Gear change Q
#1
Gear change Q
This is for the been there done that guys.Anyone went from 3.73 to 4.10s and not adjust the PCM?What to expect? I am sure not much effects with this small of a change of ratio.Did it effect the shift points/RPM?Speedo reads faster or slower now?Im thinking faster.Anything else?Im pulling the cover off tomorrow as soon as the parts arrive.Only reason Im making a change because I am starting to hear pinion bearings noise.It's from hard launchs (many) and lots of heavy towing.Only if i really like the ratio change then I will do the front.
#6
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iTrader: (16)
If your PCM is set to shift on MPH, yes it will shift early. I think normal throttle driving is done by MPH. WOT can be setup by MPH and RPM, so its possible that your WOT running will stay the same if setup by rpm. Expect a 10% change in speedo - if it shows 55mph, you'll really be near 50.
#7
some guys have been having abs and brake lights flashing and setting codes. happened to me a couple times not resetting gear/tires with edit with a new tune. someone correct me if i'm wrong but all your shift points will be affected. normal and performance shifting is done by mph, since your truck will be going slower than the speedo says that will affect the shift. at wot it is controlled by rpm, and your truck will be spinning more rpms per tire rotation so it will shift different there too.
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#8
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Join Date: Apr 2003
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yes it will shift early as stated above, your speedo will read faster than what you are going. i think mine read 5 mph faster until i got to about 60 then it started getting i think 10 mph off. so at 90 on the speedo i would really be going 80.
#10
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iTrader: (16)
Yes. The old hypertech changed shifts by MPH. I alter shifts by RPM with edit. In edit I can do it with RPM and MPH. I once saw a guy with a custom EdW tune at the track. He had just gotten a torque converter, and it wouldn't shift, it kept bumping the limiter. Had it been set to shift on rpms, I don't think it would have had that problem.