At a tech session my 87 300E was inspected and there was a 1x1 cm rust stain on the rubber part of the aft flex disc. A mechanic said if the bolts holding it on are not loose(they were not) then the disc needs to be replaced. Is this true?

I would replace disk only if disk is torn. Yours sounds OK to me.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

No comprende. So if the bolts are loose, then the disk is good? I thought the condition of the disk was a function of the condition of the disk.

My guess is that the mechanic meant to say: if the disk is flexible and has not turned rigid then the disk is good but if the disk is no longer flexible and has turned hard and rigid then the disk needs to be replaced.

If so it sounds like the mechanic is trying to dig up business or he is strongly into preventive maintenance.

My guess is that there is still plenty of life in the current disk and the disk material is flexing enough to do what it is supposed to do... that is take initial stress off the drive train.

It prevents the rear end "clanging" sound once common and possibly still so in Fords and Chevys.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

The front flex disk is checked by torquing the driveshaft back and forth with the trans in Park (first or reverse on a manual), parking brake off, and looking for cracks. If the disk rubber is cracked, the cracks will be obvious.

If your drivetrain feels like it's made out of rubber bands, the front flex disk is suspect, and they usually only last about 60K miles. They're basically a maintenance item.

The rear flex disk is much more robust, lasts MUCH longer, and is easily checked the same way with the trans in neutral and the parking brake on. When checking flex disks one should always verify that the bolts are tight, but I don't think a rust stain has any signficance.

Duke

the disc have no tears. Thanks for the advice.