Bimetallic Corrosion

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Anyone have any luck in removing tight mudguard stay studs and the pinch bolt stud from fork sliders?
Or is it not worth the risk of damage to the slider threads?

Were these studs cad plated or natural steel from the factory?

I am restoring a bike which has been sitting under a tarp outside for probably 20 years.
With the head off.
Much of the steel in aluminum is frozen tight: Spark plugs frozen in head, oil feed bolt, etc.

I would assume the 3 studs in the head are also frozen solid on this bike.
 
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The bolts would have been either Cadmium or Zinc plated depending when they were made. The best method for removal is to heat them so they expand. When cool they should start to move. Also try some Plusgas or the U.S. equivalent. For some parts an Induction heater would work well if you can buy/hire/borrow one.

Martyn.
 
Heat is your friend. Aluminum expands more than steel so the bond is broken when heated. The best penetrant by far is 50/50 ATF and Acetone, but you have to be able to get to the threads. Might work for plugs but those pinch bolts are recessed.
 
If the factory used plated studs on the forks, the plate is gone over time.

I have not had much luck with using heat to remove frozen steel fasteners from aluminum. The bolts will come out usually destroying the thread in the process. The heat burns out any penetrant used.

What about those 3 head studs? Those were never plated and I'm not sure why the factory would use bare steel studs into aluminum! At least the factory used plated studs in the cases.

I think it might be better to let sleeping dogs lie. Or buy a case of thread inserts.
 
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This why, although I'm curious by nature, I've been hesitant to delve into my 850's gutty works for any preventative measures..... I'll await the catastrophic failure which shall surely occur one day as something in there flat goes above and beyond and then weep.
 
I watched a video where all types of penetrating oil was used to find the best. At the end of the video they heated the bolts and it worked better than any of the products, How hot to get it without damaging anything is the key.
 
I have had mixed success not damaging threads by double nutting original Norton studs so will finally buy an extractor.

Did you use the 3 grip version which looks like a spark plug socket, or single grip side cam-type version?
 
I have had mixed success not damaging threads by double nutting original Norton studs so will finally buy an extractor.

Did you use the 3 grip version which looks like a spark plug socket, or single grip side cam-type version?
I have the 3 grip versions. I bought a set, wasn’t very expensive. First time I used it I was both frustrated and embarrassed at not having bought a set YEARS before !!
 
Lot of potential to gain experience with HeliCoils! ;)
I know. That is why I've let sleeping dogs lie until now. Will get the 3 grip version and see how stuck they are.

I sometimes get tired of looking at the tops of slightly rusted studs on the cases which don't match the re-cad plate on the nuts.
 
Halfords do a galvanised effect paint here, for trailers and the like. Thats a dead ringer for plating on fasteners !
 
Seen some videos of folks using a good few whacks on to bolt or screw heads to help free threads before applying torque. Also use of a manual type (hammer hit) impact driver is a must.
 
Some people dissolve steel stud remains out of aluminium with a solution of potassium aluminium sulphate (alum).
 
That is interesting. Can this method be trusted as it seems almost too easy. Not there,just curious.
 
My 850 sat for 40 years in an unheated storage in SE Alaska. It was a mess. When I got it home I flooded the engine with the ATF-Acetone mix and let it stand for a few months. It was amazing how well stuff came apart. Ruined the stator in primary but every thing else liked it. I'd be tempted to submerge large assemblies in a tub of the stuff and forget about it for a while. Then use mild heat to help swell aluminum and remove steel. No, I'm not kidding. Yes I know it sounds kinda crazy.

The fact the aluminum expands faster than steel is also helpful in getting some kind of lube into the interface. Chose something with a high ignition temp, I've used Corrosion Block this way. I do not know its exact ignition temp but it handles the heat pretty well.
 
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