4.88 install - Ring gear warped!

[alia176]

I'd like to hear some suggestions on what to do in this situation. I have a 4.88 R&P set new to me (bought from a Mud member, uninstalled) two years ago. This is for the rear, no factory lockers. It appears as though this is a Motive gearset (package has no descriptions).

The run out on the ring gear is at .004" max. This makes the back lash tight in one spot and way too large in other spots. I spoke to a machine shop and they "claim" that they can make the ring gear true again. But I don't know what this would do to the heat treated metal. Shop charge is $50/hour and he thinks that it'll take less time than one hour.

random thoughts:

-returning to vendor is not an option
-not the seller's fault. It is what it is.
-I know Precision gears are awesome (have their set on the front)
-the ARB flange that this ring gear is mating too has an acceptable run out of .002" (ARB says this is ok.)
-yes, I filed the ring gear and the ARB flange before installing (4 times) just like Zuk does.
-yes, the side adjusters are properly setup and tightened.
-yes, the carrier bearings are pressed in all the way.
-my 80 is part time (Tcase mod) so this R&P will see 100% of engine torque most of the time.
My previous 4.56's were fine on the same ARB air locker so that isn't an issue.

Ideas, suggestions?

Thanks.

 

[Letsgomoreplaces]

gears

It is rare that a ring & pinion will be the culprit for run-out, yet it is possible. Did you file between the case halves of the arb? did you check the arb for axial run-out? (measured on the ring gear pilot) Also, you can check the ring & pinion for small burrs or dings. I would reccomend taking a 1-1.5" sanding wheel and putting a very slight chamfer on the edges of all the teeth.

I'd like to hear some suggestions on what to do in this situation. I have a 4.88 R&P set new to me (bought from a Mud member, uninstalled) two years ago. This is for the rear, no factory lockers. It appears as though this is a Motive gearset (package has no descriptions).

The run out on the ring gear is at .004" max. This makes the back lash tight in one spot and way too large in other spots. I spoke to a machine shop and they "claim" that they can make the ring gear true again. But I don't know what this would do to the heat treated metal. Shop charge is $50/hour and he thinks that it'll take less time than one hour.

random thoughts:

-returning to vendor is not an option
-not the seller's fault. It is what it is.
-I know Precision gears are awesome (have their set on the front)
-the ARB flange that this ring gear is mating too has an acceptable run out of .002" (ARB says this is ok.)
-yes, I filed the ring gear and the ARB flange before installing (4 times) just like Zuk does.
-yes, the side adjusters are properly setup and tightened.
-yes, the carrier bearings are pressed in all the way.
-my 80 is part time (Tcase mod) so this R&P will see 100% of engine torque most of the time.
My previous 4.56's were fine on the same ARB air locker so that isn't an issue.

Ideas, suggestions?

Thanks.

 

[RedTacoma]

I'd like to hear some suggestions on what to do in this situation. I have a 4.88 R&P set new to me (bought from a Mud member, uninstalled) two years ago. This is for the rear, no factory lockers. It appears as though this is a Motive gearset (package has no descriptions).

The run out on the ring gear is at .004" max. This makes the back lash tight in one spot and way too large in other spots. I spoke to a machine shop and they "claim" that they can make the ring gear true again. But I don't know what this would do to the heat treated metal. Shop charge is $50/hour and he thinks that it'll take less time than one hour.

random thoughts:

-returning to vendor is not an option
-not the seller's fault. It is what it is.
-I know Precision gears are awesome (have their set on the front)
-the ARB flange that this ring gear is mating too has an acceptable run out of .002" (ARB says this is ok.)
-yes, I filed the ring gear and the ARB flange before installing (4 times) just like Zuk does.
-yes, the side adjusters are properly setup and tightened.
-yes, the carrier bearings are pressed in all the way.
-my 80 is part time (Tcase mod) so this R&P will see 100% of engine torque most of the time.
My previous 4.56's were fine on the same ARB air locker so that isn't an issue.

Ideas, suggestions?

Thanks.

If that was me I would just shell out money for new R&P.
Its your Diff.. and new gears will be cheaper then new gears + new ARB + new axle.

 

[Tools R Us]

… The run out on the ring gear is at .004" max. ...

Measuring on the backside of the ring?

… This makes the back lash tight in one spot and way too large in other spots. ...

What is the difference in backlash?

… My previous 4.56's were fine on the same ARB air locker so that isn't an issue. ...

Did you measure the backlash around the ring before removing, how much backlash variance?

If it were mine the first attempt would be to measure the backlash all the way around the ring and mark the tightest spot on the ring and carrier. Remove the ring and measure the carrier run out, marking the highest and lowest spots. My bet is the highest carrier spot will be about the same spot as the tightest backlash. Now reassemble with the tightest backlash spot on the ring matched with the lowest carrier mark, put it back in and see if the backlash measurement changes? Nothing is perfect, you may have a all of the high errors stacked up in the same place, so by moving them it may come into tolerance?

Also I would measure the machined ring where the ring gear ID presses over, if there is radial run out this will effect backlash variance.

IIRC the ARB carrier is a two piece unit? You may want to split it and make sure they didn’t trap a piece of debris, burr, etc, in the mating surfaces causing the run out?

 

[alia176]

Measuring on the backside of the ring?

Yes

What is the difference in backlash?

Super tight, .00" to super loose .015"

Did you measure the backlash around the ring before removing, how much backlash variance?

Super tight, .00" to super loose .015"



If it were mine the first attempt would be to measure the backlash all the way around the ring and mark the tightest spot on the ring and carrier.

did that

Remove the ring and measure the carrier run out, marking the highest and lowest spots.
did that

My bet is the highest carrier spot will be about the same spot as the tightest backlash. Now reassemble with the tightest backlash spot on the ring matched with the lowest carrier mark, put it back in and see if the backlash measurement changes? Nothing is perfect, you may have a all of the high errors stacked up in the same place, so by moving them it may come into tolerance?

I did that but need to do it again

Also I would measure the machined ring where the ring gear ID presses over, if there is radial run out this will effect backlash variance.

Will do

IIRC the ARB carrier is a two piece unit? You may want to split it and make sure they didn’t trap a piece of debris, burr, etc, in the mating surfaces causing the run out?

did that but can't hurt to recheck it. Thing is, this ARB unit has been in service in my 80 w/o issues. It does have a runout of .002" which is acceptable according to ARB.


Thanks very much for the info. Will report back