Need help with bleeding brakes

[ProjectResponder]

No matter how hard I try, I can't seem to get the rear brakes fully bled. I believe that the large vertical drop from the frame to the axle is the main culprit. The distance is about 18 inches and the braided brake hose from the frame to the axle is about 28" long. I'm convinced that just pumping the brakes while opening the bleeder screws is not enough to overcome this distance. I'm considering buying a vacuum system such as the Vacuula or the Mityvac compressor assisted units. All I know is that with the dual piston Dana 60 brake calipers, I should have a lot more braking performance than I do currently.

Photos: http://www.projectresponder.com/gallery/gallery-main.asp?g=10&p=3

Obviously gravity bleeding is out due to the the vertical drop. I'm about settled on vacuum assisted bleeding in order to move the brake fluid fast enough to get the air bubbles out of the system. But, before I do, I'd like to get some advice as to how I can get these brakes firmed up.

Thanks

 

[blacksnapon]

No matter how hard I try, I can't seem to get the rear brakes fully bled. I believe that the large vertical drop from the frame to the axle is the main culprit. The distance is about 18 inches and the braided brake hose from the frame to the axle is about 28" long. I'm convinced that just pumping the brakes while opening the bleeder screws is not enough to overcome this distance. I'm considering buying a vacuum system such as the Vacuula or the Mityvac compressor assisted units. All I know is that with the dual piston Dana 60 brake calipers, I should have a lot more braking performance than I do currently.

Photos: http://www.projectresponder.com/gallery/gallery-main.asp?g=10&p=3

Obviously gravity bleeding is out due to the the vertical drop. I'm about settled on vacuum assisted bleeding in order to move the brake fluid fast enough to get the air bubbles out of the system. But, before I do, I'd like to get some advice as to how I can get these brakes firmed up.

Thanks

Are you not getting fluid from the bleeders? The vertical drop shouldn't make that much of a difference. Are the bleeders at the uppermost portion of the calipers? This has happened more than once (mismatch of parts).

 

[ProjectResponder]

Yes, I get plenty of fluid out. Yes, the bleeders are at the top.

But I can't achieve a good, solid pedal. This is very frustrating. I believe that with the brakes I have, I should be getting much better braking performance than I am currently.

 

[blacksnapon]

Yes, I get plenty of fluid out. Yes, the bleeders are at the top.

But I can't achieve a good, solid pedal. This is very frustrating. I believe that with the brakes I have, I should be getting much better braking performance than I am currently.

Check the condition of the "rubber" lines. If they are deteriorated internally, they will "balloon" when you press on the brakes. Bad wheel bearings and/or bearing adjustment will cause this as well.

 

[ProjectResponder]

Everything on this truck is new. The lines are either steel or braided stainless steel.

 

[blacksnapon]

Because of the abundance of fluid when bleeding, I don't think power bleeders will help. I believe you have a parts problem. Excessive bearing movement, clearance between the caliper and mounting bracket. I've even had pads that were of poor quality (push the brakes,and nothing happens).

 

[d-kuzmen]

Because of the abundance of fluid when bleeding, I don't think power bleeders will help. I believe you have a parts problem. Excessive bearing movement, clearance between the caliper and mounting bracket. I've even had pads that were of poor quality (push the brakes,and nothing happens).

 

[ProjectResponder]

If I had old parts on the truck, I would be inclined to go with that diagnosis. But everything is nearly new. I've bled the brakes until the bubbles quit showing up. It's not an abundance of fluid, just what you get when you press on the brake pedal. I'm still convinced that with the length of the vertical drop, that there is still air in the line collecting at the junction where the hose attaches to the brake line in the frame's cross-member. Now, one thing I'm going to do is convert to Hydroboost for the master brake cylinder. This will double my brake line pressure which will help a great deal. Then I'm going to take it over to Midwest Four Wheel Drive and hope that they have the experience to get the lines fully bled.

 

[blacksnapon]

OK, I hope you find it!