Gear ratio help

[Rogersocal]

I have a 2020 wrangler Recon that supposedly came 4.10 stock.

The guy i bought it from said it was regeardd to 4.88 which is perfect cause I'm on 37s.

I'm trying to measure it.

One rear in the air, neutral, brake off. Mark on the driveshaft, using the forging mark at rhe bottom of the dif as my reference.

Mark on the tire, using upper control arm as my reference so I can see both marks clearly.

Spin the tire one full rotation and I count 2 and a tiny bit more.



Obviously I don't have a 2.10 gear ratio, I was more betting I had a 4.10 and was lied to about the regear.



Am I doing something wrong? I really don't wanna do the work to open the dif cover.


I'm trying to rule out possibilities chasing down an issue.

Using a tazer i set gear to 4.88. I dont have any issues until i go to 4 wheel low and role, when i get to an obstacle and have to stop waiting my turn i get a serv 4wd error that is cleared by ahuting off the engine and restarting and again is fine till the n3xt stop.

i works fine in 4whigh. Never ever get an issue

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[azwjowner]

With one tire fixed, you have to rotate the free tire twice instead of once. Do that and then count driveshaft rotations. You should get 4.88 (or 4.10, whatever), and you should be able to distinguish between 0.10 of a driveshaft rotation vs 0.88 of a rotation.

Your current data is insufficient to determine if you have 4.10 or 4.88 because "and a tiny bit more" has to be multiplied by two and I don't know if your tiny bit is 0.05 or 0.44 that you measured.

Note that if for whatever reason you still feel uncertain in your measurements, you could rotate the free tire four times and compare 8.2 vs 9.76 driveshaft rotations. That would be very easy to distinguish.

 

[JEEP4U]

Need both wheels off the ground...........most accurate is to pull the cover.

with the gear ratios being so close.....gear lash can be an issue.

 

[grimmjeeper]

Yeah, with one tire on the ground the other tire turns twice as fast. So multiply that 2 and change by 2. So it's 4 and change. 4.88 would be just shy of 2-1/4 driveshaft turns. 4.10 would be just a hair past 2. 4.56 would be right in the middle.

 

[Tonopah]

Isn't the gear ratio stamped on the axel or differential or whatever?

 

[Rogersocal]

Thanks guys, 4.10 for sure. I know what I'm doing next year.

Regear and new axleshafts.

 

[grimmjeeper]

Isn't the gear ratio stamped on the axel or differential or whatever?

Not any more.

It's a sticker on the axle tube now. And I don't think it lists the ratio.

 

[zouch]

maybe, but even if it was, if it was regeared that wouldn’t help.

Isn't the gear ratio stamped on the axel or differential or whatever?

 

[CorvZ061]

What is your RPM at 70? Does it see 8th gear often? 37’s with 4.10 will rarely ever see the trans in 8th gear.

 

[Whaler27]

Thanks guys, 4.10 for sure. I know what I'm doing next year.

Regear and new axleshafts.

Before you land on the regear decision I recommend reading the many threads on the topic. @Zandcwhite makes some compelling arguments for keeping the 410 gearing. He’s not alone in that assessment — lots of guys on the web who are happy with the 410 (Which would not have been the case with the old JK transmission.)

If you’re determined to regear for a particular use, you’ll also see lots of good debate on the 488 versus 513. Lots of good information.

 

[Rogersocal]

Before you land on the regear decision I recommend reading the many threads on the topic. @Zandcwhite makes some compelling arguments for keeping the 410 gearing. He’s not alone in that assessment — lots of guys on the web who are happy with the 410 (Which would not have been the case with the old JK transmission.)

If you’re determined to regear for a particular use, you’ll also see lots of good debate on the 488 versus 513. Lots of good information.

Thank you all, i'll definitely look into it some more

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