TV gearing.

[Gruu]

I tow my Jayco hybrid with a 2012 Chevy Silverado with the 4.8 V8 and 3.23 gears. It does just fine in Florida where it's flat. The owners manual says I can gain 2000 lbs. towing capacity changing to 3.73 gears. Does this make sense to you? How would that effect my RPMs at any given speed? Right now at 55 MPH I am turning 2000 RPMs. Just curious.

[danimal53]

Huntindog wrote:

danimal53 wrote:

dodge guy wrote:
I would use it whenever the trailer is hooked up. It will only help when towing.

I generally do, however it affects gas mileage quite a bit, that's why I ask. I get about 9-9.5 mpg with TOW/HAUL, get about 11 without.

Tow/haul is there for more than just performance.
It raises the RPMs for upshifts, and downshifts more aggressively... As much as this improves performance. it also is easier on the TV.
Short shifting under a heavy load puts a lot of stress on the drive train. Not using it just to save a little on fuel can have expensive consequences later on.

thanks for the input, I'll use it whenever I'm towing, flat or hilly. don't want to have a price repair down the line!

[Huntindog]

danimal53 wrote:

dodge guy wrote:
I would use it whenever the trailer is hooked up. It will only help when towing.

I generally do, however it affects gas mileage quite a bit, that's why I ask. I get about 9-9.5 mpg with TOW/HAUL, get about 11 without.

Tow/haul is there for more than just performance.
It raises the RPMs for upshifts, and downshifts more aggressively... As much as this improves performance. it also is easier on the TV.
Short shifting under a heavy load puts a lot of stress on the drive train. Not using it just to save a little on fuel can have expensive consequences later on.

[danimal53]

dodge guy wrote:
I would use it whenever the trailer is hooked up. It will only help when towing.

I generally do, however it affects gas mileage quite a bit, that's why I ask. I get about 9-9.5 mpg with TOW/HAUL, get about 11 without.

[dodge_guy]

I would use it whenever the trailer is hooked up. It will only help when towing.

[danimal53]

dodge guy wrote:
Yes, tow haul mode increases the shift points to prevent lugging the motor on an early upshift. It is nice to have, but does not add power. And it will shift into OD later than when in non tow haul.

so is it not needed unless towing in hills/mountains? i guess I could just see how the trans is shifting when in flats, and if it seems to shift too "early" then ill stick with tow/haul on.

[dodge_guy]

Yes, tow haul mode increases the shift points to prevent lugging the motor on an early upshift. It is nice to have, but does not add power. And it will shift into OD later than when in non tow haul.

[time2roll]

Power is just the mathematical definition of multiplying torque and speed.
Power is determined by the engine that makes the power not by the gearing.

Having said that.... lower gears will allow the engine to run at higher RPM and generally make more power at any given speed. All this constantly changes while driving as it is all dynamic. The perception of drivability does seem to improve with lower gears and more torque. This is why diesels are so loved. Some day we will go to the next level up and have electric motors.

[subcamper]

danimal53 wrote:
thanks for the replies, a follow up question:
the TOW/HAUL button, I believe basically keeps the transmission out of 4th gear, is that correct? Should I always do this when towing, or is it not necessary in flat areas?

On my 2002 Suburban, tow/haul on does two things:

1) Delays the upshifts to prevent gear-hunting. It will eventually go into OD, but it takes longer.

2) Keeps the Autoride shocks in stiff mode full time.

Steve

[Clockman]

I have 4:56's in my 2000 2500 Silverado , (6.0l 4 speed)it originaly came with 4:10', but I went up to 33 inch tires and that took away some power, My rear end is essentially a 4:15 now, couldn't be happier, also, I can tow in Drive pretty easily where you would normally be in 3rd on flat ground...Super engine breaking though, I have 240,000 on my original brake's! and they should make it to 300,000 easily!

[Turtle_n_Peeps]

Golfcart wrote:

Turtle n Peeps wrote:

In fact you get less power to the road; not more. The only thing a higher gear ratio will give you is more torque to the road.

You dont "get" less power. it just requires less power to accomplish the task

See what I mean. :R It requires the exact same amount of power to do a job no matter what gears you have.

Tell you what. You put a vehicle on a chassis dyno with 4:56's in it and make a pull. Then put 3:00's in the rear end and make a pull. See what makes more horsepower to the wheels.

Since it pretty impractical to change rear end gears to do this I will let you cheat and just make a pull in 1 gear on a chassis dyno and then make the pull in the gear closest to 1 to 1. See what makes more horsepower.

Get back to me and let me know.

[time2roll]

subcamper wrote:
I didn't see smkettner's post while I was replying, so I didn't mean to duplicate his answers.

Steve

Sometimes it is good to read the comparison two different ways.

[danimal53]

thanks for the replies, a follow up question:
the TOW/HAUL button, I believe basically keeps the transmission out of 4th gear, is that correct? Should I always do this when towing, or is it not necessary in flat areas?

[dodge_guy]

And "just dropping a gear in the trans" is not the same as changing the gear ratio! When you change the ring and pinion each gear in the trans is much more efficient at moving a load!

Go with the swap!

[Golfcart]

Turtle n Peeps wrote:

In fact you get less power to the road; not more. The only thing a higher gear ratio will give you is more torque to the road.

You dont "get" less power. it just requires less power to accomplish the task