[danj_otr]

This is not so much of a maintenance question as a question of weather or not this will do damage to the tranny.

When I was driving I was told that the 9 Speed Eaton Fullers can be shifted into 4th(or 5th if you consider the granny a gear) gear by means of going into high range and shifting into the what would be the low gear.

I have done it numerous times when I have been driving, but wanted to be sure it really is a problem or not.

[Kranky]

This has been discussed here before: http://www.classadrivers.com/phpBB2/...ic.php?t=22928 .

I have done that, and I personally don't see how it would cause any harm, but I'm not an Eaton Fuller transmission engineer.

It does work good when turning a corner, you don't have to make a range shift, just leave it in hi range and shift the stick into lo.

[danj_otr]

That's kind of what I thought, Thank you!

[roadranger]

That gear is more like half way between fourth and fifth. See http://www.classadrivers.com/phpBB2/...ic.php?t=22928 8)

[Birken Vogt]

The reason they say not to use it, is that the range (rear) box isn't designed to take all the torque in high range that the main (front) box throws at it when in the "L" position. Obviously this depends on the engine and how much torque it has. Just depends who pays the repair bills I guess!

Birken

[roadranger]

Originally Posted by Birken Vogt

The reason they say not to use it, is that the range (rear) box isn't designed to take all the torque in high range that the main (front) box throws at it when in the "L" position.

I've heard that too - but I think it is just "CB" talk. In high range the rear box is staright thru - no gears involved. In low range it is using a gear reduction that should be more fragile than a straight thru lockup! I've challenged folks in the past to point out where Eaton states this and so far no winners :lol: .

[Birken Vogt]

I agree it sounds strange but for liability purposes they are never going to reveal their reasons for such things. All they will ever do is tell you not to.

Can you point to anywhere it says why you can't split the low range in a 13 speed? Yet we all know it is the same reason.

Birken

[Kranky]

Can you point to anywhere it says why you can't split the low range in a 13 speed? Yet we all know it is the same reason.

Because on a 13 speed the shift knob has an interlock that won't permit the splitter button to come out of under when the range selector is in low range.

An 18 speed is essentially the same transmission, just the knob does not have this interlock and the splitter can be used in low or high range.

[Birken Vogt]

An 18 speed has the same parts but is much stouter than a 13 speed. Why not put an 18 speed knob on your 13 speed transmission and see what happens?

Birken

[Kranky]

Originally Posted by Birken Vogt

An 18 speed has the same parts but is much stouter than a 13 speed. Why not put an 18 speed knob on your 13 speed transmission and see what happens?

Birken

The only 18 speed that would be "stouter" would be the 22918 rated at 2250 ft lbs of torque.

Any of the other Fuller models are the same torque capacity whether 13 or 18 speed, for example a 18913 and a 18918 are both rated for 1850 ft lbs, and a 20913 and a 20918 are both rated for 2050 ft lbs.

Why not put an 18 speed knob on your 13 speed transmission and see what happens?

The only thing that would "happen" is that you would now have an 18 speed.

And if referring to Mack 13 and 18 speed transmissions the same holds true- all the T200 series of Mack transmissions are rated in excess of 2500 ft lbs of torque due to the triple countershaft design.

A Mack T2130 13 speed can be converted to a T2180 18 speed by simply installing an 18 speed shift knob.

And while we're discussing this, yes I do use the "mystery gear" (LO on the stick while in HI range) on a regular basis, and have never observed any ill effects on the transmission from doing so.

It works great for turning corners, no need to go to lo range for 4th, then right away go back to hi range for 5th, instead I just downshift into "mystery gear, turn the corner, and go up from there.