95 xlt Hard Knock in drive line / 4wd

[Rusty Hale]

95 XLT with 2wd 4hi 4low switch on dash. When I drive in the mornings 2wd mode I have a hard knock that feels like in the drive shaft / 4wd system. IT will knock sporadically until I get up to speed and when cold. Once warm and spinning fast knock seems to go away. Knock feels like it is just in front and to the right of the gas pedal. Used to get a similar knock when the system was not all the way out of 4wd low after getting out of the woods. I was not sure if this could be a vacuum solenoid issue and not sure how to diagnose problem.

I have had issues with the 4WD high not working or being able to tell if it is working or not as i get stuck in places with it in 4wd high that I should not get stuck. I dont use the 4wd high anymore because this issue. Would like to see how to diagnose this as well.

 

[EB4X]

Could just be one of the front U-joints...

 

[Rusty Hale]

thanks for the suggestion. checked the cv joints and no play in the joints. rear or front. Any other suggestions

 

[EB4X]

U joints ....not CV.... did you check both?

 

[Rusty Hale]

U joints ....not CV.... did you check both?

I checked u joint and could not detect any play in joints. They are original so I may replace them anyway

 

[410Fortune]

95 has passenger side center axle disconnect
Built into your front diff there is a shifting fork operated by vacuum that locks abs unlocks the passenger side axle shaft. If this part fails to work you will not get 4wd

Clunk could be many things
Especially in a 95 with control trac t case

Start by checking the basics like the double cardan joint in your front driveshaft
And check the operation of the cad ( center axle disco)