Galvanic corrosion concern

[Wallowgreen]

About to attempt a repair on a split engine case boss for the alternator cover on a 2004 CBR1000RR. Planning to use a time-sert insert as I've had good results with them repairing similar issues. However, this one is likely to be in the presence of oil most of the time so I'm wondering what material the insert would be best made of. Not sure if oil is considered to be a "corrosive environment" but as I know very little about galvanic corrosion and avoiding it I figured I'd ask if anyone here has advice.

Seems I can get standard carbon steel or stainless steel inserts. If they're my only options, any thoughts on which would be best?

[salty_monk]

Going into Aluminium?

My inexpert 2 cents....

I would think the best thing to do would be to match it up to the fastening, that's where you don't want the corrosion. The oil presence will help not hinder I would think.

Any corrosion between the timesert & the Aluminium will only serve to lock it even more firmly in place which should be a good thing.

[Wallowgreen]

Excellent point, no idea what material the stock bolt is made of. Maybe anti-seize is all I need to think about?

Crap design by the way, no gasket! Shop manual says to use sealant goop which is how the lug got split in the first place I suspect. Goop in the hole, torque the bolt, split the lug. Brilliant!

Thanks for waking me up and stating the obvious Dan.

[salty_monk]

Thought about using a crush washer on it (or both sides of it?) or a doughty seal? I don't really know what you're working with but might help.

My guess is the stock bolt will be steel with a zinc plate of some description. Probably an 8.8 in that location.

[GregT]

Got a CBR600RR apart here at present so things are pretty similar. No gasket...standard now on a lot of jap engines, just use threebond.
I wouldn't worry about your timesert material, if the boss is split, I'd assume there's a weld to do first ?
If there's a dowel in that hole, make very sure you've got the cover centralised on the rotor....

[Nessism]

A good quality epoxy primer in the hole prior to installing the insert is recommended. That's what we do when we install inserts into aluminum where I work (aircraft industry).

[Wallowgreen]

This is what we found when we took the cover off, except for a damaged flywheel and the toasted stator we were expecting. The bolt in that lug was not torqued at all, there was enough goop in there to sink a battleship but it was still seeping a little oil.



Unless there's a reason not to go this way, my plan is to clean all the goop out and fit a 6mm x 1.0 12mm stainless steel time-sert insert (the bolt threads 13mm into the lug) using permatex cold weld 14600 (https://www.permatex.com/products/ad...ding-compound/) as a bonding agent. I'm hoping I can force the cold weld into the cracks to make a permanent repair with the insert.
Might be overkill Ed but I have all that on hand, it's my Sons machine and 250 miles away so I have to make a trip to fix it. Want to be as prepared as possible to make a good repair.

What you think, potential problems?

[Nessism]

That's an odd looking crack. You gotta be careful or the crack could propagate further. A Timesert may be the best option after all since it will reinforce the hole.

[Wallowgreen]

Hoping the cold weld will help reinforce it as well. Never used it before but read good things about it, apparently it can be drilled and tapped if necessary when cured. That might be another advantage if it gets somewhere unintended.

[GregT]

FYI - the 600 has just been re-nicasiled locally. The company who did it tell me they've seen three CBR1000's with split barrels. The material between cylinders is actually thinner than the 600 - which wasn't generous...Opinion is that it's the head gasket leaks water into the cylinder and the cylinder wall is the weakest point...
Worth re-torquing the head while you've got the chance.

[Wallowgreen]

Good to know, thanks Greg.