Tell me my gears are shot in my 14 bolt

[sneekyeye]

Or tell me my backlash is bad at least.

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I have been wondering for some time about the cause of my driveline lash. You can be on and off the throttle and get a driveline shock. It is most easily reproduced in first.
I thought it was my collapsed motor mounts for a while, but when they were replaced, the clunk remained. So I zip tied a camera under the truck pointed toward the transfer case, and saw no unusual flopping of that, but my driveshaft wiggled suspiciously.

So here we are. It made the drive to Durhamtown and back and handled three days of light offroading with no complaint aside from the occasional uncomfortable knocking. What I need to know is if it is likely I can just tighten up the lash or if the gears are toast. I'll have to pull the cover on it at least for a look-see, but is this a common issue on the 14 bolt by any stretch?

 

[Chaski]

That is normal in my opinion for a 14 bolt with a Detroit locker. Also a clunk going from forward to reverse is normal. What you are seeing isn’t backlash in the ring and pinion.

 

[sneekyeye]

I'll do a little more looking into the normal behaviour of a detroit locker I suppose. This is the first truck I've had with a locker anyway. It just made me think something was wrong when it thumps going on and off throttle.

 

[HETvet]

Chock the front wheels, put trans in neutral, jack up the rear end so the tires are off the ground and put the rear axle on jack stands, then Climb up under the truck. Grab that drive shaft and twist it in both directions. Make a mental note of the clunking in each direction before the tire begins to move. The felt clunking is going to be the coast side and power side gear mesh. This is a very rough estimate of actual back lash, but can easily give you an idea of what’s going on. Any movement from clunk to clunk more that like 1/32” is excessive back lash. Your talking about .01-.05” of back lash clearance is spec. (Really rough estimate, just using those numbers to show how tight factory spec back lash is)

 

[Chaski]

From Eaton Detroit.......




Vehicle PerformanceThe performance of a vehicle equipped with a NoSPIN/Detroit Locker differential is somewhat different from that of a vehicle equipped with a conventional differential. For example:

When turning a corner, the sound of component disengagement and re-engagement may be audible, and the transfer of driving torque from both wheels to one wheel may be noticeable.

When going from drive (acceleration) to coast (deceleration) in a turn, a "metallic" sound may be heard as torque flow is reversed (inside wheel engaged during acceleration; outside wheel engaged during deceleration).

These characteristics are normal because of backlash designed into the NoSPIN differential,*which is of a fixed amount (1 to 2 inches of rotation at the tire tread).

Backlash or slack between the driving and driven clutch teeth is an inherent part of the NoSPIN and necessary to permit automatic operation when driving in forward and reverse. The total backlash in the driveline is increased by the amount of the reduction between the ring gear and pinion. If the ring gear pinion ration is 5 to 1, the total backlash in the drivetrain with the NoSPIN would be about 30° . This in turn is increased by clearances between planetary gear, sliding splines, and the ring and pinion gear. We feel that the total driveline slack can amount to as much as 1/4th*turn of the driveline without being abnormal, but if it exceeds ¼ turn, other parts in the drivetrain could be checked. Further clarification of operational and performance characteristics is available through Technical Bulliten No. 81-1044. A copy is available by writing to our marketing department

 

[sneekyeye]

So upon further research, it appears that this is a normal characteristic of the detroit locker. I guess I'll just have to live with it. I did think there was something messed up. It performed admirably off road, so I didn't really know.