1970 Velocette Thruxton recommissioning

This week saw me back into the shop after a small hiatus. The thought of finishing up the fork leg both inspired me but also put me on reservation.  It's been a few years since tackling a Velo front end. There are some peculiar points to keep in mind. 

The last job was re-soldering  the fork leg. Next was to repaint. My approach may not be what you would consider to be usual. Most people would either take the parts to a paint shop or pull out the aerosol cans and give it a whack.  The cost and time for a paint shop is out of the picture for me and with it still being below the 50's in Fahrenheit, aerosols are also out of the picture. I've done the oil tank and forks on the scrambler with brush with good results, so it should be ok here too. The idea is to keep within an older approach to repairs; easy, simple methods that are reproduceable. Everyone has a brush.

The first set was to get the primer coat on. I did two coats with light sanding in between each. The sanding is a regular theme in brush painting parts.

The final color was done in four thin coats, each coat is wet sanded to remove dust and level out the overall finish. I'm not looking for perfect, just a respectable finish that blends in with the original finish.

A few pictures of the final finish after wet sanding, buffing and waxing. The picture below is a final comparison of the original Thruxton leg on the lower right and the repaired and painted leg on the upper left.

Once the leg was painted and had a few more days to 'cure', the assembly began by removing the fork tube from the triple clamp, stripping off the spring and spring holder. I also needed to  remove both upper and lower bushings so as to replace the fork seal.  Fork seals are the same as BSA C15 seals for note.  I could slide the fork seal and upper bushing down from the top of the fork tube making it easier to use the home made driver. It's possible that some fork tubes will not allow you to do this, in which you would need to in stall the spring holder, spring, fork seal and then the upper bush plus use a two piece driver tool to install your upper bush into the leg followed by the seal. It's a good idea to draw out and give your self a good looking at before you install. Another item to install is the damper assembly into the bottom of the fork leg. It could be done later, but as you can see in the picture; it's the easiest way to make sure of it being centered. 

Once the fork assembly is ready, it's time to begin the fitting into the triple clamp setup. The spacer/spring holder might be a very tight fit into the lower triple clamp. With a wedge expanding the pinch opening I used a brake hone to clean up the surface and make it slightly wider. On the spring holder Ed G. suggested to use a file and lightly reduce it's diameter. Since it wasn't too far off I used the interference marks as an indicator as to where to file.

1970 Velocette Thruxton recommissioning

 

It's funny how the bike gods work sometimes.  When I left the workshop last night I was pondering how to approach the solder joint repair to the fork legs. The little propane bottle was melting the solder but just missing out on the heat and then the question of how to grip the tube... Ok, I'll sleep on it.

After morning coffee, in came the mail and with it the latest Fishtail.  Wouldn't ya know-  they had a write up on the process of re-soldering fork tubes. Well it seems that yes, I was not using enough heat. That and an added trick of twisting the tube as the solder melted. So I gave Ray B. a call at 'Toy shop East'  to see what he might have on hand.  The 'Toy shop' as it is, is an old chassis/speed shop with all manners of equipment for causing great mayhem. Ray bought the shop a few years ago. It's the same shop that I would buy sheet steel for my 440 Datsun project in my youth [  https://newenglandzen.blogspot.com/2010/12/datsun-1200-with-440-or-youthful-folly.html ] the same shop that built Jungle Jim's Vega back in the day. I find it comforting that I can go to places like this and be at home as it were, just a good feeling of living nostalgia.

Ray was in, so I was on my way.  We talked about it for a few minutes; the process, the technical aspects and all involved. As we talked, tools came out and we gave it a go. Putting the axle lug in the vise and a section of flat stock across the top so as to have it catch on the springs tab retainers, I put Ray's larger propane heater to it.  After not too long I gave a slight twist to the flat stock and heard a slight squeak in the joint. With a couple more twisting actions the whole unit loosen up and was able to be pulled clear of the casting! Excellent, we had success in making many from one!

So now what? Well, on to finding a few tools, gathering the proper flux and solder, give it all a good cleanup and put it back together. I'm just excited that it came apart as well as it did. 

1970 Velocette Thruxton recommissioning

 

It was a little difficult jumping back into the Thruxton, I hadn't made up my mind what to do about the front tire. Rather than take the front wheel on and off several times, I thought to make it all into one go around. The right side clip on was cracked meaning that either the triple clamp needed to be removed or the fork tube would need to be dropped. The wheel and fender need to be removed if one wants to install the lower fairing section as well. As for a tire, currently the selection out there is somewhat thin. I'd like to stick with an Avon speedmaster MkII or Dunlop K model; I'm not finding much...

But then there was the drip...

At first you get hopeful, a spot of oil on the floor could have come from anywhere. Wipe it up and hope for the best. Just keep an eye on things over time. Maybe a loose crush washer, maybe a loose nut on the bottom of the fork leg. There was silicone sealant on the bottom of the fork tube, but I knew better. It was more likely crash damage to the slider. Velocette sliders are made of three parts; the upper bushing/seal and spring holder, the lower casting to hold the axle and a section of tubing between the two. All of these components are soldered together and one of the reasons NOT to powder coat the legs as the ovens used in the  powder coating process will melt the solder. 

This is not the first time I've faced a leaking solder joint on the right hand side leg. In fact it seems to be a common location as this is also where all the brake plate is pinned to stop it rotating in operation.

In reality, I kind of expected this the second time I saw the leak, it's a thing.  The repair sounds somewhat straight forward;  clean off the paint, de-solder the joint, clean up the parts, tin the tube, reassemble and re-solder. Maybe....

Having an older right side leg with the same leak meant I could try and see how difficult this could be.  First was stripping the paint back, followed with setting the casting up in the vise and heating it with a propane torch for a bit. I was able to get the solder melted but didn't quite have enough heat to completely soften the whole solder joint in the casting.  From what I recall, the tube is set quite deep into  the casting. So that is that for the time being.  We'll approach this later.

While on the subject of soldering, I'll also need to make up a new throttle cable. The crash also did a fair bit of damage to the throttle.  You can see where the safety wire had done it's job keeping the throttle together.

So, tires, solder, paint, throttle cable, fairing....  on goes the list. Just keep pressing forward we'll get there.

1970 Velocette Thruxton recommissioning

Not much work was done to the Velo this week.  I'm trying to figure out which task to work on next. Possibly it will be the front end, as the clip on handlebar needs replacement. To do that will mean pulling the front end apart. That would also be a good time to change the front wheel, reinstall the front fender and install the lower fairing. However, I'm not sure that it's finished enough to have the fairing reinstalled.  Trying my best to balance tasks to a minimum. But in the interest of the Thruxton's past history, it had been safety wired tied for racing. Here are a bunch of pictures of such as it stands. Most of this wire will need to be changed out and redone. Enjoy.

 

1970 Velocette Thruxton recommissioning

The last time in the shop, I confirmed that the carb body was warped and needed some work or replacement. Since a replacement will take some time and money before getting on with it, I'll have a go at making this body work.  I've experienced this with early BMWs; 1950 ~ 1969 Bing carbs. They would become over tightened, bent, hammered and all other manners of abuse causing the flanges to become distorted. Usually this would only cause an air leak between the head and the carb. Many of the Bings were no longer available so a little deft file work and light smoothing on a surface plate got them back into service.  The Amal suffers a slight complication when it bows the flange, the slide can stick within the bore. The fix for that is to make an mandrel or arbor to fit within the carb to bring back to a round state. 

Since there was such a heavy bow, I tried to use the press and "push" the ears back closer to a flat.  After which I used a hand file to flatten the high spots.  The final passes were done with wet or dry paper on a granite plate. 

Even after finishing on the granite plate the fit was still sloppy. Upon closer inspection it looked as if the material around the stud was pulling out. Easy enough, I took a five fluted countersink bit in a hand chuck and lightly removed the excess material. I also did the same on the carb body as well just to keep this from happening again.

a better fit than before

with the thin paper gasket

 Yet another chore done and one more step towards a spring ride.