Hey guys,

I have a 2006 Dakota Sport with a 3.55 rear end. I want to swap out the gears for a 3.92. Do I have to get the speedo calibrated?

Any help would be appreciated.

 

yes if you want it to read right and if it's a 4x4 you have to do the front as well. just an fyi it's not as easy as just swaping gears out there is a lot of setup work required, grear mesh paterning, backlash and preload ect.... if you have never done this don't try you need dial indicators ect... I've done it on old ford 9" diffs and it takes some know how. a shop will charge 300+ for this not incl. parts also note that your mpg will be lower.

 

I had the exact gear swap done on my truck. It will cost you around 400-500 at a shop, thats including gears. You will see around a 1-2 MPG drop on the highway, but about the same increase in MPG in the city, along with a feel of increased torque. I would say that this is a good upgrade for the price. I have not had my speedo callibrated yet. At 35-40 MPH you will only be going about 2-3 MPH faster......around 65-70 you will be going about 5-6 MPH faster. If you can remember that or don't care about speeding a little, then you don't need it. A .5 increase in gear ratio is what is recommended to feel the difference, so going to 3.92 is a good increase, if you were to already have the 3.92, then skip the 4.10 and go to 4.56. I think I covered everything.

 

Bigger tires would nearly calibrate it for you. You can use tables and calculatorsto find an ideal size that are listed on this site: http://www.4lo.com/calc/geartable.htm

Just depends on how much room you have to work with.

 

Wow, you guys know yours stuff!! Thanks for the info. However, I'm inCanada here and a local shop quoted me $388CDN for the parts, plus 6-8 hrs labour at $106.00/hr!!! Thats almost $1300 !! Am i getting hosed?

 

yes you are getting hosed.

 

my complete swap was 1600.00 for my 4x4 went from 3.55 to the 4.10. dont just do a swap. get the whole kit. i received, gears. axle seal, bearing kit, oil, plus labor. and it is worth the money.

 

It depends on the exchange rate for Can-US $ if you are getting hosed.

Did I miss something...I thought our speedo pickup was on the rear gear (vs the old style trans pickup), which would rotate at a constant no matter what the ratio of the pinion.This would mean that you should not have to recalibrate it. Should only have to recalibrate if changing tire size. I know I saw a picture of this on here somewhere.

You should see an increase in operating RPM for the same speed

 

Your right about the speedo and the RPM. I got me some bigger tires too! And the RPM increase on mine was only a little less than 200. Not bad.

 

I don't think it has anything to do with the exchange rate. Our dollars are dollar for dollar now, but who knows. What I got quoted for was the whole kit, including seals and brgs, Superdak. So, you went to 4.10, eh? I wonder if there is a big difference between 3.92 and 4.10...