Hello Richard, I contacted you about 18 months ago. I was lucky enough to pick up a Twindisc transmission from a Unimog in Germany and I'm busy reading the manuals before installing it into a U1700L38. Did you ever manage to film the truck in motion?
Hey Nashy - I don't think I have any videos of it rolling. Feel free to fire any questions at me about the tranny. I did a few mods to the tranny, including a larger oil reservoir.
Thats a shame, i really was looking forward to hearing and seeing the big red beast shift. I have an enquiry in with Twindisc to see if i can put a more modern controller on the Unit. Why the larger reservoir? was it getting hot?
Hi Richard, excellent video, thank you very much. Really nice Unimog, the top end model available back then. It is a 6 litre-engine though. The Mercedes-Benz OM 366 LA engine to be specific. With intercooler (german "Ladeluftkühler" => L) and turbocharged (german "Turbo-aufgeladen" => A). The Twin Disc transmission is really interesting, they weren't used very often in the Unimog. How do you rate the driving comfort? I read that the comfort of the shifting process was a big issue with this transmission. The transmission cooler is quite impressive and impossible to fit on the short wheelbase models. Was this Unimog a fire rescue truck before? In the United States manual transmissions are pretty common at trucks as I know, so there has to be a special reason for the automated transmission. Keep on taking care of the beautiful U 2450 L. ;-) Best regards from Germany. Tobias
Tobias - thanks for pointing that out! I was thinking of my Gwagen when I said 5L! Also I said the tires are 395/80 but of course they are 395/85. I have trouble talking and thinking and filming all at the same time. The driving comfort is quite good. If you turn off the engine brake switch, it is really smooth. Otherwise it can downshift very aggressively. Of course it has to in case you have 12,000 lbs in the bed and you are going down a steep hill. I think this transmission is intended for fire work. There is a mode for "pump and roll" where you can use a hand lever to control the speed of the truck separate from the engine speed, so that a water pump on the pto would keep pumping even if you stop. It's very clever, but I never used it! It was built to compete for a US Army contract, but it was too expensive for that. I think there are 20 or so in the German military, I found a German language handbook on ebay. More here... w5yk.squarespace.com/unimog-for-sale/
Hi Richard, thank you very much for your answer. I believe that the engine brake downshifts were most likely the comfort issue with this transmissions back then. With a manual you can decide when to shift down, the automatic will do what it wants to. Back then manual transmission were still used very often in European trucks, so the more expensive automatic wasn't necessary. Nowadays there are mainly automated transmissions used in European trucks so the modern Unimog are available with this option too. However those are no torqueconverter automatic transmissions but manual transmissions which are shifted and clutched automatically based on a computer programm. Am I right that you can limit the maximum gear with the shift lever? So D4 means that it shifts till the fourth gear as a maximum but in the gears below too? The original Unimog manual transmission has an integrated transfer case. Is the transfer case of the Twin Disc transmission integrated into the transmission too or is it mounted separately behind the transmission? By the way, the german military ("Bundeswehr", means something like federal army) had tenthousands of U 1300 L's in use. They were an older and lighter version with an maximum weight of 7500 Kilogramms and the older OM 352 engine with 5,7 litres, 125 DIN-HP and without turbocharger and intercooler. A part of them are still in use, some were even totally rebuildt including a light armoured cabin. Kind regards from Germany Tobias
Hi Toby - yes, if you select 4th then it will use 1,2,3, and 4 only. The transfer case function is built into the transmission, so there are independent output drives to the front and rear torque tubes. You lock them by applying air to a connector on the transmission, so it can still be controlled by the Mercedes original switch on the dashboard. I you have the engine brake on, then the Twindisc will downshift as soon as you touch the brakes, but if you have the engine brake off, then the Twindisc does not know you are using the brakes so it does not downshift until the rpms drop. That's why it feels a bit smoother. The Torque Converter helps a lot. Much better than the U500 etc.
Hi Richard, thank you very much for pointing that out too. Very interesting. I downloaded the german documentation about the Twin Disc from your webpage and read a bit and this is really interesting in detail. Thanks for that too, I never knew about this document before. If I understand it right then even the so-called "Wandlerschaltkupplung" (Torqueconverter paired with an hand-shifted manual transmission) for the Unimog generations 427 and 437 was manufactured by Twin Disc too. Those were used more often, especially when the Unimog was used as an industrial road tractor oder as an road/rail tractor. The torqueconverter alternates the torque when you start pulling and allows to start pulling in a higher gear because it slowly fits the engine output rpm to the transmission input rpm without mechanical wear. As an rail shunting tractor these Unimog were allowed to handle up to 1000 metric tons. The combination with the manual transmission had the advantage to be cheaper, you had the opportunity to have more gears and the standard Mercedes transmission could be repaired and maintained at any Mercedes workshop around the planet. Thanks for our interesting discussion and best regards to the US Tobias
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Danke.
Hello Richard, I contacted you about 18 months ago. I was lucky enough to pick up a Twindisc transmission from a Unimog in Germany and I'm busy reading the manuals before installing it into a U1700L38. Did you ever manage to film the truck in motion?
Hey Nashy - I don't think I have any videos of it rolling. Feel free to fire any questions at me about the tranny. I did a few mods to the tranny, including a larger oil reservoir.
Thats a shame, i really was looking forward to hearing and seeing the big red beast shift. I have an enquiry in with Twindisc to see if i can put a more modern controller on the Unit. Why the larger reservoir? was it getting hot?
I think you will be stuck with the controller that came with. It is a bit of an orphan project, although it is well documented.
Hi Richard,
excellent video, thank you very much.
Really nice Unimog, the top end model available back then.
It is a 6 litre-engine though. The Mercedes-Benz OM 366 LA engine to be specific. With intercooler (german "Ladeluftkühler" => L) and turbocharged (german "Turbo-aufgeladen" => A).
The Twin Disc transmission is really interesting, they weren't used very often in the Unimog.
How do you rate the driving comfort? I read that the comfort of the shifting process was a big issue with this transmission.
The transmission cooler is quite impressive and impossible to fit on the short wheelbase models.
Was this Unimog a fire rescue truck before? In the United States manual transmissions are pretty common at trucks as I know, so there has to be a special reason for the automated transmission.
Keep on taking care of the beautiful U 2450 L. ;-)
Best regards from Germany.
Tobias
Tobias - thanks for pointing that out! I was thinking of my Gwagen when I said 5L! Also I said the tires are 395/80 but of course they are 395/85. I have trouble talking and thinking and filming all at the same time.
The driving comfort is quite good. If you turn off the engine brake switch, it is really smooth. Otherwise it can downshift very aggressively. Of course it has to in case you have 12,000 lbs in the bed and you are going down a steep hill.
I think this transmission is intended for fire work. There is a mode for "pump and roll" where you can use a hand lever to control the speed of the truck separate from the engine speed, so that a water pump on the pto would keep pumping even if you stop. It's very clever, but I never used it!
It was built to compete for a US Army contract, but it was too expensive for that. I think there are 20 or so in the German military, I found a German language handbook on ebay. More here...
w5yk.squarespace.com/unimog-for-sale/
Hi Richard,
thank you very much for your answer.
I believe that the engine brake downshifts were most likely the comfort issue with this transmissions back then. With a manual you can decide when to shift down, the automatic will do what it wants to.
Back then manual transmission were still used very often in European trucks, so the more expensive automatic wasn't necessary.
Nowadays there are mainly automated transmissions used in European trucks so the modern Unimog are available with this option too. However those are no torqueconverter automatic transmissions but manual transmissions which are shifted and clutched automatically based on a computer programm.
Am I right that you can limit the maximum gear with the shift lever? So D4 means that it shifts till the fourth gear as a maximum but in the gears below too?
The original Unimog manual transmission has an integrated transfer case. Is the transfer case of the Twin Disc transmission integrated into the transmission too or is it mounted separately behind the transmission?
By the way, the german military ("Bundeswehr", means something like federal army) had tenthousands of U 1300 L's in use. They were an older and lighter version with an maximum weight of 7500 Kilogramms and the older OM 352 engine with 5,7 litres, 125 DIN-HP and without turbocharger and intercooler.
A part of them are still in use, some were even totally rebuildt including a light armoured cabin.
Kind regards from Germany
Tobias
Hi Toby - yes, if you select 4th then it will use 1,2,3, and 4 only. The transfer case function is built into the transmission, so there are independent output drives to the front and rear torque tubes. You lock them by applying air to a connector on the transmission, so it can still be controlled by the Mercedes original switch on the dashboard.
I you have the engine brake on, then the Twindisc will downshift as soon as you touch the brakes, but if you have the engine brake off, then the Twindisc does not know you are using the brakes so it does not downshift until the rpms drop. That's why it feels a bit smoother. The Torque Converter helps a lot. Much better than the U500 etc.
Hi Richard,
thank you very much for pointing that out too.
Very interesting.
I downloaded the german documentation about the Twin Disc from your webpage and read a bit and this is really interesting in detail. Thanks for that too, I never knew about this document before.
If I understand it right then even the so-called "Wandlerschaltkupplung" (Torqueconverter paired with an hand-shifted manual transmission) for the Unimog generations 427 and 437 was manufactured by Twin Disc too.
Those were used more often, especially when the Unimog was used as an industrial road tractor oder as an road/rail tractor.
The torqueconverter alternates the torque when you start pulling and allows to start pulling in a higher gear because it slowly fits the engine output rpm to the transmission input rpm without mechanical wear.
As an rail shunting tractor these Unimog were allowed to handle up to 1000 metric tons.
The combination with the manual transmission had the advantage to be cheaper, you had the opportunity to have more gears and the standard Mercedes transmission could be repaired and maintained at any Mercedes workshop around the planet.
Thanks for our interesting discussion and best regards to the US
Tobias
Hi Richard - just wondering if your mog is still available
SC Nomad - sorry, sold it the very first day this was posted!
Richard Russell Good for you! Just out of curiosity, what's the top speed?
SC Nomad it will do 83mph with those tyres (46”). 5th gear is overdrive and 6th is double (0.577 to 1)
Richard - any chance you might be available for a quick chat about your old truck?
Hey there SC Nomad - if you are on Benzworld, I am W5YK. Sorry I missed this for so long.