IP2 worn out options

[gripper]

When the Norton Rotaries are worn out (eccentric shafts and rotor housings) what is the future for these engines? Is it possible to regrind the rotor journal on the shaft and fit a smaller bearing and will it be feasable to line the rotor housing? I believe that the Mazda engines have a steel facing surface shrunk in to the housing. Where were the original rotor housings made and which company did the machining?

[FloridaMike]

Rotor bearing surface on the eccentric shaft is not a major problem. Standard aircraft repair (also used in cars, but not so much any more), spray weld the shaft to slightly larger than original diameter, machine back to size, polish, harden. The rotor shaft bearing area is round, so any smart, competent and enterprising machine shop should be able to do this. Problem is finding automotive machine shops any more - here, they are mostly extinct. Plenty of aircraft engine repair shops around, though, unfortunately priced accordingly.Machining the rotor housing trochoid is going to be a lot tougher. Probably not a bad idea to find someone NOW who either can do this or is interested in learning how. The expensive, difficult part of making a rotary engine is the rotor housing, most of the rest of it is simple to make, thus cheap. Perhaps talk to the people who are making the rotary drone engines, see if someone there wants to make some money on the side, or if the company itself is looking for another cash flow source for machinery they already own.Problem is that this is and always will be a very small niche market, and that market is shrinking as the years go by. While there are companies rebuilding Mazda rotary engines here (but not reconditioning the rotor housings), eventually the supply of new rotor housings will dry up. Mazda will stop making them and supplying them, and the junkyard used engines will quickly be depleted. Most (almost all) the RX-7 Mazda owners will give up and buy something else because the parts to fix their cars will simply be unobtanium, and nobody will spend $5,000+ to have two or three rotor housings custom made for an unexceptional 15 to 20 year old car that is worth perhaps $1,000 (or less) running.The life cycle of any vehicle is production (everyone has one, parts available easily), discontinued (enthusiasts, very few casual or accidental owners, parts getting thin) and just plain old (only true fanatics left, we prefer to describe ourselves as "collectors" and the vehicles as "classics" - parts unavailable, specialist suppliers of SOME parts at high prices). We're between "discontinued" and the last category, and asking the question "Who fixes eccentrics and rotor housings?" shows that parts are indeed getting thin or worse for these bikes.As an "enthusiast/fanatic" on a number of vehicles, my strategy has been to "stash and hoard", which works if you have some spare cash to take advantage of opportunities that come your way, have a safe, dry place to store your "stuff", and are either unmarried or are lucky enough to have a spouse who drives a new (or newish) car and therefore isn't worried about this strange behavior.Best Regards,FloridaMike

[Richard Negus]

Salvaging main journals is straight forward engineering and has been done several times - I had one done only last week.Salvaging an eccentric journal has only been done once, to the best of my knowledge. The finished surface has to be hard (Rockwell 64C minimum) for a depth of at least 0.75mm. At Mid-West, we ground down the eccentric of a single-rotor shaft and shrink-fitted a hardened steel sleeve. It ran on the dyno for about 100 hours, but eventually the sleeve moved and damaged the engine. Perhaps with a thicker sleeve and more interference, it would have lasted longer. That one had a wall thickness of only 2 mm; 4 mm would have been better.Salvaging rotor housings has been done successfully in the past by Norton. Defective plating can be removed, either by grinding or by reversing the plating process, and a fresh coating applied and then ground again. As the plating deposit tends to form around the corner of the epitrochoid, the side faces of the housing also need to be re-ground, making them narrower than the standard 68.21/68.19 mm. A-grade is the first regrind & measures 68.11/68.09; there are also some B-grades in service (which have been salvaged twice, measuring 68.01/67.99. Obviously, rotors and apex seals have to be narrowed accordingly.The UK plating company has aerospace approvals and would not consider Fred turning up at their front door with a pair of housings for re-plating as a viable business opportunity. However, someone turning up with, say twenty identical housings might get their attention.The UK machining/grinding company is more 'commercial' and has reground 'chattered' race housings for me at a very reasonable cost. Knowing the epitrochoid formula and the three generating dimensions, any company with a good CNC grinding machine should be able to do that job but, as ever, there is a learning curve.I haven't yet found it necessary to salvage rotor bores, but the day will come when new rotors are not available.As an aside, the last RX7 housing that I saw had a thin, finned, steel liner around which the aluminium housing was cast. This gave a very strong mechanical connection between the two and good heat transfer. The inner surface was plated (hard chrome??) and presumably could be stripped and replated if required.R.

[Wayne]

Hi AllThere are air coold engine parts and compleat rebuilt engines still in existance, as sugested some were bought for that just incase senario. What i can say to anyone is lable up what you have, keep it well oiled and check the stuff regularly or it can turn to scrap? I inspected 2 ecentric shafts offerd for sale to me which were only fit for door stops due to been stored with no oil on them.The labling is for the worst case senario, i am sure i junked useful stuf from my late fathers estate because we had no idea what it was and because there was so mutch of it there was no way of finding out?Regards Wayne

[Dell Boy]

I agree Wayne with you 100% on the labelling of stuff. When my son died he had a garage full of japanese bike parts & was running road & race bikes. Suzuki`s & Kawasaki`s.It was a struggle to dispose of his possessions anyway without the added problem of not knowing what bike/model it came from. I am still trying to clear the parts.I now label all parts that come into my possession in the hope that it will help in there disposal & I indicate if they have a special value.I was asked last week if I could go & sort out a widows late husbands garage to identify & value his parts & projects as she doesn`t have a clue what the stuff is.Derek F.