Speedometer gear shaft
 

After having 31" tires on my 97 TJ for five years, I finally got around
to putting in the correct speedo gear. Or so I thought. I have 3.07
gears so I need a 27 tooth gear. The problem is that Chrysler doesn't
make a 27 tooth gear with the correct shaft length. It looks like my
only option is the heat gun route. Does anyone have some suggestions on
removing the gear from the wrong shaft and putting it back together on
the right shaft without royally screwing things up? I'll probably use
some epoxy or super glue for extra holding power since I'm not sure how
well it would stay together on its own after having been heated.

Re: Speedometer gear shaft
 

One important piece of information which is required is the number of
revolutions it takes your speedometer to register one mile. On most modern
cars, this may be found on the bottom (or elsewhere) of the speedometer
face, usually in very small numbers. Look for something like 940, 960, 1000,
or 1020, or something close. This number is the number of speedometer cable
revolutions (or equivalent in the case of electronic sender units) to
increment the odometer one mile. Most speedometers (modern ones) are 1000
revs/mile, and this is a good starting number to use.

Another vital piece of info is the speedometer drive/driven gear ratios, the
gears inside of the transmission or transaxle. The drive gear is the one
which is turned by engine power, usually mounted right on the transmission
output shaft. The driven gear is the one which is "driven" by the "drive"
gear, and is connected to the speedometer cable or electronic sender. The
numbers entered in the program are the integer number of teeth - just count
'em up.

For example:

rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
(count them on your TJ) will result in a 30 tooth 'driven' gear.

Running the equation backwards keeping everything else the same and using a
#27 gear you would have 35" tires.

You can also calculate using drive shaft revolutions/mile (assuming 1:1),
axle ratio and tire size.

There are additional formula to use, how did you arrive at 27?

Have you contacted an 'actual' speedometer shop? There should be at least
one in any fair sized city. If necessary you can contact one via
phone/fax/e-mail.
--
..
Billy_Ray@SPAM.fuse.net (remove SPAM)
2002 Jeep WJ 4 Liter Automatic
Sharing is why we are all here....... or should be.
..
"Stewie" <CWise1978@aol.com> wrote in message
news:1127780940.605141.260130@g47g2000cwa.googlegr oups.com...
> After having 31" tires on my 97 TJ for five years, I finally got around
> to putting in the correct speedo gear. Or so I thought. I have 3.07
> gears so I need a 27 tooth gear. The problem is that Chrysler doesn't
> make a 27 tooth gear with the correct shaft length. It looks like my
> only option is the heat gun route. Does anyone have some suggestions on
> removing the gear from the wrong shaft and putting it back together on
> the right shaft without royally screwing things up? I'll probably use
> some epoxy or super glue for extra holding power since I'm not sure how
> well it would stay together on its own after having been heated.
>

Re: Speedometer gear shaft
 

One important piece of information which is required is the number of
revolutions it takes your speedometer to register one mile. On most modern
cars, this may be found on the bottom (or elsewhere) of the speedometer
face, usually in very small numbers. Look for something like 940, 960, 1000,
or 1020, or something close. This number is the number of speedometer cable
revolutions (or equivalent in the case of electronic sender units) to
increment the odometer one mile. Most speedometers (modern ones) are 1000
revs/mile, and this is a good starting number to use.

Another vital piece of info is the speedometer drive/driven gear ratios, the
gears inside of the transmission or transaxle. The drive gear is the one
which is turned by engine power, usually mounted right on the transmission
output shaft. The driven gear is the one which is "driven" by the "drive"
gear, and is connected to the speedometer cable or electronic sender. The
numbers entered in the program are the integer number of teeth - just count
'em up.

For example:

rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
(count them on your TJ) will result in a 30 tooth 'driven' gear.

Running the equation backwards keeping everything else the same and using a
#27 gear you would have 35" tires.

You can also calculate using drive shaft revolutions/mile (assuming 1:1),
axle ratio and tire size.

There are additional formula to use, how did you arrive at 27?

Have you contacted an 'actual' speedometer shop? There should be at least
one in any fair sized city. If necessary you can contact one via
phone/fax/e-mail.
--
..
Billy_Ray@SPAM.fuse.net (remove SPAM)
2002 Jeep WJ 4 Liter Automatic
Sharing is why we are all here....... or should be.
..
"Stewie" <CWise1978@aol.com> wrote in message
news:1127780940.605141.260130@g47g2000cwa.googlegr oups.com...
> After having 31" tires on my 97 TJ for five years, I finally got around
> to putting in the correct speedo gear. Or so I thought. I have 3.07
> gears so I need a 27 tooth gear. The problem is that Chrysler doesn't
> make a 27 tooth gear with the correct shaft length. It looks like my
> only option is the heat gun route. Does anyone have some suggestions on
> removing the gear from the wrong shaft and putting it back together on
> the right shaft without royally screwing things up? I'll probably use
> some epoxy or super glue for extra holding power since I'm not sure how
> well it would stay together on its own after having been heated.
>

Re: Speedometer gear shaft
 

One important piece of information which is required is the number of
revolutions it takes your speedometer to register one mile. On most modern
cars, this may be found on the bottom (or elsewhere) of the speedometer
face, usually in very small numbers. Look for something like 940, 960, 1000,
or 1020, or something close. This number is the number of speedometer cable
revolutions (or equivalent in the case of electronic sender units) to
increment the odometer one mile. Most speedometers (modern ones) are 1000
revs/mile, and this is a good starting number to use.

Another vital piece of info is the speedometer drive/driven gear ratios, the
gears inside of the transmission or transaxle. The drive gear is the one
which is turned by engine power, usually mounted right on the transmission
output shaft. The driven gear is the one which is "driven" by the "drive"
gear, and is connected to the speedometer cable or electronic sender. The
numbers entered in the program are the integer number of teeth - just count
'em up.

For example:

rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
(count them on your TJ) will result in a 30 tooth 'driven' gear.

Running the equation backwards keeping everything else the same and using a
#27 gear you would have 35" tires.

You can also calculate using drive shaft revolutions/mile (assuming 1:1),
axle ratio and tire size.

There are additional formula to use, how did you arrive at 27?

Have you contacted an 'actual' speedometer shop? There should be at least
one in any fair sized city. If necessary you can contact one via
phone/fax/e-mail.
--
..
Billy_Ray@SPAM.fuse.net (remove SPAM)
2002 Jeep WJ 4 Liter Automatic
Sharing is why we are all here....... or should be.
..
"Stewie" <CWise1978@aol.com> wrote in message
news:1127780940.605141.260130@g47g2000cwa.googlegr oups.com...
> After having 31" tires on my 97 TJ for five years, I finally got around
> to putting in the correct speedo gear. Or so I thought. I have 3.07
> gears so I need a 27 tooth gear. The problem is that Chrysler doesn't
> make a 27 tooth gear with the correct shaft length. It looks like my
> only option is the heat gun route. Does anyone have some suggestions on
> removing the gear from the wrong shaft and putting it back together on
> the right shaft without royally screwing things up? I'll probably use
> some epoxy or super glue for extra holding power since I'm not sure how
> well it would stay together on its own after having been heated.
>

Re: Speedometer gear shaft
 

I've run 31's with 3.07 and never got pulled over for speeding, I think the
cops may generally give you a 5 mph window or something, around here
anyways.

Troy

Re: Speedometer gear shaft
 

I've run 31's with 3.07 and never got pulled over for speeding, I think the
cops may generally give you a 5 mph window or something, around here
anyways.

Troy

Re: Speedometer gear shaft
 

I've run 31's with 3.07 and never got pulled over for speeding, I think the
cops may generally give you a 5 mph window or something, around here
anyways.

Troy

Re: Speedometer gear shaft
 

According to these websites and some other postings I've seen by people
with my same setup, I need a 27 tooth gear.

http://www.sierrajeep.com/speedome.htm
http://go.jeep-xj.info/HowtoSpeedoGears.htm

and the equation (NewGear*NewTire=OldGear*OldTire) solving for new
gear. This came from http://www.jeeptech.com/javaAps/Speedo.html

I'll check out the numbers on my speedo and try your equation, too.


Billy Ray wrote:
> One important piece of information which is required is the number of
> revolutions it takes your speedometer to register one mile. On most modern
> cars, this may be found on the bottom (or elsewhere) of the speedometer
> face, usually in very small numbers. Look for something like 940, 960, 1000,
> or 1020, or something close. This number is the number of speedometer cable
> revolutions (or equivalent in the case of electronic sender units) to
> increment the odometer one mile. Most speedometers (modern ones) are 1000
> revs/mile, and this is a good starting number to use.
>
> Another vital piece of info is the speedometer drive/driven gear ratios, the
> gears inside of the transmission or transaxle. The drive gear is the one
> which is turned by engine power, usually mounted right on the transmission
> output shaft. The driven gear is the one which is "driven" by the "drive"
> gear, and is connected to the speedometer cable or electronic sender. The
> numbers entered in the program are the integer number of teeth - just count
> 'em up.
>
> For example:
>
> rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
> (count them on your TJ) will result in a 30 tooth 'driven' gear.
>
> Running the equation backwards keeping everything else the same and using a
> #27 gear you would have 35" tires.
>
> You can also calculate using drive shaft revolutions/mile (assuming 1:1),
> axle ratio and tire size.
>
> There are additional formula to use, how did you arrive at 27?
>
> Have you contacted an 'actual' speedometer shop? There should be at least
> one in any fair sized city. If necessary you can contact one via
> phone/fax/e-mail.
> --
> .
> Billy_Ray@SPAM.fuse.net (remove SPAM)
> 2002 Jeep WJ 4 Liter Automatic
> Sharing is why we are all here....... or should be.

Re: Speedometer gear shaft
 

According to these websites and some other postings I've seen by people
with my same setup, I need a 27 tooth gear.

http://www.sierrajeep.com/speedome.htm
http://go.jeep-xj.info/HowtoSpeedoGears.htm

and the equation (NewGear*NewTire=OldGear*OldTire) solving for new
gear. This came from http://www.jeeptech.com/javaAps/Speedo.html

I'll check out the numbers on my speedo and try your equation, too.


Billy Ray wrote:
> One important piece of information which is required is the number of
> revolutions it takes your speedometer to register one mile. On most modern
> cars, this may be found on the bottom (or elsewhere) of the speedometer
> face, usually in very small numbers. Look for something like 940, 960, 1000,
> or 1020, or something close. This number is the number of speedometer cable
> revolutions (or equivalent in the case of electronic sender units) to
> increment the odometer one mile. Most speedometers (modern ones) are 1000
> revs/mile, and this is a good starting number to use.
>
> Another vital piece of info is the speedometer drive/driven gear ratios, the
> gears inside of the transmission or transaxle. The drive gear is the one
> which is turned by engine power, usually mounted right on the transmission
> output shaft. The driven gear is the one which is "driven" by the "drive"
> gear, and is connected to the speedometer cable or electronic sender. The
> numbers entered in the program are the integer number of teeth - just count
> 'em up.
>
> For example:
>
> rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
> (count them on your TJ) will result in a 30 tooth 'driven' gear.
>
> Running the equation backwards keeping everything else the same and using a
> #27 gear you would have 35" tires.
>
> You can also calculate using drive shaft revolutions/mile (assuming 1:1),
> axle ratio and tire size.
>
> There are additional formula to use, how did you arrive at 27?
>
> Have you contacted an 'actual' speedometer shop? There should be at least
> one in any fair sized city. If necessary you can contact one via
> phone/fax/e-mail.
> --
> .
> Billy_Ray@SPAM.fuse.net (remove SPAM)
> 2002 Jeep WJ 4 Liter Automatic
> Sharing is why we are all here....... or should be.

Re: Speedometer gear shaft
 

According to these websites and some other postings I've seen by people
with my same setup, I need a 27 tooth gear.

http://www.sierrajeep.com/speedome.htm
http://go.jeep-xj.info/HowtoSpeedoGears.htm

and the equation (NewGear*NewTire=OldGear*OldTire) solving for new
gear. This came from http://www.jeeptech.com/javaAps/Speedo.html

I'll check out the numbers on my speedo and try your equation, too.


Billy Ray wrote:
> One important piece of information which is required is the number of
> revolutions it takes your speedometer to register one mile. On most modern
> cars, this may be found on the bottom (or elsewhere) of the speedometer
> face, usually in very small numbers. Look for something like 940, 960, 1000,
> or 1020, or something close. This number is the number of speedometer cable
> revolutions (or equivalent in the case of electronic sender units) to
> increment the odometer one mile. Most speedometers (modern ones) are 1000
> revs/mile, and this is a good starting number to use.
>
> Another vital piece of info is the speedometer drive/driven gear ratios, the
> gears inside of the transmission or transaxle. The drive gear is the one
> which is turned by engine power, usually mounted right on the transmission
> output shaft. The driven gear is the one which is "driven" by the "drive"
> gear, and is connected to the speedometer cable or electronic sender. The
> numbers entered in the program are the integer number of teeth - just count
> 'em up.
>
> For example:
>
> rev/mile: 1000, tire diameter 31", differential: 3.07, drive teeth: 15
> (count them on your TJ) will result in a 30 tooth 'driven' gear.
>
> Running the equation backwards keeping everything else the same and using a
> #27 gear you would have 35" tires.
>
> You can also calculate using drive shaft revolutions/mile (assuming 1:1),
> axle ratio and tire size.
>
> There are additional formula to use, how did you arrive at 27?
>
> Have you contacted an 'actual' speedometer shop? There should be at least
> one in any fair sized city. If necessary you can contact one via
> phone/fax/e-mail.
> --
> .
> Billy_Ray@SPAM.fuse.net (remove SPAM)
> 2002 Jeep WJ 4 Liter Automatic
> Sharing is why we are all here....... or should be.