Drive shaft play rotational play

Hey guys,
Been getting a clunk from under the truck. I just pulled the shaft and Im changing the 3 rear u joints and the carrier bearing tomorrow. CB had a good amount of play in it. But I noticed when I was pulling the shaft that it had a slight rotational play in it. Not being caused by the joints, but rotational play at the T case and Diff. Once i had the shaft off I am able to grab the base on the T case and Diff (that connects the drive shaft to it) and freely rotate it maybe 1/4 of an inch back and forth. Is there supposed to be free rotational play like this? Or am I staring down the pipe of a huge repair bill going forward...

This is the part that has slight rotational play in it. (Same thing for rear diff).

 

mine has it too....

 

Its normal

 

So now that the drive shaft is removed, I realized the u joints have no play in them. So they are fine. What else could by my knocking noise when shifting?

 

How is your driveshaft carrier bearing? Can you describe the sound, when it makes the sound, and from what area on the truck?

 

The bearing has more play than normal. That is being changed tomorrow. Could that be the clunking?
I'm not sure exactly where, but I can shift from r to n to d and back and forth and there is a clunk when going to drive.
That's why I thought it was just the u joints. Now that I have the shaft off, i seethe joints don't have any play. Which makes me wonder if it's the t case and diff rotational play that's causing the clunk. And if that is setting me up for more damage.

 

I didnt ask your mileage. The rear difs and transfer cases are bullet proof for 300k plus miles assuming normal use and occasional off road use. There are posts regarding the carrier bearing making both vibration noise while driving, and producing a clunk sound which with an automatic trans, can be pronounced since it is loaded while in D or R, and switching between the two. That clunk is the unloading and loading tension in the carrier bearing. There are quite a few guys that have done the single drive shaft conversion which they rave about. I think its about $500 for the new driveshaft with ujoints. Not bad really. your output and input shafts on your transfer case and rear dif are supposed to have some rotation before engagement. Just the factory play when rotating back and forth between the gears. More when cold, less when hot. Hope that helps.

 

I have 77k on mine. But why would the CB clunk? I'm thinking since there is play in the T case and diff, it clunks when it catches gear going from F to R. You see what I mean?

 

Poly carrier bearing. Problem solved.

 

.... no matter what carrier bearing or joints I use, there is still free rotational play in the t case and diff. That's the issue

 

Your rotational play is a non issue.

 

how so?

 

Non issue cause there has to be a little bit of "slop" in the gears cause when they heat up the tolerances become tighter.
When you say that theres a klunk, is it a low pitch or high pitch?
When was the last time the joints were greased?

 

grease them every oil change. i have the shaft out and there is no play in any of the joints. its a pretty low pitch clunk if id say. why?

 

Trying to help narrow down cause, sometimes bad joints will cause a higher pitch like hitting the side of the drvshft with a wrench.
Have you checked to see if its a bad trans mount?

 

The clunk you hear may very well be from the CB. You have to replace it and install driveline to rule it out. With engine off and trans in neutral you will have more rotational play at transfer case output flange. We tend to over think things sometimes.

 

How would i check the trans mount?

the truck is off and in park, and i still have a fair amount of rotational play. I wish a toyota tech could chime in.

 

Crawl under and see if the rubber in the mount is ripped or torn, see if you can push up on the transfer case or try twisting it, maybe lightly use a pry bar to see.

DUDE you gotta let go on the "rotational play"

 

what do you mean let go on "rotational play"? thats what it is.. and thats my issue at hand

 

I have to ask a simple question. What is the education / experience of those who think there should be NO movement whatsoever in the gears?

In order for a ring and pinion to work they SLIP as they rotate. They are not straight cut gears. Do a bit of google magic and look at the pictures of a pinion. It spirals from the base to tip of one single tooth. So as the pinion meshes with a ring gear tooth it slides as it meshes. In order to do this there needs to be some clearance between the drive and coast side of the ring gear. This clearance is set by moving the ring gear further towards the pinion or away which changes the clearance between the pinion and the ring gear. We measure the clearance by using an indicator with the pinion touching the either the drive or coast side of the ring gear and measuring the "backlash"as you rotate the pinion to touch the opposite side. The backlash has to be set to specified tolerances to ensure you have enough clearance to avoid binding at all operating temperature ranges. The goal is to have enough clearance to operate properly with no binding but to avoid excessive slop which will allow the gears to slam from one side to the other (drive / coast). The other danger is putting too much stress at the crown of a tooth and shearing the teeth.
In addition the pinion depth has to be set to get a wear pattern set towards the center of the ring gear tooth to distribute the load properly but this doesn't affect the backlash. While not affecting backlash if this pattern it not set towards center you can break the teeth at the ends.

At the transfer case there are a ton of gears and moving parts. I can not comment directly on the Toyota TC but many use a chain to drive the front DS which allows for some slop at that end. At the rear there so many places that have slight clearance between each set of gears. Multiply that by the numerous gears and 1/4" amounts to nothing. It has been a while since I tore into one so I won't try to BS and spout crap in more detail because I would have to look at one apart or get out some books to remember more than this. End result is some movement is nessecary at each end or it will gernade as it binds.

Toyota pinion / ring gear backlash specs are .006-.010". (Differentials- Inspection, restoration and repair. Written by Jim Allen and Randy Lymon (of Randy's ring and pinion fame))