Speedo 8-9 mph off

[JoeV21]

I'm new to the Jeep community and this Forum. I bought this 97 wrangler sport with the 3 speed auto in it.... I know gross an auto.

My main concern is my ODO and Speedo is off, it's about a 8-9mph difference. My my Speedo says 60 I'm really going 68-69. I have already installed a 31 tooth Speedo gear bc there is BFG 32x11.5 on my jeep. Should I jump to instal a 34 tooth? The VSS is clocked in the correct positon for my 31 short gear

Any other advice would be greatly appreciated

 

[Chris]

Is this the chart you're going off of?

 

[TheBoogieman]

Do you have stock 3.07, 3.55, or 3.73 gears?

 

[JoeV21]

Do you have stock 3.07, 3.55, or 3.73 gears?

Do you have stock 3.07, 3.55, or 3.73 gears?

That's the thing I don’t know, I try to run the VIN build sheet but it's confusing for me lol. I thought I had 3.07 so I put in a 30 tooth, didn't do anything, threw in a 31 tooth to see maybe I had a 3.55 but it's still way off. I know I can count the drive shaft rotations. But I'm being lazy. But that's probably the smart option

 

[JoeV21]

Is this the chart you're going off of?

View attachment 672841

No it's not a chart I'm going off of, I actually wasn't aware of their being a chart

 

[macleanflood]

But that's probably the smart option

You can pull the diff cover...

Also there is listed tire size vs actual tire size.

-Mac

 

[TheBoogieman]

That's the thing I don’t know, I try to run the VIN build sheet but it's confusing for me lol. I thought I had 3.07 so I put in a 30 tooth, didn't do anything, threw in a 31 tooth to see maybe I had a 3.55 but it's still way off. I know I can count the drive shaft rotations. But I'm being lazy. But that's probably the smart option

There should be a tag on the rear diff stating the gear ratio.

 

[TheBoogieman]

I try to run the VIN build sheet but it's confusing for me

The instant build sheet site doesn't work for a 1997.

https://fcagroup.my.site.com/RAM/s/equipment-listing

 

[JoeV21]

There should be a tag on the rear diff stating the gear ratio.
View attachment 672862

I have to see if that tag is still on, I remember I changed the diff fluid, and I don’t remember if I put that tag back on

 

[Ashim]

I'm new to the Jeep community and this Forum. I bought this 97 wrangler sport with the 3 speed auto in it.... I know gross an auto.

My main concern is my ODO and Speedo is off, it's about a 8-9mph difference. My my Speedo says 60 I'm really going 68-69. I have already installed a 31 tooth Speedo gear bc there is BFG 32x11.5 on my jeep. Should I jump to instal a 34 tooth? The VSS is clocked in the correct positon for my 31 short gear

Any other advice would be greatly appreciated

As tire size gets bigger, the tooth number of the speedometer gear needs to decrease. I'm guessing you have 3.07 gears and you need a 26 or 27 tooth gear.