When to turn off Overdrive switch on Tundra?

When should the overdrive switch be turned off with an automatic transmission Tundra? What's the difference(s)?

Reply to
Phisherman
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  1. Going down a fairly steep grade where you're tapping the brakes (or hitting them pretty hard) to drop speed and hold your desired cruising speed.

This will let the engine take some of the braking load, and keep you from wearing out your brakes - or worse, overheating the brakes to the point where the pad material goes into heat-fade and become far less effective, or past that point to where the brake fluid boils in the calipers and you get temporary total brake failure.

(This is Not Good.)

  1. Going down a fairly steep grade when fully loaded and/or towing a heavy trailer - See #1.

  1. Going up a moderate grade when towing a trailer, or up a steep grade when moderately loaded, and you notice that the transmission keeps "hunting" back and forth between 3rd and OD to hold your desired speed. Better to lock it into 3rd and save the wear on the trans.

And in all these situations, if it's a really steep hill and/or you are heavily loaded, and the transmission is hunting between 3rd and

2nd, drop it into 2nd manually and don't be in a hurry.

The rule the Heavy Truck drivers use is "Do not go down a hill any faster than you can go up it." You don't have to be quite as paranoid about it in a small truck, but being a little more cautious can save a lot of unneeded wear on the equipment.

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Reply to
Bruce L. Bergman

Good advice. A point can also be made to turn off the OD whenever you are towing a heavy load. OD gears up the transmission and tends to put more stress on parts. Without OD, the engine will turn faster, but the transmission will be in 1:1 (depending on the tranny) gear. The strongest gear you got.

If you need the engine to slow you down and stop the brakes from burning out, then you are going too fast with too heavy a load. Slow down. Brakes are dirt cheap next to a transmission rebuild.

Reply to
Eddie

Yes, but it's not just a question of money and what is cheaper to repair. If the transmission fails under those conditions, you pull over and stop. Annoying, expensive, but not normally hazardous to life and property.

If the brakes overheat and fail you DON'T STOP - and that can get you killed, or seriously mess up your vehicle...

Given those two choices, I'll drop a gear (or two) and ease down the hill without overloading the brakes every single time. Save the brakes for when traffic comes to an abrupt stop at the bottom of the hill.

Welcome to the North I-405 approaching the US-101 interchange at any time of the day - a 3-mile 8% downgrade with a perpetual traffic jam at the bottom. Being able to stop when you need to is a good thing.

Been There, Done That, Have the T-Shirt.

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Reply to
Bruce L. Bergman

On Mon, 30 Jan 2006 05:03:24 GMT, Phisherman found these unused words floating about:

If you RTFM, it will tell you.

Overdrive = no engine braking and lower torque.

If you're pulling not only switch off the OD, but switch ON the "Power Boost" (IF the Tundra has one - Tacoma does).

Reply to
J. A. Mc.

I read the manual, then posted here. The 2006 Owner's Manual says nothing about when to turn the Overdrive off, just how to do it. By default the Overdrive is ON.

To make matters a bit more confusing, there is a "Shift L" switch on the dash. The manual says to turn this Shift L switch on to enable maximum braking--does this mean the Overdrive switch should be off when the Shift L is on? Further, it says not to use the Shift L switch for "a long time" when climbing a hill or hard towing, else it could result in severe transmission damage or overheating. So what's "a long time?"

Reply to
Phisherman

While climbing very long hills, and the transmission constantly shifts out of OD -- downshifts -- and back again -- upshifts -- it is a good idea to use the button to defeat the OD functiion. Let the truck climb the hill in

3rd of 4rt, whichever the highest gear is that you have, but is not overdrive.

The same rule of thumb applies to ANY overdrive transmission, not just the Tundra.

Reply to
Jeff Strickland

2000-2002 Tundras have a weak overdrive section in the transmission. Always switch out of overdrive when towing or when hauling a heavy load. The other advice given is also very good, except the part about not using the transmission to slow the truck on long downgrades. If your brakes overheat and fail, you crash. The brakes are best for short downgrades, and the transmission best for long downgrades. On a long downgrade, downshift to the gear that keeps you near the speed you feel is safe. When you gain to your max safe speed, brake moderately hard to slow below that safe speed, then get off the brakes and let them cool. When you're back up to your max safe speed, brake again, etc., etc.

Ken

Reply to
Ken Shelton

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