Transmission Issues-Story...Questions

[wngrog]

BACKGROUND

My nephew has a 1997 40th.

Great truck, he is the 3rd owner, 199,996 miles.

The truck runs and drives great, it had a slight vibration at 35 mph and then again at 65 mph that we attributed to needing a tune up.

Just ordered a tune up kit from ACC when the following happened.

Dopey nephew decides to go mud riding in his 7000# pig with 295 Terra Grapplers and gets it stuck as hell.

No one can verify what happens next but when I arrive home, the truck is in front of my shop with a broken front driveshaft.

I pull the driveshaft, turns out one of the "lifetime" joints in the front shaft...the one next to t-case broke up and took out the shaft.

When I get the truck, the long portion of the shaft is hanging and beat up from hitting the sway bar and the slip yoke is gone.

I pull the shaft and walla...the vibration is gone...

Not the spark plug wires like we thought, but it was the shaft because all vibrations are gone without the fornt shaft in the truck.

NOW TO THE TRANNY QUESTION....

OK, since said mud riding incident, the transmission in first and reverse slips. RPMS rev to 1500 or so then the tranny catches and it drives great, shifts great, runs great (no vibs)

The slip is there. It is bad, something is wrong. I can't get a real story out of the kid, so I am assuming he beat the crap out of it trying to get it unstuck and fried something. The tranny fluid smells new and looks new.

Here is the other thing...it won't go into park. It will shift into park, but the cog will not engage. I tried to adjust the linkage but that does not help.

So the questions I have are:

1) Are there any "quick fixes" like on the FJ62 tranny with a flush or anything that may get him some more miles out of this tranny with the slipping. It is a $5000 truck. Putting a $4000 tranny in it totally defeats the purpose.

2) What is the deal with Park? I adjusted the linkage with no help. Thoughts?

I need some answers because I need to advise the dad...my brother in law on what to do.

I never have heard of this problem with a late model 80 so I am looking to you guys for help.

Thanks!

 

[Kernal]

Sounds like the original problem may have been a U-joint getting ready to go?

I've learned from Mud that you must lock the center differential (CDL) if one of the driveshafts are out, otherwise you will burn up the viscous coupler which is inside the transfer case; that might explain the slipping. The "cheat" method to lock the CDL but drive the rig in high range is to put the transfer case in low range with the engine On, you should then get an ABS and a Diff Lock light which indicate that the CDL is locked (when the CDL is locked you lose ABS). After you see those lights come on shut off the vehicle then pull the 30 amp Diff fuse in the dash fuse box near your left knee; that fuse is located in the position that's marked Diff on the fuse box diagram. Then turn the vehicle back on and shift the transfer case to Hi range, the ABS and Diff Lock lights will remain on. Now the CDL is locked and you can safely drive with one driveshaft out and it will not hurt the the transfer case/viscous coupler to drive it that way. The CDL will remain locked as long as the 30amp fuse is out. As you've experienced you also lose park without the CDL locked when one driveshaft is out. This may not be the cause of all your problems but IMHO you should do this and then come back and post how it's shifting. Others with more experience may chime in if I missed anything.

Here's a link that talks about a rig rolling with a driveshaft removed:

https://forum.ih8mud.com/80-series-tech/418677-park-issue-pulling-front-drive-shaft.html

In the fuse box photo below the blade-type 30amp Diff fuse has been removed, it should be in the lower right corner just above the square pink 30amp power fuse.

 

[ppc]

The 35 mph vibration is an indication of drive shaft/ ujoint failure. The 65 mph is normally a tire balance problem. The unbalance could be caused by mud stuck on the backside of the rim or even a defective tire. A vibration is not a sign of needing a tune-up. An engine problem will be based upon changes in load not a set speed. A tune-up is always good if the components are aged and the MPG has degraded.

 

[yOHda]

for what its worth, i just got done putting a transmission in my cruiser this weekend. mitchell on demand at work calls for 6.90 hours to do the job. i only had $450 in the transmission and i did it by myself in 9 hours on a lift taking my time. it wasnt that bad at all...pm me if you have any questions it is still fresh in my head.

i was lucky and was able to see the donor truck run and drive b4 the junkyard pulled the trans. trans has 100K less miles so i feel pretty good about it lasting.

in surgery last night

 

[jonheld]

Sounds like the truck is doing exactly what it should be doing with the front driveshaft removed. Listen to Kernal.

 

[wngrog]

Awesome source of information Kernal!

I am on it.

ppc....FYI, I have had a few people tell me from personal experience that the vibration is really a stumble in the straight 6, especially since it comes and goes with the RPM change.

Tires are new and nicely balanced.

Of course, now it looks like it was the front driveshaft.

 

[wngrog]

100% fixed it.

God bless IH8MUD

 

[Kernal]

wngrog: Glad it worked out. Got any photos of the driveshaft carnage?

yOHda: Did you take photos as you worked? It would be great if you write down all the steps, tips, tools used when you swapped your transmission and post them up, maybe start a new thread??

 

[wngrog]

The ujoint at the case died and when it fell out, the sway bar kept it off the road but it really beat it up. No way it will ever be balanced. Nice spare though. All I need it a slip yoke.