4WD trouble

[Eduardo]

Hi all,

Today I took my 1993 3500 6.5 TD for a ride. When I tried to engage the 4wd, it did some strange, loud clunking that would go away only when I disengaged it. Upon arrival home I crawled under the truck and found that the front differential shaft u-joint by the transfer case had disintegrated. Obviously, the front shaft became loose and turned eccentrically, smashing in the process the harness to the transmission and the plug & socket. The pictures speak by themselves.


http://www.members.shaw.ca/el-pescador/Pics/Damage1.jpg

http://www.members.shaw.ca/el-pescador/Pics/Damage2.jpg

The damage to the transmission pan appears to be minimal, but somehow I think that the internal and external harnesses will have to be replaced.

Has anyone had this problem before? I think I am in for some

[azblazor]

Wow, I have never seen that or heard of that happening. Did the trany keep shifting OK on the way home?

[Dimsdale]

I have to agree. I have never seen one get that bad. No doubt it was an original U-joint, with no Zerk fitting. Be sure to get replacements with the Zerks, and lube them fairly frequently. Any play in the U-joints is reason to replace them. My old 87 would routinely trash the rear U-joint at the differential if I didn't lube it at every oil change. It became pretty routine though, and I try to lube every couple of oil changes nowadays.

You would be well advised to inspect, and probably replace the other three U-joints. It is unlikely that this was the only one that was failing.

It was a good thing that you were quick to drop it out of 4WD! That driveshaft could have done lots more damage under there!

I think you can get a splice kit for the plug to the tranny, but you might have to replace the internal harness as well (I am speaking from a late model 4L80E frame of reference though.

The thing I would be most worried about would be damage to the tranny case, particularly around the plug. It looks like some of the plug casing and pan took the brunt of the damage. I would worry that the new plug may not be able to mate securely with the male plug in the tranny, but I doubt there is much stress on it (other than driveshafts spinnning like the Tasmanian devil under there!

[Eduardo]

Originally posted by azblazor:
Wow, I have never seen that or heard of that happening. Did the trany keep shifting OK on the way home? Yes, I made it home with the tranny shifting OK. I took it this morning for a very short ride, and it still shifts (at least, two of the gears). I never passed from 60 km/h, but I wanted to make sure that the truck is still driveable.

In all fairness, and despite the mishap, it looks to me that the truck is tougher than I originally thought. :D

[Eduardo]

Originally posted by Dimsdale:
I have to agree. I have never seen one get that bad. No doubt it was an original U-joint, with no Zerk fitting. Be sure to get replacements with the Zerks, and lube them fairly frequently. Any play in the U-joints is reason to replace them. My old 87 would routinely trash the rear U-joint at the differential if I didn't lube it at every oil change. It became pretty routine though, and I try to lube every couple of oil changes nowadays.

You would be well advised to inspect, and probably replace the other three U-joints. It is unlikely that this was the only one that was failing.

It was a good thing that you were quick to drop it out of 4WD! That driveshaft could have done lots more damage under there!

I think you can get a splice kit for the plug to the tranny, but you might have to replace the internal harness as well (I am speaking from a late model 4L80E frame of reference though.

The thing I would be most worried about would be damage to the tranny case, particularly around the plug. It looks like some of the plug casing and pan took the brunt of the damage. I would worry that the new plug may not be able to mate securely with the male plug in the tranny, but I doubt there is much stress on it (other than driveshafts spinnning like the Tasmanian devil under there! Thank you for the advice. My first step will be to determine whether the shaft yokes by the transfer case side are still fit to handle new u-joints; otherwise, a local wrecker has a front driveshaft available. In either case, I will be installing/replacing new u-joints. I already purchased this morning two "precision universal joints" with a Zerk fitting.

I also intend to inspect the rear driveshaft.

This coming week I will request the expert opinion of a local tranny shop about replacing the internal harness and whether splicing/re-using the outer one is an option. I also would like them to have a good look at the tranny case, but I cannot see any damage arouond the socket.

Cheers.

[DA BIG ONE]

Holy^$#@%#^& what a mess.

If I were you I'd hit the bone yard for that section of harness (about 1') then splice it in, then look into getting a new switch.

Get that shaft balanced w/u-joints in place.

Good luck!

[markrinker]

I have replaced both 'propellor shafts' in my two '94 3500s. Both have high hours in 4WD snow plowing, both made noise before coming loose, so I never had this scenario happen, thankfully!

[Eduardo]

Originally posted by Mark Rinker:
I have replaced both 'propellor shafts' in my two '94 3500s. Both have high hours in 4WD snow plowing, both made noise before coming loose, so I never had this scenario happen, thankfully! In my case, I did not notice any previous noise. When I purchased the truck in an auction a few months ago the gas-filled 4wd actuator was not working, so I assume the 4wd had not been used for a long time. Since I replaced the original actuator for a mechanical 'posi-lok', I haven't used the 4wd for more than a few minutes at the time on two or three occasions. So I admit this caught me off guard.

[ 08-07-2005, 11:56 AM: Message edited by: Eduardo ]