Rear differential out of spec on 6.7

[GuyPNW]

Hi all,

My first post here. This forum has been very helpful and now I’m looking for some feedback about my rear differential.

My 2014 Ram 2500 6.7 Laramie Longhorn Megacab had some work done about a year and a half ago at a reputable shop that I’ve been pleased with. While recently looking back at the invoice to organize my maintenance notebook, I noticed that the shop noted that my “backlash is .028 and spec is .006-.010. Recommend having rear differential rebuild in the near future.”

My question is how out of spec is this? Is it particularly dangerous?

I have a 275 mile round trip vacation planned in July, for which I’ll be towing my 5th wheel.

Curious what you all think. Since getting the rear differential rebuilt (worst case scenario will cost upwards of $5k), would I be ok for one more trip before getting it rebuilt?

Thanks guys!

 

[Burla]

So your oil spec is 80 or 90? Might want to run 75w140 and just make sure you are easy from the start and no major gunning it. If there is any issues being too loose you should be able to hear it when moving from a stop, maybe tape your phone down there record your take off. I doubt there will be an issue while cruzing. Just an opinion, but I don't see any issue with using 140w and it will fill that gap. Metal expands with heat so once warm even less of an issue.

 

[GuyPNW]

So your oil spec is 80 or 90? Might want to run 75w140 and just make sure you are easy from the start and no major gunning it. If there is any issues being too loose you should be able to hear it when moving from a stop, maybe tape your phone down there record your take off. I doubt there will be an issue while cruzing. Just an opinion, but I don't see any issue with using 140w and it will fill that gap. Metal expands with heat so once warm even less of an issue.

Thanks for your thoughts. They did refill it with 75W-140 Schaeffer's Full Synthetic Moly Gear Oil.

Actually, I do hear a bit of a clank when I’m at lower speeds, just taking off, and then completely release the gas pedal - like in stop and go traffic for example. I tend to try and be gentle when releasing the gas pedal to avoid that clank. Not really sure if that’s normal or not.

 

[Burla]

Have you tried towing the 5th since the repair, like a year and a half ago? So the 2500 diff is 85/90 weight, so they were thinking like me and went up to 140 to fill the gap. It's a risk of course, I cant say how much on the risko meter. What the cost to rent a truck another option.

 

[GuyPNW]

Have you tried towing the 5th since the repair, like a year and a half ago?

Yes, several times. No issues.

 

[Burla]

See if they have a united truck rental near you, might be cheaper then you'd think.

 

[Sherman Bird]

Hi all,

My first post here. This forum has been very helpful and now I’m looking for some feedback about my rear differential.

My 2014 Ram 2500 6.7 Laramie Longhorn Megacab had some work done about a year and a half ago at a reputable shop that I’ve been pleased with. While recently looking back at the invoice to organize my maintenance notebook, I noticed that the shop noted that my “backlash is .028 and spec is .006-.010. Recommend having rear differential rebuild in the near future.”

My question is how out of spec is this? Is it particularly dangerous?

I have a 275 mile round trip vacation planned in July, for which I’ll be towing my 5th wheel.

Curious what you all think. Since getting the rear differential rebuilt (worst case scenario will cost upwards of $5k), would I be ok for one more trip before getting it rebuilt?

Thanks guys!

Take the trip. You have a normal issue.... wear and tear. .28 backlash isn't fatal. Low or contaminated oil is.
With that much backlash, I'd hazard a guess that, at higher speeds, the differential whines. Maybe only slightly, but it likely whines. The clunking is a symptom of the looseness you refer.

 

[Dean2]

A good driveline shop may be able to get backlash back into spec, or at least a whole bunch closer. It is an adjustable clearance. This will give you a rough idea how it works but if you haven't done this kind of work I suggest you take it to an expert.



If backlash is too tight or loose, you’ll need to shift the ring gear side-to-side.

To increase backlash: Move the ring gear away from the pinion (thicker shim on the ring gear side or tighter adjuster on the opposite side).

To decrease backlash: Move the ring gear closer to the pinion.

Always maintain bearing preload while adjusting backlash. This may mean adjusting both sides of the carrier equally but in opposite directions.
Adjust as Needed
5. Check the Pattern

Apply gear marking compound to several ring gear teeth and rotate the assembly through a few full revolutions in both directions. Observe the pattern left by the pinion gear on the ring gear teeth.

A correct pattern will be centered on the tooth both face-to-flank and toe-to-heel. If the pattern is too deep or too shallow, adjust the pinion depth. Recheck backlash after every change.
6. Final Torque and Verification

Once you have acceptable backlash and a good gear pattern, torque everything to spec. Rotate the assembly several times to ensure smooth operation and recheck backlash to confirm it remains in spec.

 

[mdc1990zr1]

Thanks for your thoughts. They did refill it with 75W-140 Schaeffer's Full Synthetic Moly Gear Oil.

Actually, I do hear a bit of a clank when I’m at lower speeds, just taking off, and then completely release the gas pedal - like in stop and go traffic for example. I tend to try and be gentle when releasing the gas pedal to avoid that clank. Not really sure if that’s normal or not.

I’m all for the thicker oil and making a go of it until the “clunk” part. If it grenades it’s gonna get real expensive. I think you’re playing with fire at that point

 

[GuyPNW]

Take the trip. You have a normal issue.... wear and tear. .28 backlash isn't fatal. Low or contaminated oil is.
With that much backlash, I'd hazard a guess that, at higher speeds, the differential whines. Maybe only slightly, but it likely whines. The clunking issymptom of the looseness you refer.

Take the trip. You have a normal issue.... wear and tear. .28 backlash isn't fatal. Low or contaminated oil is.
With that much backlash, I'd hazard a guess that, at higher speeds, the differential whines. Maybe only slightly, but it likely whines. The clunking is a symptom of the looseness you refer.

Thanks for your helpful input. If it’s not ridiculously out of spec, like it sounds like your saying, then I really would like to take the trip before spending the cash on rebuilding the differential.

And if there is any kind of winding sound, I can’t hear it at all due to the 5 inch straight pipe that came with the truck when I bought it. All I really hear is full beast mode, haha!