Help with 4l60 and new gears
11-08-2005, 01:10 PM
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Help with 4l60 and new gears I recently put in 3.73 in place of 2.73. I was reading in the LS1_Edit User Guide about firming up your transmission but I didn't want to do it till i got the gears, since I was going to have to change the speedometer anyways. So I followed the directions, or at least I think I did, and every time the tranny should shift at WOT it hits the rev limiter for about 1 to 2 secs and then shifts. I thought that I made have done something wrong so I changed it back to stock file that I had before the rear end change and its still doing the same thing. So I don't know what to do. I have compared the difference with the file I am running now to the file that I too out when It was totally stock and there is no difference. Maybe someone could look at it or something because I do not know what to do any more. I cant race because I fear that I will tear something up if it keeps hitting the rev limiter. Any thought on this? Thanks Josh
11-08-2005, 01:31 PM
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There are two tables the PCM uses to upshift under WOT. The first is based off of RPM. Keep in mind, this table may need to be fudged a little as it takes several hundred rpms to shift. So for a 6,000 rpm 1>2 shift, I'd try setting it at 5800 rpms and log a few WOT shifts to see what rpm it's actually shifting at. Then adjust accordingly up or down to make is shift later or sooner. The other table is based on MPH. Stock, these are set significantly lower than the corresponding rpm shift points. So, I would lower them to be at the same theoretical rpm as stock. In other words, if stock the 1>2 WOT shift is at 31 mph and that's roughly 4100 rpm, I would find out how many mph 4100 rpms is with your new gears and set that as the new mph. Find a gear calculator, measure your actual tire height (don't use the presets), and then plug in the rest of your #'s. http://www.f-body.org/gears is a commonly used calculator. G/L!
11-08-2005, 03:10 PM
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So change the pref. and hot only not the normal right. So I can change the mph or rpm...or do i change both of them? This is even happening 3rd to 4th when im at 125 mph or so.
11-08-2005, 04:05 PM
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I don't believe our cars use the performance settings in the trans. That's more for cars that have that little button on the console that says "Performance" and I've yet to see that in an LS1. You need to change the normal settings for sure and then use judgement when adjusting the hot settings. Try to follow the pattern set by the factory if it differs from normal, but adjusted for your new gears. Yes, these changes apply to all gears....even the 125mph 3>4 shift.
11-08-2005, 10:32 PM
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Ok just to check I am going to use "28mph" 1 to 2 "54mph" 2 to3 "87mph" 3 to 4 and 5800rpm 1 to 2 5700 rpm 2 to 3 and 5700rpm 3 to 4. Do theses numbers sound right ? I just want to make sure i was reading the table that you link me to right. My tire size is 275/40/18 and 3.73 ratio Thanks Josh