350 vs 400h towing questions

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04-06-10, 07:02 PM

#16

biff44

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Quote:

Originally Posted by geko29

This is why towing is ALWAYS supposed to be done with overdrive OFF. With OD on, the torque converter will frequently unlock, which causes the temperature in the transmission to increase and will eventually cause transmission failure. Towing in 4th allows the TC to stay locked for significantly longer stretches, lengthening the life of your tranny.

The 1mpg you save by towing in 5th gear isn't worth the $4,000 bill you'll get down the road...

Really. I did not thing the RX had a true overdrive (where all gears get bumped up 1-4), but instead was just a 5th gear. Am I wrong? Obviously, if I had an actual overdrive mounted in the transfer case, I would keep it off.

But I believe you, you do not want to tow in 5th gear position allowed!

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04-07-10, 02:11 PM

#17

biff44

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BTW, it does not say OD on the tranny, it says 1-2-3-4-D. I think D just means 5th gear.

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04-11-10, 12:16 PM

#18

Brian06

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The boat I was looking at is actually a 17ft seadoo. I need to double check the weight.

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04-11-10, 02:42 PM

#19

geko29

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Quote:

Originally Posted by biff44

Quote:

Originally Posted by biff44

BTW, it does not say OD on the tranny, it says 1-2-3-4-D. I think D just means 5th gear.

Overdrive in tractor trailer terms is indeed an additional gear that modifies the "regular" gears. In a passenger car/truck, it typically refers to any gear that is taller than direct drive (1:1). In the case of the 2007-2009 RX350, 5th gear is 0.76:1, and therefore an overdrive. Fourth at 1.05:1 is basically your direct drive, and your ideal highway towing gear.

The 6 speed in the 2010 RX actually has two overdrive gears, 5th at 0.71:1 and 6th at 0.61:1. So you'd want to restrict that one to 1-4 for towing as well.

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12-12-12, 07:45 PM

#20

Stealth1

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Does anyone have pictures showing the tow prep package transmission cooler? I am buying a 2008 RX400h and haven't been able to find any way to confirm it has this. There's a cooler in front of the ac condenser but i've seen people say it's in the lower corner of the bumper.

Please help!