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Discussion Starter · #1 ·
i need a new speedo gear, my t-case finally went and took my speedo gear with it. got a new t-case but still need a gear. 4 banger 5 sp.

my stock gear was a 28 tooth and i had 3.58 and 31's and it was dead on. now i have 33's and 4.88's and it read 15 - 16 mph fast at 60. what gear would i need to get me close? im also thinkin bout getting larger tires in the near future, probly 35 or 37's and i will also want to be close with that. i know i cant have it all right but would like to get an idea on how to figure it out. also do all the gears interchange? i have a cable driven speedo so will the newer electric speedo gears fit it? thanks
 

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jhorn_007 said:
i need a new speedo gear, my t-case finally went and took my speedo gear with it. got a new t-case but still need a gear. 4 banger 5 sp.

my stock gear was a 28 tooth and i had 3.58 and 31's and it was dead on. now i have 33's and 4.88's and it read 15 - 16 mph fast at 60. what gear would i need to get me close? im also thinkin bout getting larger tires in the near future, probly 35 or 37's and i will also want to be close with that. i know i cant have it all right but would like to get an idea on how to figure it out. also do all the gears interchange? i have a cable driven speedo so will the newer electric speedo gears fit it? thanks
the best you can do is a 33t gear pt# 33403-39415. this will get you closer but not that great. But I'm a little confused. You say you had 3.58s stock along with the stock 28t gear. those gears came with 28" tires (225s) and unless your speedo was way the heck off from the factory you couldn't have been "dead on" with 31s.
 

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Discussion Starter · #3 ·
hytenor said:
the best you can do is a 33t gear pt# 33403-39415. this will get you closer but not that great. But I'm a little confused. You say you had 3.58s stock along with the stock 28t gear. those gears came with 28" tires (225s) and unless your speedo was way the heck off from the factory you couldn't have been "dead on" with 31s.
yea u are right... the door sticker says either 225 or 235 tires, not totally sure. it had 31's on it when i got it and speedo was right according to 2 different gps's and the speed check signs the road dept. sets beside the highways. so i'd say it must have been pretty bad off. i know 33 tooth is the biggest one, but u dont think it will take me way farther than i wanna go do ya? any idea on average how many mph difference each tooth extra will bring it down? i am right in saying that the more teeth it has the less the speedo will read correct? it reads ~15 mph faster than actual.
 

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jhorn_007 said:
yea u are right... the door sticker says either 225 or 235 tires, not totally sure. it had 31's on it when i got it and speedo was right according to 2 different gps's and the speed check signs the road dept. sets beside the highways. so i'd say it must have been pretty bad off. i know 33 tooth is the biggest one, but u dont think it will take me way farther than i wanna go do ya? any idea on average how many mph difference each tooth extra will bring it down? i am right in saying that the more teeth it has the less the speedo will read correct? it reads ~15 mph faster than actual.
each tooth is good for a little more than 3% error correction. If you are actually running 60 and reading 75 you are 20% off so you would need 6 more teeth than you have now.

are you sure you had 3.58s? did you check them when you regeared?
did your speedo gear have "28-11" stamped on it?

did you get the truck used? 2.7s with 3.58s got either 225 or 205 size tires. 3.91/4.10s came with 235s but they were often replaced with 265s to make them all look like the newer trucks with lower gears. 4.30s/4.56s came out in '00 with 265s. this is in general and not absolute.

ya got me :rolleyes:
 

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Discussion Starter · #5 ·
hytenor said:
each tooth is good for a little more than 3% error correction. If you are actually running 60 and reading 75 you are 20% off so you would need 6 more teeth than you have now.

are you sure you had 3.58s? did you check them when you regeared?
did your speedo gear have "28-11" stamped on it?

did you get the truck used? 2.7s with 3.58s got either 225 or 205 size tires. 3.91/4.10s came with 235s but they were often replaced with 265s to make them all look like the newer trucks with lower gears. 4.30s/4.56s came out in '00 with 265s. this is in general and not absolute.

ya got me :rolleyes:
thanks for clarifying the tooth thing.
yes, definite of 3.58's
yepp had 28-11 stamped and i also counted teeth to make sure thats what it meant
and yea got it used, had 31's on it when i got it, but door sticker had probly 225's. according to door jam sticker. its not here right now as i busted the rear end and have to get new r&p but i know it said either 225 or 235, probly 225 though cuz u seem to know u'r gears and such pretty well.
 

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jhorn_007 said:
thanks for clarifying the tooth thing.
yes, definite of 3.58's
yepp had 28-11 stamped and i also counted teeth to make sure thats what it meant
and yea got it used, had 31's on it when i got it, but door sticker had probly 225's. according to door jam sticker. its not here right now as i busted the rear end and have to get new r&p but i know it said either 225 or 235, probly 225 though cuz u seem to know u'r gears and such pretty well.
dang, then that speedo was WAY off from the factory, LOL

the only way to get perfectly accurate is to instal the Dakota Digital for around $70. the speedo gears are only $20 shipped from Chris & Barb but it's hit or miss as to accuracy.
 

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Discussion Starter · #7 ·
hytenor said:
dang, then that speedo was WAY off from the factory, LOL

the only way to get perfectly accurate is to instal the Dakota Digital for around $70. the speedo gears are only $20 shipped from Chris & Barb but it's hit or miss as to accuracy.
u know i would love to install the dakota digital... lol but as i specified in the first post its a cable driven speedo. :D im assuming the gears should still work on mine though.
 

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jhorn_007 said:
u know i would love to install the dakota digital... lol but as i specified in the first post its a cable driven speedo. :D im assuming the gears should still work on mine though.
yes the gear will work but you will have to carefully remove the plastic portion from each one and swap the new one onto your metal shaft. (or so I've been told) :D
 

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Discussion Starter · #9 ·
hytenor said:
yes the gear will work but you will have to carefully remove the plastic portion from each one and swap the new one onto your metal shaft. (or so I've been told) :D
cool, thanks a Lot for all your help.
 
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