I need to change the speedometer gear on my 2004 Jeep Wrangler TJ with 6 cyl, auto, but I don't know my differential ratio. I put 32.1" 255x70x18 Goodyear Wranglers on it and the speedometer is about 54-55 mph on the speedometer, compared to 60 mph on my GPS.
How do I determine my axle gear ratio?
- Thread starter Hal Mc
- Start date
Crawl under the jeep and look for a Tag on 2 of the diff cover bolts and report back
if they haven't been changed you can go here and get your build sheet and it will tell you'
https://wranglertjforum.com/threads/where-can-i-find-my-factory-tj-build-sheet.74944/
https://wranglertjforum.com/threads/where-can-i-find-my-factory-tj-build-sheet.74944/
Just drive a little slower like I do. I didn't change the speedo gear on my Rubicon with 35s. ( only Rubicon owners get that) Cops and Judges love my ignorance when I go to court.
If tr21triton would change his screen name to something easier to remember, I'd quote him more.
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What does your screen name mean? It bothers me more than personalized license plates that I can't figure out. Thank God I'm clear.
It's the perfect plate for boogie since he's definitely a lost cause.
You don’t need to know your gear ratio to correct the speedo. What you need to know is the tooth count on the current speedo drive gear. Pull it and take a look - the plastic gear will be marked with the tooth count.
You need to speed up the rotation of the speedo gear by about 5% to correct your speedo, so you need a new speedo gear with about 5% fewer teeth.
(Someone check me here, but this should be correct)
Edit for the OP: Bad info here. Not 5%. Either 9% for 55 mph or 11% for 54 mph.
Thanks for the correction,Triton.
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Does 04 use a gear? I thought they were a hall effect sensor that needs one of the speed correction electronic gizmos
I mistakenly typed 5 (the mph change) instead of 9%. Thanks for the correction.
But it’s 9%, not 10%. The speedo is showing 55, and needs to increase by 5 mph indicated. 5/55=9%. Does that sound correct?
But if it is off by 6 mph, it’s 10.9%. Depends which of the OPs numbers you use.
Any TJ with a 241 transfer case needs to use the gizmo.
close enough it's somewhere between 9-10 because he said 54-55 at 60 corrected.
OP indicated he had a speedo gear, so I assumed a non-Rubicon 231.
Thanks,i assumed it was a later model change,not 231-241.
To the O.P.- be aware the gear needs to go back in the correct orientation for the tooth count it has. The housing has tooth counts on it for proper setup
Yup. Really depends on how close you can get to the tooth count you need. I must have 4 or 5 of those gears from driveline changes over the years.
Any TJ can use the gizmo to intercept the speedo signal from the transfer case. It's just easier and cheaper on a 231 to change the gear.
Nice. I’m a go-fast boat guy from way back. Those Tritons are rocket ships
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