Crankcase repair (53 Vincent restoration)

Re: Crankcase repair

Buellingvincent said:

The machined primary cover seen from the inside:

Increased the oil hole between the crank and oil pump worm to 5mm as suggested (don't remember who right now):

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NEW LINKS TO THE PICTURES IN THE ORIGINAL POST:

Re: Crankcase repair

Buellingvincent said:

In order to get the ends of the timing spindles on level I made up a temporary tool using a magnetic carpenter's level. Purchased a set of neodymium magnets and used a metal ruler and 4 of the shims I acquired for the crank shaft bearing distance pieces to get the right height:

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NEW LINKS TO THE PICTURES IN THE ORIGINAL POST:

Re: Crankcase repair

Buellingvincent said:

The outer distance piece (just before assembling the outer race of the second conical roller bearing) consisting of two 3mm washers and three 0.5mm shims. This was needed in my case to later get the conrods centered in the pistons/cylinders:

Ratchet shaft bevel and bearings with lock screws and applied Loctite:

Just before the case goes together:

Finally bolted up. At last

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NEW LINKS TO THE PICTURES IN THE ORIGINAL POST:

Re: Crankcase repair

Buellingvincent said:

Old clutch shaft and new before assembly of Constant Mesh Pinion G6:

Location of "1" as described in the Workshop Instructions Sheets:

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NEW LINKS TO THE PICTURES IN THE ORIGINAL POST:

Re: Crankcase repair

Buellingvincent said:

Yesterday a job colleague helped me shorten the spline section of the clutch hub in a lathe. About 4 mm shorter. Will probably need to enlarge the conical chamfer a bit more to really move the clutch as far inwards as possible over the shaft splines.

Before:

Opened:

After:

Have not tested on the shaft yet as I met up with some old friends last night for a few beers. Very nice but feeling a bit slow today.

One of the pictures is showing the loose balls bearing of the clutch. We didn’t want to remove the spindles and studs so we used the biggest lathe in our prototype shop and managed to clamp the chuck on the rim.

I also picked up my mates kickstart crank and the primary cover from the welder yesterday. Now I have some more alu on the outside so it should be possible to machine the inside enough (I hope) to fit it over the belt drive. Some filing, grinding job of the outside will hopefully make it look nice and almost as stock.

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NEW LINKS TO THE PICTURES IN THE ORIGINAL POST:

After fixing the old picture links, now a new post.

I chamfered the inner spline end of the Newby clutch hub to get it all the way in over the shaft. Now almost 10 mm further in compared to before machining. I don't think I can do much more than this.



Spent quite some exhausting hours removing more material from the primary cover to fit it over the 68 teeth Newby clutch and 30 mm belt. Used my pillar drill machine, files and grinding flap wheels fitted to my cordless screwdriver.

Went back to the welder once again to fix two holes (marked with blue arrows); the threaded hole and the hole I created by grinding the outside flat where the chain tensioner blade pivot hole is.








In order to get the crank shaft pulley in line with the clutch pulley I need a bigger crank pulley to get it over the bearing housing of the crank case (mounted reversed). The standard Newby pulley has 36 teeth.

36t pulley:


After some calculations and a few phone calls discussing with Bob I ordered a 40 teeth pulley from him and a longer 112 teeth belt from the Bando dealer in Sweden. Now just waiting :|

Started planning next step in the rebuild during January and order more parts (as usual). Finally got the main shaft oil seal solved and the shims and distances sorted out. Bought two new new pulleys for the primary to get the right tension and get it in position under the cover. More material removal and then it is was done! Puuh! Now psitons and cylinders in place. Will post pictures soon...

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My, you have been busy!

Some more material removal from the primary cover was needed to make room for the dynamo belt pulley. Now it's only about 2,5 mm (1/10") material left on the primary cover behind the lower side of the dynamo cover.

I also ended up ordering yet another pulley from Bob Newby. This time a 41T. With the 40T I felt the slack was too much. With 41T I get a pre-tension of the belt. I hope it will work even on a hot summer day.

Testing without head bolts and the primary cover just hanging on the belt.

Front and rear ends just waiting to be united with its engine.

Pre tension, with a Newby belt, on a Vincent?!

Newby belts are supposed to run quite slack, and those honking great lumps of alloy of a Vincent engine are surely going to grow quite considerably when hot?

Both big factors in making pre tension sound a little concerning to me.

Of course, I don’t know how slack you mean by slack, or how tight you mean by having pre tension, but pre tension in this application would concern me.

That makes the 41 tooth look like the best option.

But it’s not a Mitsubishi. Or a timing belt!

What does Bob Newby suggest? Surely that’s the best info source?

A little while ago Patrick Godet told me he still had some belt drive bits for twins in stock, but that he ain’t gonna use them. The only road going twin he tried a belt on (mine) failed twice and he decided never to use them again!

If you call him, he might be happy to sell you what he has left cheaply.

To this day Im still uncertain what proper BNR adjustment should be (on a Commando). Those belts get warm quickly and tighten. The thing that
troubles me is when slack they flop about and wear on the back side (outer side). Wonder if a idler would keep them from flopping when cold
and might even cease to contact the idler when at running temperature. Out of fear I go with the chain adjustment approach of too loose
safer than too tight.

Onder said:

I go with the chain adjustment approach of too loose safer than too tight.

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Me too!

I found a couple of pics of the set up that Patrick did on my Egli.

Note the double sided belt to drive the Alton alternator. Also note the one off cush drive he made for it, very clever and neat.

Second pic is the one off outer cover he made, deeper than standard and slotted for ventilation.

The double sided belt is tricky in this application. The big Vin motor expands a lot. Precise distance of alternator drive centre to clutch centre doesn't matter much with a chain as the teeth can slide in and out a lot and cope with the expansion and contraction.

With a belt though, its a lot more sensitive. Too tight and the belt is 'crushed' and the alternator bearings put under undue load. They'll probably fail before the belt (as mine did), so you'll at least catch the belt in time. Too loose and too much tension is put on the teeth of the belt, and it will fail. I also think the belt is put under a lot more heat in this application, so probably not aiding long belt life.

Race bikes, without an alternator, are a different ball game and are very straightforward of course. Patrick was dead against doing this on a road bike and only did it because I twisted his arm. We both regretted it! That's why this was the first, and last, road going Egli Vincent Godet with a belt drive primary!