jagracer wrote:
One can drill out Titanium. Cobalt drills and lots of pressure and use drill speed as for cast steel. Its awefull stuff to machine, but the right tools will work. Yes you need to take the Calipers off and use a proper drilling machine, or better still, a good universal milling machine. Use wizard machine taps to clean the threads out. A lot of people are seduced by stainless nuts and bolts in the Classic world. Most of the Stainless nuts and bolts one sees advertised are L306, which is soft and Galls into the thread, welding the metals together. Even Stainless High Tensile 13.2 Cap Heads will lock if you do not use graphite on the thread before putting it in. Many people "just try" a Stainless bolt for fit, and it welds itself in and will have to be drilled out. I used to do a lot of Vacuum testing on Stainless vessels, and drilled out many seized bolts over the years. The internals of Nuclear Reactors are a minefield of working with chemically pure Stainless componants. Titanium is fine as long as one knows the pitfalls as well, and I am sure Phoenix in his experience, would agree.
You know what, you're right.
I was trying to think of where S/S fasteners are used on automotive - even on fixed diesel engines - the best I could come up with is exhausts - 409L or 410 for high temperature stuff, and fuel lines in the engine bay, particularly 'crash resistant' parts - mainly 420J1 or J2.
Automotive fasteners are in the main high-carbon steel, usually plated with Zinc or other passivating material or heat-treated for defined plasticity (cylinder head bolts etc.), I can't think or visualise having seen or used any S/S fasteners, for a start, they (306/316) fracture easily, and as you say, gall easily. Galling happens during installation, not removal, either due to lack of lubrication (nickel grease) or over-torquing.
Back to the brake calipers, the Brembo are especially prone to corrosion on the outer bleed nipple due to.... excessive washing. Water is forced into the bleed nipple when jetwashed and sits there, quietly eating into the seat and bleed nipple, yes, there's galvanic corrosion as well but in the main, trapped water and the heating/cooling causes most of the issues.
Personally, I'd replace the bleed nipples every other brake fluid change for OEM parts, there's no reason to use Titanium - otherwise it'd be standard equipment. I've seen 10-12 year old vehicles with the original bleed nipples & calipers still in good condition, but they have had a BFC every 2 years (and haven't been 'detailed' to within a millimetre of their brakes...)
One of the things I do for 'fun & profit' is TiG & Oxy-Propane brazing & welding - mainly repairs to sh**y castings, I do like to keep my eye in by welding dissimilar metals, Titanium is a challenge but I've successfully brazed a M8 bolt to a seized Ti bleed nipple for removal - I'd never recommend using them unless you just like the colour....
out of the Brembo calipers ( maybe not ) , but worth a try
