Engine/Transmission (1994 - 1998) Drive shaft "clunk"

[FATCAT]

Last week I asked about U-Joint part numbers ... but on closer inspection this weekend on the truck's two piece drive shaft it seemed that the U-joints were OK ... for the most part.



I can turn the drive saft by hand about 1/8" to 3/16" and then "clunk". I can hold the rear drive shaft still and turn the front drive shaft a little (maybe 1/16 or 1/32").



I'm not sure if the play (slop) is in the rear axle pinion or transfer case output shaft.



I now have 177,000+ miles on the original driveshaft U-joints, so I thought that these were definitly the culprit, but maybe not.



One thing DC machanic told me that last time I was there was that the rear axle pinion should not be replaced if it ever "loosens" up because of so many miles driven that it has been grooved and a new one would never fit correctly causing leaks. Now this was a few months ago and I had mentioned that I was getting a small clunk at that time.



Now my clunk is getting worse (probably due to all the torque being output), and I'm wondering if I have a situation that it is something I will have to live with for good.



I also get a "clunk" up the steering shaft when ever I just hit the accelerator or let off of it and am wondering if the driveshaft clunk could somehow travel up the steering wheel shaft?

 

[drrhoades]

It sounds like your slip yoke on the driveshaft is alittle loose and maybe your u-joints too, unless they are new. The only way to fix the slip yoke is a new one. On the rear pinion seal if the yoke is grooved from the seal then just replace the yoke when you replace the seal.



Good Luck

 

[FATCAT]

Originally posted by drhoades

It sounds like your slip yoke on the driveshaft is alittle loose and maybe your u-joints too, unless they are new. The only way to fix the slip yoke is a new one. On the rear pinion seal if the yoke is grooved from the seal then just replace the yoke when you replace the seal.



Good Luck

That sounds about right (at least as far as the DC machanic said).

But, could there be a problem on the output shaft side from the transfer case? That would be more of a problem, unless the yoke should be replaced (along with the carrier barring at mid shaft), as well as the rear.



Now, I would have to assume that replacing the rear yoke would involve removing the gears in the differential ... now that is stuff WAY above my ability or time or tools. What is involved in something like this? I will have to defer to my local machanic for this job no doubt.

 

[drrhoades]

The splines that the slip yoke mate with may be worn too. If this is the case then the stub shaft will have to be machined off and a new one put on. If you replace any components on the driveshaft then it should be rebalanced, which is debatable on the balancing of new u-joints and carrier bearings. More then likely u-joints and carrier bearings will not affect balance and you wont have a problem, but if you do have a vibration after replacing one of these components then more then likely you need to rebalance the entire system.



Replacing the pinion yoke is not that big of a process. You will need a new pinion nut, somthing to hold the yoke in place with and a large torque wrench. Since the Dana 80 is a hard shimmed axle you do not need to install a new crush washer when you remove the pinion nut. (The pinion nut is a one time use only) Since this is the case you do not need to take the differential and pinion out of the housing. I would also recommend changing the rearend lube when you do this just to be safe so that nothing gets into the axle when you are messing with the yoke and seal.



Doug