This is a 1993 300D in my shop. The owner had it towed in because it had a loud rattling and wouldn't go anymore. I got it on the lift this is what i found. WTF? I just replaced that flex disc and balancer about 4 months ago. What did i do wrong? You can see the direction I put the allen bolts that came with the flex disc. Should they go the other way maybe? I was careful to get the flex disc guide pins into the transmission propellor and align the balancer with the mark What would cause this to happen? Lucky, no damage to anything else was done.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

all i can think is that the flex disk guide pins came out of the propellor on the transmission and the bolts started hitting the propellor and getting worn on. The nuts , its hard to see , but they are completely stripped.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

I dont see washers in your setup...where are they?
obviously the bolts are too long...washers would take some 6mm off...

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

I guess this is an example of over tightening old nuts and bolts - the FSM does say to replace the nuts with new...

...may be I should replace mine on the W201 with new ones after all?

(I know I should and I will get round to it - honest gov)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I don't think the bolts will fit past the transmission if you try putting them the other way. I would replace the yoke on the transmission.
I would get a new flex disc and be SURE the correct length bolts are used. Replace the centering bearing as well...

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My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
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1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Indeed they won't go that way (unless you remove the yoke and then fit it back on the transmission with the bolts sticking out before you fit the flex disc - daft idea I've just had! What would you do when you need to remove the bolts again? Oh the ball ache - do it properly - repair it properly!)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

The bolts go in on the side where the drive shaft connects. There are 6 washers, and the washers should be against the flex disc. So on three sides the washers will be on the bolt head side, the other three it will be where the nut it.

The raised boss on the flex disc seats into the flange, so the flat part does not contact a flange.

Some more info here:
Flex Disc Orientation, safety and durability issue.

He said he used the allen bolts that came with the flex disc, so I don't think this happened because he re-used the old bolts...

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"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

I am not sure what make Flex Disc was used but it looks like it has washers on it that are similar to the ones in the disc. Pictured. This is a pic from one of our Members who also had their Disc fail.

There is a pic of a Flex Disc with the same type of washers in the Mercedes Factory Manual. And in the Manual there is a special procedure in there where you are suppose to free up and rotate the Steel Tubes before you install the disc and tighten up on it.

Due to the odd shape of the Washer if the Washer rotates you can see that it comes out of alignment with the hole an that rubber wall that goes around part of the washer.

I say avoid Flex Discs with those type of Washer and get something like Lemfoerder Flex Discs that have round washers to start with.

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84 300D, 82 Volvo 244Gl Diesel

Unless I am mistaken this wiggling of the steel tubes is done when you remove the flex disc not when you do it up.

The problem (as far as I am aware) is that the ends of the metal tubes stick in the yoke on the gearbox. If you just lever them off you could just rip them out of the flex disc because they are kind of floating in there (for this type of flex disc - not applicable for the solid ones).

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Thanks all. Yep, these have the floating bushings in the flex disc . They will spin and spin if you turn them hard enough. This is a lemforder disc. I got a new set of bolts from one I had in the shop. I think i know what happened. The allen bolts are too short and don't go in the flex disc to transmission. When i tried putting new ones in i could barely get the nut started. But if you tighten it you can get the nut pretty much all the way on. But i guess it wasn't enough. Looking at the hex head bolts, they stick out a good 1/2 inch when tight on the balancer disc. Thus they are much longer than they need to be.

Check out the pic. It shows the same hex head bolt through to tranny and to balancer disc. Not how little is coming through the nut on the tranny yoke. I used two washers even though the kit only comes with 6 total -- one set. I'm not really sure where the washers are supposed to go. Maybe with the allen bolts. Do you guys think that is enough bite on the bolt now -- it is about 1/8 -o 3/16 inch through the nut. The angle makes it look a little less than it is.

I was fooled because an allen head bolt makes a lot of sense to go through the balancer disc into the flex disc to transmission because you can tighten it down with a ratchet through the balancer disc. My socket wont fit through there like an allen will . Using the hex head bolts you have to use wrenches and much less room to work.

So long story short, use correct length bolts -- long to tranny. I was lucky and no damage was done to the yoke or flex disc and it all went together nice. I just left the long bolts in the balancer disc . I loosened them and jacked up tranny so driveshaft was level and got everything good and tight with wrenches. I think it will be good now.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

bp:

Although it may be simply an illusion, in you most recently posted pic, it appears that the bushing through the rubber that should be seated in the socket of the transmission three-legged flange, is not in the socket of the flange, but is along side of the socket. That would explain why there is so little thread engagement of the nut on the bolt, and why the previous bolts were damaged.

Use of washers:
Washers are used where a nut or bolt head is against rubber (the flex disc).
Washers are not used where a nut or bolt head is against the steel of the three-legged flanges.
Hence, a total of six washers are used per flex disc.

Ya something doesnt look right there.

I was popping heads off bolts on flex disks for a year, every several months. Ended up the trans I had got used had a bent flange.

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1995 E420 Schwarz
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Whunter's 2008 thread linked above by Ceristimo should be required reading. I remember being confused about bolt orientation the first time I changed out flex disks.

OK.

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84 300D, 82 Volvo 244Gl Diesel

I'm thinking the problem may have been the placement of the washers. The FSM calls for them only on the end with the nut.

Check page 5:
http://www.startekinfo.com/StarTek/outside/12264/disc_2/Program/Chassis/41-050.pdf

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Sam

84 300SD 350K+ miles ( Blue Belle )