d0dg301

Was at the dealer the other day having some fluids changed and asked them if they could recalibrate my speedo to match my 35 in. BFG's. They told me that they could not do it. Now they say they are a 5 star dealer. You would think that they should be able to handle almost anything.
My question is don't other dealers perform this task?

crobtex

The dealers around here do it. One wants $80, the other $41.

BigBlue

You have to tell them how to do it and what the revs/mile is for your tires. Mine did it for free cause he was curious if he could do it.

phox_mulder

That's a great idea.

Go back to the Dealer and tell the service dept manager you'll show the techs how to do it.
No charge for you of course, but if you let him know he'll be able to charge upwards of 50 bucks for future customers wanting this service,
I'm sure he'll be more than happy to let you play the teacher for 15 minutes or so.


phox

BigBlue

Mine still does it for free.

chucktownsend5

So how do you do it?

d0dg301

Well when I asked the guy at the counter about it he told me that the tech is not capable of the task. I am not sure if the dealer does not have the right equipment or what? Talked to a guy at work who uses a dealer just south of me and says that his dealer will do it for about 40$. Guess I'll have to trade dealers.

sjester

On my 98 12 valve the dealer was able to adjust the speedo for 255-85s through the computer by going to the rear end section and changing the number of teeth. We tried to change by going to the tire section but on the 98 there was not a circumference that was big enough. I was able to get it done for free and we had to go up and down on teeth until the speedo and my GPS matched up.

J BODY

DC does not train us on how to correct modified trucks. There is no section in the service manual to guide anyone on making a speedo correct with non stock tires. You call tech line and you fall on deaf ears as soon as they hear "non stock". The procedure for adjusting this has changed from year to year. According to an instructor years back Dodge had every intention on having a ways and means to easily adjust the speedo using a wide variety of tire sizes but the EPA put a stop to this. To the govt changing tire size is technically changing the emissions of the truck and in this day and age is against the law. That is also why in the abs module when you go to the menu to change there are only stock equippment tires to choose from. Also the rev's per mile selection start and stop in the same sizing as the stock tires. Sometimes when you max it out it will bring the numbers in close enough. There was also a reference to "tone wheel teeth". Some years you by pass the tire sizing and it refers you to the number of tone wheel teeth. Different axles will have different tone rings thus the number selection. I have had parts check on the tone ring teeth number and though the parts catalog shows the rings, there is nothing refering to how many teeth they actually have. Maybe by changing the number this was there way to "sneak" around the guidelines set by the epa, who knows. I'm just not sure if I'm comfortable with changing an input to the anti lock brake system to make a speedo read what someone wants. I certainly wouldn't want a work order showing a modification to the abs system.

d0dg301

Yes, I agree with that. I would not want to make any mods to ABS system. I have heard that you can replace a gear mechanism on the tranny which will correct this problem. I will have to check it out and let everyone know.

Whitmore

I know there is a way to calibrate the speedo for larger diameter tires but there is limitations to it, Its only a few percent then it is maxed out, My tires are 35.2" diameter and I had to buy a truspeed calibrator and tap a wire from the abs module in order to get my speedo correct.........got it from Rickson tire, also there is a switch on the box that will allow me to calibrate for 2 different sets of tires.

Cheers, Kevin

diesel_kid

I found something called a JET Accuspeed Caliburation module from Summit. It is a bit pricey at $150, but it recalibrates everything for bigger or smaller tires. What interests me is that you can use it over and over again. I didnt think there was a computer on our 12 Valves to adjust but it says for 1992-2003 Rams. The part number is JET-50110. It would be nice if your like me and change tires for winter and summer.

-Jared

CTD NUT

Kid: The speedo on the 94 IS electronic but the speed sensor is driven of an old style mechanical speedo gear. When I went to 265's from 245's on my 94, I just went to the dealer and bought the correct gear (about $14.00 cdn). Of course if you are putting a much larger than factory tire on this won't work.

firestorm

Check out this thread, just like "hukd on foniks, it werkd fer me."

Tire rpm's http://discounttire.com/dtc/brochure/info/tireMath.jsp

https://www.dieseltruckresource.com/...450#post502450

d0dg301

A buddy of mine is taking his 04 in tomorrow to a dealer who is going to do it for $75's. I'll find out what they actually did and post it.