Another 1967 Triumph Mountain Cub in the shop
A 1967 Triumph T20M Mountain Cub has been working its way through the shop. Bought as a roller with a bucket of parts and a locked up engine, I had no idea what I was getting myself into. The availability of parts for these bikes is slim at best, with some items near impossible to find without some luck, or paying dearly. A lot of new old stock parts went into the build, particularly the electrical system. A number of parts were missing, or in unusable shape, and had to be found. The bike is near completion as of now, but there have been challenges…
As the bike came to me. Most of it is there, but the missing headlight, carb, and oil feed were costly or difficult to find. I had seen an ad online from Big D Cycles, offering the bike in pieces, and stating it would be taken to the Barber Vintage Motorcycle swap meet, if no taker was found. I thought about it a week or so, and called them, only to find it already on the road to Barber. I told them if it came back, I wanted it, and they said they would call if that was the case. Three weeks later, I walked into Big D Cycles for another unrelated bike, and they told me the cub had returned from Barber unsold only a few hours before! A deal including an NOS coil was made, and the build was begun.
Everything was well worn and some things downright abused. As bad as it all looks, the muffler, brake pedal, and airbox in this pic were all usable.
Some serious water vapor damage. The rusty standing waterline can be seen on the inside of the side cover. Luckily, the water level never reached the crank shaft or transmission shafts, but some of the vapor caused some pitting. Most all of the primary was rebuilt, with the clutch basket and hub rebuilt, and all new chain, plates, springs, cushions, posts, bearings, and outer pressure plate. The ignition stator was replaced with a new Lucas brand unit, made for Triumph ET ignition systems..
With the engine locked up, it took more than a few hours to break it down to this point.
Fortunately, the crank ends were pristine.
The cam was badly pitted, and the lack of a replacement forced other options to be considered. A shop in the North West of the country was found that could recondition it and the followers.
After return from Delta Cams in Spokane, Washington, The welded and re-ground lobes look great.
The entire rear wheel aside from the repaired brake panel was scrapped. The bosses for the sprocket were chipped up, and drilled out, with through bolts holding the sprocket on. Definitely a hardware store fix. Finding a new hub was a little challenging, but after finding one, a second in even better shape was found. The shocks were shot and were replaced with Hagon brand units with NOS springs added by Mitch Klemph of Klemph’s British Parts.
The original hardware before stripping. After a hot degreaser ultrasound bath, they are vapor honed, burnished on a wire wheel, and then cadmium plated at Texas Precision Plating in Garland, Texas. There were quite a few missing, damaged, and incorrect replacement nuts, washers, screws, and bolts. I actually did two batches of stuff because it took a while to find some parts, and I didn't want to delay the build waiting till everything was collected.
A fresh tray of cad plated hardware is so satisfying.
The tail light assembly had been whacked at some point, denting the fender, and bending and tearing this plate. The bends were easy enough to smooth out, and the tears were aligned and welded.
The finished tail light face after welding. It will get sanded a little smoother and then sent off for powder coat.
The inside of the engine shows how water coming through a removed valve cover went down the pushrod tube and onto the timing gears and cam. The timing gears were replaced with NOS pieces, and all bushings bearings and seals were renewed.
Things look a lot better with all the new parts. A new layshaft and two gears, shift plate, quadrant pawls, and selector rod were put in along with the new oil pump.
The head was also in such poor shape, it was scrapped. The valves were so thoroughly stuck, that two different valve compressors were bent trying to press them out.
An NOS head was found in pristine condition. The guides were already pressed in and reamed, and the new valves slipped in perfectly. The exhaust spigot had never been mounted, and needed sone tapping out. Lacking the proper tap, another spigot was fashioned into a tap by some notching. It took a bit if time, but in the end, it worked just fine. All new springs, valves, clips, and retainers were used in the assembly.
After some clean-up, sludge trap replacement, and a new crankshaft pin placed in, the crank was re-assembled, and aligned.
The cushions for the clutch hub were replaced. They were somewhat difficult to source, which is what I have come to expect from a Cub restoration.
One end of the frame member supporting the kickstand and brake lever was ripped, where it had been welded to the swingarm bolt and frame sub member. The frame member was replaced with a decent used one. The brake pedal was badly bent, and was heated and re-formed.
Everything after degreasing, prior to paint stripping. The parts are then run through the vapor hone machine prior to repair.
The used replacement member had some extra holes drilled through the tube, and some brass around all the brazed joints. The front fender stay also needed some repair on the screw hole.
The sub-frame where it had been welded. This was obviously a bush fix by someone inexperienced. The brass in the joints will make for weld contamination, and porous wells. It also looked like some of the brass was melted out by the heat of the weld.
After some welding and brass brazing, it looks a lot better. Some additional touch-up was done on the steel, and then off to powder coat. On the bottom right, the other frame member can be seen after the extra holes were welded up, and the brass along the brazed joints cleaned up. Behind the fenders, the front fender screws hole repair can be seen peeking over the edge.
Another repair was necessary on the rear brake panel due to gouging from the sprocket screws.
After repair.
Quite a bit of work to get to this point. The frame parts and front wheel hub were sent to Triad Specialty Coating in Lewisville, Texas for the gloss black powder coat. There was also a second batch of powder coat done later in the build after a rear wheel hub was found, and some fender brackets fabricated. The painted parts will be done by Jason Small, and the hardware sent off for plating.