automatic transmission shifting procedure
Just checking my methodology to see if "all" agrees. I am towing a 5000 lb TT with a 2006 Chevy Trailblazer with the 5.3 vortex v8. I tow in 3rd. When going up a steep hill, I wait until the comput...
Forum Discussion
OP states "max speed in 2nd is 45mph at 3500rpm"
This is part of the problem. Modern small block Overhead Cam V8s DO NOT have a ton of low end torque, most torque and power is made by spinning the motor. This is the opposite of the way V8s used to be and is disconcerting for those who have driven older big block V8s. Peak torque for the 5.3 is around 4400rpm, and peak power around 5300! At 3500 rpm you are falling off the torque curve and only making around 220hp.
DO NOT be afraid to put your foot in it and let the engine run, it may sound to you like it is going to blow up, it is not, and will happily spin at peak torque for a long time.
If the transmission is waiting too long to down shift into second, like 2500rpm, then it is letting you fall too far off the power curve and shifting down won't get you far enough back on it. I saw this all the time with my dad's old chevy truck Pre-empt it. When the tach hits 3200rpm manually drop it into second so you will hit second around 4200rpm and stay in the power band.
And no, something is not necessarily wrong if you have to use 1st. Depending on the grade, elevation, and axle ratio you could have to use it. 1st on the 4sp is not particularly low at 3.01, and you could likely have 3.39 axle gears. If you are talking 6% at 200ft, then yea, you should not need 1st, but somewhat mountainous driving with some elevation, yea. Going from Palmdale CA to table mountain was over a 5000ft elevation gain, even with my 6spd, I definitely had some 1st gear work, but it let the engine stay at 4000-4500rpm at peak torque.
This is part of the problem. Modern small block Overhead Cam V8s DO NOT have a ton of low end torque, most torque and power is made by spinning the motor. This is the opposite of the way V8s used to be and is disconcerting for those who have driven older big block V8s. Peak torque for the 5.3 is around 4400rpm, and peak power around 5300! At 3500 rpm you are falling off the torque curve and only making around 220hp.
DO NOT be afraid to put your foot in it and let the engine run, it may sound to you like it is going to blow up, it is not, and will happily spin at peak torque for a long time.
If the transmission is waiting too long to down shift into second, like 2500rpm, then it is letting you fall too far off the power curve and shifting down won't get you far enough back on it. I saw this all the time with my dad's old chevy truck Pre-empt it. When the tach hits 3200rpm manually drop it into second so you will hit second around 4200rpm and stay in the power band.
And no, something is not necessarily wrong if you have to use 1st. Depending on the grade, elevation, and axle ratio you could have to use it. 1st on the 4sp is not particularly low at 3.01, and you could likely have 3.39 axle gears. If you are talking 6% at 200ft, then yea, you should not need 1st, but somewhat mountainous driving with some elevation, yea. Going from Palmdale CA to table mountain was over a 5000ft elevation gain, even with my 6spd, I definitely had some 1st gear work, but it let the engine stay at 4000-4500rpm at peak torque.
