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#1
08-14-2012, 09:34 PM
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240D 4 speed trans not turning driveshaft
I recently purchased a '75 W115 240D with a 4 speed manual.
When you put the car in gear, the output flange (and driveshaft) do not turn. However, the speedometer reads output shaft speed. I'm not familiar with these transmissions and haven't come across an exploded diagram. Any guesses as to what broke in the tail housing causing the output flange not to turn? The previous owner said he had experienced the issue once before. After jacking the car up to look for a cause and not finding anything, he put the car back on the ground and problem mysteriously disappeared. This makes me wonder if there is a loose/broken piece in the trans that somehow slides in and out of engagement? I won't have a chance to pull the trans for a couple days so I'm just trying to get an idea of what's going on in the meantime. Sorry for the long read! pic of the old girl: 
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#2
08-14-2012, 09:54 PM
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These threads focus on autos, if I recall, but the problem may be the same:
no power to the wheels; transmission issue? Transmission Problem & Fix Good luck.
__________________
1968 220D, w115, /8, OM615, Automatic transmission. My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).
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#3
08-14-2012, 10:02 PM
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Quote:
Thanks!
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#4
08-15-2012, 04:39 AM
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The nut that holds the yoke into the rear of the trans has been known to come undone when the seal has been replaced . This happens when the lock washer has not been replaced or left off completely.
Undo the flex disc and push it out of the way. You will then be able to see the yoke and the circular nut that holds it into place. I have been able to simply tap it around with a hammer and punch to tighten it up again on ealier model fourspeeds. 
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#5
08-15-2012, 02:41 PM
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Thanks for the replies!
Took the guibo out today and sure enough, the nut had backed off and the flange spun freely on the output shaft. I've got a new flange and updated nut on the way. The old nut wouldn't budge with a drift and hammer so I'm keeping my fingers crossed that the local Mercedes shop foreman can hook me up with the correct socket. Guess I'll be getting creative if not. Anybody got a torque spec for the new nut?
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#6
08-15-2012, 03:59 PM
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Quote:
__________________
Remember, Safety Third! '99 E300 Turbodiesel, '82 300TD, 1996 12V Cummins Turbo, '94 Neoplan - Detroit 6V92TA
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#7
08-15-2012, 04:15 PM
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With all respect sir, if you are unable to unscrew the nut that retains the three-legged flange, how are you able to state that it backed off?
The nut is staked into a groove in the output shaft to prevent it from unscrewing. That stake is the locking device, not a lock washer. A thin, narrow chisel may be driven into the groove under the stake to bend it clear of the shaft. The nut may then be unscrewed. The replacement nut will probably be 30mm/12 point. Torque is 150Nm (113ft/lb). And do stake it! If you are very fortunate, the internal splines of the three-legged flange are the ones that have been sheared off, and not the splines of the output shaft.
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#8
08-15-2012, 09:17 PM
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Quote:
Thanks for the torque specs! I'm really hoping that since the output shaft is considerably harder than the cast flange, it has survived without damaging the splines. We'll see tomorrow
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#9
08-15-2012, 10:12 PM
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I hope that the nut does come off readily. When you do get it and the flange off, you may wish to consider removing the rear housing to facilitate cleaning the sheared off splines from the shaft and from inside the housing, rear bearing, and reverse gears. Replacing the rear seal is much easier with the housing on the bench. The threads on the output shaft may need a bit of attention also, particularly if the nut was mis-installed.
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#10
08-16-2012, 09:21 AM
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Shafts are very hard, so with a bit of luck the flange will have taken all the damage. Getting the rear housing off is a good idea. You may also consider replacing the flushing nut by a magnetic one (available at MB) so as to collect all the metal particles that will be left in there, and flush your trans after 500 miles again. ATF goes into those manual trans, not gear oil as people often do.
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#11
08-16-2012, 10:40 AM
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There is a locking 'cup' that fits behind the nut. The nut is slotted and acts as a lock. The side of the cup needs to be staked into the slot. That wasn't done before.
Inspect the flex disc for cracks and replace if necessary. Make sure to grease the front joint too if there is a grease joint.
__________________
Regards Warren Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL ENTER > = (HP RPN) Not part of the in-crowd since 1952.
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#12
08-16-2012, 01:19 PM
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Well, looks like my luck didn't hold this time.
The splines on both the flange and output shaft are wiped clean. I've got a line on another 4 speed local to me so hopefully I can get this thing back on the road pretty quickly.
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#13
08-17-2012, 01:20 AM
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Ah yes ,same old story. I've seen this before and a lot of times were because the locking washer (yes i know some folks think I am talking about a spring or wave washer but it's called a locking washer
) was never replaced . But the previous owner must have been driving with a loose flange for quite a while to wreck the rear shaft .
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#14
08-27-2012, 10:48 AM
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Picked up the replacement trans last week and cleaned her up. How much side-to-side play is acceptable with the input shaft? I'm debating whether or not to tear the trans down before it goes in the car.
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#15
09-10-2012, 11:09 AM
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Well, I overlooked a key element - My 240D has the iron case 4 speed and the supposed W115 trans I got turned out to be an aluminum getrag unit from a W123.
From what I can see, the shift linkages are different, the speedometer drive is on the opposite side, and the bellhousing seems to require a different adapter plate. Can I grab most of these parts from a W123 or will it require more fabrication? Given the differences between the two transmissions I'd assume swapping the output shafts is not an option. Has anybody tried to make this swap work or am I better off finding another iron box?
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