Lower ball joint replaced on my 91 300te 4matic and sound is gone but... I stripped the bolt running through the pinch clamp accidentally (of course), and have temporarily fitted a grade 5 nut and bolt in its place until I can get the proper nut and bolt from the dealer. How much danger would I be putting myself in by driving with this incorrect bolt and nut?

Lots, if you drive for any extended period. You need a higher grade bolt, get a grade 8 bolt or even metric higher grade based on the requirement. Think about what would happen if this came loose.

Some things matter less, this is not one of them.

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Strelnik
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1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6

That bolt takes extreme stress = why they could not use a cheaper one.

Look at the strength difference in these charts.

http://www.americanfastener.com/technical/grade_markings_steel.asp

http://www.boltdepot.com/fastener-information/materials-and-grades/bolt-grade-chart.aspx

http://www.boltscience.com/pages/faq.htm

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




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1973 300D
1973 309D - stolen
1978 280SE
1980 240D
1983 300D
1984 190D

So, what happens when you use a different grade bolt...?

Not as strong...given
Depending on the torque, it may yield with the applied preload + service loads
Different loosening behavior (especially if you can't apply the same preload)
Different material = different susceptibilities to corrosion, stress cracking, etc.

If it works...keep it the same. If you feel like modifying it - you better know what went into the design and be capable of making the proper assessment

__________________
1982 240D, sold 9/17/2008
1987 300D TurboW124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting

Thanks for the input, I plan on changing it Monday with one from the dealer. I am cautiously driving around town for essentials only until it is replaced, actually, I think I will just ride my bike to the grocery store.

Just installed the correct nut and bolt from the local MB dealership, I feel a lot more confident now with the $8.00 set in there versus the grade 5 freebie from lordco!!!
Thanks for the input.

Hope you get many years of pleasure driving it.

what's a pinch clamp?

What was the marking on the old bolt ?

8.8 metric approximately grade 5
10.9 approx grd 8
steel socket headed cap screws are generally grd 8 unless they are stainless.

http://i284.photobucket.com/albums/ll4/pwogaman/1990%20Mercedes%20300TE/100_1166.jpg

That is the pinch clamp i referred to.
The new bolt MB part number = 129 990 10 01
The old bolt has been binned.