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Metallurgy expert opinion required

West Cork Paul

Elite Member
Subscriber
I’m mounting some crash bars on my MTS and the bolts supplied are, I think, stainless steel. They are going into an threads on the engine which I think is aluminium castings. In the back of my mind I’ve a vague recollection that s’steel in contact with aluminium in contact with rain & shite of the roads will exacerbate corrosion along the thread length.

Am I dreaming this or are there some precautions I should take eg a liberal application of Molyb grease or copper slip rather than thread lock ?

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Barry Hell

Elite Member
Subscriber
I’m mounting some crash bars on my MTS and the bolts supplied are, I think, stainless steel. They are going into an threads on the engine which I think is aluminium castings. In the back of my mind I’ve a vague recollection that s’steel in contact with aluminium in contact with rain & shite of the roads will exacerbate corrosion along the thread length.

Am I dreaming this or are there some precautions I should take eg a liberal application of Molyb grease or copper slip rather than thread lock ?

View attachment 31251
If you need thread lock don't use grease. However, since the aluminium casting is much larger than the stainless bolt the aluminium (anode) won't get eaten away so quickly that it presents a problem. Generally metallurgists recommend big anodes and small cathodes to limit corrosion rates especially in threads.

Standard industry practice allows stainless steel fittings to be screwed directly into carbon steel pipework as the pipework is much greater than the 1/2" tube fittings.

Agree with AndyB 👍
 

Exige

Elite Member
Subscriber
Should be OK, no matter what you put on it will squeeze out of the threads but will fill the microscopic surface deviations - I have a tin somewhere of anti galvanic corrosion paste but can't remember what it's called and can't find it in the building site that is my garage! - looking at the attached chart zinc plated bolts will be the best cheap option if your worried.

 

West Cork Paul

Elite Member
Subscriber
Why would you put crash bars onto soft aluminium engine cases with little screws?

Even looking at the engine threads, they are prone to stripping..let alone the weight of then and the impact of a crash could wreck you engine.
This is indeed a consideration and I have pondered about it🤔.

The bars are attached to the engine by M10 and M12 bolts, so quite sizeable buggers, and Ducati have very thoughtfully provided threaded holes on the engine casings for them to be attached to.

The bars are to protect the plastics in the event I drop it in a slow speed manoeuvre which has nearly happened a couple of times as I get it in and out of the shed 🙁.

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Barry Hell

Elite Member
Subscriber
This is indeed a consideration and I have pondered about it🤔.

The bars are attached to the engine by M10 and M12 bolts, so quite sizeable buggers, and Ducati have very thoughtfully provided threaded holes on the engine casings for them to be attached to.

The bars are to protect the plastics in the event I drop it in a slow speed manoeuvre which has nearly happened a couple of times as I get it in and out of the shed 🙁.

View attachment 31259View attachment 31260
Man up, you'll be fine 😁👍
 

NOODS

Elite Member
Subscriber
General perception/advice from those that know about motorcycles is not to fit them..
Reason being that if an MS is involved in an accident the masses would prefer to see the loss of said MS, eg no possible protection to said machine and thus would prefer to see it as a total, there being one less MS on the roads to pain people’s eyesight..

In Irish ☘️ thats..

Leave the fecking crash bars be, just push the MS off your nearest cliff and be done with ya...

X
 

Barry Hell

Elite Member
Subscriber
General perception/advice from those that know about motorcycles is not to fit them..
Reason being that if an MS is involved in an accident the masses would prefer to see the loss of said MS, eg no possible protection to said machine and thus would prefer to see it as a total, there being one less MS on the roads to pain people’s eyesight..

In Irish ☘️ thats..

Leave the fecking crash bars be, just push the MS off your nearest cliff and be done with ya...

X
My pansexual has crash bars integrated under sacrificial parts of the fairing, should I be concerned 🤔😁 TIA
 

sev

Elite Member
My pansexual has crash bars integrated under sacrificial parts of the fairing, should I be concerned 🤔😁 TIA
nah cos your pan's crash beams were designed into it from the start like the ones on the CBR1000 hyperbarge way back when.
Problem with lots of badly designed crash gubbins is that they do a really good job of giving kerbs and sticky out stuff things to hook on to and tear off given half the chance.

In answer to your question Paul, it's really things like stainless exhaust studs that cause many of the problems, where you're exposing them to huge heat cycles which accellerates the aging process of the dissimilar metals. We used to see this sort of thing all the time in CREST chambers and other enviromental chambers, and it's generally why any old bike of some years has exhaust nuts and studs either galled solid or snapped off.
 
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