How do I determine my axle gear ratio?

tr21triton · Dec 4, 2023

NashvilleTJ said:
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.

I never found the need to change gears ! I know if i'm off 10% to add 2 to 20mph, 5 to 50mph and 7 to 70mph ! my brother ain't that smart and needed a speedo-healer

I mean it doesn't take a rocket scientist to know if your showing 50 your actual speed is 55

tr21triton · Dec 4, 2023

NashvilleTJ said:
Nice. I’m a go-fast boat guy from way back. Those Tritons are rocket ships

that was one of Earl's earlier ones, i think it was his 2nd year in business. I went to see it being built in Marysville Tenn I think it was . The one I test drove scared the shit out of me and I said I have to have one !!!!

John Cooper · Dec 4, 2023

tr21triton said:
25 years old and she'll still do over 80MPH !
View attachment 479649

That's because he is pulling it with his pickup truck!!!

Boat probably hasn't seen water in 20 years

Jerry Bransford · Dec 4, 2023

Hal Mc said:
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.

Unless a previous owner removed it there's an axle tag bolted onto the differential cover at its 9 o'clock position. Your TJ very likely has a 3.73, that's what the factory installed with the 42RLE automatic.

The below shows that tag, it indicates a 3.73 is inside the axle.

inkedrose · Dec 4, 2023

@Hal Mc the "gizmo" they are talking about is called a speedo healer. 15 minute job and can be changed as many times as needed if you change tires, gearing, ect... For me it was money well spent.

https://www.polyperformance.com/hea...QVP84jXDrltQ1QsrB6Fsxw2o-42lJu6RoCgB4QAvD_BwE

Hal Mc · Dec 5, 2023

inkedrose said:
@Hal Mc the "gizmo" they are talking about is called a speedo healer. 15 minute job and can be changed as many times as needed if you change tires, gearing, ect... For me it was money well spent.

https://www.polyperformance.com/hea...QVP84jXDrltQ1QsrB6Fsxw2o-42lJu6RoCgB4QAvD_BwE

Thanks man

Hal Mc · Dec 5, 2023

P man said:
Crawl under the jeep and look for a Tag on 2 of the diff cover bolts and report back

Thanks, will do. Its in the shop now getting aligned

TheBoogieman · Dec 5, 2023

tr21triton said:
I never found the need to change gears ! I know if i'm off 10% to add 2 to 20mph, 5 to 50mph and 7 to 70mph ! my brother ain't that smart and needed a speedo-healer I mean it doesn't take a rocket scientist to know if your showing 50 your actual speed is 55

I'm the same way. I replaced the speedo gear on my first TJ and from then on, I knew how far off my speedo was and never did it again. I haven't driven the speed limit in 30 years. When I get pulled over now, I claim "I just bought this Jeep with Big Knobby tires". I swear my speedometer said 55. It only works for my wife with DD's.

Cops are bad.

Hal Mc · Dec 5, 2023

I got what I needed. Thanks guys

inkedrose · Dec 5, 2023

tr21triton said:
I never found the need to change gears ! I know if i'm off 10% to add 2 to 20mph, 5 to 50mph and 7 to 70mph ! my brother ain't that smart and needed a speedo-healer I mean it doesn't take a rocket scientist to know if your showing 50 your actual speed is 55

My Jeep only had 35k miles on when I got it. With gears and tires it was running up milage faster than I was actually driving. $160 to keep milage lower was worth it for me. If it was showing lower miles I would have left it lol

Search

Search

How do I determine my axle gear ratio?

tr21triton

TJ Expert

tr21triton

TJ Expert

John Cooper

Twilight Zone

Jerry Bransford

No Longer Participating

inkedrose

washed up superhero

Hal Mc

New Member

Hal Mc

New Member

TheBoogieman

TJ Guru

Hal Mc

New Member

inkedrose

washed up superhero

Similar threads