what kind of bolts? Flexplate to torque converter. - PeachParts Mercedes-Benz Forum

spamman450 · #1 03-19-2009, 05:03 PM

The car is a 1979 300CD coupe non turbo Diesel. I can tell someone has done tranny work on her because there is orange paint all over the flywheel. The bolts holding the torque converter to the flex plate are currently 12.9 mm with washers on them.
Can anyone verify that these bolts are the correct ones? The car has a slight shimmy in neutral and park, and a HORRIBLE clunking / loose converter or flywheel noise from the front of the tranny/ back of the engine, when in gear. The flex plate itself looks crack free(from what little i can see). I just want to verify that the bolts are indeed correct before i tear into this thing.

Thanks

Rory

Alastair · #2 03-19-2009, 06:50 PM

Quote:

Originally Posted by spamman450

The car is a 1979 300CD coupe non turbo Diesel. I can tell someone has done tranny work on her because there is orange paint all over the flywheel. The bolts holding the torque converter to the flex plate are currently 12.9 mm with washers on them.
Can anyone verify that these bolts are the correct ones? The car has a slight shimmy in neutral and park, and a HORRIBLE clunking / loose converter or flywheel noise from the front of the tranny/ back of the engine, when in gear. The flex plate itself looks crack free(from what little i can see). I just want to verify that the bolts are indeed correct before i tear into this thing.

Thanks

Rory

from your description they sound correct....

They are pretty short, and do have a flat washer....

mplafleur · #3 03-19-2009, 08:06 PM

I didn't have washers on mine, but they are 12.9 (and short).

I'm going to a pick-n-pull tomorrow and pull them off a SD.

Caduceus · #4 03-19-2009, 08:22 PM

With metric bolts 12.9 is the bolt grade. I don't believe that is the size of the bolt in question. Every time I remove a bolt from my car I replace it with grade 12.9 because that is awesome.

spamman450 · #5 03-19-2009, 08:43 PM

The bolts on my SD do not have washers on them either. I was thinking maybe the guy installed bolts that where a little too long and where tightening against the back of the converter. Its a long shot i know, but i would rather it be this than major tranny work

Billybob · #6 03-19-2009, 09:02 PM

Quote:

Originally Posted by spamman450

The bolts holding the torque converter to the flex plate are currently 12.9 mm with washers on them.

These flex plate to torque converter bolts are marked 12.9 not to designate their size but to designate the metallurgical grade or simply the strength of the bolt!

When you think for a moment about how these 6 small bolts are the only link between the raw horsepower output of the engine and the enormous stresses of the drivetrain it's easy to understand why they by neccessity are of the highest grade.

http://euler9.tripod.com/bolt-database/22.html

Kudos to Caduceus! You posted the info as I was typing.

spamman450 · #7 03-19-2009, 09:53 PM

wow those are some strong bolts! I guess what i am looking for is the length. Anyone know where to find that?

mplafleur · #8 03-19-2009, 10:41 PM

Quote:

Originally Posted by Billybob

These flex plate to torque converter bolts are marked 12.9 not to designate their size but to designate the metallurgical grade or simply the strength of the bolt!

I thought that was common knowledge..

Billybob · #9 03-19-2009, 10:46 PM

It appears that the original poster didn't have this knowledge.

"The bolts holding the torque converter to the flex plate are currently 12.9 mm with washers on them."

spamman450 · #10 03-19-2009, 11:04 PM

I did not know what that the numbers represented metallurgical grades. I do now. Thats why i like to ask a lot of questions. everybody has to learn sometimes

whunter · #11 03-19-2009, 11:07 PM

Quote:

Originally Posted by mplafleur

I didn't have washers on mine, but they are 12.9 (and short).

I'm going to a pick-n-pull tomorrow and pull them off a SD.

I have a full set with washers on my bench.

come get them..

mplafleur · #12 03-20-2009, 10:42 AM

Quote:

Originally Posted by Billybob

It appears that the original poster didn't have this knowledge.

"The bolts holding the torque converter to the flex plate are currently 12.9 mm with washers on them."

You're right. I saw the 12.9 (as apposed to the normal grade 8.8) and that is what registered with me.