3

I'm replacing some broken bolts in my front Subaru brakes. Specifically these are the 17mm bolts which attach the caliper bracket to the hub / knuckle assembly. The calipers separately attach to those brackets.

I ordered these parts from Autozone as they are specifically supposed to be matching replacements for my vehicle. But I was surprised they had no markings about bolt grade. Since these are the front brakes I don't want to take any chances with using the wrong part or a sub-standard part and thought I should check if this seems fishy or OK to use.

Its a little hard to make out in the photo but there is a semi-triangular marking on the tip of the bolts but I don't think this is the same as a grade marking that would normally be on the head.

Photos of packaging & bolts - the last one is the original bolt, marked with a 6:

enter image description here

enter image description here

enter image description here

enter image description here

Improve this question

1 Answer 1

Reset to default
2

Metric bolts are supposed to show the grade above M5. When there is no marking I would not trust them and always have a bad feeling when driving around. Instead, I would get them from the dealership. The certainity to have good material would offset the higher price (At least for me).

Edit:

It appears that the bolts are galvanic coated. Galvanic coating and high yield bolts (grade 10.9 or better) dont mix well, as the coating induces hydrogen embrittlement.

A good sign (among others) would be a matte gray coating, like this:

enter image description here Von Erikviking, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8994272

This is zinc flake coating, a good method for bolts with grade 10.9 or above.

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .