Driveline Questions

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Idaho Savage

Idaho Savage

GOLD Star
Joined
Mar 9, 2017
Threads
48
Messages
1,028
Location
Idaho
1996 LX450

I have read just about everything I can find on here and have arrived at a driveline in need of replacement or service.

Low speed vibration and high speed deceleration growl are the symptoms, plus a very small hesitation moving from a stop—almost a clunk without the noise, if that makes any sense. I just got my gears changed to 4.88s and in one of the threads here I read that such adjustment can accelerate a failing driveline.

So I put the rig in neutral and played with both drivelines to start. Front feels tight with nothing odd.

Rear, however has just a bit of play in the driveline where the shaft meets the sleeve of the rear portion. It’s very small but when I pull and push on the line up and down, I can hear the play in the middle or near that juncture.
IMG_3953.webp

My first question is if this is normal. I know there should be just wee bit of play in the twist of the drive lines but I’m unclear on the vertical play of the shaft itself. Seems like it’s indicative of splines wearing out but that’s my own imaginative conjecture.

Also, see the picture. Looks like it relatively recently threw grease on the skid and muffler next to it. I lube the u joints on the reg and I’ve never seen this before.

Edit. I shot this video and unfortunately it’s hard to hear with background noise but on my phone if I crank it and put it near my ear, I can hear the play. Sorry I couldn’t t do better.



Any thoughts are appreciated.
 
Last edited:
robnicko said:
The high speed deceleration growl I had a few years back and it was the Uni joint on the rear shaft at the Diff end. Whilst bolted to the Diff could not feel any issue however once unbolted was very evident it was no good.
Click to expand...
Ok, this is helpful (as was Landtank). I was dubious that any issue could be detected while bolted on.
 
Idaho Savage said:
Ok, this is helpful (as was Landtank). I was dubious that any issue could be detected while bolted on.
Click to expand...
Also, whilst you have it unbolted, its worth separating the tailshaft at the splined section (be sure to mark its orientation so its put back in correct phase) and clean out the old grease and regrease with new Moly grease in there.
 
Play in the splines means a new shaft or a new slip yoke and a balance. But doing the slip yoke and balance doesn’t mean you are done as you could still have bad u-joints.

I encourage people to just buy a drive shaft especially if they can install it themselves.
 
The joint you're referring to is called a "slip yoke". It is a splined joint that allows the driveshaft to expand and contract as the suspension flexes.
There should be ZERO rotational play in a slip yoke.
There should be ZERO rotational play in a universal.

The most common cause of a "growl" or "buzz" at highway speeds when coasting is a worn slip yoke. Some folks will tell you to add grease, but that is only temporary. On that note, you shouldn't over-grease a slip yoke.

If you decide to purchase a new OEM driveshaft, keep in mind that it will come with assembly grease in the yoke and universals. It should be thoroughly greased before installation.
 
jonheld said:
The joint you're referring to is called a "slip yoke". It is a splined joint that allows the driveshaft to expand and contract as the suspension flexes.
There should be ZERO rotational play in a slip yoke.
There should be ZERO rotational play in a universal.

The most common cause of a "growl" or "buzz" at highway speeds when coasting is a worn slip yoke. Some folks will tell you to add grease, but that is only temporary. On that note, you shouldn't over-grease a slip yoke.

If you decide to purchase a new OEM driveshaft, keep in mind that it will come with assembly grease in the yoke and universals. It should be thoroughly greased before installation.
Click to expand...
Appreciated. I’m going to test each driveline independently via center diff lock and removal once I have a minute.
 
If you pull one of both driveshafts and decide to rebuild them (use new OEM U-joints) as mentioned above you can separate the slip yolks, clean the splines out, then regrease before reassembling the shafts.

One option (see link below, this was a new shaft showing the yellow assembly grease but same can be done to a used shaft).


K

Post in thread 'New driveshaft'

Good place to add this for future searches FWIW

The FSM (Factory Service Manual) calls for a Moly (Molybdenum) fortified grease for the slip yolk. Pump grease until the shaft starts to push apart OR (too late this time) first remove the zerk fitting then pull the slip yolk out from the driveshaft before you install it to grease the splines. Be sure to mark both components to help line them up later.

FWIW one option (not required) is to coat the splines with a dry Moly coating followed by Moly grease. Another method is to brush Loctite LB 8012 Moly Paste (65% Moly) on both the slip yolk...
  • Like
 
Last edited:
Update: Had a little time so I removed the front driveline, seeing that the noise *seems* to be coming from the front. The driveline seems fine, the joints are smooth and the spline was well lubed and feels firm. After locking the center diff, I took it for a spin and still have the noise. I will reattach.

One thing that really surprised me: I was working on a small incline with e brake on and wheels chocked. After removing the blocks and taking the brake off, the vehicle began to move forward, even in park. I would have guessed that the rear driveline would have held the vehicle while in park?
 
When I was looking at rebuilding my driveshaft with new joints I discovered that if they have been messed with in the past with hammers and aftermarket joints, they will never be the same. The OEM Toyota joints were installed with precision ground shims for centering and to eliminate play. After a beating with a hammer and some aftermarket joints that may or may not fit well, it's difficult to impossible to get the shaft to perform as new.

Turns out an OEM driveshaft fully assembled isn't that expensive and you also get a new slip yoke.

The rear driveline should hold the vehicle in place in P if your CDL is locked.
 
Kernal said:
Was your CDL locked when you did the test drive with one driveshaft removed??
Click to expand...
Yes it was. But to be clear, I had not engaged it when the truck rolled in Park.
 
Idaho Savage said:
Yes it was. But to be clear, I had not engaged it when the truck rolled in Park.
Click to expand...
Which is why it rolled.
You had a driveshaft missing so there was an "open" in the driveline.
 
jonheld said:
Which is why it rolled.
You had a driveshaft missing so there was an "open" in the driveline.
Click to expand...
Thank you. I figured the two were related.
 
Be aware that the ONLY thing holding the truck in place when it's in park is the light pressure between the 1st/Reverse clutches and their steel plates. You cannot use the transmission as a wheel chock.
 
Malleus said:
Be aware that the ONLY thing holding the truck in place when it's in park is the light pressure between the 1st/Reverse clutches and their steel plates. You cannot use the transmission as a wheel chock.
Click to expand...
I don't think that is correct. Automatic transmissions (including the A440/A442/A343) have a parking pawl that engages with notches in the output shaft. It should not be used as a 'chock' for sure, but it is more than just some clutches holding it in place. If auto trans used just clutches, we'd see vehicles rolling off unattended as a regular occurrence as clutches wore out. I do seem to remember some other vehicles that have made the new with this type of tendency, but the cruiser is not one of them.

With the cruisers AWD system, all four wheels need ground contact to prevent rolling in park since there are three differentials involved If the CDL is engaged which locks the center diff then you can lift the front or rear off the ground and the truck will not roll beyond the play in the parking pawl system. I wouldn't trust it for jacking operations for sure.
 
sbman said:
I don't think that is correct. Automatic transmissions (including the A440/A442/A343) have a parking pawl that engages with notches in the output shaft. It should not be used as a 'chock' for sure, but it is more than just some clutches holding it in place. If auto trans used just clutches, we'd see vehicles rolling off unattended as a regular occurrence as clutches wore out. I do seem to remember some other vehicles that have made the new with this type of tendency, but the cruiser is not one of them.

With the cruisers AWD system, all four wheels need ground contact to prevent rolling in park since there are three differentials involved If the CDL is engaged which locks the center diff then you can lift the front or rear off the ground and the truck will not roll beyond the play in the parking pawl system. I wouldn't trust it for jacking operations for sure.
Click to expand...
Nope. The pawl only serves to lock the transmission into position; it doesn't prevent the output shaft from rotating.

And to be clear, there isn't really a "park" gear, it's 1st and reverse engaged simultaneously.
 
Malleus said:
Nope. The pawl only serves to lock the transmission into position; it doesn't prevent the output shaft from rotating.

And to be clear, there isn't really a "park" gear, it's 1st and reverse engaged simultaneously.
Click to expand...

That’s why I come here. I never, ever would have guessed that.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom