Speed didn't increase with downshift

Down shifting into 3 will give you more power for pulling not speed. Higher gear and more torque will give you speed. Also don't forget that a MH has the aero dynamics of a small barn so the faster you go the more air you are pushing, slowing you down.

We have V10 but the earlier transmission called 4R100. You should have 5R110 which is also called TorqShift. I can say the V10 package is a very "busy" sounding setup. Ours seems to downshift when I wouldn't think it should need to, and a lot of revving noise comes with it. Our chassis doesn't have a tach so I can't put a number of RPMs difference on it.
I've driven the TorqShift a few times and it seemed to manage shifting a lot better. That button on the end of the shift lever causes TorqShift to do a lot of tricks not possible with 4R100. Are you driving with that switch in the Tow/Haul position or the "normal" position?

It is not enough to just downshift, you have to step on the gas. It is also possible to cruise on level ground as speedsthat you don't have enough power to maintain on a grade. You don't get full power until the throttle is floored at 4000-5000 RPM.

I've been able to accelerate on 5-6% grades, after being slowed by big trucks, but this would be in the 35-45 MPH range, and in 2nd gear, same gear as 3rd on the 5-speed.

It just depends on grade and speed. If grade and speed needs 400 hp for your weight, and you can get at most 250-300, under very specific speed and gear conditions, you are going to slow down to a speed that matches the power output. Your RV is not going to perform like a 200 hp, 4000 pound car on grades. To do that it would need close to 700 hp over a wide range of road speeds, and simply doesn't have it.

Depends on what you are towing or driving. All vehicle have limits and when towing or driving close to yours there may just not be enough power to accelerate quickly. I assume that it will eventually gain speed if you continue holding the throttle open.

locster wrote:
I would just take it out of 3rd and back to D and really floored it to force it to downshift..

I'm not sure what you are trying to say here:h

You were in 3rd, weren't going fast enough so you upshifted into D, then mashed to pedal to the floor so you were in 3rd again? Why not just give it more throttle to begin with, and let the truck do the thinking. The 5R110 usually makes pretty good decisions. Keep Tow/Haul mode on so it will hold lower gears longer, and also provide grade-braking assist.

carringb wrote:

locster wrote:
I would just take it out of 3rd and back to D and really floored it to force it to downshift..

I'm not sure what you are trying to say here:h

You were in 3rd, weren't going fast enough so you upshifted into D, then mashed to pedal to the floor so you were in 3rd again? Why not just give it more throttle to begin with, and let the truck do the thinking. The 5R110 usually makes pretty good decisions. Keep Tow/Haul mode on so it will hold lower gears longer, and also provide grade-braking assist.

The difference is when I manually went into 3rd, the speed didn't increase as much as when the tranny automatically downshifted. I think I'll just leave it to the computer to do the shifting from now on and drive with a heavier foot on the gas when needed.

I've also tried the tow/haul mode and getting myself used to the jolts from the braking assist from the tranny.

Sounds like I just need more road time with this thing.

why do you want to speed up going up a hill? are you trying to go up the hill as fast as you drive on the flats. I guess I don't understand the question.

locster wrote:


The difference is when I manually went into 3rd, the speed didn't increase as much as when the tranny automatically downshifted. I think I'll just leave it to the computer to do the shifting from now on and drive with a heavier foot on the gas when needed.

Sounds like you may be used to smaller motors with a less-flat torque-curve. You did not get more power simply by downshifting because the V10 has a such a flat toque-curve. But, when you downshift, you can make more power with more throttle, since peak HP is around 4200 RPM.

Just sit back, and let transmission do the work:C

I am not sure you understand what gear you are in. Leave it in D and just press harder.
Usually just pull the lever to hold the gear if the transmission is hunting.
It is OK to go a little slower up the hills.

" You did not get more power simply by downshifting because the V10 has a such a flat toque-curve"


This is not correct. If there is a flat torque curve then the downshift should make more horsepower. Assume the torque was the same before and after the shift. Then when in the lower gear more rpm with the same torque before the shift will be more horsepower to the rear wheels.

But due to the size and weight of the unit the extra horsepower is not going to accelerate very fast but it should accelerate until he reaches the point that the horsepower demand is equal to what the engine can produce.

A flat torque curve will give about a 45 degree horsepower curve. The older Cummins had very flat torque curves thus with the horsepower increasing at the rate it did with rpm is why they made very good towing engines.

It is horsepower that moves things up the mountain.