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Re: I'd change all the strut bolts (archive)

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Posted by Chris Rose on August 03, 2001 at 21:51:28:

In Reply to: I'd change all the strut bolts posted by craigwatanabe on August 03, 2001 at 21:35:38:

Yes, I agree with you. You sound like a Mech. Engineer. I think I will replace all bolts in both front struts but I don't know if the upper strut mount has bolt studs already on it or if it is drilled through so a seperate bolt is used. Obviously, if it has bolt studs then I'm looking at replacing the upper strut mount as a unit. If I do that then I will replace everything from the upper spring pad up to get the car back to stock '95 setup. As a result of tonights incident I found out that according to Fig 5 of the Bently manual pg 310-4, I have the top part (if not the whole strut) of an '89-'92 series car and not the 1993 and later setup that I should have on my 1995.

Sounds like your strut bolts encountered a lot of stress. Check the grade of your bolts, and rely only on OEM or bolts purchased from a reputable supplier. I've seen Grade 8 bolts fail under moderate torque because they were improperly or illegally stamped (big underground market for bad bolts).

Otherwise your struts may have undergone severe stress enough to pass the maximum tensile strength of those bolts. I'm not sure what the grade is for strut bolts, but I do know that if you want strong bolts, use Grade 8 or better carbon steel. Don't use stainless steel as their tensile strength is less. And always when reassembling bolts, use a good bolt dressing like Anti-Seize so removal the next time is a painless event.

Anytime you have to re-bolt on high-stress application, you should always use new bolts as torqued bolts have reached their tensile point once and are considered stressed with a good possiblity of fracture under normal conditions.





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