Toyota Bolt strength codes?

tintop, Sep 26, 11:42pm
Putting the front suspension on my 1998 ST215 Caldina back together.

Because there was no UK imports, there is no Haynes manual to refer to.

The bolts that attach the lower ball joint of the front strut to the wishbone have the code '10' or perhaps 'I0' raised on the heads.

Anyone know what that may mean as a bolt grade ?

Thanks

mimik3, Sep 27, 1:30am
Normally means the tensile strength of the bolt in MPa.

tintop, Sep 27, 1:56am
Mmmm - Perhaps, that would make the material of the bolt (10) about the same strength as the weakest mix that can be made and still be called concrete.

A decimal point missing ?

h.e, Sep 27, 2:11am
Just a guess but mine would be that it's a grade 10.9 bolt, which is getting up there in terms of tensile strengh for a bolt

tintop, Sep 27, 2:35am
Reasonably high duty job - bottom ball joint to wishbone, brake caliper to hub, brake piston assembly to caliper.
Nothing that I want to break or come loose. :)

tintop, Sep 27, 3:02am

mimik3, Sep 27, 3:26am
Concrete you are measuring compressability, while the bolt you are measuring the expansion, ie, how much pressure the bolt can safely handle before it deforms.

tintop, Sep 27, 6:34am
Yes - I appreciate that that . I just wanted to illustrate the scale of the difference.

It seems that a grade 10.9 bolt has a min yield strength of 940 MPa, so the the numbers on the Toyota bolts may well indicate yield/100

However the main problem has been solved, I torqued up according to the table I found - and all is well.

kcf, Sep 27, 8:17am
From investigating this question, the answer I was told by supposedly wise folk, the numbers on the Toyota OE bolts merely indicate to the factory a code to tell them how tight to do it up.

So if this is true, it is not any indication of tensile properties.

Note suitable use of disclaimers.

tintop, Apr 27, 5:15pm
Yes - but not directly, see the table I found, link in #6.

The table can be interpreted to show that the larger the number, the higher the material tensile strength, although a direct relationship to any actual MPa strength can only be guessed at.

I have 3 bolts

12 mm x 1.25 code 10
12 mm X 1.25 code 11
8 mm X 1.00 code 11

That is sufficient to determine the fastening torque.