I'm trying to figure out what is "bumping" when I start off in 2 WD. Don't think its doing it in 4WD I'ts not terribly hard... but I don't think it right. tIt only happens from a standstill, similar to a universal joint, but will not do it in reverse so I don't think its a universal. Does the 4x4 components have anything that could contribute to this? thanks

 

It sounds like the driveshaft slip yoke is binding slightly under load, a common complaint. The problem is more noticeable on 4x4's and other Rangers with factory lift blocks between the spring and axle.

You can improve the slip/bump by regreasing the slip yoke splines but the bind will return eventually. I've owned 3 Rangers and they all got the treatment at least once. Installing traction bars completely and permanently eliminated it on my latest truck but that's a more expensive fix.

Try searching this site for "slip bump" or "slip yoke" for more info on the problem and how to correct it.

 

There is a TSB for this. Ford has a special grease that is suppose to lessen the problem

 

Yes, I bought a can of the special Ford PTFE grease and it does help for a while. In my experience, sooner or later, the bump returns. In the case of my 3 Rangers, the grease fix lasted 6 months to a year. After the traction bar install, the slip/bump has been gone for several years.