Clunking when letting off the throttle around town/ daily driveability

[Daveyd]

I just found out I’m going to be a father, so my wife wants to start saving a little better. So like any wife she told me 3 vehicles is too much so we will be selling my Silverado. (She insisted the bronco stays) I’m trying to get the drivetrain sealed up and properly moving. I have a strange clunk when letting off the gas around town. My guess is worn out u joint. I know I need the seals and possibly the bearings for the transfer case and rear end. My question is about the u joints. My bronco is a 68 but it has the later style spicer set up correct me if I’m wrong. Also, can I get these seals local? Also, any advice on daily driver mods? It’s pretty much all streets with occasional highway. I’m not worried about od tranny’s or fuel injection, just a good ole truck. I’ve gone through the ignition system and the carb runs great with the exception of slightly rich exhaust smell. Any tips would be great. Thanks guys.

 

[surfer-b]

if you can put the rear on jack stands, put in neutral, crawl under and move the driveshaft up an down, its prob like you stated just a ujoint but make sure the pinion yoke on rear is not moving which would mean the pinion bearings need replaced, as for the seals the t-case and rear don't look too bad but I don't know how much/often you have been driving it.
As for a DD I would suggest adding PWR steering and PWR disc brakes if you haven't already, other than those 2 I would keep it stock height and get everything working as should

 

[JSBX]

As surfer-b said. Check your drive shaft for slack including u joints on both ends, yoke and spline for slack, rear diff. and check the u bolts holding the rear end in place and make sure they are tight. I highly recommend a roll cage or a least a roll bar if you don't already have one. A bronco top does not offer very good roll over protection.

 

[SHX669]

A worn " slip joint " on the driveline can have those symptoms.

 

[Rustytruck]

Block the tires and set the parking brake and remove the rear drive shaft. then check the rear transfer case and the rear end yokes check that they are not wiggly like they are loose. If they are then they will need to be fixed. Then check the driveshaft carefully. look of signs of rust around the bearing caps where they meet the crosses. check that the centering bearing on the CV is there and in good condition. Check for side play in the splines and that they extend and compress smoothly. You could even engage the hubs and transfer case into 4wd and drive the truck a mile or 2 and see if the clunk you experience is gone. Then grease the driveshaft paying particular to the recessed cups in the CV joint and centering ball then put the driveshaft back in and grease the rear u-joint. If you suspect you have any problems take the drive shaft to a drive shaft repair shop and have it check out or even buy a new one. You don't want to be driving on a bad worn out drive shaft.

While you under the truck check the bushings on the ends of the springs as the clunk could be coming from there. I would also re torque the U-bolts on the springs make sure nothing is loose. Some of the worse clunks I have had was from bad shock bushings. I drove 60 miles once on a wash board trail with 2 bushings out and I felt like my brain was going to pound out of my head after the first hour.