Question for the Mad Dr.

[88Racing]

Yes I was wrong!

Turning off the od will eliminate the back and forth shifts from 4th to 3rd, 3rd to 4th, but not the lock up.

Once again I apologize "put the cart before the horse"

Thanx for the correction.

Lars

[Jackpine]

I was actually having a bit of trouble with several points in this thread, but I decided to wait just a bit before coming back in.

Isn't it the case that when the torque converter is unlocked, it acts as a torque multiplier? (Since it allows the engine to rev at a higher RPM where it has more power to deliver).

And, my somewhat limited understanding of torque converters suggests to me that if they are unlocked, they generate a lot of heat - that energy coupling through the fluid has to go somewhere. But, if the converter is locked, then it is really doing nothing (relatively speaking) so it's not producing heat at all.

Isn't it the case that there is the least amount of wear on the powertrain if the transmission stays in one gear and the torque converter stays locked?

- Jack

[RED4]

Originally Posted by 88Racing

Turning off the od will eliminate the back and forth shifts from 4th to 3rd, 3rd to 4th, but not the lock up.

When towing heavier loads, you still need to be aware of what the TC is doing. Even with OD off, your truck can still lock and unlock the TC and have heat problems. I always have Comm Gear and TFT Temp on my Gryphon and look at it way more than my speedo or any other gauge when towing.

My driving habits when towing have really improved since my Gryphon purchase and I'm sure my truck thanks me.

[Jackpine]

Originally Posted by RED4

When towing heavier loads, you still need to be aware of what the TC is doing. Even with OD off, your truck can still lock and unlock the TC and have heat problems. I always have Comm Gear and TFT Temp on my Gryphon and look at it way more than my speedo or any other gauge when towing.

My driving habits when towing have really improved since my Gryphon purchase and I'm sure my truck thanks me.

These are good points, RED4. We're going to tow our trailer up to Sedona in two days. I'm monitoring the gears and TFT now and it will be interesting to see what happens. There are some long hill climbs on this route.

- Jack

[88Racing]

After further research and trial by error my ford f150 stays in second.
OD and 3 speed trannies have a built in feature that locks first and second gears together by the use of the torque bands. In manual tranny terms like starting out in second gear with feathering the clutch.
However on the way home in the gmc while from a dead stop put it in second and stayed in second. Did this again with trailer mode on and had a 1-2 shift. Retried same results. The gmc has the 5 speed auto. Does the trailor mode overide the torque bands electronically? All tests in lower gears in both vehicles produced sluggish trannies.

[Jackpine]

Cool! I'm happy to learn that if you select 2nd, that's what it starts out in. I'd have designed it that way myself. But, you're saying the GMC upshifts when it's in "trailer mode"? That's an interesting way to modify it too and it also makes sense. You'd want a 1-2 upshift when towing, I think.

About this sluggishness, I don't know. I wonder if the torque converter locks up quickly? It has to unlock to allow the vehicle to remain stationary with the engine running, but maybe once it's moving, it locks.

As another observation, I've never seen a lock indication when accelerating in drive with the OD on until I reach 4th gear, no matter how softly I try to accelerate or stabilize the speed early. And, we talked about this in another thread and I think it should lock in third if the OD is off and in 2nd if the transmission is set to run there and so on.

- Jack