bleeding brakes help?

[dmaxx3500]

first ive been bleeding car/truck brakes for 30+ years [cert tech too] ive seen most problems too,but this one has me stumped,,on a customers 07' classic 3500 cc dually 4x4 d/a,we've replaced the hyd-booster,master,p/s pump,and the steering box,,,all new pads and rotors,rear calipers are less then 1 year old,,whole system has been flushed with fresh brake fluid and bleed ,including using a tech2 to bleed and ck abs,,brake pedal still seems low with less then normal pressure and seems spongy,,brakes have been bleed 3-4 times [gravity,2- person manual and vacume] customer says pedal feels the same as when he brought it in,

 

[saratoga]

Have you made sure that the caliper pins and bushings are clean, lubed and that the calipers can slide freely back and forth (compress the pistons first)? For whatever reason, these trucks are hyper sensitive to this... the caliper binds up and twists instead of sliding on the pins when you hit the brakes causing that spongy feeling.

I replaced the pins and bushings when I did brakes on my 06 not too long ago... the pedal feels super firm- better than when it was new.

 

[dmaxx3500]

yep,i just pulled everything apart and cleaned and ck'd everything again

 

[dmaxx3500]

UPDATE--- well i just went nuts and kept bleeding the rear brakes,5 times on left,,and 8 times on the right,and in between did 2 ABS bleeds using a tech 2,,now i seem to have a much better pedal and have rear brakes,,i never saw any bubbles during this bleed session

 

[Fireman469]

Look for the high spots in the system/lines and then find the nearest downstream fitting. Crack the fitting but not enough to open. Then have pressure applied to the system open slowly till fluid comes out and then quickly close before you loose pressure. Usually very slight opening will work best.

I had a similar issue once on the wifes unit and that was the only way I could get it right. Prior to that I was ready to get aditional insurance on her

 

[stacks04]

UPDATE--- well i just went nuts and kept bleeding the rear brakes,5 times on left,,and 8 times on the right,and in between did 2 ABS bleeds using a tech 2,,now i seem to have a much better pedal and have rear brakes,,i never saw any bubbles during this bleed session

I recently did a 1500 that had a broken line. I bled them every which way and never got a good pedal. I drove it did abs stops and did the abs bleed also. Never got a good pedal. Finally we have a flushing machine here at the shop so I used it and finally got a good pedal. I think I went through 8qts of fluid when all was said and done. For some reason they suck balls somtimes:nonod:

 

[jrsavoie]

I've always had my best luck power bleeding back to the reservior when it's possible.