Need help with diff head to crossmember mounting bolts.

[chrisstandring]

I am replacing the diff head in my VY wagon and according to the various google searches and a downloaded manual, the four M12 bolts that attach the diff head to the sub-frame need to be replaced with new ones due to being torque to yield. I rang Holden and the bolts are listed but there are none in NZ or Australia. It would seem they are discontinued? If that is the case how do people get on when changing out diff heads? Especially those people who claim to have changed them out 2 or 3 times in a week! I could be a mongrel and just re-use the bolts but I am sure there will be problems when I crank in the extra 30 - 45 degrees after torquing them to 90 N.m. I would prefer to find new ones if anybody knows of a source. Failing that it would seem that I will have to find substitutes from and engineer's supplies outlet. They are grade 10.9 but need to find flanged washer-head style items. Any help here would be greatly appreciated!

 

[chrisstandring]

Sorry, posting here because I have not had any replies in the VY section and it looks like much more traffic here!

I am replacing the diff head in my VY wagon and according to the various google searches and a downloaded manual, the four M12 bolts that attach the diff head to the sub-frame need to be replaced with new ones due to being torque to yield. I rang Holden and the bolts are listed but there are none in NZ or Australia. It would seem they are discontinued? If that is the case how do people get on when changing out diff heads? Especially those people who claim to have changed them out 2 or 3 times in a week! I could be a mongrel and just re-use the bolts but I am sure there will be problems when I crank in the extra 30 - 45 degrees after torquing them to 90 N.m. I would prefer to find new ones if anybody knows of a source. Failing that it would seem that I will have to find substitutes from an engineer's supplies outlet. They are grade 10.9 but need to find flanged washer-head style items. Any help here would be greatly appreciated!

 

[chrisstandring]

Anybody willing to share? Surely somebody has changed out one of these diffs before!

 

[chrisstandring]

Anybody willing to share? Surely somebody has changed out one of these diffs before!

 

[_R_J_K_]

I didn't think they were torque to yield, I think everybody just reuses them with a decent thread locker. Maybe ask Mace?

 

[Lex]

I've had my diff out twice. Each time just reused the old bolts.
A couple of years later, its still there. Hasn't fallen out yet.

 

[Lex]

Just use the old bolts.

 

[chrisstandring]

I've had my diff out twice. Each time just reused the old bolts.
A couple of years later, its still there. Hasn't fallen out yet.

Hey thanks for that. What torque did you tighten them to?

 

[chrisstandring]

I didn't think they were torque to yield, I think everybody just reuses them with a decent thread locker. Maybe ask Mace?

Thanks. I did some calculations based on the factory spec and that indicates they must be torque to yield. I found on the net a crowd that does aftermarket replacements for those bolts. In the states if I recall correctly.

 

[Immortality]

I have re-used the bolts, how tight? bloody tight but not a lot of room for a torque wrench in there.