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There’s an awful lot of discussion and controversy surrounding this part of the build. Chain drive or Belt drive, Leaky Oil Bath or no Oil Bath. Build regulations are tighter here in UK so we’re not allowed to change any mechanical parts from the standard, approved ones supplied by Rotorway..
OK, the chain and oil bath system is crude, time consuming to assemble and potentially dodgy if the oil should leak over the hot exhaust but I’m not sure I would change it even if I could. So, we’ll do our best to make sure the oil bath doesn’t leak.
First thing is to get the components to fit together correctly. Matthew trimmed the top cover halves and prepared the channel that would later accept the rubber seal. There’s no easy way of doing this except by hand. Rub down and fill the surface of the channel until it is smooth and level. Trial fit the rubber to ensure that you have a tight, uniform fit. All the surfaces will later be primed and painted with a 2 pack epoxy paint.
Matthew improved the fit between the two halves of the top cover by dressing off the high points and rebuilding the mating flange with new GRP
Here’s the old faithful packing tape mould release again, preventing the two panels from bonding together as the assembly is Clekoed together whilst the GRP cures.
The new flange.
We’d seen this mod somewhere and though it was a good idea. Matthew made a viewing panel for inspecting the bolts securing the main sprocket to the main shaft. He warmed a square of Plexiglass with a hot air gun and hand-formed it to the shape of the top cover. Temperature is critical here. You’ll need soft gloves. Don’t get the Plexi too hot or it’ll bubble and show imprints of the glove texture. Mould it in a couple of stages if necessary.
The plexi panel will be screwed and sealed with silicone.
We’ve been given a new oil seal and fitting instructions for the bottom of the main shaft. I think this is a new mod from Rotorway.
FITTING THE OIL BATH
The first thing to do when fitting the chain oil bath is to accurately measure the distance between the shaft centres and mark the shaft positions as accurately and centrally as possible on the inside of the oil bath. There’s not a lot of bonding surface on either seal so it’s important to get the seal positions spot on. I used a trepanning cutter to cut the 2 1/2 inch hole for the new front seal location shoulder. The manual suggests wrapping tape around the shaft to bring its diameter up to the I.D. of the seal. For the rear seal I began by cutting a hole just large enough for the secondary shaft.
I’ve painted the oil bath with 2 pack paint inside, to reflect some light around and thus help with visual inspections and outside, to match the frame.
There’s not a lot of room for error here so I decided to make an alignment bush from aluminium. (Top diagram and below). I also made a marking ring to drop over the secondary shaft to mark the hole the rear seal. (bottom diagram)
Here’s the new front seal and my alignment bush.
Here I’m using the marking ring to mark the hole for the rear seal
I cut a disc of 60 grit abrasive paper and glued it to the face of an old slitting saw blade in a small stub arbor on my milling machine. I could then hold the oil bath on the bed of the machine and dress the seal glue faces flat and square
I used a magnet on a stick to locate the centre of the frame tube below the oil bath before drilling and fixing.
Jumping ahead a little. Here’s the latest chain link mod supplied by Rotorway. Now split pins instead of the old regular joining link. Good idea I reckon.
I think Rotorways idea of hooking the opened-up springs through rivets is particularly naff. For a start, re-bending the wire at the end of a spring can only reduce its inherent strength and secondly, what’s a sharp piece of wire poking through the rivet going to do the the soft rubber seal behind? So, I thought I’d make some hook plates for the springs. I’ve seen a similar idea on someone else’s site but I think it still involved bending the spring. I made these plates from 0.050in stainless steel and riveted them to the cover with the rivets supplied. I made this simple, vice-held tool for knocking out the rivet pips and flattening out the rear of the rivet.
I fed the spring through a 1 1/4 long piece of 10 mm bore PVC tubing to protect the frame paint. And it works a treat.
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