Down shifting the transmission for braking assist

Fellows pnichols and carringb,

I don't raise RPMs anywhere near "Red-Line" on the tachometer going up inclines using the throttle.

It's when going down-hill. I get close to red-line when engine braking going down long decents in lower gears. I apply the brake before hitting red-line. If I didn't, the tachometer would be in the red zone.

Understand?

Yes I always use full synthetic 5W-20 motor oil....exclusively Mobil One since the second oil change.

On descents I always downshift to maintain speed rather than ride the brakes. If I have my cruise control on the Benz will often do it for me. Around town or low speeds (if towing) I may just shift manually through the box to keep it in a lower gear so I have boost and braking. The tip shifter makes this quite convenient. I even shift up nudging the shifter with my knee sometimes.

BTW - once the breathing is freed up on the V10, it actually sounds good at high RPMS. Especially in tunnels!

pnichols wrote:
Ron, I assume you use full synthetic? I switched to Mobil 1 Extended Performance in our E450 several years ago.

Bryan, I'm curious as to when you're needing that much shaft torque from your V10 - it must be when towing that trailer I see in your van's photo? You're really getting some torque to the ground from those 4:56 diff gears at those high RPMs. That's the same gearing as is in our motorhome - which I assume weighs much more on average than your setup - and I haven't had a need yet to rev that high, even in the Sierras. I'll bet you're sometimes giving the diesels a run for their money!

We grew out of the trailer in the pic. The new race trailer weighs about 12,000 loaded, and then there's at least 3,000 pounds of people and gear in the van, so it scales about 22,000 most of the time. At that weight, I can keep 65-70 on any of the major I-5 climbs like Siskiyou and the Grapevine.

When I had the Weekend Warrior (it broke), I would top 25,000 pounds and that would slow me down a little, but I could still do about 55 on the big western climbs. The only climb that gets it are some of the taller summits in the Rockies, where it would drop to 45 or so because of the elevation.

PS - I run sythetic too. If I'm doing mostly towing, I'll go as far as 12,000 miles between oil changes. But cold starts are still as bad for synthetic as conventional. I had a recent job change so now I commute in-town, so for the time being I'm back to 5k changes at least until the van goes back to towing-only duty.

Ron, I assume you use full synthetic? I switched to Mobil 1 Extended Performance in our E450 several years ago.

Bryan, I'm curious as to when you're needing that much shaft torque from your V10 - it must be when towing that trailer I see in your van's photo? You're really getting some torque to the ground from those 4:56 diff gears at those high RPMs. That's the same gearing as is in our motorhome - which I assume weighs much more on average than your setup - and I haven't had a need yet to rev that high, even in the Sierras. I'll bet you're sometimes giving the diesels a run for their money!

ron.dittmer wrote:
I engine brake all the time but get nervous when the tach gets close to red-line. I suppose full synthetic motor oil gives a little "edge" when in that condition.

What do you consider "Red-Line"?

The computer simply won't let you over-rev unless somehow you manage to top out OD (which would be somewhere around 130MPH with 225 tires). The stock rev limiter only cuts fuel, but the engine can actually handle higher RPMs. I've raised my shift points to 5400 RPM, and I think I set the new fuel cut at 5600, which I sometimes hit (that's WOT in 2nd gear at 70MPH), and I'll hold 5000+ RPM at WOT for 15-20 minutes at a time. I'm pretty sure no-throttle is MUCH easier on the engine than WOT :)

I engine brake all the time but get nervous when the tach gets close to red-line. I suppose full synthetic motor oil gives a little "edge" when in that condition.

eric1514 wrote:
Downshifting for grades is the thing to do.

Downshifting for stop lights is tranny abuse. That's why we have brakes.

Well ... many late model Class C RV transmissions - such as my 2005 Ford E450 cutaway van based motorhome - have computer controlled transmissions with an electronically invoked (button on the gear shift lever) TOW/HAUL mode.

This mode is to be used whenever the van is carrying a load or towing something. Since a cutaway van under a motorhome is always carrying a heavy load, these type motorhomes can be driven in their TOW/HAUL mode all of, or most of, the time if desired.

When in TOW/HAUL mode my E450 downshifts whenever I lightly tap it's brake pedal ... even when approaching stop lights. My motorhome now has about 42,000 miles on it's original pads and rotors - with around 85% left on it's front brake pads. Use of TOW/HAUL mode can automatically help save the brakes all the time and can automatically help to save lives on long downgrades.

paulsm87 wrote:
I have a question about the proper use of down shifting my transmission in my motor home

I have a 2001 Jayco
With the V-10
The question is; when driving and towing my Escape I will down shift my transmission when stopping or slowing down for a stop or going down a long grade; I use my transmission as an engine brake to save my brakes and to avoid over heating them.
I was told yesterday that it is bad and could damage the transmission, a lot of us have been doing this for years so I thought I would ask RV NET for there opinion
Thank you
Paul

In my workhorse manual it encourages the use of down shifting...

I always use mine for engine braking, for some really heavy loads. If I'm towing really heavy I will use the transmission even for just getting off the freeway, or traffic lights on highways. You can't really hurt it. The computer won't let you over-rev it. 353,000 miles on my transmission, so far so good (and that's with combined weights over 25,000 pounds.