Very astute, grasshopper.

Usually, it's a fix of a "quote failure". The HTML tags get deleted and the quote does not post properly.

Sometimes I'll fix spelling and/or composition errors when the mood strikes me.............

Just finished the transmission swap, which of course meant new flex discs. Its a good thing too, they were about done.

Here are some pictures.

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1985 300SD "Sady" 235k miles
Wont Start for Anything!

Yikes,

Yeah those needed to be changed out alright. But then again I've seen some many a disc like that so they must last awhile like that.

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76 300D 130K "Stella" (Sold )
74 240D 299K (Donated to Highschool For Senior Project WVO)
83 300TDT 290K (My one and only)
Sanford, NC

I would like to have a digital camera right about now.

I inspected my flex disks, and both of them look pretty much the same. There are some visible surface cracks all over the rubber, and some deeper cracks where the enlarged rubber bosses meet the thinner section. On each side of the M-B star and the printing on Sady's disks above. There is no sign of any deformation or separation of the metal inserts from the rubber. No cracks in the direction of rotation, as I see in a lot of the pictures in this thread. There are lots of pictures of disks that clearly need to be changed, but none of disks which aren't new, but are still serviceable. We have the "no-go" part only, of the "go, no-go" test.

I was going to change them, but now I think I'm just going to see how they look after another 10K.

What's a flex disk?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

Flexdisk has the same job as a u-joint on the drive shaft.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Similar job, but it won't deal with very much of an angle. The Benz has a body-mounted final drive unit, so the driveshaft doesn't move around when the suspension moves.

U-joints fail on RWD live-axle cars also, with similar very bad results. Drag racers are required to have driveshaft hoops to contain the shaft in the case of a joint failure.

That is good info. Those hoops would be good on production cars as well.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Ahh, I see. But on my truck, when the U-joint starts to go out, it vibrates like hell around 50 mph.

Any similar symptom on the flexdisk?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

I have not experienced a bad flex disk yet, but from what I have read, yes, the syptoms can be the same, or sudden and catastophic. Flex disks need to be checked just like u-joints. After reading stories about people being killed by a u-joint failure at highway speed, if I notice any type of drive line issues, the vehicle is parked until I can get it repaired.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I wish I had a picture...

But from my experience, If you can feel it... you'd better pull over and have a gander.

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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

I just replaced my rear disc, which was cracked. It seemed to clear up a vibration at lower RPMS.

It does not look like the rear disk can catastrophically fail. The drive shaft has a hole that engages a pin on the rear differential. If the disk were to fail the shaft would spin, but not flail about causing damage. The front disc is a different matter though...

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Just during the past few days, I have been noticing mild shudder on my 84 D during startup at lower speeds (0-25mph) and disappears as I speed up. The vibration seems to be coming from the shaft/propeller area.

Is this an indication that the discs are going bad? I have not crawled under the car yet to check. Would a loose disc/shaft be obvious?

I plan to check it tomorrow since its a bit late to tinker right now. Am also not driving the car until I am sure what it is.

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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth...
2007 Honda Accord EX
2007 Honda Accord SE V6
96 C220
97 Explorer - Found Another Home
2000 Honda Accord V6 - Found Another Home
85 300D - Found Another Home
84 300D - Found Another Home
80 300TD - Found Another Home
Previous cars:
96 Caravan
87 Camry
84 Cressida
82 Vanagon
80 Fiesta
78 Nova
Ford Cortina
Opel Kadet
68 Kombi
Contessa

That depends on how obvious it is.

It gets obviouser as it gets obviouser.

It can be hard to see depending on the position of the wear relitave to the shaft position, and how well lit your checkup is... If you can get the rear wheels off the ground and rotate the shaft, like up on a lift it would be easier to see.

As a general rule I would say the more drive shaft vibration you are having the less agressivly you would be advised to drive until you can get it checked out..

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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

I've had a bit of a vibration at higher speeds, -could be rear tire balancing issue, but when I was pulling out the diff and drive shaft (to change diffs) I found the center bearing rubber support was worn loose. It was not supporting the shaft properly. The bearing seems o.k., and the flex disks seem fine, but I am replacing both disks, bearing support, and bearing anyway. Heck I have it all off so it is the price of the parts only, not a lot more labour. And when the replacement diff goes in it will be with all new seals, and new boots on the axles. I kinda like working on the old girl but no where near enough that I want to do stuff like this twice cause I cheaped out the first time.
Not that I'm throwing any rocks at those who need to take the cheap route. been there done that, had to. But this car is fairly low miles (140k) and I'd be happier if I don't need to get under there again for a while, and (at least till the next recession) I can afford the parts.
Maybe I'll save the old disks in case I ever am running a much older 240 and use them on that...

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Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR