Steel Bolt, Aluminium casing, a shear delight on a B7200

[HWwelds]

I already drilled out and tapped my top bolts on both sides of my ROPS. It was a horrible and heartbreaking experience, but the mission must be completed and it was.
I don't know what to call the chemical reaction between the steel bolt and the aluminum casing but I was wondering if there is a grease or other compound that can be put on a steel bolt in order to help protect these two metals from interacting?

The other question I have is why were only the top Left & Right bolts for the ROPS/PTO cover affected to such a degree that they sheared off, compared to the lower four bolts?

 

[Wbk]

You could try never seize, or prefer stainless steel bolts.

 

[200mph]

Galvanic corrosion.

Anti-seize will go a long way in making bolt extraction easier the next time.

 

[Tooljunkie]

Stainless bolts going into aluminum will gall on the way in. Aircraft industry uses a barrier grease. Blue loctite will work also. Nickel anti-sieze is another sure fire siezure prohibiter.

Just watched a video using alum and water (heated) to dissolve steel bolts in an aluminum casting.

 

[WoodyBlue]

So which bolts are you speaking of? Why did you have a problem with them?

 

[MFL]

There is a product called Eck made by Van Nay, LLC that is designed to be applied to fasteners or between items mated that are of dissimilar metals. I would suggest using Zinc coated fasteners. The best would be aluminum but that is not practical. Stainless fasteners would actually be much worst. Depending on your area and environment, galvanic corrosion can be a tough situation to prevent.

 

[HWwelds]

Good information everyone. Thanks.

 

[HWwelds]

So which bolts are you speaking of? Why did you have a problem with them?

I was installing a ROPS. The top bolts on both sides of the housing were seized. I did a lot of pre-soaking with penetrating solvents and tried heat and both bolt heads sheared off.

I tried soaking with penetrating solvent with the heads sheared off and then tried heat along with using my Mig to attach a bolt to the sheared off bolt, but my welds kept shearing off. Eventually, my only choice was to drill and tap the threads. While drilling, when I got to the drill bit width and getting into the threads, there was a noticeable powder drilled out along with the steel chips. The powder was from chemical reaction of the Aluminum and Steel. Why it was only in those top two bolts, I have no idea.

Btw, along the process of drilling out the bolts, I did try using a screw extractor after being able to spray penetrating oil on the backside of the bolt through the drill hole, but I still could not get the bolts to budge. The penetrating oil whether Kroil or PB Blaster just wasn't touching it. Like it just couldn't soak into the threads.