Thanks, that is interesting. I was just reading a magazine and happened onto an advertisement for Avon Roadriders. They show the front tire tread just the way yours is, but they show the rear fitment the other way around from yours (grooves oriented the same direction for both front and rear wheels in the ad). I guess I was thinking mostly of the grooves shedding water on a wet road, but what both of you have said makes sense. It's good they put the arrows on the sidewall to remove all doubt.
'64 TR6R Plus some Twins from other countries (U.S., Germany, Japan)
There are 'universal' roadriders for front and rear fitment and then dedicated 'front' or 'rear' tyres. As Rob C said it has to do with the belts and the universals will always be reversed in tread 'direction' between front and rear. My roadriders that I had fitted have turned out the same and I find that to me it looks a bit wierd. Aesthetically I think the arrangement for the rears shown 'looks' better but, after all, function is important.
I had forgotten to consider the reversal for the universal tyre when making my selection.
What I am unsure about is if the tread 'direction' will be the same when you have dedicated front and rear fitment tyres fitted. I suspect so, but could be wrong.
...that's the Triumph and Velocette serviced and ready for spring, so I got back working on the Triton today.
I picked up an engine and gearbox separately via eBay, the engine started out as '55 T110 but has been assembled with a T140 crank and top end with what looks like 60's rocker boxes. I stripped it down and it's certainly a "bits", I am still deciding on the spec that I will rebuild it to, but that's for later. The gearbox is a 1960's AMC; possibly from an Atlas? I haven't opened it yet but all the gears select and it turns over OK.
Before overhauling the engine and gearbox, I wanted to assemble the crankcases and gearbox in the frame. I went for a new set of Dresda plates and made up a set of stud bolts myself.
The trial assembly went well and the engine plates were an exact fit, I still need to do a bit adjustment to get the alignment right but things look pretty close as a starting point.
...things have been a bit slow on this project lately, mainly due to work travel commitments and taking the opportunity when I am at home to get some riding in while the weather is good here. But I have made some progress.
I started to machine up a set of gearbox adjusters these but due to limited workshop time and increased internet time while travelling I found and purchased these from RGM Norton, they are well made and fitted right.
I then started to work on the engine, gearbox, swing arm, frame and wheel alignment. First thing was to get the gearbox positioned correctly between the engine plates. This required a slight adjustment to the mounting lug faces of the gearbox housing by skimming the faces in the milling machine, necessitating a strip down of the gearbox. This also gave me an opportunity to inspect the gearbox internal components, which I am pleased to report are in very good condition and will only require replacement bearings, seals and service items as a matter of course plus some of the recommended upgrades for AMC gearboxes (which I am still evaluating), when I overhaul the gearbox for final assembly.
Next it was necessary to adjust the lower rear frame engine plate mounting lugs by 3mm. I decided to cut off the existing lugs and make new ones and weld them to the frame.
With the engine casing and gearbox fitted and aligned in the frame I set up the gearbox sprocket to rear sprocket alignment. This involved inverting the swing arm as there is a 5mm offset in the swing arm that was on the wrong side as I had originally mounted it. I was glad that I had only tack welded the lower shock absorber mounts on, as they had to come off. I then set up the swing arm on the tapered roller bearings on its spindle between centers on the lathe and checked alignment and parallel of the sections where the rear wheel mounts, this was found to be ok with no adjustment necessary.
The swing arm and wheel were then mounted. I measured and set the distance between the swing arm spindle center and the rear wheel axle at both sides. Then I used a laser alignment tool to set the position of the swing arm and rear wheel using temporary washers to align the rear and engine sprockets. I then measured the stack height of the washers and machined up suitable spacers in stainless steel.
Next I checked the fork and yoke (triple tree) alignment using a pair of straight edges.
The front wheel was checked for center location between the forks, this need a slight adjustment of 1mm offset by adjusting the spokes.
I secured two straight edges to the rear tyre that projected past the front wheel on either side. I was necessary to offset the rear wheel by 4mm by adjusting the spokes to achieve alignment.
�I got the primary case fitted today. This was an eBay purchase a few months back, originally from a T6 I believe. A slight modification was required to the main shaft aperture in the inner case to suit the increase in crank / gearbox centers due to the Triumph engine and Norton gearbox combination. I removed the sealing washer retaining plate by drilling out the rivets and cut a new partial hole using a trepanning tool and filed the finished profile. I made up the fixing screws for the inner case, but will leave the outer case screws for now as I may have to make a spacer to fit between the inner and outer cases, depending on the clutch and belt drive that I use.
The engine work is moving on, I purchased a Morgo 750 kit that I will use with the 10 stud head I have and SRM billet alloy 650 (long) con rods.
I have sent the crank off to SRM with the pistons and associated items. They will inspect and magna flux the crank and if all ok refurbish and dynamically balance. I have also sent the timing cover for them to modify to accommodate a crank end oil seal.
The cylinder head is also with SRM for new lead free seats, valve guides and conversion of the exhaust ports to accept stubs for push over type exhaust pipes.
Although by no means a priority job, I decided that I had to repair the dent in the primary cover that was there when I purchased it as it was bugging me every time I looked at it. Instead of using the pedestal grinder mounted polishing wheels I decided to do this the manual way using various grades of wet and dry paper, lubricated with WD-40 and copious amounts of elbow grease. It was actually much less work than I though it would be to totally remove the dent and blend the surrounding area.
...I got some work done on the rocker boxes today. The exhaust rocker box cover had a repair made by a PO to 3 of the fixing stud holes where they had been drilled and tapped over size with modified stepped studs. The quality of the work was pretty poor, and the gasket surface around the studs was damaged by what looked like cuts from a grinder used to reduce the stud diameter. I decided that the best option would be to fill up the holes and damaged gasket face using aluminum brazing and drill and tap new holes.
After filling the holes I filed off most of the excess filler material then surfaced with a sheet of wet and dry paper on a piece of plate glass.
I used the other rocker cover on a surface table as a reference to transfer the locations of the new holes.
The castings were distorted where the cylinder head and fixing bolts passed. I reamed these true and spot faced the washer land areas.
Excellent skills and thread. Maybe I missed it in a post but see no mention of your lathe/mill. That particular model is one of the most versatile machines available with the extreme centre height and work station at the compound mount.
Lathe/mill is a chinese made Chester Centurion 500, although it is plated as a White Eagle. I bought it through a UK dealer, it did require a bit of setting up and there were a couple of badly made parts that the dealer sent replacements for with no problems.
...the rockers and rocker shafts were found to be a mix of oil fed and later oil groove type. There were 3 oil fed and 1 one later type of rocker and one later spiral groove type shaft. I ordered a replacement oil fed rocker to make the set, however this had been ground at the ends of the arms more than the other three existing ones, so I ground those to make them the same. I was considering using the unmatched rocker shaft but decided against it incase it created a bias of oil flow and besides the ends for the domed nut are a different thread from, so an earlier type LF Harris made replacement is on order. The existing one that I'll use needed a tidy up at the end on the lathe where it had been slightly mushroomed by hammering in. I will put all of the parts into my ultra sonic cleaner tomorrow to break up any crud in the oil ways and will then blow out with an airline.
...I got the cylinder head back from getting new valve guides and seats, and threaded push over type exhaust stubs fitted.
I could now get the cylinder head steady fabricated.
I decided to go for a simple arrangement using HE30 plate. I set out the layout using AutoCAD then printed out paper templates and transferred the pattern on to the plate.
I cut out and shaped the smaller horizontal part using a hacksaw and file. For the larger vertical part, I rough cut this out using a powered reciprocating saw and then finished the profile using a cutter in the milling machine.
After assembling, I tack welded the parts together then clamped to a cast iron table for welding and during cooling to prevent distortion.
I cut out a fixing lug for the frame cross member from mild steel flat bar and tacked this on, I�ll fully weld this when the engine is removed again. Finally, I made up a set of fixing nuts. I used washers under the bottom plate of the steady to compensate for the base and rocker box gaskets but will leave drilling the bolt holes for the lugs until I assemble and fit the engine with all gaskets in place to ensure I get the position right to match the height of the top of the engine.
I would be taking the tyre off the rear and checking the spokes are not now proud after moving the rim 4mm. Puncture prevention.
Good point, thanks, certainly worth a check.
I removed the rear tyre this afternoon, and the spokes at one side were all a bit proud of their nipple as a result of adjusting the rim offset. I resisted the temptation to take the dremel to the ends in situ and removed and refitted the spokes one at a time cutting them back with a hacksaw in the vice so they are now recessed in the nipples.