Speedometer reading to fast.

[tateinca]

I have had my 93 350 dually for 9 months and

am very pleased with it. It has 365K on it so

it has a lot of "bugs", but I am getting there.

Right now I am trying to get the speedometer and

odometer to read correctly. At 10 to 30 MPH it

reads 5 MPH fast. After that it reads 10 MPH

fast. It is progressive. I just tried a new

speed sensor and have the same readings. The

Getrag has been rebuilt previously by parties

unknown.

Anyone have any ideas??

Thanks, Hugh.

 

[formula]

If your tires are smaller than the stock tires it will cause this problem. Also, if your rearend gears have been changed with a lower ratio, i. e. 3. 54 to 4. 10. You may be able to get a different speed sensor gear that will correct the speedo readings.



SP

 

[DPKetchum]

speedo error

Hi. I had this problem on my 93 4x4 after going from 3. 55 gears to 4. 10 it was dead on 10 mph off at 60. On mine thou it has a speedo adapter on transfer case. Any how it was a pain to correct the Dodge part # and descriptions were not totaly clear and it took a while to get right part. Your dually may not be as difficult. But anyhow it sounds like it has had a differantial swap,not a trans concern. The dealer can bring up on parts fiche and it will describe tire size etc. with gear ratio. The dealer service dept can also run a VSS while you wait and bring up build sheet on your truck they can print it also. To find out your gear in differantial jack truck up mark a tire and watch/mark rear u/joint etc and turn tire 360 degrees and if shaft turns 4 rotations etc. its a 4. 10 if it turns 3. 5 turns its a 3. 55. Then parts person can locate proper speedo gear for trans to match differantial. Hope this was any help.

 

[paccool]

I had the same problem on my 93 only in reverse. I went from 4. 10:1 back to 3. 55:1 and the speedometer read slow. Ordered 2 different gears from the stealer, neither one was right. Finally gave up with them and went to a local speedometer shop. Told the guy what I had and what I did to the rearend, he said" oh, you need to replace the gear with a ---- toothed gear" (I can't remember what the count was) He went to a cabinet full of stuff, moved a few things around and came out with the right gear. Cost me $12. Put it in the sensor at the transmission and the speedometer is dead on.



I have my old gear, you can have it if you want. My transmission is an auto, don't know if the gears are the same for the manual. I'm going to be gone for the next couple of days so be patient if you want it. I'll let you know what it costs to ship and you can send the $ later.