240z Front Brake Calipers - how to read markings on castings... and what is the bridge bolt torque?

[inline6]

I am re-assembling my caliper parts after bead blasting, painting, getting hardware plated, etc.  Looking at the factory shop manual, it says to not take them apart... to replace them as a unit.    And it doesn't provide a torque spec for the "bridge bolts".

If you don't take them apart, you won't get them clean.  And that won't be good, because there is garbage and rust in the passageways after this many years:

 

Bolts are M10 X 1.25 I believe.  So, what is a range for torque values?  Also, I am curious as to how to decipher these markings:

  

  

 

 

[heyitsrama]

I’d say from 30-45ft lbs.

make sure you orient them to the correct side when you go to install it. 
 

the blasting looks great, zinc plate?

[Racer X]

6 hours ago, inline6 said:

I am re-assembling my caliper parts after bead blasting, painting, getting hardware plated, etc.  Looking at the factory shop manual, it says to not take them apart... to replace them as a unit.    And it doesn't provide a torque spec for the "bridge bolts".

If you don't take them apart, you won't get them clean.  And that won't be good, because there is garbage and rust in the passageways after this many years:

 

Bolts are M10 X 1.25 I believe.  So, what is a range for torque values?  Also, I am curious as to how to decipher these markings:

  

  

 

 

I’ve done the same to two piece calipers, for the same reasons. For the bolt torque I used a setting appropriate for the bolt size and grade. 

A general torque chart lists 10mm x 1.25 grade 8.8 bolt torque at 36 ft lbs.

[inline6]

7 hours ago, heyitsrama said:

I’d say from 30-45ft lbs.

make sure you orient them to the correct side when you go to install it. 
 

the blasting looks great, zinc plate?

Regarding correct side, I learned the hard way one time.  So, always remember, bleed screw location is at top.

The calipers were painted with zinc primer, and then https://www.eastwood.com/ew-spray-gray-detail-paint-aerosol-12-oz.html.  To me, it looks close to the original finish color of most calipers that I have seen.  I like the finish.  On this member's page, there are pics of a new old stock caliper.

"Zinc rich" primer:

 

Waiting for final torque of bridge bolts:

 

Edited August 12, 2022 by inline6

[CanTechZ]

Your calipers look great. I see that the M10's that you are inquiring about a torque spec have a 10T marking on the heads. The Datsun (Nissan) general torque spec book shows tensile strengths and torques for 4T, 7T and 9T bolts. It would likely be safe to assume that a 10T bolt would be 11% (= 142,000 psi) stronger than a 9T and likely could be torqued 11% (= 31 - 42 ft-lb) higher than the 9T spec as well. Extrapolated values are for M10 x 1.25. 

General-Datsun Torque Specifications.pdf

[inline6]

Ok, I will go with 38 ft-lbs.