Downshifting 4R70W on Long/Steep Grades...Damaging ???

8mmag · #1 12-20-2002, 08:50 PM

Where we live there are lots of long steep hills. I normally downshift to 2nd on these grades to maintain 40-45 MPH with minimal braking.

Is this hard on the transmission? If so, what does it do to it?

Thanks!

Tom

IAmGeeky · #2 12-20-2002, 09:09 PM

Tom, I tow a 6500# GVWR 5th wheel in the mountains of Colorado and use the engine braking technique you speak of. I have never seen the tranny temp go up when descending a grade in 2nd gear. If you apply the throttle your torque converter will unlock for 10-20 seconds then lock up. At that point the RPM's will go a little higher. When the TC is unlocked it generates more heat, which is your tranny's worst enemy.

I recommend installing a tranny temp gauge so you will always know if you are pushing (or pulling) it too hard.

I hope this helps.

PS I noticed you went to LT rated tires, wise choice.

hmustang · #3 12-20-2002, 09:23 PM

I down shifted several times in the mountains when I was out west on vacation or in the smokey moutains in the east with no problem but i wasn't towning at the time but it beat keeping my foot on the brakes on the way down.

Mark Kovalsky · #4 12-20-2002, 11:19 PM

That's what the 2 position is for. It's designed to do that.

SLCScrew · #5 12-23-2002, 12:23 PM

I use it all the time coming down from the ski resorts in Utah, usually in pretty heavy traffic. It's funny, I put it in 2nd, and it runs about 2500-300o rpms, but does just fine. I rarely have to use my brakes, while the person in front of me has their brake lights on the whole time (as most people in front of me do). When we get close to the bottom, the mouth of the canyon reeks like scorched brakes. Not my truck though. However, I do have a tranny cooler that comes with the towing package, so it might be a little safer.

I've always used this type of engine braking technique, though.

8mmag · #6 12-24-2002, 01:03 AM

Thanks, guys! I feel a lot better with what I've been doing (and will continue to do).

FYI...the wife and neighbors don't do this, but they (me in the case of my wife) replace brakes at least once a year. My brakes last 2+ years.

Tom

F150Forever · #7 12-24-2002, 01:48 AM

From the Owner's Manual:

"2 (Second)
Use 2 (Second) to start-up on
slippery roads or to provide
additional engine braking on
downgrades."