Eprom work for the 4L60E downshifts??

[viper6383]

OK, I will probably have to learn somethings on the autos but plan to beef up the 4L60E for possibly a stroker motor. I have heard all the stuff about them shifting like crap and more importantly, not downshifting. I have it bad!! I run large tires with 4.56 gears. Everytime I slow up either by braking or rolling, it sticks in a taller gear and I have to pedal it to get a downshift out of it. This has to be hard on it and and am always causious about that.

I have heard about drilling the valve body and all sorts of stuff but those are hard to correct if done wrong. I am wondering if I can solve all my problems with tuning the parameters of the trans? I also run into a brick wall at 4500rpm and rev limit hits soon after. I will need a higher limit (like 5500) for the new motor. I am wondering if thit can be worked out with tuning as well or if the distributor system is to blame for some of the flatness up top. I know it probably cannot get any more air either so that is probably half of it.

[oldred95]

A 350 TBI's operating range is idle to 4k rpms, anything more and you're just wasting time. You can rev them higher but stock its pointless because they won't make any power up there. And yes the 95's especially got the worst shift tables known to man. Mine loved to slip into 3rd gear at 17-18 mph and like 500 rpms, yea loads of power there especially with 3.08 gears. A downshift pretty much required jamming the pedal through the floor too. I can post the stock shift tables but its so sad you may not want to even see it. Just to give you an idea a 4-3 downshift requires roughly 75% throttle at 65 mph to make it happen. I have mine set at 38% right now and its still too much throttle movement for my tastes. Anyway yes you can make your 4L60E shift like it should via tuning and there is no internal mods necessary to the trans, although a shift kit and servo's are very good and worth while mods.