The galvanic corrosion issue frequently gets blown out of proportion in forums. All the motogp bikes have massive amounts of titanium, and they don't seem to suffer much problem with it. Galvanic corrosion requires the presence of an electrolyte between the two metals, so it isn't much of a problem in dry environments. It can be a real pain in salt water environments.
I've picked up a pretty good selection of Ti bolts, and some Ti nuts, in non-metric sizes on ebay, and at good prices. I used to be able to find them at local Socal surplus outlets, but that dried up some years ago. Most of the aerospace companies that used to dump their surplus fasteners on the market have quit because of concerns over liability. I've seen barrels of brand new surplus NAS Ti bolts at scrap metal yards, but they wouldn't sell them except to companies that melt them down.
I picked up a fair supply of 6AL-4V Ti bars for axles and spacers, and some tubing and plate some years ago from a scrap yard in Texas that handled scrap from the oil industry. I don't know if that sort of stuff is still available.
You do need to be careful of the alloy. You can find a lot of Ti nuts and bolts made out of plain, unalloyed Ti that are used in the food and chemical industries, and for marine applications. They are not strong enough for the highly stressed applications, but great for things like fender and body mounting. For things like axles and stressed chassis fasteners, you need something like 6AL-4V, the alloy most commonly used for high strength fasteners. Most of the Ti fasteners (non-metric) on ebay are surplus NAS parts, and are high strength.
For exhaust systems, the usual choice for Ti is a lower strength, but more malleable, alloy, frequently just pure Ti. Much easier to form, and less likely to develop cracks.
I confess to using Ti wherever I can on the race bikes for lightness, but in all honesty, I think I mostly do it just for fun. Any weight saving is good on a race bike, but in most cases, I don't think it has a significant contribution to winning. You can do almost as well by carefully drilling and trimming steel fasteners. The one place you will notice it is in reducing unsprung weight. I use mag wheels with Ti axles and fasteners to reduce the unsprung weight, and the difference in suspension performance is definitely noticeable on the track.
I replaced almost all the steel fasteners on my Commando-engined featherbed AHRMA racer with Ti or aluminum, trying to get the dry weight below 300 lbs, and finally managed it. I don't think it will ever win or lose a race because of the difference. It was just a challenge that I enjoyed. The real limitation to getting it much lighter now is the heavy production frame. A nice replica Manx frame would save a lot of weight, but would also lighten my wallet way too much.
Ken
