Monitoring Engine RPMS when accellerating

[Gary RVRoamer]

Transmissions have been protecting engines (and themselves) for a long time. Even my old 56 Olds would upshift from Low if I tried to hold it there too long.

[CD]

Originally Posted by Gary RVRoamer

Transmissions have been protecting engines (and themselves) for a long time. Even my old 56 Olds would upshift from Low if I tried to hold it there too long.

I may stand corrected but I have never experienced that. Was that while accelerating or holding back going down hill?

[CD]

Originally Posted by Gary RVRoamer

Transmissions have been protecting engines (and themselves) for a long time. Even my old 56 Olds would upshift from Low if I tried to hold it there too long.

I did a test with my 91 Pontiac tonight. It has a V6 and a 3 speed auto with a locking torque converter. As I was moving onto a freeway I shifted into low range. When I hit 60, the tac Red lined at 6K. It would not shift until I manually shifted it. I stand by what I said earlier. It just proves that all tranies are not created equal.

[Easyrider]

A better test would have been to leave it in "drive" or high gear and put your foot in it and see where the shifts occur. In high gear your automatic tranny will prevent over revving the engine and will upshift when needed to prevent over revving from happening. If you have it in "low" when you start out it will not upshift untill you do it manually. Another test would be to go down a long steep hill and downshift and see if the tranny goes all the way to low gear or only when your vehicle slows enough to do it without over revving the engine. All your previous test proved is that your "manual" operation of an "automatic" transmission works.

[CD]

Originally Posted by Easyrider

A better test would have been to leave it in "drive" or high gear and put your foot in it and see where the shifts occur. In high gear your automatic tranny will prevent over revving the engine and will upshift when needed to prevent over revving from happening. If you have it in "low" when you start out it will not upshift untill you do it manually. Another test would be to go down a long steep hill and downshift and see if the tranny goes all the way to low gear or only when your vehicle slows enough to do it without over revving the engine. All your previous test proved is that your "manual" operation of an "automatic" transmission works.

You are correct, but if I am faced with a long steep hill I am not going to wait until it won't shift down before trying to. I will start at the top in low and work up if too low. I followed a MH down a gradw in Or. that did that and about 2 miles down he was sitting beside the road with smoke rolling off all 4 wheels. I don't know how he got down as he still had about 10 miles of 8% grade.

[trower]

I pull a 27 ft travel trailer with my 99 suburban and 454/7.4 with 4.10 gears and i, like you, want to limit the rpms when climbing. I let the tach go down to 3000 before adding gas and letting trans. Shift. This usually raises the rpms to around 3600-3700. I hope this limits the excess wear on my engine.