Topic: Stainless Hardware for 750 crankcases

[edwardmorris]

I can't find the thread that had a related topic, but I do recall that changing out the 10 crank supporting bolts with stainless ones was a big NO NO!

Other than that, does anyone have experience with, or would caution against, using all stainless replacements for the crankcase bolts nuts and washers?

Belmetric seems to carry all the flange type bolts in stainless so hopefully they'll be a direct replacement. As for the big 10, I've seen builds (Tige's K1 GT for instance) that use HD studs instead, so that solves it. Another thread that I can't find talked about what kind of antisieze to go with when using stainless hardware in the 750 Aluminum Alloy cases. IIRC, copper was to be used (some science about metal nobility and such). Want to be absolutely sure before buying anything, thoughts?

[markb]

Really?  I'm curious as to why.  I wouldn't think it would be any worse than steel as far as dissimilar metals are concerned.  I hope someone replies.

[Retro Rocket]

Its been covered here plenty of times before, don't use stainless for the lower case studs, or any high tension studs, they are softer and stretch more, this will effect torque values, use the HD studs, as for the rest, stainless will react more than mild steel in our aluminum cases, all different metals act differently, some worse than others, use some sort of anti seize, some recommend copper type anti seize some don't, this topic is similar, but not as bad as an oil thread, the stainless will promote corrosion with out the use of a heavy grease or anti seize, just which one is best, I don't know...

[markb]

Thanks, good to know.

[calj737]

I differ on whether stainless bolts or studs are suitable. In fact, depending upon the "stainless" it's much stronger. Consider ARP bolts. They are used in the most high performance motor applications and are far more than strong enough to handle bolting cases together. They are expensive, but they are among the best quality bolts you can find.

I use silver Antiseize in all my stainless bolts when threading into aluminum wihtout incidident. 

Finally, not all stainless is the same as there many different grades of it, just like alloy and other steels.

[seanbarney41]

Strength is not even an issue with these bikes.  What is the torque spec of the main bearing caps?  We are talking about like what? 40 ft lbs.?  Everything else in the entire engine is like 20 ft lbs. or less.  Tell ARP to cast us up some stronger cases.

[calj737]

Strength is not even an issue with these bikes.  What is the torque spec of the main bearing caps?  We are talking about like what? 40 ft lbs.?  Everything else in the entire engine is like 20 ft lbs. or less.  Tell ARP to cast us up some stronger cases.

My point exactly.

[edwardmorris]

OK! So a little more searching tells me this is another oil thread topic so I'll wrap it up. Looks like Cal's had good experience with SS and Silver Anti seize so I'll PM him for details.


I was considering going all stainless for my 836 K3 build, and the HD crank studs are good for a little added insurance.

The only remaining concern now is what to do with the non standard length bolts. There are a couple of 56mm ones and one 82mm one. Is it ok to substitute these with 55mm and 80mm ones? Or get 60mm and 85mm and cut them down to size?

[calj737]

cut or substitute, your preference

[edwardmorris]

Much rather substitute, as long as losing a millimeter or two won't hurt things...,

[flybox1]

I bought longer where I had to.  Cut and then prepped with a flap wheel
better to have more threads engaged than less 

[edwardmorris]

Typically that'd be my thinking too, but 1 and 2 mm, will it really make that much of a difference on non-crank bolts?

[calj737]

No, it won't. Especially since the torque on these is mostly 6#. You're talking a 1/5 to 1/3 of a 1/4". Think about it, maybe one full thread, two at the most.

[edwardmorris]

Cool. Check PMs !