Correcting Speedometer in LS1 Edit for non stock tranny
08-27-2003, 03:01 PM
#1
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Correcting Speedometer in LS1 Edit for non stock tranny I just hooked up my speedometer in my car and haven't had any time to get on the dyno yet. The problem I have is I switched to an M6 PCM and a TH400 transmission. I have the rear gear set at 3.70 which is what is in the rear and the tire size set at 26.22 which is the diameter of what I have on the car. On the first trip I traveled out on a 55 mph zone where most people drive between that and 70. The speedometer was reading past 150 a large majority of the time. The odometer showed I went about 25.x miles and I actually only traveled 11. If you guys could give me some insight on what I need to do to get the numbers kinda close so I can find tune it I would appreciate it.
I'm assuming I'll have to raise the gear ration to something higher than 3.70 like 5.50 or something and then lower the tire size? If you have any specific numbers that will get me close I would appreciate it.
Also what happens if it takes more than 6.0 gear and a certain size tire? The program version I have is limited to that gear at max or should that be plenty of gear regardless of what I end up running. I play to run at least a 4.10 or 4.30 later.
Thanks
I'm assuming I'll have to raise the gear ration to something higher than 3.70 like 5.50 or something and then lower the tire size? If you have any specific numbers that will get me close I would appreciate it.
Also what happens if it takes more than 6.0 gear and a certain size tire? The program version I have is limited to that gear at max or should that be plenty of gear regardless of what I end up running. I play to run at least a 4.10 or 4.30 later.
Thanks
08-28-2003, 04:14 AM
#2
Re: Correcting Speedometer in LS1 Edit for non stock tranny The gear and tire parameters in LS1edit for the speedo are pretty messed up. I've made both gear and tire size changes, and had to stuff phoney values in there to get it to read right both times. All I can say is experiment until you get it right. I used mile markers on the freeway, but if you can get your hands on a handheld gps, that might be easier. I just calibrated for some 26.6" dia tires and 4.11 gears tonight, and I had to put in 24.7" to get it right. I've also used 3.42 and 31.09 to make it read right for 4.11 gears with 25.87" inch tires. Oh and BTW, when you correct for the tire size, you have to compensate in reverse; i.e. increasing the tire diameter in LS1edit has the effect of making the odometer read lower per mile and the speedo read slower for a given rpm--just the opposite of what you would expect.
08-30-2003, 08:12 AM
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Re: Correcting Speedometer in LS1 Edit for non stock tranny One of the new features in v1.3 is adjustment of pulses per mile. You might have a look at that. There's also been some updates related to tire sizes.
