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Unread 07-02-2013, 10:21 AM   #1
StanF
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1995 YJ Wrangler 
 
Join Date: Feb 2013
Location: Austin, Texas
Posts: 1,193
Changed Speedometer Gear...still way off (the other direction!)

Changed to 32" tires (BFG ATs) with my stock 4.10 gears, and using the chart here, determined that I needed a 36 tooth gear:

http://www.quadratec.com/jeep_knowle...article-46.htm

Bought one, installed it, but now my Jeep appears to read about 5mph over the correct speed at 65mph. I verified this by driving next to a friends car, and by timing between mile markers. So my speedometer reads 70 when I'm going 65mph. I checked a few other online speedometer charts, and they all seem to say 36 teeth for my situation.

I was a little disappointed, as at first I thought the speedometer gear was some magically performance upgrade!

Has anyone else seen this issue? If 36 isn't the right number, what would be? I hate to keep buying gears!

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Unread 07-02-2013, 10:29 AM   #2
pasinbuy
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1994 YJ Wrangler 
 
Join Date: Feb 2007
Location: florida
Posts: 3,840
Forget trying to check the mph by driving next to your friend or mile markers.

Borrow a GPS and check your mph that way. Then go up or down as needed.

By the chart 36 is right although remember that not all tires are the same in height and changing tires brand to brand may or will throw off the speedometer a bit.
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Unread 07-02-2013, 12:00 PM   #3
Siva283
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1995 YJ Wrangler 
 
Join Date: May 2011
Location: Falling Waters, WV
Posts: 3,698
Quote:
Originally Posted by pasinbuy View Post
Forget trying to check the mph by driving next to your friend or mile markers.

Borrow a GPS and check your mph that way. Then go up or down as needed.

By the chart 36 is right although remember that not all tires are the same in height and changing tires brand to brand may or will throw off the speedometer a bit.
^^^^This is the best advice you will get. Alot of 33's for instance are actually 32's
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[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

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Ask me how I know...[/QUOTE]

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Unread 07-02-2013, 12:04 PM   #4
rage4order
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1990 YJ Wrangler 
 
Join Date: Jun 2010
Location: San Antonio
Posts: 160
If you have a smartphone, there are speedometer apps, not to mention gps apps.
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