So a while back there was this thread on the topic: https://www.apexspeed.com/forums/sho...nut-life-reuse
Thought I'd get a little more specific and address a problem of my own making.
When I bought this car, it had the M8? bolts and they were inserted from the flange side, meaning that it was a PITA to line them up and install the joint (have to do that on the outside joints anyway and I've since figured out an easier way to do it). The other problem with this setup is that if for some reason you lose the nut the bolt will back into the case side plate and machine off a nice little groove. The upside was that whether one used 10.9 socket head cap screws or hex bolts, it was relatively easy to torque them up with a low profile hex on the flange side, one could get a box wrench around it or a shortened allen key.
Of course, at first opportunity, I tore into the trans, replaced the 8mm with 5/16 and flipped the bolts around to make it "easier" to change out the bolts if necessary..... which I needed to do too often.
And just like in the previous thread, the AN bolts were too soft for the torque required and I spent a lot of time re-torquing them at the end of every day because they'd loosen up at the torque you could live with. Last year I replaced them and maybe the AN bolts were at the soft end of the spec, but I pulled the threads out of about a half dozen of them and so I decided to try to address this for good.
My first attempt was with a mix of NAS and Grade 8 bolts (couldn't get enough of the NAS). I believe they were -32's on the inside and -34's on the outside. I was both guessing a bit and having to make do with what I could find in stock. The outer ones were fine, if a tad long. The inner ones required a couple of washers under the head of the bolt and one under the head of the nut to ensure the nut didn't bottom on the thread and to keep the bolts out of the transmission case.
This worked but for one thing - the joint needs 24 ft-lbs and at 20-22 I could not find an open end wrench that would not spread apart and round off the nut. the first pic is my collection of wrenches I've used for this task - the first is a flare wrench that was ground off here and there, and it would open up. The second one is a box that I tried to grind down with no luck, and the other two are craftsman open ends where you can see the damage to the wrench from torquing the nuts so high. Obviously I had to do something else.
So I took the joint apart, measured everything, and then figured out the min bolt length as I should have before. What I came up with was a -29 would be marginal depending on tolerance stack-up. A -30 would be better. Unfortunately, I couldn't find any -30s in stock at a reasonable price. So I gave the NAS6605-29S's a try.
The shorter bolts allowed me to buy a 6-pt box wrench and grind it down enough to sneak in there. Second pic is this wrench ground down: https://www.amazon.com/dp/B00T3M9638...roduct_details
Third pic is the comparison between the longer bolts and the -29. Fourth pic is the wrench in place. I have a thin stainless washer under the head of the bolt, nothing under the nut. There's about 1.5 threads showing.
I was able to get them to 24 ft-lbs pretty easily. I might grind the 1/2" socket down to get it to fit close on the bolt head so that there's less of a chance to rotate off the bolt head when applying that much force. And for once the wrench didn't torture my hands, although I ought to make a 3DP sleeve for it.
If I could have found -30s I'd have used those, maybe with a thicker hardened washer under the bolt, but the last set stayed pretty tight (only had to check them before the weekend and didn't have to touch them during) at 22 ft lbs so I feel pretty confident at 24.
With the NAS-30s though I could bite the bullet and tear apart the gearbox again and insert the bolts through the flange no longer having to worry about goobering up the bolts.....