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Discussion Starter #1
In the process of rebuilding the front suspension, I ordered replacements for the lower A-arm-to-chassis and A-arm-to-spring-pan bolts. This was mainly because they are available from Classic Alfa, relatively cheap, and shiny. But I justified it to myself with the idea that it makes sense to replace bolts under high tensile loads, in the same manner as rod bolts. Upon receipt, I find the bolt heads are marked "8.8", which according to a chart found online means "medium strength carbon steel", equivalent to US grade 5.

The original bolts are marked "LOBO 100". Does anyone know what grade/strength that equates to? I don't want to replace the original bolts with lower-strength parts, shiny notwithstanding.
 

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I bought a Berlina once that had hardware-store-grade American bolts, smaller than the hole by a fair amount, holding the spring pans on. The car drove fine, the springs didn't come out. All by way of saying realistically it's probably fine. But yes, them front springs are strong items, no question.
Andrew
 

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Discussion Starter #5
Looks like I'll go with a hybrid (or hodgepodge) solution: Will use the original "LOBO 100" for the dog-bone-to-chassis bolts since nobody seems to know what grade that translates to, and they cleaned up pretty well. And likely will use new grade 8.8 spring pan bolts from CA because the original bolts say "LOBO 8.8" and they're somewhat more chewed up from contact with the pan. I am probably totally over-thinking this. (What else is new.)
 

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But Mad North-Northwest
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So this was actually discussed in a different thread. I believe the 100 refers to a DIN 6921 class 100 bolt. These are serrated self-locking flange bolts that are case hardened.

"These self-locking hexagon flange bolts are designated property class '90' or '100'. The flange bolts are case hardened in order to perform their self-locking function, and therefore cannot be classified as property class 9.8 or 10.9, although their tensile strength is at least 900 resp.1040MPa."
 

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There is nothing wrong with re-using the original screws and nuts. However, I would replace the lock washers and nylox nuts with new.
AGREE, Suspension bolts must have shear strength as well as tensile strength but they are not subjected to the reciprocating tensile stress of rod bolts. Inspect your old bolts and resuse them if they are not damaged. Alfa had a better quality assurance program for supplier parts than any vendor can possibly have.
 

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Discussion Starter #10
@alfaparticle -- thanks for the explanation of why we replace rod bolts. That makes perfect sense, and also makes sense to reuse undamaged suspension bolts.
 
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