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X rated bolts
cliftyhanger - 3/3/18 at 10:48 AM

Got some bolts holding calipers together. They are X rated, no other symbol. Seem them before on other calipers, so believe them to be OEM.
I am spacing the calipers, so need longer. bolts. What is the modern equivalent grade to X?? Google seems remarkably unhelpful. (could just be me)
Cheers
Clive


bonzoronnie - 3/3/18 at 11:30 AM

Here is a PDF of the X rating system of bolts

http://www.idot.illinois.gov/Assets/uploads/files/Doing-Business/Manuals-Guides-&-Handbooks/Highways/Materials/Metals/fasteneridentificationguide. pdf

Not got any cross reference information but would seem that the X rating of bolts is an American bolt standard.

Personally, if in doubt I would just use 12.9 grade bolts


DW100 - 3/3/18 at 11:31 AM

This help?

http://www.idot.illinois.gov/Assets/uploads/files/Doing-Business/Manuals-Guides-&-Handbooks/Highways/Materials/Metals/fasteneridentificationguide. pdf

[Edited on 3/3/18 by DW100]

Ah beaten to it

[Edited on 3/3/18 by DW100]


cliftyhanger - 3/3/18 at 11:37 AM

That is the site I found (once I added -browning to the search box)
Sadly it isn't on there, they say X is unrated, which couldn't be true for bolts holding a caliper together.
And the diagrams on the pdf show a relatively small x, on these bolts it uses the whole head and is raised.

I may have to use 12.9 bolts, they should be adequate. Not a place to skimp though!


SPYDER - 3/3/18 at 11:53 AM

You won't be scrimping by using 12.9 bolts. What calipers are they?


davew823 - 3/3/18 at 12:45 PM

The "X" mark on top of the bolt is the manufactures ID mark. The X mark does not indicate the grade of the bolt. If there is not any other marks, then the bolt is low grade, per IFI. Davew823


cliftyhanger - 3/3/18 at 05:52 PM

quote:
Originally posted by SPYDER
You won't be scrimping by using 12.9 bolts. What calipers are they?


Girling type 16PB (metric versions) as fitted to TRr and a few other BL cars of that era. Very similar to M16 except lug spacing, they even use the same pads.

And I don't think these are a low grade bolt at all. holding the 2 halves of a caliper requires a serious bolt!