Front brakes Dragging

['94IDITurbo7.3]

I have the correct rotors for my truck.
My vaccum pump is working good.

My teacher said this amt. of drag was normal and when dirving the bumps in the road would loosen the brakes up but i'm not sold.

I don't know what gearing i have in my rear end but is it normal to be cruising @ 55 mph & let off the gas pedal and loose almost 5 mph right away?

I also dialed in my booster pushrod. That was a little short.

Hopefuly i will get to vaccum bleed my brake system @ school.

Other than making a mark on the rear axle and tire & watching how many times it goes around is there any other way of telling what reaend gear i have? my door sticker says "C5" axle.

 

[Compu Doc]

Are the hubs hot to the touch on the front axles when the truck is driven?. Do you smell any burning brakes?

 

['94IDITurbo7.3]

Are the hubs hot to the touch on the front axles when the truck is driven?. Do you smell any burning brakes?

No for both. i can go on a 20 mile drive and then touch the hubs and they are just warm to the touch.

 

[Agnem]

OK. I'm a little frustrated here. I just read this whole thread from begnning to end, and in the first 5 posts, there were 3 people who told you to just open the bleeder on your caliper to relieve any line presure, and then see if the drag is reduced. I do not see anywhere where you posted that you tried this.

DID YOU DO IT?

 

['94IDITurbo7.3]

OK. I'm a little frustrated here. I just read this whole thread from begnning to end, and in the first 5 posts, there were 3 people who told you to just open the bleeder on your caliper to relieve any line presure, and then see if the drag is reduced. I do not see anywhere where you posted that you tried this.

DID YOU DO IT?

no i have not done this, but i will monday in shop class.

 

[DeepRoots]

trapped air reacts differently than fluid.

Just saying.

 

[icanfixall]

Any trapped air in a hydraulic system will continue to build pressure. This happens when the air expands from heat. The cooling system traps air and causes this issue also. Sometimes it takes several days of running to get the air out of the cooling system. If the overflow tank is kept full it will pull whats needed back into the system. Our brake system isn't that way. Trapped air will heat up and expand the brakes causing drag. If your hubs are not blistering hot it sounds to me like things are ok but. Without actually being there feeling and turning the wheels its difficult to know whats going on. Please do as suggested and open up the bleeders. Post back what happens.

 

['94IDITurbo7.3]

sorry about not doing the tests you guys suggested but my dad doesn't want me to really work on it until i get out of school in 3 weeks since it seems like everytime i do something on the truck it seems to cost me quite a bit of time and money.
again i'm sorry.

i do know that i will crack open the bleeders next monday in school and then i will post back w/ results.

Thanks for all the help.

 

[jhenson2211]

I still say your brake booster is bad. Keep us posted, I gotta know lol

 

[DeepRoots]

db post

 

[DeepRoots]

Thanks Icanfixall. That is what I felt like saying, I just lacked the energy.

so, bleed the brakes again, and do it well. As also mentioned, the rears being out of whack will screw up the fronts, tho that is normally most apparent when you lock up the front brakes and rears are still a mile away.

 

[Knuckledragger]

I have also read everything from the beginning, wondering what would fix it. I will restate Gary's (Icanfixall) post in a different light.

The trapped air in the brake system will not disperse because it has nowhere to go. In fact, it will act like a spring, and as it warms up, it will get stronger due to the pressure brought on by heat dynamics. So, if your brakes were dragging noticeably when you had the truck up on a lift, imagine how much more drag will be induced by speed and heat, say, 55 mph? So, if you have air in your calipers, you also have an unwanted preload spring in there making the brakes drag.

Do yourself a favor and take 5 minutes to get under the truck and open the bleeder screws. Make sure the master cylinder is full and do not pump the brakes or have anyone help. Just get a 5/16 box wrench (or whatever is the correct size) and open the passenger side 1/4 - 1/2 turn. Watch what happens. If a little fluid seeps out, close the bleeder and go to the driver's side and repeat. If air and/or bubbles happens, close the bleeder and get in the cab and pump the pedal ONCE. Then do it again until you get only fluid. It should only take one or two pumps at most. Not kidding, this process will only take about 5 minutes and cost nothing, as long as you do not break a bleeder.

Here is something for everyone - the bleeders do not have to be torqued down with a 4 foot breaker bar. they have a sealing seat that will resist leakage at very low torque settings. Pull the bleeder shut by hand and give it a little extra tug. That is all that is necessary.

 

[franklin2]

Some of you don't know how the brake system works. The front and rear brake fluid lines are open to the reservoir under the master cylinder cap. That's why there is a rubber bellows under every master cylinder cap on every auto. The bellows expands and contracts for the expansion of the brake fluid in the lines while keeping the introduction of outside dirty air and moisture from contaminating the reservoir fluid.

That's why if the rod between the master cylinder and the booster is adjusted too long, it will push the rod in the master cylinder enough to cover the ports in the bottom the the reservoir, thus blocking the path from the reservoir to the lines, and that will cause the brakes to lock up as you drive down the road and the fluid heats up and expands. These are called compensation ports. If you had air in the lines and the fluid and air expands(and it will) it just pushes fluid up into the reservoir of the master cylinder if the ports are not blocked.

 

[MIDNIGHT RIDER]

Some of you don't know how the brake system works. The front and rear brake fluid lines are open to the reservoir under the master cylinder cap. That's why there is a rubber bellows under every master cylinder cap on every auto. The bellows expands and contracts for the expansion of the brake fluid in the lines while keeping the introduction of outside dirty air and moisture from contaminating the reservoir fluid.

That's why if the rod between the master cylinder and the booster is adjusted too long, it will push the rod in the master cylinder enough to cover the ports in the bottom the the reservoir, thus blocking the path from the reservoir to the lines, and that will cause the brakes to lock up as you drive down the road and the fluid heats up and expands. These are called compensation ports. If you had air in the lines and the fluid and air expands(and it will) it just pushes fluid up into the reservoir of the master cylinder if the ports are not blocked.

Although the part about the air expanding when hot, I go with what ^ he ^ just said.


Simply pushing the fluid level up in the reservoir is the path of least resistance, thus that will be the path of the extra gain from heated air.

 

[Knuckledragger]

I was trying to keep the explanation simple. I know about the compensation ports and blockage. The fact is that while the fluid is trying to get back into the reservoir, there is pressure in every direction. the air doesn't play favorites while trapped in the caliper. It pushes in every direction, including on the puck, and the fluid transfer is not so fast back to the reservoir because of the size of the ports. On purpose.

You are right, if the rod is too long, there is going to be a problem that will not be solved by bleeding. But bleeding is the first thing to try (because it is the easiest) and he hasn't yet. I was trying to illustrate how easy it is to do.