Brakes very touchy and has excessive pedal free play. Could it be the footvalve?

My new to me 2006 Volvo 780 has extremely touchy brakes. When I depress the pedal, its almost no braking effect and then super grabby. I've adjusted slack adjusters and replaced shoes on tractor and trailer with no noticable difference. It really isn't an issue on dry roads, but in wet or slick conditions, it is exceedingly difficult to keep from locking the brakes with the slightest application of brake pedal.

Also..
The brake pedal is very low and I have to use a bungee on pedal to keep cruise control working as just riding down the road bumps would cause the brake pedal to turn cruise off.


Could this be a footvalve issue or ? Any suggestions on how to proceed?

Thank you

 

I pulled the pedal and plunger and it moves freely.

I'll replace the footvalve and go from there.. thanks for reply

 

I have an E6 Footvalve t-290181-f casting number on body. The plunger moves freely and no air leaks, do they have the same touchy brake issues as the e8? Should I just replace to try or is that wasted $$ spent?

 

It was DEFINITELY a bad E6 footvalve. Since I've head the truck, its always needed a bungee to keep the brake pedal up to keep from cutting off cruise on bumps. I installed the new footvalve and pedal height is back where it should be! I drove it down the road and it was night and day stopping so much smoother as it should with no more hard jerks.

Best 66.00 I've spent on the truck!


Thank you for your help!