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Discussion Starter · #1 ·
Thinking about the speedometer calibration. While searching I found some post about changing the speedo gear. I believe I have the formula for the change.

Current tire size 35" diveded by stock tire size 28.3" equals 1.237
Then take current gear ratio 4.88 divede by 1.237 equals 3.945

That is close to the 3:91 gear ratio on the gear chart. So I need to replace the speedo gear with one for the 3:91 equiped trucks. That should get my speedometer close to where it should be. This is my understanding according to an old post by Nuke. Can someone confirm this, or did I miss something? Just want to make sure I understand this correctly. It has been out of calibration for years now, but I thought I would fix it. BTW, it is a 1996 2.7l regular cab with manual transmission. Here is the old thread:

http://www.tacomaterritory.com/forum/showthread.php?t=10027&highlight=speedometer
 

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Discussion Starter · #4 ·
Paul
Thanks. Maybe Hytenor will chime in. I am confused about how the gear change plays into the equation. Not sure if the formula only works with the original gears. If so, probably another step in the equation to account for the gear swap.
 

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Discussion Starter · #8 ·
Hytenor
Just an update. Put in the 33 tooth gear today. It looks like it is going to be pretty accurate. Definetly better than before, and good enough for me. Followed my father-in-law up the road today, and our speedometers were reading about the same. I will check it out better this week because we were only going about 35 mph. BTW, it is a 1996 2.7 with manual transmission. Thanks for the link. I also found some more post after doing a search over the whole forum instead of just the Performance/Engine/Exhaust section. Just something to keep in mind for those who don't find what they are looking for in the section they think it should be in.
 

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Going John Galt
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Hytenor
Just an update. Put in the 33 tooth gear today. It looks like it is going to be pretty accurate. Definetly better than before, and good enough for me. Followed my father-in-law up the road today, and our speedometers were reading about the same. I will check it out better this week because we were only going about 35 mph. BTW, it is a 1996 2.7 with manual transmission. Thanks for the link. I also found some more post after doing a search over the whole forum instead of just the Performance/Engine/Exhaust section. Just something to keep in mind for those who don't find what they are looking for in the section they think it should be in.
I have the same gear/tire size combo at the moment and with a 33t gear I run about 1mph below actual at 70...when I can get it up to 70, LOL

5.29s should be in soon.
 

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I have the same gear/tire size combo at the moment and with a 33t gear I run about 1mph below actual at 70...when I can get it up to 70, LOL

5.29s should be in soon.
Then you'll have to go with a digital speedo correction, no? I'm at a 33T with 31's and 4.30's and I'm right on... but when I put on my 33's and 4.88's I'm pretty sure I will be out of the stock calibration range.
 

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Then you'll have to go with a digital speedo correction, no? I'm at a 33T with 31's and 4.30's and I'm right on... but when I put on my 33's and 4.88's I'm pretty sure I will be out of the stock calibration range.
I'll probably just leave it as is. I lived with it being 2-3% off (what you will wind up with) for so long that going back to that won't be a big deal ;)

interesting that the 33t got you right on...stock speedo gear is a 32 for the 2.7/5sp with 265s.

but, from the factory, they can be up to 5% off either up or down :rolleyes:

The Dakota is only $70 with fairly easy install so I might finally get one...don't know.
 
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