gear question

[djag12]

Do your front and rear gears have to be the same ratio?

[jtdesigns]

Only if your in 4wd.

[DirtyComanche]

And if you have the same sized tires front and rear...

[djag12]

OK. thanks guys

[CWLONGSHOT]

And if you have the same sized tires front and rear...

 

And expect your TCase to be in one piece after shifting into 4WD at 45 like the manuel says you can.... :yes: :rotf: :rotf:

 

CW

[Eagle]

What's the reason for the question?

 

Basically, the answers given above are all correct: "Yes." But ...

 

There's also an issue that occasionally comes up as to what "the same" ratio means. Read enough about our Jeeps, and you'll see references to the 4.0L 5-speeds beiing a 3.07 ratio -- unless it's 3.08. The 4.0L automatics have 3.55 gears ... unless they have 3.54 gears. And the 4-cyl 5-speeds have 4.10 gears ... unless they have 4.11 gears.

 

If the point of your question is that you have noticed you have one axle that says 3.54 and one that says 3.55 ... that is considered the "same" ratio. The discrepancy arises when the front axle has a smaller ring gear than the rear axle, so the tooth count is different. The gear ratio is the tooth count on the ring gear divided by the tooth count on the pinion, so it usually works out that the ratio on the front axle is "different" from the rear in the second decimal place of the ratio. That small amount of discrepancy is acceptable, because in any situation where you could/should use 4WD, there's enough slippage and tire tread "squirm" to cancel out the difference.

 

What you don't want to do is mix a 3.07 rear with a 3.55 front, for example.

[DirtyComanche]

I think the max streetable safe difference is 3%.