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66' Unimog 404
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Discussion Starter #21
Glad to see you back working on it,I have the first adapter plate I made that was 1/2 inch thick but went to 3/4 because the mog input shaft was bottoming out in the tdi crank recess where the pilot bearing goes.You are welcome to have it just pay the shipping maybe you can just cut 1/4 inch off the input shaft and all will be well,or just copy it to 3/4.My plate has an 11 degree tilt towards the pasenger side that would help keep the injection pump from protruding too far into your right leg.I ended up drawing a new flywheel up and had that machined and it wasnt cheap and it pretty heavy,like 30 pounds heavy.Give me a call if you would like to chat Ill be posting hopefully tomorrow as im supposed to pick my body up from the paint shop.Hope all goes well Earl 609 685 1456 oh and im on the east coast so im 3 hours ahead
Thanks a bunch for the information and the adapter plate Earl! It will help a ton.
 

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66' Unimog 404
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Discussion Starter #22
Thanks @RPMz.

I'm currently investigating whether I could fit the Unimog flywheel onto the TDI. I'll hopefully get a chance to remove the flywheel from the M180 and get the gyst of what that would look like next to the TDI tonight.

Flywheel fitment will be null if the stock clutch / pressure plate wont hold the power. I've heard people using it with the om617 (~240ft-lb of torque). I found an "HD" new unimog flywheel on Ebay from Lancaster that is stronger than stock. Hopefully I'll hear good news from "blueman636" about it's potential soon.
If I can balance and tap new holes in the unimog flywheel, I might be able to skip some of the engineering / work Earl did with his VW m1 flywheel gear ring and starter. I'd just keep things 24V and sort out the 12V glow plugs for cold starts later.
 

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66' Unimog 404
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Discussion Starter #23
I took the flywheel assembly off of the M180. Sorry about the poor picture quality.
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If I’m not mistaken, the puck clutch disk was in backwards with the thicker center mass towards the transmission. One of the springs was off and there was finger wear from rubbing on the disk. I’m happy about this because it makes all this work a little more necessary in my mind.

The flywheel seems to be the same size as the TDI flywheel, which would probably fit the diameter of the bellhousing.

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The TDI six inner bolts are further from the center than the Unimog flywheel. I imagine drilling the Flywheel holes out to reach the TDI holes wouldn't be a problem for a machine shop to do while maintaining center.

I’ve found a performance OM617 clutch kit from Yorkshire that’s “good for 600 hp” with the same, 10 spline count. I imagine it’s the same input shaft diameter because I’ve read about using clutches from OM617 equipped G-wagons in Unimogs. I don’t know if the OM617 G-wagon flywheel is the same flywheel as this kit.
I emailed Luke Dale at Diesel Pump UK to see if the OM617 clutch is the same as a G-wagon and for dimension drawings.

The kit is ~$1,000, which is similar to the cost of modifying the Unimog clutch and buying a new clutch plate and disk. if it lasts much longer than the "HD Unimog pressure plate" and puck clutch, then it would be worth sorting out. I don't know about the clutch pedal positioning or how much of a PITA adjusting that could be.
 

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[’ve found a performance OM617 clutch kit from Yorkshire that’s “good for 600 hp” with the same, 10 spline count. I imagine it’s the same input shaft diameter because I’ve read about using clutches from OM617 equipped G-wagons in Unimogs. I don’t know if the OM617 G-wagon flywheel is the same flywheel as this kit.
Be very careful... There are multiple 10 spline clutch patterns and, as far as I have been able to find, the 10 spline Unimog clutch plate is different from all other common MB passenger/truck clutch splines. (The exception being some MB Trac and various tractors by Landini/Putzmeister/Steyer/etc.)

The Unimog clutch (404, 419, some 406/416) uses a 26x32-10N spline pattern. In the 404, it is a 225mm or 228mm clutch disc, depending on where it is sourced. For instance, below on the left is a new 404 clutch (plate style, E.Sassone #0168, listed in the catalog as 225mm but measures 228mm). On the right is a common MB clutch, in particullar for a 1967 MB 250S (M180 engine, Sachs 1861-515-336, 228mm). Both are 10 spline and look identical. But the 250S clutch is actually a 23x29-10N, slightly too small to fit on the Unimog transmission shaft. Additionally, though the disc is the same size, and the M180 uses the same crank bolt pattern, the 250S flywheel is nearly an inch larger in diameter and does not fit in the 404 bellhousing.


Second note: The one true diesel 404 (Angolan military 404.117 with OM615) used a 250mm clutch disc. The .117 used a different engine-bellhousing mount plate, it is unclear to me at the moment if the flywheel and bellhousing were larger or not.

I have spent hours going thru various clutch manufacturer catalogs and have lots of part numbers for 26x32-10N clutches, but few fit the size requirements.
 

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66' Unimog 404
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Discussion Starter #25
Thanks choprboy.

I won't be buying the OM617 clutch kit.
I'll be ordering a replacement clutch puck disk and the "HD" pressure plate tomorrow.

I'm hoping to avoid some of the trouble Earl had with adapting a VW flywheel to the Unimog, by adapting the Unimog flywheel. We'll see if it happens.

The Unimog flywheel bolt holes aren't close to matching up with the TDI flywheel bolts. you can see with the small TDI spacer behind the Unimog flywheel.

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Drilling six holes into the Unimog flywheel won't look pretty, but it seems to be easier than alternatives. It's ~1/2" thick so I don't think it'll be a failure point. I used red marker on where the holes would be drilled. but with better precision that I can do. The crank balance compensation hole is big. I've read about some people in Europe adding Zinc to balance it.

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The Unimog flywheel has a lip around it on the engine side. The TDI has no space for it, so it's got to go.

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All this work will need to be done at a machine shop. I know of one that can do it, but they'll want a CAD drawing with aligned bolt holes to be drilled.

I got the hardware to install the turbo. It's bigger than stock but I don't see fitment issues with it yet.

2607593
 

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Yeah... I think I have settled on machining up a new flywheel for my needs. There have been several conversion projects that milled the old M180 flywheel to rebalance it for the new engine, but I think that is a bad idea as it permanently destroys it for the old engine and leaves the old without any practical way to rebalance (without a full tear down at least). The other option is to find a junkyard M180 engine that is internally balanced and pull that flywheel. By my measurements, the M108 engine flywheel from the 250S could be turned down to fit in the bellhousing, but I do not thing there is not enough meat left to refit the smaller M180 ring gear (do to the thinner radial web vs. the M180 engine flywheel).

As you are using a VW engine, perhaps a look around to see if a compatible VW flywheel exists from another model/engine? It looks like your engine was mounted to an automatic transmission (looks like a flex plate)? It also looks like the crankshaft has a non-symmetric bolt pattern (two of the bolts are closer to each other than the rest).

Note to those who do not know: As has been written up in other threads, the M180 engine as used in early (most?) 404 Unimogs and MB 2xx series cars use what is known as a externally balanced engine. The flywheel mounted to the engine is integral to the crankshaft balance of that engine and can not be swapped with another flywheel without precise balance matching. Later production M180 engines, and all those fitted to automatic transmission vehicles, are known as internally balanced engines and use a separately balanced flywheel which can be freely swapped.
 

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1960 404 and 1970 406
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paul dont commit to anything yet till you get the adapter plate ,remember that is going to add 1/2 inch to depth,Ive been on vacation since I spoke with you but am going to try shipping out tomorrow.
 

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66' Unimog 404
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Discussion Starter #28
Thanks guys. I'll hold off on the flywheel stuff for now.

I've got plenty of other stuff I can do in the mean time.
 

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66' Unimog 404
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Discussion Starter #29
I go Earl’s adapter plate in the mail the other day (thanks a ton!) and finally got around to checking the fit a few times. I’m considering adding the stock adapter plate so there’s more room, it might help starter placement. It’s that or shave off ~1/8” from the end of the input shaft.

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The alignment plate is great. All the bolt holes seem to be spot on. The holes for the alignment stubs seem to be ~1mm too close together. I put the plate in the oven to see if it would expand enough to pop on. No luck. I’m a little nervous to file down the alignment holes, but I probably will.

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I flipped the clutch disk and re-installed the pressure plate. I’m not sure what’s going on but the assembly didn’t go far back enough to clear the stock adapter plate. I adjusted the clutch pedal so the stock adapter plate would fit over the clutch assembly.

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The TDI crankshaft extend out less than the M180. I should have measured to the face of the crank and not the back.
I think I need an extension puck for the flywheel that’s the depth of the adapter plate plus any flywheel lip.

The stock ALH clutch and Unimog disk are both 228mm. The width of the friction material looks similar in the picture.
Top half is TDI disk and the bottom half is Unimog disk.

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The Unimog puck style disk might have clearance issues in a VW pressure plate. Less so the disk style. I don’t know yet. The automatic ring gear would fit in the bell-housing. so I bet a standard transmission flywheel would fit diameter-wise.

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I gave the M180 away for parts, so the Unimog flywheel doesn’t need to stay intact, but that’s probably going to be a mute point as I'm leaning towards using a TDI flywheel.

I learned that the stock clutch is rated for 200ft-lbs. I’m more inclined to Earl’s idea of adapting a VW system. With a Unimog clutch disk if it fits. I know it’ll eat clutch disks, but it shouldn’t slip as easily with a vw performance pressure plate / flywheel.

So now I just need to learn if I can fit a unimog clutch disk in a performance VW flywheel / pressure plate and if the flywheel will fit in the bell-housing. I've had a hard time finding dimensions online.

Because I tilted the injection pump towards the engine (for clearance), it was tricky to get the injectors out. A 12MM nut & bolt helped get the last one out.

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66' Unimog 404
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Discussion Starter #31
Man so how the swap is going?
I've been a bit pre-occupied. I talked with Earl yesterday and got a lot of good info on flywheel / pressure plate / clutches so I'm going to make a decision this weekend. I'll probably get a TDI semi-performance clutch kit and use the Unimog disk. I'll need to grind out ~1/8" of the interior of the bell-housing to get it to fit. I'll probably need to get a 1/2" spacer puck made and maybe a throw out bearing spacer too. I'll need to get the TDI starter reversed, and installed deeper in the bell-housing so it'll contact the ring gear.
Hopefully I'll have a new post with pictures up soon enough.
 
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