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speedometer Gear?


thorpe991
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so i herd that i could change this to adjust what my speedometer shows as im running 32s soon to be 33s i did a caluculation on my tire size and i am most likely ar8und 67 mph when my speedo is showing 55mph i know you have to know the axel radtio as i have done some research and found that i have a stock rear axal i was wondering what my axal ratio would be and what is the make of our transmissions

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Just get a gps that shows speed and find out how far off you are then follow Hardb0dys? thread on how to adjust. It might work, he wasnt sure whether it would work when changing tire size....

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i seen the vid i dont really want to do that

 

Get a Scan-Gauge II and mount it on your dash. It has the ability to correct for speed errors caused by tire-size changes.

 

Or, you could get new axle gears with a 4.636:1 ratio (tallest available for R50), but that's only 6% different from your stock 4.363:1 gears. With 32" or 33" tires, your speedometer/odometer will still read too slow.

Edited by XPLORx4
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Get a Scan-Gauge II and mount it on your dash. It has the ability to correct for speed errors caused by tire-size changes.

 

Or, you could get new axle gears with a 4.636:1 ratio (tallest available for R50), but that's only 6% different from your stock 4.363:1 gears. With 32" or 33" tires, your speedometer/odometer will still read too slow.

 

How do we know what gearing we have in our rigs? Is it stamped somewhere on the rear end?

 

-Kyle

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Sweet, HG46!!!

 

i think that's good, bigger number means fast acceleration i think? :blush02: The SUV diff numbers confuse me with having to factory in tires and what not,

 

I only know that I installed a 2.73:1 in my buddies E30 to go long distance driving to keep the RPM's down and get better mileage. But normally it has has 3.73:1 LSD, which is way more fun, past that that i don't understand diff gearing, :laugh:

 

 

-Kyle

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Sweet, HG46!!!

 

i think that's good, bigger number means fast acceleration i think? :blush02: The SUV diff numbers confuse me with having to factory in tires and what not,

 

I only know that I installed a 2.73:1 in my buddies E30 to go long distance driving to keep the RPM's down and get better mileage. But normally it has has 3.73:1 LSD, which is way more fun, past that that i don't understand diff gearing, :laugh:

 

 

-Kyle

Basically, Pathfinders have really "low" gearing in relation to just about any other truck at 4.63. Meaning, our engines spin more revolutions per revolution of the rear wheels. For instance, even a power wagon only has 4.56s, while your average ram has 4.10s at the most. Same is true with toyotas- 4.10s are the lowest on the 3rd gen 4runner. Most domestics (jeeps included) run 3.73 or 4.10s at the low end, 3.33 or 3.55 at the god awful high end. Hence, we, as pathfinder owners (first gen Xterras too) are really lucky to have ultra-low gearing. This makes acceleration more brisk, control off road improved, and mpg terrible. Plus it helps make up for the rather tall 2.00 low ratio on our t cases.

 

Hope that helps.

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we, as pathfinder owners (first gen Xterras too) are really lucky to have ultra-low gearing. This makes acceleration more brisk, control off road improved, and mpg terrible. Plus it helps make up for the rather tall 2.00 low ratio on our t cases.

 

Hope that helps.

 

Plus, it allows us to run big tires without having to always drive in 2nd gear!

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So about that. So does that mean when, for example, if I were to go from a 31" to a 33" tire, does that have the effect of gearing it up? Because the tire has a longer circumference, so it will lower engine speed (at Highway speed) but also have to make the engine work harder to get the new, taller wheels moving?

 

Is that right?

 

-Kyle

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So about that. So does that mean when, for example, if I were to go from a 31" to a 33" tire, does that have the effect of gearing it up? Because the tire has a longer circumference, so it will lower engine speed (at Highway speed) but also have to make the engine work harder to get the new, taller wheels moving?

 

Is that right?

 

-Kyle

Yes that is correct. For any given road speed (MPH), the engine will rotate slower (RPM) with larger tires than with smaller tires, which is essentially the same thing as gearing up (having a numerically lower gear ratio).

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Nope,

 

No gears in out pathfinders, the R50's went electronic. But they do make kits that allow you to correct the difference when installing new tires.

 

MADDDD

 

-Kyle

 

My '96 is still mechanical. Isn't yours?

 

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No, I have had my cluster apart and out several times recently and there is no cable running to it. The only "mechanical" part in my speedo gear is the gear itself where it connects to transfer case I believe.. Other than that it's electronic the whole way.

 

I even have an early production date 96. Born in, 11/95

 

-Kyle

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The R50 speedometer is electronic. The instrument cluster receives electrical pulses from the Vehicle Speed Sensor, and the rate of pulsing determines the speedometer needle position.

 

This device might work:

http://www.frsport.com/Dakota-Digital-SGI-5-Universal-Speedometer-Signal-Interface-Controller_p_17569.html

http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/

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No, I have had my cluster apart and out several times recently and there is no cable running to it. The only "mechanical" part in my speedo gear is the gear itself where it connects to transfer case I believe.. Other than that it's electronic the whole way.

 

I even have an early production date 96. Born in, 11/95

 

-Kyle

 

 

The R50 speedometer is electronic. The instrument cluster receives electrical pulses from the Vehicle Speed Sensor, and the rate of pulsing determines the speedometer needle position.

 

Hm, I assumed since the odometer looked mechanical, that it was all mechanical, and that in '97 they switched to electronic odometer/speedometer.

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yeah, i thought it was too before i started experiencing all of my speedometer and tachometer freak out sessions.

 

But, the only change in the cluster from 96 to 97 is printed words saying "service engine soon" rather than the traditional check engine symbol, at least that's all i can find different between my 96 manual trans cluster, and the spare 97, manual trans cluster i have next to me.

 

-Kyle

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yep looks like im going to have to look into the mcm thing as im deff not changing my gears i am running 32s right now and my spedo reads 55 the gps i used yesterday was reading 63-65 :doh: i had to slow down to about 50 to do 55 i dont understand y but at 30 im actully soing 30 then 45 im dong about 47 and 50 im doing 55 then 55 im doing about 63

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The different readings on your speedometer are due to a % difference not a constant (mph) difference. That is, x% of slower speeds is a smaller mph difference than x% of higher speeds. That is why your speedo is closer to actual mph at lower speeds.

 

Calculate the tire size diameter difference from original to current: new tire (size/orig size) - 1 = % difference. Then for any speed, multiply the speed by the % and that is how much to add to the speedometer reading.

 

For example, if the tire size % difference is 10% then:

30mph speedo reading = 33mph actual

55mph = 60.5mph actual

65mph = 71.5 actual

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The different readings on your speedometer are due to a % difference not a constant (mph) difference. That is, x% of slower speeds is a smaller mph difference than x% of higher speeds. That is why your speedo is closer to actual mph at lower speeds.

 

Calculate the tire size diameter difference from original to current: new tire (size/orig size) - 1 = % difference. Then for any speed, multiply the speed by the % and that is how much to add to the speedometer reading.

 

For example, if the tire size % difference is 10% then:

30mph speedo reading = 33mph actual

55mph = 60.5mph actual

65mph = 71.5 actual

this is really help full thank you

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BTW, I ordered a Dakota Digital SGI-5 Universal Speedometer Signal Interface (link on previous page). I read the manual and it looks like it will correct our speedometer inaccuracies. I'll let you know how it goes after I give it a try.

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