure you're going to see any improvement in braking efficiency and, unless you're into extremely hard braking, the difference in ERBP probably is immaterial.
Anyway, here's a good discussion on various brake fluids along with their pros/cons: http://www.stoptech.com/whitepapers/brakefluid1a.htm

 

Ok, you convinced me not to go to DOT 4. I should really change my fluid though since I haven't done this since I bought the vehicle. How much fluid do I have to replace? How do you remove the fluid without getting air bubbles?

 

Suck out as much of fluid as possible from the master cylinder with a turkey baster. Refill with clean brake fluid and then bleed each wheel cylinder and caliper until the fluid appears lighter in color. Make sure you keep the master cylinder reservoir filled so you don't introduce any air. When done, take it to some place where you can hit the brakes fast enough to activate the ABS. This will allow the ABS to fill with fresh fluid.

It's not a bad idea to flush the brake fluid every few years or when you change the front pads.

jimbo

 

I go a power brake bleeder that fits over the master cylinder, it cost like $60. You fill it with brake fluid and pump it up and, when you crack the bleeders, it pushes the old fluid out as the new stuff flows in. Works perfect for changing fluid. Got it off the web but can't remember where. If you search for power bleeder it should pop up.

 

You'll probably need 2 small bottles. Also, you might want to use a small clear hose (like aquarium tubing) and attach it to the caliper or wheel cylinder bleeder nipple. Run the other end into a clear container. An assistant pumps the brake pedal 3 or 4 times, then holds it firm. Use the open end of your wrench to open the bleeder and watch the fluid. Your assistant will feel the pedal go to the floor. Don't let them lift the pedal until you close the bleeder snug or air will be sucked into the system. Don't over tighten the bleeder, you're going to do this quite a few times. When It runs clear, add 5 pump/hold cycles and you're done. But watch out, don't let the new fluid you put in the master cylinder get too low or you'll be sucking air into the system. Keep it at least 1/2 full. I check it every 8 cycles or so. The turkey baster trick rules. It allows you to remove lots of the old fluid at once. But beware, don't get it on your paint as it'll eat it off. If you do, quickly wipe it up and use lots of soapy water to rinse/rub the area. Brake fluid absorbs water until it becomes inert. That's why you replace it. It gets heat wear and water contaminated. An open bottle will suck moisture right out of the air over time contaminating the fluid.

Hints: Open all the bleeders once with the boxed end or a small socket as they have a tendency to get stuck. Then close them up snug before bleeding.

Also, if the bleeder is open and very little fluid is coming out, it may be clogged. Close it, have the assistant take a break then remove it completely. Use a small wire to clear out the clogged passage.

Hope this helps out.

Bill

 

I'm not going to use DOT 4 fluid instead I'm going to be using Valvoline SynPower brake fluid (exceeds DOT 3 & DOT 4.)

Thanks for all the help, I really appreciate it.

Now, I just have to find a brake bleeder that fits over the top of the master cylinder.

 

Brake Bleeder

I didn't waste the $$. Besides, I always thought a pretty assistant was better than automation. You get to "thank" them. 8)

Bill

 

Jim be careful. I heard talk of someone else looking to switch to synthetic (and it sounds like that's what you'll be using), and there was talk about the synthetic not acting right in an existing non-synthetic system. It's less viscous and may leak. Just something I saw on the issue. If you do do it though, make sure to bleed thoroughly and flush the entire system so as to not to contaminate anything. Heard the two types of fluids shouldn't mix as well.

my 2¢

 

I've been using the SynPower brake fluid in "the fleet" here (Durango, Lexus, Caravan) for years with no problems. YMMV.

 

http://www.motiveproducts.com/01products.html this is the one I have. You can have the pretty assistant pump it up, but after using it once I'll never bleed brakes the old fashioned way again.

 

You'll probably need 2 small bottles. Also, you might want to use a small clear hose (like aquarium tubing) and attach it to the caliper or wheel cylinder bleeder nipple. Run the other end into a clear container. An assistant pumps the brake pedal 3 or 4 times, then holds it firm. Use the open end of your wrench to open the bleeder and watch the fluid. Your assistant will feel the pedal go to the floor. Don't let them lift the pedal until you close the bleeder snug or air will be sucked into the system. Don't over tighten the bleeder, you're going to do this quite a few times. When It runs clear, add 5 pump/hold cycles and you're done. But watch out, don't let the new fluid you put in the master cylinder get too low or you'll be sucking air into the system. Keep it at least 1/2 full. I check it every 8 cycles or so. The turkey baster trick rules. It allows you to remove lots of the old fluid at once. But beware, don't get it on your paint as it'll eat it off. If you do, quickly wipe it up and use lots of soapy water to rinse/rub the area. Brake fluid absorbs water until it becomes inert. That's why you replace it. It gets heat wear and water contaminated. An open bottle will suck moisture right out of the air over time contaminating the fluid.

Hints: Open all the bleeders once with the boxed end or a small socket as they have a tendency to get stuck. Then close them up snug before bleeding.

Also, if the bleeder is open and very little fluid is coming out, it may be clogged. Close it, have the assistant take a break then remove it completely. Use a small wire to clear out the clogged passage.

Hope this helps out.

Bill

Bill, can you explain the 5-pump thing in bold above? What I understand is that, after the fluid comes out clear and the bleeder screw is tightened, the assistant needs to pump the brake 5 more times and then hold it before moving to the next wheel??

Thanks.

 

Brake Bleeding

Not exactly Kevin. My old instructors taught me that there are contaminants you just can't see. We determined through lab tests that "on average" 5 pump/bleed cycles will clear the line of most all contaminants. Not just pump and hold and bleed once.

HTH

Bill

 

Bill - got it. Once it's clear, 5 more times and the stuff we can't see will be out.

One more question - silly as it may be. When bleeding the brakes, is the truck supposed to be running so I get the brakes boosted?

 

One more question - silly as it may be. When bleeding the brakes, is the truck supposed to be running so I get the brakes boosted?

Doesn't need to be running, boost isn't going to help anything. It's probably better to do it with the engine not running.

 

Also

Tom is right. Also, when pumping the brakes, use even steady pressure, not jarring motions. ABS vehicles are sometimes sensitive to this.

Bill

 

Unless you're racing, the only real reason to go synthetic is for hydraulic component life. If you flush your system regularly (once a year) your system should last a lifetime on regular fluid.

If you're talking DOT 5 fluid, I was told by the fluid manufacturer's tech folks (a few years ago), that to convert, you should replace all of the rubber in the system due to flaking problems with the used hoses and other rubber. Fleets see an improvement due to the massive total miles that they drive per year. This justifies the cost.

I have never had to replace any hydraulics on my D's brake system with over a 135k and it still stops like it did when new. I don't drive very lightly either. My only problem with the D's brakes is they're too small (a typical Chrysler problem for over 45 years.)

 

All of this is well and good if you can get the damn rear drums off. PITA!! Managed to get the passenger rear off so at least I know I can do it. Will take another look this coming weekend. Ended up having to keep working on the adjusting screw until the shoes gave enough to release the drum.

Next step will be to see if the original drums can be turned (I'm betting not) and then new shoes followed by brake bleeding. Great info though on the site. Don't forget to place a block or something from keeping pressing the brake too far down? will keep gunk from getting into the system.

I have DOT 3 Heavy Duty from NAPA.

Forgot to mention that the originals drums say Bosch "Made in Mexico." I think those are pretty good but will end up with Bendix if they need replacing.

Should probably invest in a filter mask as banging on the drums kicks up some dust. No telling what I'm inhaling? you can only hold your breath for so long :lol:

 

One more question - silly as it may be. When bleeding the brakes, is the truck supposed to be running so I get the brakes boosted?

Doesn't need to be running, boost isn't going to help anything. It's probably better to do it with the engine not running.

Thanks. I was wondering how my assistant (aka wife) would hear me yelling instructions from underneath the running D!

Unless you're racing, the only real reason to go synthetic is for hydraulic component life. If you flush your system regularly (once a year) your system should last a lifetime on regular fluid.

If you're talking DOT 5 fluid, I was told by the fluid manufacturer's tech folks (a few years ago), that to convert, you should replace all of the rubber in the system due to flaking problems with the used hoses and other rubber. Fleets see an improvement due to the massive total miles that they drive per year. This justifies the cost.

I have never had to replace any hydraulics on my D's brake system with over a 135k and it still stops like it did when new. I don't drive very lightly either. My only problem with the D's brakes is they're too small (a typical Chrysler problem for over 45 years.)

I bought the Valvoline SynPower DOT3/4 fluid. I don't flush once a year (at least I haven't up to this point), but do change the fluid in the resevoir at least once a year.

 

My new Motul fluid is 5.1.

5.1 was a higher wet and dry boil point, matching the silicone 5 ratings, yet is compatible with 3 & 4 (albeit I'd bleed as much of the 3 & 4 out while adding 5.1 if I were you or you lose the most of the benefits of 5.1.)

5 is basically uncompatible with anything not intended for it by design. Seals, rubbers, etc are effected differently.

3, 4 and 5.1 (sometimes called 4.5 and 4Plus) are cross compatible because it is mainly the same chemical makeup as 3 & 4 with no similarities to 5.

5.1 was the natural progression of the naming scheme, but still confusing due to the differences in 5 from the other three.

IndyD

 

Most brake fluid is really vegetable oil and just plain acts like a water magnet. That's why wheel cylinders/calipers rust, the fluid starts holding water. Flushing the system completely removes that water content and cuts the rusting.

Fleets went to 5 to cut down on maintenance costs of replacing/rebuilding cylinders/calipers/master cylinders. For them it was worth it.

We don't delvelop enough heat to boil brake fluid in normal driving. That's why Detroit never went beyond DOT 3/4 fluid.

The best thing for improved braking is better sized calipers and good linings and rotor construction for heat dissipation.

As stated previously, Dodge has been notoriously undersized for for 40 years. For some reason they felt that a 440 could be stopped by 10" drum brakes after everyone else had gone to discs.