I am no mechanical newbie , I have been turning wrenches for over 40 years , but I cant seem to wrap my head around the advantages of a 12 point bolt. Less surface contact , smaller head and you are forced to use a 12 point socket.

The reason I ask is previous owner used them alot , oil pan, etc. I am considering replacing them with 6 point , but maybe I am missing something.

 

Your assumption of "less surface contact" is flawed. Sockets engage at the corners, not the flats. More corners means MORE contact, and more even distribution around the circumference. High-torque applications nearly always use 12 point heads - look at the nuts on your rod bolts, for example. MIL-SPEC fasteners are typically 12 point. The reduced head diameter both reduces weight (very important on an aircraft) and requires less clearance for a socket.

Do you need them for valve covers and oil pans? Heck no. The P.O. was just adding bling.

 

This is definately true if you use a 12 point socket, but if you use a 6 point does this theory still hold true? Not really trying to be argumentative, just trying to understand. In my industry ( big iron chiller mechanic) a high torque bolt is usually of the grade 8 variety.

As a former aircraft mechanic I can definately vouch for the last part of the statement. As light as you can make it is always the best and some of the bolts were in some very tight spaces.

 

Yes. The socket has clearance to allow you to slip it onto the bolt head. The flats do NOTHING for load transfer, only the corners. The only advantage of using a six point socket on a six point bolt is that you have slightly more engagement at the corners. I doubt this extra torque capability is more than you get by using a 12 point socket on a 12 point bolt. You are right, however, that the size of the head matters. A 9/16 hex six point will transfer more torque than a 1/2 12 point. The issue is the reduced head diameter, not the fact that it's a 12 point head.

 

Thanks for your help. It makes more sense now. I think you are right about the PO, more bling with the aluminum tranny pan.

 

Another advantage to a 12 point is you have 12 different angles of wrench to play with as opposed to 6. Might be helpful in tight spaces. Irrelevant with ratchet drivers on sockets. I think 12's also fit tighter, so there's less slop before lockup.

 

I know that 6 point bolts/nuts are sometimes necessary over 12 point bolts/nuts. When I installed the headers on my 71 98 I used 1 6 point bolt and the rest are 12 point locking bolts. The 6 point bolt is installed in a tight area where I needed access for an open end wrench. Unfortunately, a box end wrench wouldn't even fit (of course sockets were out too).

 

12 point seems to be less forgiving if you don't have the socket on squarely, either the socket or bolt will round off more easily, the TORX is even worse. just venting here, not to change the subject but I also think the metric system should be sh*tcanned on cars sold in the US, the SAE system works just fine, it got us to the moon. I would love to dump my metric tools in the recycle bin. Sorry but that's my opinion.

 

I can see Joes point about clearance . As a air craft mechanic there were plenty of tight spaces and of course the lighter the better. Honestly for my cars and the type of work I do on the job, I have gotten away from 12 point sockets all together. They have given my plenty of grief over the years. I dont buy into the "universal" set either. I can see where they could be useful for cylinder heads and other places on the engine.

 

Good luck with that Shiftb. It's you against the world.

 

We have been Metric since the 70's up here. My parents were the old Imperial system. The 80's GM stuff is annoying being a blend of both. My 88 is pretty much all Metric.