Drive shaft or transfer case noise

[AndrewL76]

My father-in-law has an 88 Ranger XLT 4x4 5 speed that when he takes off, there’s a knock that you can feel right under your feet. Once it gets going, it stops. It just happens when you’re taking off.
A mechanic told him it was the drive shaft. Could it actually be the transfer case, or more simply, the universal joints?

 

[Paulos]

Is it just one knock, or knocking? When it's in 2WD, 4WD, or both? The rear driveshafts are known to make a single knock/clunk/thump/etc when the slip yoke needs to be lubed. The front driveshaft does not have the same PTFE/Teflon coated splines that the rear shaft does (at least on mine it doesn't), so unless it's the u-joints I doubt it's the front shaft.

 

[AndrewL76]

The sound is a knock-knock-knock...until there’s not as much throttle pushing it to spin. It was when it was in 2wd.
He also told me that the shaft has fallen out before. The transfer case was replaced but I’m not sure if the yoke is worn that goes into the transfer case or what. I mean it still drives and is quiet when it is up to speed, but taking off...it basically is knocking until you’re up to cruising speed and past 1st and 2nd
They told him it was the rear drive shaft. From what I can find...they must be made of gold...prices are crazy

 

[Paulos]

It's probably the u-joints or the the center support bearing (if it's an extended cab), so all you have to do is remove the shaft(s) and take it and new u-joints to a machine shop to have them change them. The last time I had it done it cost me $75.
I would check the u-joints first, engine off, e-brake on, in gear, and just try turning the shaft back and forth while watching each joint to see if there is any play. The rear joint usually goes out first (in my experience). If you have a ball joint press you can probably change them yourself. There are YouTube videos that show you how. If the u-joints appear to be okay it MAY be the slip yoke, but I've never had one that made more than one clunk when taking off from a stop.

 

[AndrewL76]

They said that the drive shaft fell out at some point, and that it had “wallowed around” in the transfer case. That’s why they had replaced the transfer case

 

[Paulos]

If they replaced the transfer case, they should know what's going on there. Sounds like you should let them deal with it since they've already worked on it.

 

[AndrewL76]

If they replaced the transfer case, they should know what's going on there. Sounds like you should let them deal with it since they've already worked on it.

Know anywhere to find a drive shaft cheap?

 

[JerryC]

IMHO, before you do that, check the radius arm bushings.

 

[Paulos]

The only place I know of to find them cheap would be to check the pick-a-part type wrecking yards in your area. I know the one in Shelby has good prices, usually less than they post on their website. But you have to walk the yard to see if they have anything. https://autopartsupull.com/auto-parts-u-pull-pricing/
You can try this other link also, but it would be more expensive. https://www.car-part.com/index.htm