brake 101

[sadystikal1]

alright, need help quick. front right brake caliper locked up, bought new one and replaced, tried bleeding the brakes and nothing, once it gets stiff I tighten it all up and crank up the engine to test run and the brakes get loose all over again. then to top it all off the battery went kaput. great.

 

[Yardape]

You should change both calipers when one goes, or you can get brake pull. Now would be a good time to completely change out your brake fluid, its cheap and easy to do.

 

[sadystikal1]

so why would the brakes stiffen when the engine is off then get loose when it is on? should i bleed the brakes with the engine running?

 

[Roadkill]

Not sure what you mean by "stiffen". After the engine shuts off and all the vacumn reservoir is exhausted, the pedal should get harder to push down. In other words, the same amount of pressure on the pedal should make it go further towards the floor when the engine is running and for the first few pumps after you shut it down.

That being said, you should bleed the brakes with the engine off and the vacum exhausted. That means after the engine shuts off, pump the pedal until it dose not get any harder to push. Then bleed the brake system starting with wheel nearest the master cylinder and work your way to the one furthest away.

Also, Yardape is right, always do things in pairs, (both front brake calipers, or both rear, just like you would not change brake shoes/pads on only one side at a time.

 

[noahsdad]

If you are fixing the front brakes and going to bleed the entire system you can go to autozone and buy a new/ rebuilt master cylinder for under 20 bucks. Even though yours may not be bad you miight want to throw a new one in just to be on the safe side and the price is unbeatable

 

[firelt90bronco]

so why would the brakes stiffen when the engine is off then get loose when it is on? should i bleed the brakes with the engine running?

They stiffen because the brake booster is off, that is 100% manual brakes. The brake booster receives its power from the running engine's vacuum lines and atmospheric pressure.

 

[sadystikal1]

Bled 3 of 4 brakes, passenger side caliper was replaced. Getting brake fluid but won't squirt fluid out of the fitting after 30 minutes of pumping brake. Fitting's sucking and blowing air.

 

[sadystikal1]

ok lesson learned today.....pump brakes at least 15-20 times open drain **** on caliper press and hold brake pedal, repeat process till pedal is firm. as for the battery it died because everything was corroded, i cleaned it all up and she fired right up good as new.