last memorial day while offroading i cracked my driveshaft. about 2 months later it got bad enough i had to replace it. i replaced it myself. 2 days ago, my truck started shuddering again in the same manner. i got underneath to check the driveshaft and see if somehow i broke it again, but instead found something different. the bolts on my driveshaft (all 8 of them, 4 at the x-case, 4 at the rear diff) were loose. i'm not talking just not fully torqued down. i'm talking FINGER-TIGHTENED LOOSE. i know i didn't torque them to the "proper" torque spec, but i know for dang sure i tightened them as much as i could (my general torque spec for everything is GFT, good 'n frickin tight). what could possibly cause them to randomly come loose?

also, when in gear with the brakes on (no possibility of rolling), i was able to rotate the driveshaft maybe like a 1/4 - 1/2" before it engaged at the diff/x-case. i also noticed that my front driveshaft does the same thing. is this normal?

 

the play in the drive shaft is normal..my 89 dose the same...but make sure the new driveshaft is balneced...

 

uh, i'm sure i'll feel stupid for asking this, but how do you balance a driveshaft? and why? i've never heard of balancing a driveshaft before.

 

you have to take it to a drive shaft place. it's also depend on where you got it from and if you took it apart and not put it back the same way. it's similar to a tire. If it spins, it has to be balanced.

 

interesting. how much might that cost?

and what is the actual torque spec for the driveshaft bolts?

 

the cost to balance depends on where you live. Torque spec..56ft lb.

 

its kind of difficult to get a torque wrench in to torque them to spec, so i just use my two 14mm wrenches and get them as tight as i can. 100 miles down the road or a week later i check them again, usually there are a couple that need a turn or two.

its like the lug nuts on alloy rims. after the second torquing, they are good.

 

Yeah, I thought the torque numbers were for laughs. I found it near impossible to get a torque wrench on mine after I took it off to troubleshoot some vibration issues.

So, I just tightened them back as tight as I could get them. That reminds me, I need to check them again.