J56 Brake Caliper Attaching Bolts

[Gary F.]

What are the lengths of the two attaching bolts for the J56 calipers for a 1967 application? What is the correct finish? Do they require a flat washer or a lock washer? Thanks

[Joe L.]

Re: J56 Brake Caliper Attaching Bolts

What are the lengths of the two attaching bolts for the J56 calipers for a 1967 application? What is the correct finish? Do they require a flat washer or a lock washer? Thanks

Gary------


For the front calipers, the bolt which also goes through the caliper support brackets is 7/16-20 X 2-1/4". The short bolt is 7/16-20 X 1-1/4", the same as non-J-56. Both are used in conjunction with a split lockwasher.

The rear caliper bolts are both 7/16-20 X 1-1/8" and used in conjunction with split lockwasher. This is the same as non-J-56.

The bolts were black phosphate finish. However, it's possible that the long front caliper bolts were zinc plated. I can't be sure at the moment.

[Robert K.]

Re: J56 Brake Caliper Attaching Bolts

Joe,

1) Are these Grade 8 bolts?
2) Do you know what material they were made of, or perhaps you could tell me where I might find that information?
3) Are there any specific markings on them that you may be aware of?

Thanks and take care,

[Joe L.]

Re: J56 Brake Caliper Attaching Bolts

Joe,

1) Are these Grade 8 bolts?
2) Do you know what material they were made of, or perhaps you could tell me where I might find that information?
3) Are there any specific markings on them that you may be aware of?

Thanks and take care,

Robert------

Yes, they are all grade 8 (GM 300-M). I do not know the specific metallurgy of these bolts and I do not know where this information could be found.

The 1-1/4" and 1-1/8" bolts have a slightly recessed center with 6 radial lines around an "o" in the center. I do not know the headmarking of the 2-1/4" bolt but I do know it's GM 300-M material grade like the other bolts.

[Orjan S.]

Re: J56 Brake Caliper Attaching Bolts

Gary, Joe and Robert.

Photos from my -67 J56 original caliper bolt.
I hope it helps.

Orjan.



IMG_1263.jpgIMG_1262.jpg

[Robert K.]

Re: J56 Brake Caliper Attaching Bolts

Orjan,
Thank you - a huge help!! That looks like the longer bolt for the HD Support Bracket - am I correct? Would there be any chance you could also post a pic of the bolts holding the Caliper Halves together (with their head markings) and also the short bolt (that one may be tuff tho' since I think it's inserted from the opposite direction.....)!

thanks again,,,

Bob

[Joe L.]

Re: J56 Brake Caliper Attaching Bolts

Orjan,
Thank you - a huge help!! That looks like the longer bolt for the HD Support Bracket - am I correct? Would there be any chance you could also post a pic of the bolts holding the Caliper Halves together (with their head markings) and also the short bolt (that one may be tuff tho' since I think it's inserted from the opposite direction.....)!

thanks again,,,

Bob

Bob-------


The bolt pictured is the 2-1/4" bolt I described previously; you can see the caliper support in the photo.

As far as the caliper clamp bolts go, there was a change during the 1967 model year. Early 1967 used the 1st design calipers. These caliper halves were clamped with place bolts for both front and rear calipers. Later 1967 were equipped with 2nd design calipers. These caliper halves were clamped with standard, non-indented head (trimmed) hex bolts of GM 300-M material grade. "TR" was one headmark, "M" was another but there were likely many others. So, incidentally, the head of these clamp bolts would appear virtually the same as the caliper retaining bolt shown in the photo.

Whether place bolt or standard hex head, the bolts were black phosphate finished. Typical place bolts can be seen in the link below:

https://wilsongarner.com/placebolts/

[Robert K.]

Re: J56 Brake Caliper Attaching Bolts

Joe,

Thank you so much. That clears it up for me! Now I understand why Ido not have washers under my bolts holding the caliper halves together as Ihave the first design calipers on my '67.....

[Joe L.]

Re: J56 Brake Caliper Attaching Bolts

Joe,

Thank you so much. That clears it up for me! Now I understand why Ido not have washers under my bolts holding the caliper halves together as Ihave the first design calipers on my '67.....

Bob------


The 2nd design caliper half clamp bolts did not use any washer, flat or lock, under the head of the bolt. Apparently, after using the locking place bolts on the 1st design, GM engineers decided that no locking feature, at all, was necessary when they transitioned to 2nd design. In truth, the place bolts do provide worthwhile locking while split lockwashers provide very little meaningful locking.

[Robert K.]

Re: J56 Brake Caliper Attaching Bolts

Thanks again Joe,

Take care,