Thanks Eric - as i have gotten older and had this DIY thing for almost 50 years i have come to the realization that proper tools make all the difference. I saw a "how to" on YouTube and the pro - with a hoist and air tools - literally changed it in 20 minutes or so.

I did one on the 300E and remember what a hassle it was on my back with the car up on jackstands - took a couple hours as I recall

With rusted bolts I have learned to just apply some penetrating oil and walk away for awhile

 

Man that some rusty car.....


I only use the factory Mercedes part(from the dealer), sadly no OEM stuff.. too much is riding(My life)..

The flex disk and fuel pumps are the parts that has to be Actual Mercedes parts. The flex disk can tear up the tunnel and get into the airbag wiring as i read a few stories of people using "OEM" OEM is a very loose word-Just walk into the dealer and pick up the "Mercedes OEM" part......The Airbags went off, but some cars have the drive shaft containment bracket missing, and those cars are excellent to flip over if a flex disk lets go...

http://www.benzworld.org/forums/w140-s-class/1724133-front-flex-disk.html#post5887743

That link was six months later

Martin

 

I would have gone with Mercedes original but they were back ordered at the dealer with no date as to when I could get my hands on one.

So the options were to not drive it until they have the part or buy the best German made OEM part I could get my hands on.

That is a pretty amazing deterioration - was there any warning before that disc blew apart?

 

If they are German(made), you are fine...

Some get this instant vibration, and then this bang-explosion..

The vibration is always...

The originals will desegregate slowly when buying a used Benz one has to inspect them, and look for the 3mm-4mm diameter embossed Mercedes symbol star on the face of the rubber...

I bring ramps. Crawl under with a flashlight(torch). Look at the conditions of the rubber, and look for the Mercedes Star... Very important-always on that first drive home...

Not to scare you, but I had a friend flip a GM car as the universal joint quit, but these cars have a bracket or two on the shaft tunnel to hold the shaft in...

Martin

 

I'm due to replace the flex discs on my 1993 SL500 when I can get it over the inspection pit in my garage.(There's a 1998 SL500 sitting there at the moment minus a fuel pump, but that's another story)

As Martin and Eric indicate, ONLY buy genuine Mercedes-Benz flex discs.
Just look at these recent threads that spell out the danger buying cheap knock offs,

http://www.benzworld.org/forums/test/2422625-test.html

http://www.benzworld.org/forums/off-topic/2422633-seriously.html

The supplier ÜROparts has applied to be a site sponsor, however there is an active campaign to urge BenzWorld not to allow this company to become a site sponsoring vendor.

 

As Martin and Eric indicate, ONLY buy genuine Mercedes-Benz flex discs.
Just look at these recent threads that spell out the danger buying cheap knock offs,

http://www.benzworld.org/forums/test/2422625-test.html

http://www.benzworld.org/forums/off-topic/2422633-seriously.html

I could not find a supporting thread with those links. In any case problems with "cheap knock offs" is not an argument for buying dealer parts over OEM parts. You need to make the case that there is a difference in quality between dealer parts and the same manufacturer through alternate channels - that is that the OE manufacturer produces two quality levels - a high quality part for the MB box and a lower quality part for the box in which they put their own good name.

 

Some good Readings..

Some good Readings :thumbsup:

http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1608368-uro-flex-disc-warning.html

http://www.benzworld.org/forums/r-c107-sl-slc-class/2394505-has-uro-gotten-better.html#post12462321

W124, 1995 E320 wagon, new front flex disc failure - PeachParts Mercedes ShopForum

URO part bad in two days flat, headlight switch... - PeachParts Mercedes ShopForum

URO & cheap aftermarket parts - Tales of Woe

Opinion on aftermarket "Uro" brand M103 fan clutch bracket? - PeachParts Mercedes ShopForum

Put me down as another Uro hater- tie rods this time - PeachParts Mercedes ShopForum

are Uro parts utter s***T? - PeachParts Mercedes ShopForum

Any feedback on Uro Door Seals W123? - PeachParts Mercedes ShopForum

Martin

 

OK, I'm a bit stuck here

I've got both flex discs loose but I can't see how to get them past the the male and female shafts from the gearbox and differential.

I can't seem to find any exploded views of this area, and I don't want to start forcing anything.

There must be a simple answer, so those who have done their flex discs, can you please give me a helping hand

 

At the support bearing in the middle of the driveshaft is a large "nut shaped" part on the driveshaft itself. This is a clamp nut that prevents the sections of the driveshaft from moving relative to each other. It has to be loosened so that the driveshaft can be collapsed or shortened.

Alternate method:

Use a pry bar and do one at a time.

There is a small pin that projects out of the driving flange on the transmission shaft as well as at the differential. On the drive shaft is a matching hole with a brass bushing in it for the pin to center the driveshaft.

You have to pry the driveshaft back from the driven flange to get it off/over the pin, which will then allow you to pull it out of the way and drop it.

Be sure to apply a good sized blob of grease on the pin and in the bushing hole before you reassemble.

Dan

 

Thanks Dan, yes it is the pin and bush that I can't separate to drop the flex disc, I'll investigate when I get underneath the car tomorrow sometime.
It's just that these annoying hurdles that are thrown up, usually have a very simple answer

 

Old thread, I know, but...

So was it the case where both flex discs were loosened up, front one removed and did that allow you to slide the shaft toward the engine/forward to free of the rear center pin/bushing?

If you can imagine, need these done, not even going to drive the car, front one has chunks missing from it...

Regards,
D

 

Hey Guys, I got a quick question. On a 1997 320SL is there enough room when bolts are removed from flex disc to separate the rear drive shaft from the differential for tow purposes? I am using a tow dolly with rear wheels on the ground. Thanks

 

I would be really reluctant to do this, as I'm not sure how you would keep the pieces apart while the car was moving. There's not a lot of room between them with the flex disc removed, and with things like the rear suspension allowing things to move around while on the road it would seem likely that the parts could potentially touch or come together.

Dan

 

Thanks Dan. I didn't buy the car just so I thought I'd ask. I guess I will tow it with front wheels on the ground and secure the steering wheel instead.

 

When I replaced my flex discs and centre bearing I had to drop the exhaust system.


More useful info here re. manufacturer. Buy whatever brand you like as long as it is stamped with "SGF " see post #7.
https://www.benzworld.org/forums/r129-sl-class/2500697-febi-bilstein-spare-parts.html

 

More useful info here re. manufacturer. Buy whatever brand you like as long as it is stamped with "SGF " see post #7.
https://www.benzworld.org/forums/r129-sl-class/2500697-febi-bilstein-spare-parts.html

Good point indeed, read it while back, so when I ordered the set, FCP Euro promised SGF units will be set out, and SGF units I've received:

WP_20180718_19_22_53_Pro (2) by Duh_Vinci, on Flickr

WP_20180718_19_22_39_Pro (2) by Duh_Vinci, on Flickr

WP_20180718_19_23_21_Pro by Duh_Vinci, on Flickr

This is not the component to opt for anything other than factory quality of SGF, seen way to many horror posts on sub-optimal quality of failed cheap parts!

Well, my front is done, amazingly simple, had to remove absolutely NOTHING to swap the front flex disc. Once the shaft is unbolted and the old flex disc is free, the shaft has to go upwards into the tunnel, that provides ample room to slide the old piece out and slip the new one in.

Again, glad that I looked under the car when I did:

WP_20180721_11_25_11_Pro by Duh_Vinci, on Flickr

WP_20180721_11_24_41_Pro by Duh_Vinci, on Flickr


Could have given out completely at any time, and that would have ended really bad!

... I didn't have a wrench to hand for the large 46mm nut either, so I dropped the rear diff. This turned out to be stupidly easy (2 mins to unbolt axle half shafts from diff, 3 mins to position trolley jack under diff, 2 mins to undo 3 remaining bolts and lower diff 4") to enable diff to be pulled back 3/4" to release prop shaft from drive flange. Allowing time for self admiration and head scratching 30mins tops to move diff. You don't have to drain oil. Use a jack with a large cup. Everything afterwards was easy...

Rob,

You maybe on to something here! Brilliant approach, would likely go your route when its time to replace the rear. I took a close look at this morning, has zero wear, it has been replaced before by prior owner, bolts and flex disc looks brand new. I did the pry bar test all around, via "uncle" Kent Bergsma way, no stress cracks. So I'm going to do the rear next year, when I re-do entire exhaust. But definitely seem to be simple enough to just drop the diff! :thumbsup:

Regards,
D

 

The front one takes all the wear.

I had a front fail while on an uphill stretch of the auto-route. It had been making a right old racket, thought I'd be able to nurse it home, I was 300 miles short!!

The garage swapped both, rear one looked serviceable.

 

... thought I'd be able to nurse it home, I was 300 miles short!!...

On the A26 Autoroute-des-Anglais somewhere around Saint-Quentin by any chance?

For what it's worth, many of my friends have experienced some kind of trouble or other on that Autoroute, myself included. First time I drove it I hit oil on road surface near Reims. Others trouble with sudden very high cross winds and very heavy rain storms/zero visibility at night. Most of it not lit.

I stick to the tree lined N roads until south of Paris. Mostly because they're beautiful and interesting to drive.

 

are the front and rear disks the same part number? I see one listed for rear but nothing for front. The Febi just calls it a kit in the description though assuming that just means it comes with nuts, bolts and washers and not front and rear.

 

Here is a link to the propeller shaft on EPC (I hope it is). It shows both as the same number and a "kit" with both.

EPC Propeller shaft

 

Both flex discs are identical!

And remember always to buy whatever perceived brand, has to be stamped with SGF :thumbsup:

 

What do the magic letters mean? The Meyle I got from FCP doesn't have them.

 

Close

The A28 between Rouen and Abbeville. Horrible horrible road, cross winds and rain from the channel, too narrow and too busy, full of trucks nailing it along to the ferries.

Full marks to the French recovery system though!

 

My "Bette Noir" road is the A6 just south of Paris.

In my earlier days of driving I seized the crankshaft on my Austin A60 Countryman. It couldn't be fixed and the car had to be repatriated to the UK. A kindly owner of a smallholding let us put up our tent in his cherry orchard when the garage was assessing the problem.

Bugger me, the following year, same road, same car, in the same place I knocked out a big end bearing. It didn't seize the crankshaft this time so we were able to continue very slowly to the South of France albeit making a terrible racket.

Typical BMC quality at that time, the problem was later found to be a snapped off drill in the crankshaft oil-way :frown

 

Also, there's an SGF online shop at:
https://shop.sgf.de/en

RayH

 

FWIW confirmed by FCP - the Febi flexdiscs are SGF reboxed as Febi.

 

I did the same thing, I called them first, they confirmed the same as for you, SGF.

Its a piece of mind, lots of torque on those parts, and factory SGF units last a long time, trustworthy. There are just too many "other branded" failures posted all over MB forums. Good for you for exchanging the right parts!

Regards,
D

 

I can report front flex disc was easy to access and replace. I also replaced the transmission mount while there because I had to remove the transmission mount bracket to get better access to the flex disc. Once the 6 bolts were removed, I was able to pry the disc from the driveshaft flange, then from the transmission flange, and pop it out. The front half of the driveshaft moved towards the rear to allow this. The rear half of the driveshaft stayed in place as I didn't touch the center bearing support, and thankfully it was in good condition. I made sure to mark the flanges on either side of the disc so I could re-align them once the new disc was in. In terms of bolt orientation, I used the reference in the Febi instructions that came with the disc: 19mm bolt heads on the trans side, and hex head bolt heads on the driveshaft side. Washers on the disc side (not the flange side) bolts torqued to 60nm. I made sure the flex disc's protruding bushings sat into the flanges. Only issue I had was with the transmission jack I used, it was leaky and didn't keep the transmission up, and I had to keep pumping the jack while I refit the transmission mount bracket!

Old cracked disc still in place after removing bolts and prying apart from driveshaft:

Old disc removed, transmission mount also removed:

Moving the driveshaft upwards helps to create room to remove and refit the disc, the gives you an idea of how far the front half of the driveshaft can move backwards:

New disc fitted:

 

Just did the front and rear disks on my 99 M113. The front went as outlined above. For the rear, did not have to remove the exhaust, but did have to unbolt the center support bearing in order to slide the driveshaft back enough to pull the flex disk off. I think worst case scenario, if you try to force the back half of the driveshaft toward the front of the car enough so that you can remove the flex disk without unbolting the center support bearing, you run a fairly high risk of tearing the rubber surround on the center support, which would necessitate even more work, time, and expense replacing the center support. Unbolt the two exhaust hangers and the front heatshield below the center support bearing and slide the heatshield to the side while pressing down on the exhaust and you have access to the center support bearing. Much easier than trying to force the rear driveshaft towards the front of the car. Then unbolt the heatshield just aft of the center support bearing in order to give yourself space to swing the driveshaft down to remove the flex disk. Wasn't difficult.

As mentioned, make sure to wear safety goggles. The amount of rocks, pebbles, and dirt that rains down while removing these parts will otherwise get in your eyes.

With about 96k or so on my car, my front disk showed peripheral cracks and significant cracking around the bolt holes. The rear only had the beginning of a few concentric cracks around the bolt holes. Glad I got the job done.

 

I should also note that my 99 didn't have the large 46mm locking nut keeping the two halves of the driveshaft stationary to one another. I don't know what years the locking nut would apply to the R129, but a quick look at pictures online suggest that at least for the SL500, even 90-94 driveshafts didn't have the locking nut.

🥇90-94 MERCEDES R129 SL500 REAR DRIVE SHAFT DRIVESHAFT OEM | eBay

OTOH, here's a 90-93 300SL driveshaft that does have the locking nut:

Pardon Our Interruption...

Here's an early SL600 driveshaft with no locking nut:

93-95 Mercedes R129 SL600 600SL Rear Axle Driveshaft Drive Shaft Propeller OEM | eBay

Find many great new & used options and get the best deals for 93-95 Mercedes R129 SL600 600SL Rear Axle Driveshaft Drive Shaft Propeller OEM at the best online prices at eBay! Free shipping for many products!

www.ebay.com

While this listing is supposedly for 90-02 SL600 driveshaft that shows a locking nut:

90 - 02 Mercedes R129 SL600 600SL V12 Drive Shaft Rear Differential Propeller | eBay

Find many great new & used options and get the best deals for 90 - 02 Mercedes R129 SL600 600SL V12 Drive Shaft Rear Differential Propeller at the best online prices at eBay! Free shipping for many products!

www.ebay.com

🤷‍♂️

Can't say I think the job would have been as easy if I had to try to swing a 46mm wrench in the space available. I'm going to guess though that while doing the front flex disk, if the front half of the driveshaft slides back easily by a couple inches or so, your driveshaft likely does not have a locking nut.