Someone plese send post the formula I need to get my speedo readion correct. I just swapped to a m6 from 4l60e.

so now I have t56, 235/75/r15, and 3.73 gears.

Thanks alot

 

What program are you using to reprogram the computer? Most have built-in functions to rescale for tire size. You can get tire dimensions from places like Tire Rack, if you need them.

 

When you swap from an A4 to an M6, you have to have the PCM reflashed with an M6 program. Otherwise, the speedo will only read about 40% of actual speed, due to the A4 VSS producing 40 pulses/rev and the M6 producing 17.

That's a 29" tire.... does it fit in the wheel well with no modifications?

 

I'm using tunerpro. It has no calculator in it. someone with tunercat, please help me. The engine is in my truck. I could fit a huge tire if I wanted to.

 

OK.. I plugged in 235/75/15 (same tires as my '95 G20 van) with VSS of 17 per drive shaft rev and 3.73 rear gears into TunerCat. Calibration values are : Speedometer Scalar = 11 , Speedometer Scalar Fraction = 0.965, Speedometer Scalar Scantool = 44.698, Time Between Pulses For Stop = 81, Speed Correction Factor = 40 . I personally use tire revolutions per mile for a more accurate setting, as said previously almost all tire manufactures provide it on their web sites under tire specs.

 

Thanks, I'll give it a try today.

 

worked grear. Thank you. out of curiosity how much does it change with 719 revolutions per mile.


PS. It's great grabbing gears with v8 tq.

 

Glad it worked out. I punched in 719 rev/mile and the numbers came out exactly the same as using tire size (to the fourth decimal point). By the way I had a typo in the 'Speed Correction Factor in post #5', I had it as 40 and it should have been 2.4224, apparently you don't use that field.