Unimog automatic transmission

[Sailmog]

I am finally considering getting my dream truck, a Unimog. However due to some long term health issues, I need an automatic transmission. Is my only option a 406/416 with the torque converter? Any help on the following questions is greatly appreciated. Use would be small farm work and some trail riding/four wheeling. I do not want to do a complete engine/trans/T-case swap since I want the torque tubes and Unimog transmission to remain. I have mechanical and engineering background and would be willing to try an automatic transmission swap of some kind.
1) Can I get a torque converter for the 404? The 404 is cheaper and more plentiful.
2) Can I get a torque converter for the SBU square cab models?
3) Is it possible to place an automatic transmission in front of the Unimog transmission? It would be like having a 3-speed auto and an 8 speed transfer case. I know, there are fitment issues and supports that will need to be dealt with but will it work in principal. Will the auto trans survive te heat and type of use? Ideally, replacing the whole clutch assembly with a GM TH350 or TH400 seems best. I have also found a GM powerglide that is only 17 inches long at Summit Racing. With the clutch gone, could I speed shift between the Unimog gears? I could also use a manual shift auto so I could shift when needed. I just need to get rid of the clutch.
4) If an automatic were installed, would I lose the ability to run the PTO since it no longer would have the double clutch?

 

[Victorian]

I have never seen a 416 with an automatic transmission... Not sure if it's even possible. The new ones have it... Unicat converted a U1200 with a in house made one and installed one in a U2450 6x6 with a Cummins engine . All I know, it can't be easy... Good luck!

 

[mhiscox]

All I know, it can't be easy... Good luck!

:iagree:

It would be quite a project. There were two SBUs that had automatic transmissions put in them by Twin Disc, the Wisconsin company that makes marine and industrial transmissions, but those were big and expensive trucks, not really a good match with your use even if, magically, one became available.

If you haven't already done so, you might join the Unimog Mailing List and ask the question of the group there.

http://www.tx4x4.com/index.php?page=uml

 

[jostein]

Hm, hard to see a doable option as long as you need to keep the unimog gearbox. If it helps, it would be relatively easy to make an air or electrically operated clutch.

 

[mogwildRW1]

Mike,

There were more than two. I've seen several come up for sale on Mobile.de, Merex had one a year or two back. Few big firemog's were built using the Twindisc, and it actually shows up in the EPC as an option from factory on the 2150L, not just in the Uniwolf.

-trev

:iagree:

It would be quite a project. There were two SBUs that had automatic transmissions put in them by Twin Disc, the Wisconsin company that makes marine and industrial transmissions, but those were big and expensive trucks, not really a good match with your use even if, magically, one became available.

If you haven't already done so, you might join the Unimog Mailing List and ask the question of the group there.

http://www.tx4x4.com/index.php?page=uml

Another option is the factory air assisted clutch option. This lightens the clutch push to a minimum, not sure if you could tie into it to use another device to push the clutch or not:

 

[toylandcruiser]

a U500 is automatic

 

[mogwildRW1]

No it's not. It has electric auto shift.

 

[toylandcruiser]

No it's not. It has electric auto shift.

you can have either option. You can use the clutch to shift or not use it. Same difference.

 

[toylandcruiser]

http://www.truckinginfo.com/channel...1/unimog-introduced-with-automatic-shift.aspx

 

[mogwildRW1]

Yes, but it's still a standard transmission. I didn't say it wasn't a great option, just commenting it's not a true automatic. You should see the reset procedure for that system should it have issues. Still has a throw out bearing (which had a recall for air ingestion), etc.

Automated gearbox

It's called Electro Automatic Shift, or EAS, and it's what's generically known here as an automated mechanical transmission. It does the clutching and shifting while the driver merely punches the accelerator and steers. EAS has no torque converter or powershift functions, so is not a full automatic, but McTernan and his colleagues feel it's close enough, while still retaining the preciseness inherent in a manual.

it uses electronically controlled clutching and shifting that the driver needn't be concerned with, except that he/she should know that a clutch is there to avoid abusing it. Indeed, with EAS the clutch can still be used manually, and should be while in the transmission's optional low-range modes. Otherwise, the clutch pedal folds up and out of the way, and the tranny becomes a two-pedal type.

Driving impressions

The gearbox is the same Telligent eight-speed used in all U500s, and its standard "highway" ratios take the truck up to 70 mph. You choose Auto or Manual with a rocker switch near the paddle-like shift selector, both on a small console next to the driver's seat. In full manual mode, you move the selector to Drive, engage the clutch with the pedal, apply power, then upshift by tapping the paddle up and quickly punching the clutch. Downshifting is similar; you preselect the next lower gear by tapping the paddle backward and punch the clutch.

In Auto mode with the clutch pedal folded up, you simply switch to Drive and depress the accelerator. Usually it'll start out in 2nd or 3rd and upshift as the engine revs up. It will downshift as road speed falls, eventually going to one of the lower gears and declutching as the truck comes to a stop. There was some clunking as the transmission descended into its lower gears, but it never missed any. To move out, you take your foot off the brake pedal, which signals the controls that they can engage the clutch as soon as you again get on the accelerator.

If you use a very light foot, EAS will "short shift" — upshift at low rpm — but pressing the pedal to get moderate to snappy acceleration causes the engine to rev almost to its 2,600-rpm limit in each gear. I found this a little disconcerting because I was taught years ago that high revs waste fuel. Shift "progressively," keeping engine speed low until you really need the horsepower that comes at higher rpm, the old pros told me. And you really don't need a lot of horsepower until you're on the highway.

So I used EAS's semi-manual feature: I tapped the paddle selector to initiate an upshift, usually for each gear change. The clutch still works automatically, and I could watch the tachometer or just listen to the engine and command a shift whenever I thought it necessary, which was almost always below 2,000 rpm. I could floor the accelerator and still short shift, and could downshift while braking to get more engine drag. Or I could leave it alone and the automated shifting would proceed as the transmission's controls thought best.

As capable as the EAS is, it's not fully automatic and therefore might not fully answer the Allison question posed by some potential customers. But engineering an Allison RDS into a low-volume vehicle might not make much economic sense. So the automated variant of the manual 8-speed is the answer, and it's a clever one.

Source

 

[mogwildRW1]

Though import would be a hassle (some might argue it could be brought in as a tractor :ylsmoke: ) The Zetro's has an Allison transmission.

 

[rblackwell]

I am finally considering getting my dream truck, a Unimog. However due to some long term health issues, I need an automatic transmission. Is my only option a 406/416 with the torque converter? Any help on the following questions is greatly appreciated. Use would be small farm work and some trail riding/four wheeling. I do not want to do a complete engine/trans/T-case swap since I want the torque tubes and Unimog transmission to remain. I have mechanical and engineering background and would be willing to try an automatic transmission swap of some kind.
1) Can I get a torque converter for the 404? The 404 is cheaper and more plentiful.
2) Can I get a torque converter for the SBU square cab models?
3) Is it possible to place an automatic transmission in front of the Unimog transmission? It would be like having a 3-speed auto and an 8 speed transfer case. I know, there are fitment issues and supports that will need to be dealt with but will it work in principal. Will the auto trans survive te heat and type of use? Ideally, replacing the whole clutch assembly with a GM TH350 or TH400 seems best. I have also found a GM powerglide that is only 17 inches long at Summit Racing. With the clutch gone, could I speed shift between the Unimog gears? I could also use a manual shift auto so I could shift when needed. I just need to get rid of the clutch.
4) If an automatic were installed, would I lose the ability to run the PTO since it no longer would have the double clutch?

I know I might have missed something here (as I didnt see what Unimog you are thinking of getting) but since you are in the US (and Unimogs generally are scarce) you could consider looking for a U500 with the automatic (8/6 Telligent) transmission. The U500 are getting a bit scarce but I am sure there are still a few out there.

 

[nick disjunkt]

Jay at Couch Offroad in Denver has done some unusual conversions. He would be a good person to talk to about the options.