How much is too much Rear Drive shaft play? (1 Viewer)

[chbrow10]

I'm trying to diagnose a "tink" sound in my 87 FJ60 with an H55. I can hear a "tink" sound when I first start moving after changing directions (forward to reverse, reverse to forward).

Sometimes, but not all the time, I can feel a slight movement in the gear shift knob at the same time I hear the 'tink".

At first I thought U-joints. Now I am not too sure. I note that there is some play in the driveshaft. I took a videos of the play with the transmission in neutral and in gear.

Is this play normal?

 

[mattressking]

That's definitely wearing, now try moving the driveshaft up and down, side to side. If it moves up and down/side to side, note whether its the universal joint or the pinion flange. If it's solid and no movement up or down, I'd keep running it. Just make sure the fluid is good in diff.

My assumption is there is play in the pinion bearing for that much play, however I don't see a leak from the pinion flange seal yet.

 

[OSS]

Rotating it back & forth isn't a good test. It's going to do that a little. Just from that video alone - it seems pretty normal. It's the up & down/sideways movement that shouldn't be there.

 

[blbuck12]

I've always wondered about this as my rear diff has a similar amount of rotational play.

How does one adjust or reduce the amount of slop in the rear diff?

 

[The Machinist]

I've always wondered about this as my rear diff has a similar amount of rotational play.

How does one adjust or reduce the amount of slop in the rear diff?

There will always be a certain amount of rotational play in any geared assembly when changing the direction of rotation; that rotational play is known as backlash. Backlash is essentially the result of the clearances between the two contact faces of the gear teeth.

60 series cruisers use a crush sleeve on the pinion gear to set the projection of the pinion into the ring gear; which controls the "mesh" of the gears. The only way to adjust your gearing mesh is to pull the differential, replace the crush sleeve and check/adjust the preload on crush sleeve. With that said, you will still always have a certain amount of rotational backlash when changing from forward to reverse. As @mattressking and @OSS already said, up & down/sideways movement is what you don't want to see. Up & down/sideways movement would indicate a bad pinion bearing or worn universal joints.

 

[chbrow10]

I attempted to move the rear diff pinion side to side and up and down. There was a feeling of slight movement, but you couldn't see it, you felt it more...

So the "tink' sound is normal? My 15 year old daughter drove the truck yesterday and she is still getting used to the 5 speed. She would dump the clutch after the gear change into 2nd and 3rd and I heard it then too. Trying to figure out if that is normal...

 

[mattressking]

I've always wondered about this as my rear diff has a similar amount of rotational play.

How does one adjust or reduce the amount of slop in the rear diff?

If the driveshaft has a lot of rotational play, that also isn't ideal, however that is only resolved with resetting preload and backlash on the diff out of the car. Since the pinion shaft sits at a 90* angle to the ring gear and as it wears you can start to see the backlash grow and the play in the rotation of the pinion shaft will increase. A correctly preloaded pinion will have very little rotational play as the meshing of the gear set is set. Usually the culprit is when the wear on the pinion bearing occurs, then you also get rotational play as the gears have room to move, resulting in up/down movement which is the test of moving the shaft up and down.

 

[Cruiserdrew]

Pretty sure you just have wear and loss of pre-load in the pinion bearing. This is common/universal at high mileage. There is a fix, but it isn't easy. You can drive a long time as is as long as there is no leak, and you don't have in and out play at the pinion flange.

In the end, you should just rebuild the differential, reset the pre-loads to stock and keep driving it. As an alternative, the front diff usually has little to no wear. You can swap the front differential to the rear and the rear to the front. This could buy you years of driving it as is.

 

[chbrow10]

Pretty sure you just have wear and loss of pre-load in the pinion bearing. This is common/universal at high mileage. There is a fix, but it isn't easy. You can drive a long time as is as long as there is no leak, and you don't have in and out play at the pinion flange.

In the end, you should just rebuild the differential, reset the pre-loads to stock and keep driving it. As an alternative, the front diff usually has little to no wear. You can swap the front differential to the rear and the rear to the front. This could buy you years of driving it as is.

Swapping with the front is intriguing. Are the identical? Is it only a matter of pulling the axles and removal/replacement? No worries about pinion depth, crush sleeves, and back lash adjusting?

 

[Cruiserdrew]

Swapping with the front is intriguing. Are the identical? Is it only a matter of pulling the axles and removal/replacement? No worries about pinion depth, crush sleeves, and back lash adjusting?

Not a trivial amount of work, but basically as simple as it sounds. They are the same.

But seriously for most people the rear differential has 200k miles of wear and the front diff has 2k miles of wear. At most. Swap as you see fit.

If you are just swapping 3rd members, no call for resetting anything. I might replace the seal since it's 30+ years old, but even that is not needed.

 

[Sacto60]

Rotating it back & forth isn't a good test. It's going to do that a little. Just from that video alone - it seems pretty normal. It's the up & down/sideways movement that shouldn't be there.

Maybe I should take a video, but I’m hunting a gravely sound under power. Idles fine, revs fine, and goes away when clutch depressed /coasting. Grabbed my rear DS handlebar/pull-up style and there’s just a touch of rotation, just a tiny bit. When I oomph the whole DS watching the pinion flange it’s also just a little up down side to side. I’m not yanking too hard. Could that be a culprit? Note, I just returned from a pretty taxing overland trip through NV and put the 60 through a good workout. Seemed fine on the HW home.

 

[chbrow10]

Growling is typically a bearing. Especially if it goes away in coast. Might have a diff rebuild in your future