410 gearing to 488's

[panama rubicon]

Getting to know my Gladdy. Purchased used last month. Riding on 37's. My reading tells me the gearing needs to be upgraded to minimum 488 from the stock 410's? Previous owner doesn't know anything. What's the best way for me to tell if the gearing was upgraded?

Thank you

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[Greg_L]

Getting to know my Gladdy. Purchased used last month. Riding on 37's. My reading tells me the gearing needs to be upgraded to minimum 488 from the stock 410's? Previous owner doesn't know anything. What's the best way for me to tell if the gearing was upgraded?

Thank you

It's going to be tough to determine what gears you have without cracking open the diff and counting teeth. Sometimes you can turn the wheel one revolution and count how many times the pinion yoke spins, but that's going to be tough if you're trying to determine 4.10 vs 4.88. It's going to be very close. Count the actual teeth and do the math.

Divide the number of teeth on the pinion into the number of teeth on the ring gear.

 

[MoparToYou]

I used this method on prior used vehicles I have bought. Jack up one rear tire, put the transmission in neutral. Tape a string to the side of the driveshaft. Then turn the rear tire one full rotation. Count how many times the string wraps around the driveshaft. In my case I was trying to see if I had 3.73 gears vs 4.10 gears. It was easy to see that the string wrapped around the driveshaft just over 4 times, instead of just under 4 times. I think you could tell the difference between just over 4 rotations and just under 5 rotations just as easily.

 

[panama rubicon]

That is unique.

Thank you

 

[Stan H]

Getting to know my Gladdy. Purchased used last month. Riding on 37's. My reading tells me the gearing needs to be upgraded to minimum 488 from the stock 410's? Previous owner doesn't know anything. What's the best way for me to tell if the gearing was upgraded?

Thank you

There is also the issue of checking the calibration of the new tire size to the speedometer. If it isnt reading correctly compared to GPS speed ie..( I used Google maps and set a course to a close town then took off it will show speed ) then compare. . After a regear this should also have been calibrated . It is possible that neither or just one instance was calibrated make sure the settings are both changed . Tazer or Flashcal + can calibrate these settings for you .

 

[Stan H]

That is unique.

Thank you

It is a good technique but does not work on limited slip rear ends . . Works perfect on a Rubicon cause it has full spider gears ( which is why the Rubicon needs lockers while rock crawling .

 

[XraytecH]

You can check with an OBD Diagnostic tool or a Tazer. But there's always the chance that whoever re-geared it did not re-calibrate.

 

[Gregj]

The most “sure” way is to pull the cover and look at the stamps on the ring gear or count the teeth on the gears and do the math. The gasket is reusable and it’s pretty easy to do.
Gregj

 

[panama rubicon]

There is also the issue of checking the calibration of the new tire size to the speedometer. If it isnt reading correctly compared to GPS speed ie..( I used Google maps and set a course to a close town then took off it will show speed ) then compare. . After a regear this should also have been calibrated . It is possible that neither or just one instance was calibrated make sure the settings are both changed . Tazer or Flashcal + can calibrate these settings for you .

Good mention. Im driving in Panama. I didn't convert the digital on the dash from KM to MPH but I was watching my GPS and it "seemed" to be tracking. I Only took to the highway a couple short runs and didn't dig deep but that's what I deducted, it seemed calibrated. I'm back in USA now, so on my next visit I will continue to learn about the vehicle. Loving it so far!

 

[XraytecH]

The most “sure” way is to pull the cover and look at the stamps on the ring gear or count the teeth on the gears and do the math. The gasket is reusable and it’s pretty easy to do.
Gregj

100%

 

[Wheelin98TJ]

Log your RPM at 70 mph and plug the numbers in the gear ratio formula.

 

[panama rubicon]

When I left the country I put the vehicle in service for the items that were deemed in need of attention when I had it inspected before purchase. I asked them to determine if possible to identify the gearing ratio. The repairs are done. When I asked if they did the gearing check they didn't respond. The language barrier is somewhat challenging, lost in translation on Whatsapp. So I will ask in person when I see them but I am asking this question here in anticipation they did not perform my request.

 

[panama rubicon]

Log your RPM at 70 mph and plug the numbers in the gear ratio formula.

Thanks. Another great idea.

 

[RangerG]

Getting to know my Gladdy. Purchased used last month. Riding on 37's. My reading tells me the gearing needs to be upgraded to minimum 488 from the stock 410's? Previous owner doesn't know anything. What's the best way for me to tell if the gearing was upgraded?

Thank you

skip the 4:88 go to 5:13. That’s what I did

 

[panama rubicon]

skip the 4:88 go to 5:13. That’s what I did

Heck, at this point I'm just trying to identify what I'm running.

Thanks

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