Gear Ratio

[BMWBILO]

Quick question. If you change your gear ratio in your diffs.
Do you have to re program the computer for the new ratio?

[Ford_6L_E350]

Only if you want the speedo to be accurate and the trans to shift properly.

Mike

[BMWBILO]

Originally Posted by Ford_6L_E350

Only if you want the speedo to be accurate and the trans to shift properly.

Mike

Is that hard to do? I have a 1999 E350 with a 7.3 Powerstroke.
The gear ratio in it now is 3.55.

[vandiesel]

I thought it was a matter of using my chip tuner tool but John at Quadvan mentioned a re-gearing of some sort by a speedo shop nearby. Does anyone know the difference? Mine is off by 3-4 mph and my shifting seems way off. I went from a 31" tire to a 34" tire and have 4:10 gears. I'm planning on 4:56 but until then I'd like to at least have things kosher with the speedometer and transmission. I mainly want to make sure the tuner tool does the right thing since it has that feature.

Brad

[SheepShagger]

The 6.0 and most 7.3's can be done by any Ford dealer with the right ECU tool, or by some aftermarket tuners.

Autoenginuity software will re-program some ford speedos in the exact same manor as the Ford ECU tools. (IE, no new tune/ECU program) Last time I checked (~2years ago) they only supported the 6.0 on the truck, not van, not sure on the 7.3

Have no idea on the Gas engines.

I did find a thread somewhere that described a process where some 7.3 owners had done it by following some simple instructions found on the net. But I can;t find it now.
It was something like shorting 2 pins under the dash, then pressing the odo buttons to get into some programming mode. This apparently worked on a particular a ford speedo module that they put on a number of different models, all pre ABS I believe. Might be worth a few hours searching.