[Nutz 4 Benz]

How much tougher is the diesel? Fudged my 280E's slushbox at autocross and have both a diesel transmission (1984) and an eurospec gasser transmission (1981) (if there's any difference from US spec :dunno: ).

 

[Stretch]

For both manual and automatic transmissions I get the impression that the cogs inside are the same for W123 vintage. There's no beefing up because it is a diesel.

The early 722.0 (so this is an automatic transmission) were a three speed version of the 722.1 four speeds (or vise versa). These were fitted to the more powerfull V8 petrol engines with a fluid coupling rather than a toque converter. And later on I think (but not sure) that some of the 722.3s had different ratios for the lager petrol engines even though the top gear was always 1:1. As far as I know only the 722.5 had an "over drive" 5 th gear.

From what I can make out the main differences between diesel and petrol for automatic transmissions are

1) the casings - starter motor bump on different side because of IP pump placement on the OM615 / OM616 / OM617
2) valve bodies - relied more on vacuum shift assistance
3) governors - tuned shift points for a particular engine combined with differential ratios which varied quite a bit depending on engine power output

 

[Nutz 4 Benz]

Years ago, I replaced my '80 280E Euro's transmission with one from a '79 W116 300SD. They were shaped way differently, but bolted up with zero issues. Seemed to accelerate the same, but it was from a dogged out diesel.

 

[Stretch]

I was surprised to hear that that worked!

According to EverythingBenz - Mercedes-Benz Forum and Web Search Using Google

The euro 280E was fitted with a 722.112 or a 722.309 - with a M110 engine

The '79 SD had an OM617a with a 722.120 - all of the OM617s have starters on the right hand side of the vehicle (taken as sitting in the car looking forwards)

I was under the impression that the starters on the petrol engines were all on the left but that doesn't seem to be the case - looking at the stripped down EPC for the M110 engine it seems to be on the left

http://mb.ilcats.ru/part/class/1/ccode/1/cat/032/type/110/subtype/984/group/01//

Good to know eh?

Do you remember any discrepancies with the speedo?

The 280E should have had a 3.69 rear end and the SD should have had a 3.07 rear end...

 

[Nutz 4 Benz]

Yeah, had to swap the speedo thing off from the original transmission, took maybe 5 minutes. M102 4 banger is the one with the oddball stater location if memory serves me right.

 

[PlaneCrazy]

Starters for M110, M114, M123, M115, OM615, OM616 and OM617 were all on the right side of the engine. M102 was the first to move te starter to the left. Any tranny that can bolt onto OM616 will bolt onto M110, but not onto M102 or later.

Anyone slap a 722.6 from a M104 into a W123 yet?

EDIT: FWIW, info on the V8 trannies are far less forthcoming...:dunno:

 

[Stretch]

...
Anyone slap a 722.6 from a M104 into a W123 yet?

...

I'll leave that one for you to do.

 

[MBeige]

Aside from the technical points mentioned above, it also boils down to previous owner maintenance (or lack thereof) as well as how the transmission was treated.

Between two similar condition diesel and gasser transmissions, I don't think there is much difference. I do know that the drive shaft (propeller shaft) is wider on the diesel, compared to the gasser. That may be a contributing factor.

Nice thing about gasser and diesel MB's is the torque is about the same as the horsepower, compared to other cars which have higher HP than torque. This makes them rev-happy but has less torque. On the other hand, too much torque is what kills transmissions.

 

[Master7Chief]

On the other hand, too much torque is what kills transmissions.

That makes perfect scene due to increased bearing loads during high torque conditions. So is it better to down shift rather than accelerating (from ~20mph) in the same gear from 2000rpm up? That will lower bearing loads but increases wear on the clutches,bands, pistons and valves in the valve body.

 

[MB300Dave]

So a 722.6=6sp? If I follow this correctly that is!

What are those in?

 

[PlaneCrazy]

722.6 is the 5-spd auto, still being used in the most powerful AMG cars. 722.5 was basically 722.3+electronic overdrive, while 722.6 is an all-electronic 5-spd with three times the torque capacity of 722.5 - 722.3 is incredibly rugged, but the OD forced MB to derate 722.5

The W210 and W140 introduced the 722.6 with the M111, M104, OM602 and M116 and M119 V8s, so it's in theory an easy swop. Just figure out how the engine signals differ between W123 engines and these later ones.

No, I don't think the OM602 had electronic injection, so the tranny can communicate to an all-mechanical diesel. But I may be wrong, I have been before.

And no, I would always fit a manual tranny instead. My next dream project (you know, after converting Donkey to a 4Matic) is a W123 230E with the 2.3-16 engine and a 6-spd manual from the M111. And, since "Donkey" uses diesel, I shall call that beast with its petrol engine "Pferd". Oh yeah

Sorry, my bad, off-topic again...

 

[Govert70227]

For both manual and automatic transmissions I get the impression that the cogs inside are the same for W123 vintage. There's no beefing up because it is a diesel.

The early 722.0 (so this is an automatic transmission) were a three speed version of the 722.1 four speeds (or vise versa). These were fitted to the more powerfull V8 petrol engines with a fluid coupling rather than a toque converter. And later on I think (but not sure) that some of the 722.3s had different ratios for the lager petrol engines even though the top gear was always 1:1. As far as I know only the 722.5 had an "over drive" 5 th gear.

From what I can make out the main differences between diesel and petrol for automatic transmissions are

1) the casings - starter motor bump on different side because of IP pump placement on the OM615 / OM616 / OM617
2) valve bodies - relied more on vacuum shift assistance
3) governors - tuned shift points for a particular engine combined with differential ratios which varied quite a bit depending on engine power output

Early automatics for low powered engines (such as the 200D/220D) had fluid couplings so that not too much power was lost. Once MB designed a torque converter with enough efficiency, they switch to torque converters. So on the early W115s you can get fluid couplings, on the later W115s and W123 only torque converters are used.

The three speeds automatics were indeed only used for high powered V8s were the high torque range made three speeds possible. Also the automatics could more easily cope with the high torque of the engines. The test version of the 300SEL 6.3 used a truck manual gearbox, but the commercial department thought that such an uncomfortable gearbox could not be sold to the public, so it had an automatic.

The oil pressures of a gas and diesel automatic transmissions are also different, probably to account for different shift points, but perhaps also for the difference in torque output. Diesels and gas engines can have the same torque, but it occurs at different rpm.

 

[Stretch]

Early automatics for low powered engines (such as the 200D/220D) had fluid couplings so that not too much power was lost. Once MB designed a torque converter with enough efficiency, they switch to torque converters. So on the early W115s you can get fluid couplings, on the later W115s and W123 only torque converters are used.
...

Do you have a date or a chassis number for that Govert?

 

[Govert70227]

Do you have a date or a chassis number for that Govert?

I was not correct. All the models of the first series W114/115 from 1968 to 1973 had hydraulic couplings, from low-powered 200D to high-powered 280E. See here on the MB website:

W114-W115-200D-Getriebe ? Mercedes-Benz Classic Wiki - Online-Lexikon rund um Mercedes-Benz Oldtimer
W114-W115-280E-Getriebe ? Mercedes-Benz Classic Wiki - Online-Lexikon rund um Mercedes-Benz Oldtimer

Look for the text: hydraulische Kupplung im Automatikgetriebe

The second-series from 1973 all had torque converters:

W114-W115-200D2-Getriebe ? Mercedes-Benz Classic Wiki - Online-Lexikon rund um Mercedes-Benz Oldtimer
W114-W115-280E2-Getriebe ? Mercedes-Benz Classic Wiki - Online-Lexikon rund um Mercedes-Benz Oldtimer

Look for the text: hydraulischer Drehmomentwandler im Automatikgetriebe

Drehmomentwandler is torque converter.

 

[Stretch]

Great information Govert - thanks

 

[barika]

I think these facts maybe belong here:

How many W123 cars with diesel (or diesel compatible) 5-speed gearboxes were made?

33206 cars 240D (including 240TD and Long)

10320 cars 280E (including 280TE plus 16 Long)
4679 cars 300D (including 300TD and 4 turbodiesel coupés)

total 48 205.

 

[PlaneCrazy]

Also include the G-Wagen W460-series. Different ratios, but still compatible.

 

[MBeige]

Also include the G-Wagen W460-series. Different ratios, but still compatible.

How far apart are the ratios? They may be significantly different to be incompatible.

 

[PlaneCrazy]

W123 (717400):

1: 3.82
2: 2.20
3: 1.40
4: 1.0
5: 0.81
R: 3.71

W460 280GE
1: 3.82
2: 2.20
3: 1.40
4: 1.0
5: 0.81
R: 3.71

So I think it's safe to assume that they are, in fact, indentical...

 

[drizzy]

Love just reading threads like this even if they don't pertain to what I'm doing. Just to enjoy the fact that Mercedes thought to make nearly everything cross compatible.