Fully automatic Class 8 transmissions

[challenger818]

I really like the class 8 RV concept and have been researching it for about a year. I know that there are 3 basic types of transmission choices in the RV world,
Straight fully manual
Autoshift's
Fully automatic (ie. Allison 4000)
Is there any way to spec. an Automatic in a clas 8 tractor? I know they make'em strong enough, they're in all big diesel MH's, and we gott'em between 500Hp and 50,000 lbs in our firetrucks.
I just think that a volve 610 with an allison 4000 (or similar) and a N-14 with 500Hp would be one sweet rig. Can you order these from any of the big manufactures or do they hafta be retrofitted or can it just not be done at all?

Challenge

[Gary Atsma]

With enough money, you can do ANYTHING. If the power limit on the Allison is high enough, no reason not to put it in, or order it on a new truck

[Doug]

You should be able to so without too much trouble, although the increased cost might spook you. I read an article a few months ago about the specs for the newest tractors used by the military (in the on-line version of a magazie I can't locate right now). They use Freightliners, with Series 60s (duh) and a 6 speed Allison, I think. Checking with Freightliner and/or Allison should get you pointed in the right direction. (Since I loathe auto trannies of any kind, I don't keep track of this sort of thing.)

[Warpath]

Absolutely, full auto are available in 500 hp configurations. But the price is huge, I believe you are looking at $30,000 plus more for full auto and $20,000 plus more for a auto shift. (I maybe low on that)

And if you go with a used truck don't get any ideas of swapping for a auto or auto shift. There is one auto you can swap into a used truck without overdrive and that is the Allison-740. But this is a rough shifting auto and will most definitely lower your top speed. And Allison won't touch you with a ten foot pole when looking at a auto shift for a used truck.

I was really worried that shifting was going to be a major pain in the rear and that I would be really unhappy having to shift. (specially a 10 speed) But it really turns out to be no problem and with a upcoming trip to Florida, I really look forward to perfecting my down shifts in the lower range and to get a better idea of what gear to slip into at what speed.

2003 28' Show Hauler Motorhome on a 1995 FL 120 www.showhauler.com

[Gary Atsma]

Hey Warpath-
I imagine you've figured out by now that the clutch is only used for starting and stopping, or that occasional pain-in-the-ass shift that won't follow orders. Clutchless shifting is the only way to go. Have a good trip!!

[Warpath]

Gary -

When bobtailing floating the tranny was much easier. With the weight the low range does not like to be floated to often, but double clutching is real easy. High range the tranny is real forgiving and I can do either.

I will be gone for the week and I will take a bunch of pictures

Bill

2003 28' Show Hauler Motorhome on a 1995 FL 120 www.showhauler.com

[onezman]

Hi Warpath,

With the loads we RVers are hauling downshifting is really not necessary most of the time. When I have to slow up, I just kick it in neutral, and slow up using the service brakes. When I can resume speed, I shift into the appropriate gear for my speed at that time.

If I have to come to a full stop, I leave it in neutral until the light turns to caution for the cross traffic, then I shift into gear and go.

Another thing I do is find a baseline for downshifting when necessary. I check my speed at, say 1000 RPM in 5th, 6th, 7th, 8th, 9th and 10th gear. These speeds are different for each truck due to different axle ratio, tire sizes and OD ratios.

Anyway, write down the speed for each gear at 1000 RPM. That way you will know what gear you can always get into for the speed you are traveling. You can extrapolate from these basis shift points as time goes on.

onezman

[paul.zr1]

On the Freightliner I just ordered for my NRC Motorhome conversion I specified the Meritor Freedom transmission. It's a fully automatic "manual" transmission with no clutch pedal. It's a 12 speed that handles the 1550 pounds feet of torque of the Mercedes engine.

The Meritor senses the load and via computer controls skip shifts as appropriate. The computer and electrical/hydraulics acctuate the shifts and controls the clutch.

You can get a lot more info on the Freightliner web site.

I don't recall the price but compared to an Allison was very inexpensive.

[paul.zr1]

On the Freightliner I just ordered for my NRC Motorhome conversion I specified the Meritor Freedom transmission. It's a fully automatic "manual" transmission with no clutch pedal. It's a 12 speed that handles the 1550 pounds feet of torque of the Mercedes engine.

The Meritor senses the load and via computer controls skip shifts as appropriate. The computer and electrical/hydraulics acctuate the shifts and controls the clutch.

You can get a lot more info on the Freightliner web site.

I don't recall the price but compared to an Allison was very inexpensive.

[Warpath]

onezman -

Excellent info. I am fresh back from my trip to Florida and put 1800 + miles on the new RV. I totally agree on the down shift, I don't do it when coming up to a stop either. I really do need to check my rpm, speed and gears and make a note, like you say. I have a few of them down, but 7,8,9 are still a bit sketchy.

Shifting is no problem and I do not mind at all, kinda fun actually. Someday down the line if I do another conversion and put it on a new chassis I would definetly look at a autoshift, meritor or world trannies. It would be nice to know that the wife could drive it if the time ever came.

2003 28' Show Hauler Motorhome on a 1995 FL 120 www.showhauler.com