Odometer adjustment on a 97

[Dennis Garrett]

Today I moved up to Firestone SteelTex 265/75's Load range "E", had a set of 245's to start with. It's made a little difference in my speedo/odo readings. By the stopwatch, the speedo is almost exactly perfect at 70 mph. Problem is now, the odometer now only registers 9. 5 miles for 10 run, on known good mile markers. On 97's it's easy to swap out the speedo gear in the transmission. I'm think about dropping a tooth on the gear, to speed up both the speedo and the odometer. That might get the odometer closer first, then by driving with the instrument bezel out, pull the speedo needle off, & reposition it to the correct speed I'm travelling at the moment by the stopwatch. (with curise on) I remember a post about someone using this method, but can't find it. It makes me nervous to think about pulling the needle off & sticking it back on. Anybody tried it?

 

[Bigramguy]

The needle trick works,but it if your doing it to correct for tire size\gear ratio changes it will only be accurate at the speed where you put the needle on. It will be off by a percentage at all other speeds. It's not hard to do,I have done it on my truck. Gets it a little closer at least.

 

[Dennis Garrett]

Since the first post, I took the 32 tooth gear out, & put in a 31. It spun things up a little faster, and the odometer is pretty close now at about 9. 85=10 miles. The speed at actual 70 shows about 72. This is about the same way it behaved with the 32 tooth gear & the 245's. I might pull the bezel, set the cruise on 72, pull the needle, & re-stick it on it's spindel to read 70 if I have time tomorrow.

 

[Chipstien]

Go one more tooth!!

Why put more miles on your truck than you have to. The best way is when doing 70 you only read 68. My truck is 10% slow because of the 35's. So if I sell it at 100000 miles it will really have 110000..... 200000 would have 220000... . and so on

 

[Dennis Garrett]

I guess I'm kinda obcessed with accuracy. I have even factored odometer error into the total mileage of the truck, and at 150k, it was actually about 152,750 + or- a few. With this many miles, (It had 9 mile showing when I bought it, & I've put almost every mile on it myself) It's more like a quest to see how many miles I can get on it before one of us says "Uncle!" I've put about 75 miles on it for every calendar day I've owned it, & it still feels like a new one. No plans of ever giving it up for a new one. Size matters too, & the bigger the reading on the odometer, the better I like it.

 

[Vaughn MacKenzie]

Dennis, if your speedo is correct but your odometer isn't, there is no way to fix your problem without removing your speedo assembly and sending it somewhere to get calibrated. Repositioning the needle, changing drive gears, etc. is not going to fix it. The speedo and odo are out of calibration with each other . The best approach is to first get your odometer correct because it is a direct mechanical drive from your transmission. Then once the odometer is corrected with the proper gears, the speedometer can be calibrated to the odometer.



I thought on '97s though they were electronic with a sending unit instead of driven by the old fasioned cable. If yours is electronic then the only route may be to replace the darned thing but at least you wouldn't be without gauges if you had to send it in for repair.



I have a buddy with a '68 Impala where the speedo and odo are way off from each other. At 70 it reads 62 but the odometer runs almost 10% to fast. . . almost 20% total error!



Vaughn