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How to verify used gears?

Demonoid369

Demonoid369

NAXJA Forum User
NAXJA Member
Location
Salem, OR
So I'm thinking about buying some 4.88 d30 gears and I've been trying to find out how to make sure they are match gears and not mixed.what do I look for to verify they are a matched pair?
Also as I've been searching, I have also been trying to find some decent new info.
I know rear axle application it is best for new gears but for up front used is alright as they aren't under load unless in 4wd?
When regearing used gears. Are you suppose to try and match the wear pattern of the coast side or drive side more?
 
Demonoid369 said:
So I'm thinking about buying some 4.88 d30 gears and I've been trying to find out how to make sure they are match gears and not mixed.what do I look for to verify they are a matched pair?
Also as I've been searching, I have also been trying to find some decent new info.
I know rear axle application it is best for new gears but for up front used is alright as they aren't under load unless in 4wd?
When regearing used gears. Are you suppose to try and match the wear pattern of the coast side or drive side more?
Click to expand...

I installed used Nitro 4.56 gears in my dana 30 four years ago and no worries. But I credit that success to my buddy teaching me how to set up my gears and getting a good pattern after a few attempts.

The ring gear and pinion gear should be stamped with the gear ratio so they should match.

The only load the front axle gear will have in 2wd is turning the front drive shaft. And I am no expert but I would imagine you need to disregard the wear pattern and set up the gears with the pattern that shows best for you.

Good Luck!
 
I just got done putting 4.88's in my D30 and the closest I could get for my backlash was .020. I may have a tweaked housing but even with no shims on the driver's side of carrier with the bearing preload correct on my pinion, the best I could get was above. Talked to a builder friend of mine and he said run it if I had a good pattern and so far so good. No noise at all coming from either diff and since it's only under power in 4wd, I agree it should be fine.
Of course I overpower my brakes now (didn't happen with my 3.54's) if I have to reverse off an obstacle to change lines. It never ends.

Forgot to mention, there will be a number stamped on both the ring and pinion gears. It's not the ratio or the +- on the pinion. The ring and pinion gears are matched and have to run together.
 
Using previously used gears is at best a crap shoot. I've set several sets up with mixed results. You can normally get them to work, but 9 time out of 10 you will have to listen to them whine forever.
 
dan1977p said:
I just got done putting 4.88's in my D30 and the closest I could get for my backlash was .020. I may have a tweaked housing but even with no shims on the driver's side of carrier with the bearing preload correct on my pinion, the best I could get was above. Talked to a builder friend of mine and he said run it if I had a good pattern and so far so good. No noise at all coming from either diff and since it's only under power in 4wd, I agree it should be fine.
Of course I overpower my brakes now (didn't happen with my 3.54's) if I have to reverse off an obstacle to change lines. It never ends.

Forgot to mention, there will be a number stamped on both the ring and pinion gears. It's not the ratio or the +- on the pinion. The ring and pinion gears are matched and have to run together.
Click to expand...

This. There should be numbers engraved on each that are the mating pairs from the factory. If they don't match then the gears have been mismatched.
 
I hear this alot. But do you really think they custom machine 20,000 sets of gears a month to only match each other?

I've bought i think 8 sets of gears this year, and none of them have had numbers on them.. ;)
 
cal said:
I hear this alot. But do you really think they custom machine 20,000 sets of gears a month to only match each other?

I've bought i think 8 sets of gears this year, and none of them have had numbers on them.. ;)
Click to expand...


I've had the same thought.

My only hesitation is that you can probably mix and match new gears, but once they have some wear on them they should stay together just so the wear pattern matches.

But I have no kind of information to back that up. Just my .02
 
Sounds like building and AR-15. New bolt and new barrel ok, used bolt and new barrel ok, new bolt and used barrel ok, used bolt and used barrel (not used together) not ok.
 
cal said:
I hear this alot. But do you really think they custom machine 20,000 sets of gears a month to only match each other?

I've bought i think 8 sets of gears this year, and none of them have had numbers on them.. ;)
Click to expand...

Good gears, yes. Cheaper ones, not as likely. Even I rarely check on New gears, but if youre buying used gears it would useful to tell if they've been mismatched.
 
They are put in a machine that runs them in the exact configuration they would be in an axle housing. This verifies no abnormal noise or vibration, and it also helps to lap them in so the provide a noise & vibration free mesh.

This done on a machine, and not in an axle, so there is not as much force or heat buildup as when driving. It is only to verify dimensions & construction.


Copied from Randy's Ring & Pinon website in the FAQ section for gear break in:
In order to make them run cooler and quieter, new gears are lapped at the factory. However, they are not lapped under the same pressures that driving creates.
 
Last edited:
dan1977p said:
I just got done putting 4.88's in my D30 and the closest I could get for my backlash was .020. I may have a tweaked housing but even with no shims on the driver's side of carrier with the bearing preload correct on my pinion, the best I could get was above. Talked to a builder friend of mine and he said run it if I had a good pattern and so far so good. No noise at all coming from either diff and since it's only under power in 4wd, I agree it should be fine.
Of course I overpower my brakes now (didn't happen with my 3.54's) if I have to reverse off an obstacle to change lines. It never ends.

Forgot to mention, there will be a number stamped on both the ring and pinion gears. It's not the ratio or the +- on the pinion. The ring and pinion gears are matched and have to run together.
Click to expand...

... You need a new carrier dude. .020 is so wide of backlash expect a stripped ring gear. You need a 373+ carrier it moves the ring gear over roughly 1/8". FWIW I set front gears tight if they're new. First set I did .003 and it opened now to .005.
 
Last edited:
I am running used 4.88s in both of my axles with zero issues. They don't whine. Lockers work as supposed to and are quiet. I feel proper set up is more important than anything.
 
93blackxj said:
831_xj is right, when using 3.73 gears and higher gears you need a 706008x carrier from Dana or locker of correct flange height. 3.54 gears use a 706007x.
Click to expand...

Yeah, I figured as much after and I'm looking for a new front axle with a single passenger shaft and hopefully it will have the right carrier too.
 
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