Topic: Excessive Backlash on Rebuilt Differential - where'd I go wrong?

[TyGuidry]

83" pickup. Finally got the rear end put back together. Replaced the old factory unit with a 58.5" wide unit - Brand new Yukon chromoly shafts, brand new Yukon auto locker, brand new motive gear 4-88 ring and pinion. Basically did a full overhaul of the third-member including new hardware, crush sleeve etc etc. Recorded backlash at around .007" in multiple positions with what I would describe as a "decent" but not perfect meshing pattern (also not horrible by any measure). Pinion preload landed somewhere around 12 in/lbs if my memory serves me before I staked the pinion nut and called it a day.

Finally get the chevy 63's burned in and installed, slap the fresh axle under the truck and pull it out of the driveway and by the time I hit the asphalt I hear a noticeable slam. Concerning, but not loud or sustained enough for me to shut the truck down. I drive it up and down the street a few times....no noticeable humming or whining coming from the rear end. Accelerates well, no vibration, drives fine. Except when I go from drive to coast and the "SLAM" occurs again.

Get it back to the house and immediate put hands on the driveline......sloppy. Mark it on one end of the extreme and twist it/mark where it ends....measures around 5/8" of driveline play. Obviously an issue.

All that suffice to say im at a total loss where I went wrong. Did the pinion get pushed away from the ring? Or the ring away from the pinion?? Of course I wont know exactly where the issue is until I crack it open but I'm wondering if there's somewhere on the 3rd I need to look first? Its not a solid pinion sleeve. I know my lash was tight when I dropped it into the housing. All I can think is that the carrier bearing "nuts" (large rings with many holes) or whatever they're called got pushed outwards? I know their keeper tabs we're installed. Ring bolts and caps are torqued and loc-tited etc etc. Maybe the crush sleeve.....crushed? But why so soon/immediate?

The truck needs to sit for a bit while I tend to other projects but its going to fester in my mind in the meantime..

Anyone got any ideas?

[blackdiamond]

What locker do you have?  Mechanical locker add some movement in the drivetrain.

[TyGuidry [OP]]

What locker do you have?  Mechanical locker add some movement in the drivetrain.

Yukon Grizzly 8" 4cyl. My first time dealing with a locked differential..starting to think it's my inexperience that might be the issue here.

[Gnarly4X]

I believe Blackdiamond is correct.

A Detroit Locker will have 1/4 to 1/3 of a turn in the driveshaft.

I'd bet Yukon would tell you that 5/8" is perfectly normal.

Gnarls.

[TyGuidry [OP]]

Yukon Grizzly 8" 4cyl. My first time dealing with a locked differential..starting to think it's my inexperience that might be the issue here.

I believe Blackdiamond is correct.

A Detroit Locker will have 1/4 to 1/3 of a turn in the driveshaft.

I'd bet Yukon would tell you that 5/8" is perfectly normal.

Gnarls.

Well I got home from work today to take it around the block a few more times. Added maybe 2-3 miles on the ODO overall. 2WD, 4WD high and low....what began as 5/8" of slop is now 1.5". So, its growing....and i've yet to hear any ratcheting via sharp turn or otherwise. Only on coast>accel/accel>coast.

When I apply a light twist to the pinion flange I do believe I can feel the actual differential backlash and it feels minimal. So im 'mostly' convinced that the chunk of it lives in the grizzly. But as for why its growing...i have no clue.

Anybody else who wants to talk me off the ledge, please do. Regardless, I think I need to call up the folks at Yukon and verify this is perfectly acceptable.

[Gnarly4X]

Regardless, I think I need to call up the folks at Yukon and verify this is perfectly acceptable.

That's a big 10-4!

Gnarls.

[Gnarly4X]

The Yukon Grizzly is apparently a "copy" of the Detroit Locker. 

If this is true, then 1/4 to 1/3 turn of the driveshaft will easily measure 1.5".

However, you still could have forked the install.

Gnarls.

[TyGuidry [OP]]

Called Marlin Crawler this afternoon. They seemed perfectly happy to hear out my situation. It was the opinion of both the rep who picked up the phone and also another individual at MC that my described symptoms were basically "grizzly locker doing grizzly locker things". AKA par for the course.

On the other hand, I tried to get ahold of anyone at Yukon tech support and sat on the phone collectively for 1.5hrs before finally giving up (2 45 min long hold sessions). Tried to leave a call-back voicemail but the inbox is full.

 

[a1gemmel]

My grizzly definitely has more backlash than both the trutrac and the factory carriers that preceded it.

[TyGuidry [OP]]

My grizzly definitely has more backlash than both the trutrac and the factory carriers that preceded it.

Again, im a total noob to locked diffs..but I have to say after hearing the opinion of the guys at MC and on this board, I'm equal parts relieved and disappointed. The drive behavior (mainly the throttle) feels so sloppy now. It felt like it was marketed to be a much tighter and seamless system than I'm experiencing IMO.

Alongside the overhaul of the rear end, I also dropped a fully trussed & refreshed front end with an aussie locker. Didn't occur to me until today I could compare the two....with hubs locked in neutral the Aussie has just about as much play. Though in 4wd the thing hardly makes any noise. Especially in comparison to the grizz. Lesson learned, I guess.

[Gnarly4X]

I ran Detroit Lockers, Lock Rights, and LSD in both my Toyotas - 1985 and 1986.

Driving on the street with a Detroit (or a Grizzly) takes a short time of getting used to its behavior.

For me, in a short time I developed a driving style that compensated somewhat for the slop, the noise, the ratcheting, the lockup, and the unexpected banging.

The behavior of a locker never goes away, and every once in a while, and fairly frequently it will get your attention to remind you it's there.

Gnarls.
 

[blackdiamond]

Again, im a total noob to locked diffs..but I have to say after hearing the opinion of the guys at MC and on this board, I'm equal parts relieved and disappointed. The drive behavior (mainly the throttle) feels so sloppy now. It felt like it was marketed to be a much tighter and seamless system than I'm experiencing IMO.

Alongside the overhaul of the rear end, I also dropped a fully trussed & refreshed front end with an aussie locker. Didn't occur to me until today I could compare the two....with hubs locked in neutral the Aussie has just about as much play. Though in 4wd the thing hardly makes any noise. Especially in comparison to the grizz. Lesson learned, I guess.

I run an Aussie in the front of my ‘89 SAS and a Detroit in the rear.  Crazy enough I found out after more than 15 years the Detroit was missing a thrust washer that was essentially the difference between the old school No Spin and the newer Soft Locker.  It’s much smoother now. It is all about driving smooth particularly when cornering and particularly when going slow.

Have you had it load up and snap back together where it sounds like an axle just snapped?  That’s where the fun really starts!

[blackdiamond]

Check this thread out.

https://board.marlincrawler.com/index.php?topic=101468.msg1134156#msg1134156

[Prismo]

I have had people ask me if my truck was broken after my detroit banged as I was turning the corner in the parking lot. 

[TyGuidry [OP]]

I run an Aussie in the front of my ‘89 SAS and a Detroit in the rear.  Crazy enough I found out after more than 15 years the Detroit was missing a thrust washer that was essentially the difference between the old school No Spin and the newer Soft Locker.  It’s much smoother now. It is all about driving smooth particularly when cornering and particularly when going slow.

Have you had it load up and snap back together where it sounds like an axle just snapped?  That’s where the fun really starts!

I have had people ask me if my truck was broken after my detroit banged as I was turning the corner in the parking lot. 

My concerns and complaints have absolutely nothing to do with cornering noise. To be honest, I'd welcome noise in a corner. Everything I hear is during coast>accel accel>cost. I've deliberately driven the truck in the tightest circle I can muster in my cul-de-sac  to provoke staus quo "ratcheting"....nada

appreciate yours guys' input nonetheless

[Gnarly4X]

... Everything I hear is during coast>accel accel>cost.

If you are hearing "noise" during acceleration there may be something not right.

The ratcheting can be caused by a differential in the resistance at the axle shaft - for example: via a tire... like one tire has a significant lower PSI. Or... a brake drum is dragging.

If there is a clunk sound at the very beginning of acceleration (the slop being taken up) after coasting, that was normal in my rear end Detroit Locker.

I don't recall a "noise" while driving normally, or accelerating normally.

I do recall a mild clunk noise at acceleration after coasting depending upon how throttle I used.

If you are really concerned, then you might want to have an expert diff guy pull it and check it out.

As I remember, and it's been a long time... installing a Detroit Locker was a different procedure than installing a Lock Right.

I did NOT attempt to install the Detroit, but I did install my 2 Lock Rights.

Gnarls.

[blackdiamond]

My Detroit has never made the ratcheting sound, so I would not expect your “copy” to either.

The lunchbox locker are known for the noise, but it happens when they are installed in the rear end.

[TyGuidry [OP]]

My Detroit has never made the ratcheting sound, so I would not expect your “copy” to either.

The lunchbox locker are known for the noise, but it happens when they are installed in the rear end.

That's good to know, thanks.

If you are hearing "noise" during acceleration there may be something not right.

The ratcheting can be caused by a differential in the resistance at the axle shaft - for example: via a tire... like one tire has a significant lower PSI. Or... a brake drum is dragging.

If there is a clunk sound at the very beginning of acceleration (the slop being taken up) after coasting, that was normal in my rear end Detroit Locker.

I don't recall a "noise" while driving normally, or accelerating normally.

I do recall a mild clunk noise at acceleration after coasting depending upon how throttle I used.

If you are really concerned, then you might want to have an expert diff guy pull it and check it out.

As I remember, and it's been a long time... installing a Detroit Locker was a different procedure than installing a Lock Right.

I did NOT attempt to install the Detroit, but I did install my 2 Lock Rights.

Gnarls.

No noise "during" accel. only when slack is abruptly taken out of the driveline. Basically when transitioning abruptly from on/off throttle. Like I said before, at speed the diff makes no noise whatsoever. Doesn't vibrate, whine, humm, nada. It's just when transitioning from accel/coast and vise versa.

The more time I've spent dwelling on this issue the more I've come to realize that its geometrically not possible that my ring and pinion would be so far out of whack that they'd cause all this slop. It just doesn't make sense. If I can relegate all of this clunking to the mechanical functioning of a brand new out of the box mech locker than I can rest easy, i guess. All that said, I will most likely go with a selectable in the rear sooner rather than later because of this experience..

[Gnarly4X]

Based upon comments here, like from a1gemmel, and this:

https://www.greatlakes4x4.com/threads/backlash-in-a-grizzly-locker.281296/

It appears the Grizzly locker has more "play" than other similar lockers, and you are experiencing a new behavior in your vehicle that is probably normal.

Gnarls.

[blackdiamond]

Do you have it up on jack stands or a lift?  I had a lot of fun playing with the Aussie and Detroit lockers. With an open differential if you turn one tire the other will turn the opposite direction. With a mechanical locker they will turn the same direction unless you provide enough bias for the opposite side to disengage.  With my Detroit I typically had to intentionally jerk the tire I was turning by hand to get the other side to unlock and it wasn’t a quiet operation.  The Aussie mechanic is so soft that I had to be careful to keep it engaged. Very different mechanisms.

If you do this you can get a feel/visual on how they both work.  If you read the thread that I linked I am fairly certain that it explains why the “excessive” backlash is necessary.