PDA

View Full Version : Non auto locker guys: Rear diff play?


AxleIke
06-22-2009, 11:12 AM
So, question for those who don't have auto lockers (so only guys who have ARB, Elocker, open. Its not a snooty thing, just auto lockers have a LOT more internal slop by design, so your situations will be different).

How much play do you guys have at your rear diff if your tranny is in nuetral, and you try to rotate the rear drive shaft by hand?

I ask this because I have an irritating whine when I am under power, but NOT under coast. My gears have been re-set up, and I've been told that the gears need a period of time to wear themselves a new pattern. I'm trying to make sure this is all that the noise is, and not something that could be getting damaged.

I also cannot tell if it is coming from my t-cases or the diff. Sometimes it sounds like the diff, and other times, it sounds like its coming from the cases.

However, I put my tranny in neutral this weekend, and saw that I do have some play. It's not my driveline at all, it is all in the diff. Now, I realize that when turning the driveshaft, there will be some play, because you have to go from coast to drive through the backlash (which is tiny), side gear slop, and spline slop (should be VERY tiny). My pinion has ZERO in/out movement, but it seems like I have more play than I should, though I've never looked at it before.

Thanks!

DaveInDenver
06-22-2009, 11:47 AM
My diffs are ARB, Yukon gears, Robbie set-up. About 5 years old now and I don't get much detectable slop by hand. Mostly can just feel the bit of gear play if I rock the pinion flange. My driveshaft slip joint has far more visual play in it than the diff, so if I twist the driveshaft at the t-case output I can see the spline part moving relative to the yoke part of that.

Now that said, I also have this occasional whine in my drivetrain. I noticed it last summer and don't remember it before. I have it narrowed down to my transfer case as the most likely candidate, with maybe the transmission as a remote chance.

My suspicious is reinforced by the fact that my output yoke has visual play in it and my output seal sometimes leaks gear oil. The output yoke can visibly move up and down when I push on the side of it (i.e., it wobbles within the bearing, does that description make sense?).

I'm fairly certain that when the transfer was built (bought a complete Marlin 4.7 unit) the output shaft was not shimmed correctly to load the output bearing right after being broken in. The noise started after about 1,000 miles and it was leaking quite significantly by the time we reached the campground before Rubithon last year (Bruce, Nakman, Kevin and I drained the case, cleaned it up some and noticed the play). Marlin in Rubicon Springs gave me one of this super duper output seals, but the case needs to be split to reset the shims and I have just not had time or money to do that.

So I'm pretty sure I'm ruining the output bearing a little more each day I drive into work... But I'm also thinking that it's screaming at me to deal with it, which I would expect to be a bearing-like or gearish sorta dying whine. But even with that, the Marlin gears seem to just naturally have more whine than the original gears (or maybe they did too when they were new, I only have 100,000 mile old original to reference against). In 4WD-high, like on a snowy road, the front drive makes a lot more whine than it did before. Is your noise new or just nagging for a while? Could just be new gears still engaging a lot more than our original junk that was all worn in.

Red_Chili
06-22-2009, 11:55 AM
Isaac, if you want to be sure you simply have to pull the diff. There are too many additive tolerances to tell anything for sure.

One thing is for sure IMHO... your diff should not make noise, and if it was set up properly it should not have to wear in a new pattern... unless you run Gen-yoo-whine gears from 4 Wheel Parts, in which case all is normal.

My driveline made some interesting ticking and running noises too, after Cliffhanger - none really really loud. It wasn't until Wipe Out Hill that the pinion teeth finally let go. The initiating event that caused the pinion failure? Probably several moons prior.

AxleIke
06-22-2009, 12:05 PM
Well, its new, but that's only about 1/3 the story.

So, When I had a single 4.7 case, it made zero noise. When I went duals, I got a "chatter". I found out recently that the "chatter" is actually poor driveline angles. Then, over the winter, I went flat belly, and the angles were even worse. I drove the truck about 60 miles from my folks place with my old (u-joint) shaft. It was pretty noisy. Then, I went to a CV shaft, but had a bad diff angle. I drove it the same 60 miles with a much smaller vibration home, and fixed the pinion angle. That was when I noticed the whine. With all the vibration before, I could have had this noise, but it wouldn't have been noticeable with the noise.

Its possible that this is a tcase problem, though my output shaft is rock solid, which is why I posted up about putting the tranny in neutral. With my tranny in gear, I have ZERO movement.

Its not the drive shaft either. Its just the diff. When I get home tonight, I will try and take a short video of the issue, and post it.

FWIW, my diff was re-set up by Robbie. The diff is not ideal. Bill was posting up about his shims on the pinion in his gear set up thread to be close to the ideal .070". My pinion is shimmed to .268" or so. This is because the total morons who did the diff for me originally put V-6 gears into a 4cyl housing, which is a no-no. Robbie was able to make it work, with good backlash, and good pinion depth, so we went with it.

Here is why the diff was re-set up in the first place. Robbie fixed this:

http://i29.photobucket.com/albums/c263/AxleIke/IMG_3741.jpg


I'm hoping its something simple, like the gears needing more time. We'll see.

Red_Chili
06-22-2009, 12:12 PM
Well... that will certainly make noise! :lmao:

Yeah, the V6 pinion will definitely reach further in there. Actually, Isaac, I've seen online breakdowns of I-4 shimming in the .2xx so that in itself is not an indicator of something awful. I've never regeared an I-4 diff so, what do I know? But ~.070 is for V6 diffs and even that is a general guide.

If Robbie set up your diff, it's right. If it was real wrong before I can certainly see why it would maybe need to wear in now. If Robbie did it recently I'd run it for a while and see. If it was a while back, you might have a pinion bearing finally getting ready to say hasta la bye-bye.

If you're like me, and I know I am, you're gonna wanna pull the diff and have a lookee-see. Best sleep aid I know of. Be grateful you don't run Danas.

DaveInDenver
06-22-2009, 12:14 PM
Have you drained the fluid that you put in after Robbie re-set the gears? If it was gears finding their new happy place I would expect to see some evidence of that with pixie dust on the magnet.

AxleIke
06-22-2009, 12:29 PM
Well... that will certainly make noise! :lmao:

Yeah, the V6 pinion will definitely reach further in there. Actually, Isaac, I've seen online breakdowns of I-4 shimming in the .2xx so that in itself is not an indicator of something awful. I've never regeared an I-4 diff so, what do I know? But ~.070 is for V6 diffs and even that is a general guide.

If Robbie set up your diff, it's right. If it was real wrong before I can certainly see why it would maybe need to wear in now. If Robbie did it recently I'd run it for a while and see. If it was a while back, you might have a pinion bearing finally getting ready to say hasta la bye-bye.

If you're like me, and I know I am, you're gonna wanna pull the diff and have a lookee-see. Best sleep aid I know of. Be grateful you don't run Danas.

The diff has maybe 150 miles on it so far. Maybe. It's pretty recent. The gear pattern is QUITE different that it was before, with all new bearings.

The wierd part is, I can see the pattern re-setting itself causing the noise ONLY on the drive side, as, IIRC, that was the side that was the most different. I cannot see a bearing failure causing noise ONLY on the drive side, which is what its doing.

I have no problem pulling the diff, I'm just trying to make sure that's the issue before I go messing with it.

Have you drained the fluid that you put in after Robbie re-set the gears? If it was gears finding their new happy place I would expect to see some evidence of that with pixie dust on the magnet.

I have not drained the oil No magnet anymore, but I'd still be able to see the gear stuff in the fluid. Again, it only has maybe 150 miles on it. Robbie also said that it didn't need to have the normal breaking procedure. When I get to 500 miles, I'll drain it out.

DaveInDenver
06-22-2009, 12:35 PM
The gear pattern is QUITE different that it was before, with all new bearings.

The wierd part is, I can see the pattern re-setting itself causing the noise ONLY on the drive side, as, IIRC, that was the side that was the most different.

I have not drained the oil No magnet anymore, but I'd still be able to see the gear stuff in the fluid. Again, it only has maybe 150 miles on it. Robbie also said that it didn't need to have the normal breaking procedure. When I get to 500 miles, I'll drain it out.
Normal break-in on gears is as much about the final tempering as it is the faces meshing. Since your gears have already been subjected to their final heat treating the first time I would expect they'd not need it again. But I assume there is wear happening if they are going through a new face-to-face reintroduction, so more than normal fillings might indicate that. Just thinking out loud here, though.

AxleIke
06-22-2009, 12:40 PM
Oh totally. I'm just saying, I'm going to put a few more miles on it before I drain it so that I can be sure to get a good amount so that I don't drain it, see nothing really, and then refill and have more filings come in.

Red_Chili
06-22-2009, 12:48 PM
I can imagine a bearing making noise in only the drive direction. Hypoid gears push and pull that pinion pretty hard, depending on the direction. What I *can't* see is a bearing doing that after 150 miles.

Your coast side is as different as your drive side, from what it was before. But yeah, it can make noise in only one direction.

One can only imagine what the pattern looked like when Robbie first laid eyes on it, versus what it looks like now. How in the world the first guys missed that level of pinion contact is one of the dozen wonders of the Western world. Could they have missed a couple other things? ahhhh.... hmmmm....

Of course we all is armchair mechanickin' now, ain't we? We could all of us be wrong.

DaveInDenver
06-22-2009, 12:50 PM
Oh totally. I'm just saying, I'm going to put a few more miles on it before I drain it so that I can be sure to get a good amount so that I don't drain it, see nothing really, and then refill and have more filings come in.
LOL! My first response to new or odd noises is fluid R&R, which usually doesn't change anything but, you know. It's so hard to know what to worry about and what not to, though. My noise happened before the Rubicon even started and I was there, did what I could and figured that Marlin would be at Rubicon Spring if it exploded. So I shrugged and went anyway, something I probably would not have done had I not been 1500 miles from home. It worked fine, made it home and now another year more. So I dunno, from what you've said and that Robbie's the one who did the most recent work, probably safe to drive for a while more and see. Yeah, easy to say when it's not your truck, eh? There's also the thought that if it's making noise now and nothing is obviously seized or broken, that a few more miles might, uh, move the problem along a bit more and make it bit more, you know, obvious. That goes against every fiber of your, Bill's and my philosophy and sure there's the chance that you get complete system failure. But what's life if there was no unknown?

AxleIke
06-22-2009, 01:04 PM
Well, I definitely want to fix it before something blows, but I see your point. Right now, its not obvious.

It also could be the transfercases. I'm just hesitant to pull anything before I isolate the problem.

The whine is annoying, and occurs really only above 30 mph, and only on drive. It isn't what I would call, "alarmingly loud". I forgot to add the speed part.

I figure I'll start with re-greasing the driveline, checking fluids, and trying to solve it that way.

Red_Chili
06-22-2009, 01:46 PM
I second Dave's suggestion of changing the diff fluid. Pretty cheap, 150 miles after a major reconfiguration (not unlike new gears except for the heat part of the break in) so I wouldn't say its too soon. You don't want a bunch of steel 'pixie dust' :lmao: running through those nicely preloaded bearings anyway, do ya?

You're gonna wanna do it again after a few hundred anyway. Use decent but cheap 80W90 till everything stabilizes.

AxleIke
06-22-2009, 09:15 PM
I got some info from thefatkid, who is a toyota tech at Burt. He said 1/8" - 1/4" of play is normal. I didn't get the tape in the video, but I measured 1/8".

Here is the video:

http://i29.photobucket.com/albums/c263/AxleIke/th_MVI_3949.jpg (http://s29.photobucket.com/albums/c263/AxleIke/?action=view&current=MVI_3949.flv)

Red_Chili
06-23-2009, 09:27 AM
thefatkid (who is not fat... go figger) will never lead you astray. All you have is 1/8"?? Wow. Stylin'.

[edit] after looking at the video, looks more like 1/4", but still just fine. Much of that is in the axle splines, spiders, etc.

DaveInDenver
06-23-2009, 09:34 AM
I got some info from thefatkid, who is a toyota tech at Burt. He said 1/8" - 1/4" of play is normal. I didn't get the tape in the video, but I measured 1/8".
How is this measured, in circumference? So IOW, assuming the flange is 16" in circumference (just a guess), then 1/8" of play is about 3 degrees of rotational freedom? Or I guess more properly it would be about 1.5 degrees of free play between center normal and the drive and coast gear interfaces.

AxleIke
06-23-2009, 10:14 AM
thefatkid (who is not fat... go figger) will never lead you astray. All you have is 1/8"?? Wow. Stylin'.

[edit] after looking at the video, looks more like 1/4", but still just fine. Much of that is in the axle splines, spiders, etc.

Yeah, wasn't quite sure how to measure that. I twisted the driveshaft as far as it would go one way, put a mark on the flange on the side so I could bring a tape up tangent to it. Then, when I rotated it, the mark moved about 1/8". Either way, groovy.

thefatkid also said that its rare to do what I did, which is have the gears re-set up after running a pattern on them for many years. He said that could easily be the cause of the noise.

I think I'll change the fluid here, and see how things are looking, pull my new access hatch, and see if I can determine if its the t-cases or the diff a little more definitively.

AxleIke
06-23-2009, 10:15 AM
How is this measured, in circumference? So IOW, assuming the flange is 16" in circumference (just a guess), then 1/8" of play is about 3 degrees of rotational freedom? Or I guess more properly it would be about 1.5 degrees of free play between center normal and the drive and coast gear interfaces.

I'd have to measure the diameter of the flange. Those degree numbers sound a little small though, from my visual inspection.

DaveInDenver
06-23-2009, 10:55 AM
I'd have to measure the diameter of the flange. Those degree numbers sound a little small though, from my visual inspection.
Unless the flange is significantly smaller than 16", the angles are just trig. If the flange is 12.5" (say roughly 4" across) in circumference, then 1/8" arc length is about 3.75 degrees.

degrees = arc length / circumference * 360

or

angle = (arc length / radius) in radians
then: degrees = radians * 180 / pi

AxleIke
06-23-2009, 11:31 AM
Dave, you are talking to the trig master. I'm just saying that, from a visual standpoint, the distance looks like more than 3 degrees.

Also, 4" across sounds big. Three seems more likely. Which gives 4.7 degrees, which seems a lot more like what I was seeing.

Red_Chili
06-23-2009, 11:51 AM
This is men talking linear measurement. Which my wife has assured me is an unreliable pursuit.

I don't remember why though.

AxleIke
06-23-2009, 12:54 PM
This is men talking linear measurement. Which my wife has assured me is an unreliable pursuit.

I don't remember why though.

:lmao::lmao:

DaveInDenver
06-23-2009, 01:05 PM
LOL!

Didn't mean to imply anything Isaac, just wondering really how you went about measuring the 1/8~1/4" of movement since I want to do the same check sometime on my truck.

rover67
06-23-2009, 02:32 PM
mine moves 2 feet...

Red_Chili
06-23-2009, 02:40 PM
Ah. Now I remember why my wife said that.

AxleIke
06-23-2009, 02:46 PM
LOL!

Didn't mean to imply anything Isaac, just wondering really how you went about measuring the 1/8~1/4" of movement since I want to do the same check sometime on my truck.

Oh I know. I was just kidding around.

Squishy!
06-23-2009, 03:10 PM
To eliminate your rear diff (or not:rolleyes:) you can pull the rear drive shaft and drive around in FWD. if it still makes the same noises could be cases, wheel bearings, etc. If the noise changes or if the noise is gone it tells you that removing the load changes the sound, which would mean rear diff.