1995 W900L brakes hard in bobtail. HELP!

The 1/4 line came from the trailer supply valve in the dash. When you charge the trailer, that line would supply air to the tractor service relay control & allow full application of the service brakes. That line was how the valve knew the trailer was connected & take the bobtail valve out of the picture.
Another work around without replacing the valve is to remove that line from the valve & tie it off. Add a line from the supply port to the control port . It will always be in the unlimited mode & supply full service air to the rears.

 

Sounds like a faulty bobtail proportioning valve to me.

 

It should work good with the new part, I put bigger maxies on mine last summer she stops now!

 

I too have a 95 KW. It takes a lot of foot pressure to get any brake response. Also if there is a lot of moisture in the air (say at 3 am), when the brakes do come on the left front squeals big time and pulls hard to the left. Am going to check it out in the morning. Thanks for all the info you gave to 'greaseburner'.

 

No problem man!

 

Hey guys i have a t800 triaxle that is a former road tractor. I have the same valve but mine puts an ungodly amount of pressure to the rear brakes if you just touch the pedal. End result multiple flat spots. If loaded its nice but empty its scary. If i take this proportioning valve off and instal a bendix valve that was mentioned will this solve my issue,

 

Sounds like a different problem to me. Suggest doing the testing outlined by Cline in the other post. Replace the drive axle relay valve (service side) if you want to play darts.