Bolt grade question
 

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. :eek:

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

Answer
 

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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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 :)

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!!!:D
Thanks for the input.

Excellent
 

Hope you get many years of pleasure driving it. :D

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.