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Twin gears.

clevtrev

Well Known and Active Forum Website User
VOC Member
Does anyone think, that the dogs on a layshaft gear ( G10 , G7 ) should be equispaced ?
 

A_HRD

Well Known and Active Forum Website User
VOC Member
OK ClevTrev, tell us why they aren't(?!). Because they are made wrong?

Peter B
Bristol, UK
 

clevtrev

Well Known and Active Forum Website User
VOC Member
OK ClevTrev, tell us why they aren't(?!). Because they are made wrong?

Peter B
Bristol, UK
I can only conclude that the drawings they were made to are incorrect.
The gears I am referring to are G10 and G7 the fixed gears on the layshaft. These were purchased in the last year, and I have just got round to fitting them. The gears were ordered with a layshaft, at the same time.
To start with, one of the gears would not go on to the shaft, so the gear had to be filed out to fit.
With G10 in place, tried to put shaft into bearing, would not enter. Half a thou oversize. ( Both ends)
Used old shaft, gear G10 had to be further reworked to make it fit the old shaft.
Then putting the gearbox into checking fixture, found could not get 1st gear, no way. G9 would not enter G10.
Found another G 9 and that would just enter. BUT, then find that only one of the dogs was touching the G9 , the other 8 dogs were up to .025" away from touching. That means the gear would only be driven by the one dog, which I think would be a disaster waiting. Ditto for the G7.
That means there are three useless parts to go back.

So it would appear that the drawings must be wrong, given that the parts are now made to drawing. At least, that`s what we are told. I may be wrong. But I just hope no one else has fitted any of these gears, that might have appeared to assemble.
 

Vic Youel

Well Known and Active Forum Website User
Non-VOC Member
Gear Drawings

Some years ago the VOC spares company and other suppliers all obtained gears from the Holder organisation ..... sometimes known as Velocette's ....which own the original Vincent manufacturing drawings.

The VOC drawings project did draw up the gears but as far as I know gears have never been manufactured in accordance with club drawings. Or am I incorrect?

Therefore Trevor, are you saying the original Vincent drawings may be wrong?

Vic
 

A_HRD

Well Known and Active Forum Website User
VOC Member
Trev,

I have a full set of Holder-manufactured gears which I bought about 5 years ago and still have sitting on the shelf in their original wrapping and box.

I have just spent a frustrating morning setting-up those gears on the rotary table and making various measurements with a dti. (Wish I had the space-age computerised measuring system that Trev has). Anyhow, I can confirm that the G7 and G10 have dogs that are 5 to 20 thou misplaced; only some dogs touch the teeth in the corresponding gears G8/1 and G9; most don't. I can see I'll be spending some time with my Dremel trying to get a happier outcome. I have an old original G10 and those dogs are fine.

I'm happy to report that the dogs in the new double-gear are all within 2 thou or so.

I can't comment on the fit to a layshaft as I don't have one - new or old. If someone can take one to the Herts and Beds Rally this weekend we can have a trial fitting session!

So what preliminary findings can we deduce so far (still subject to confirmation of course)?
1. I can confirm Trev's findings, regarding the dogs, with unused G7/G10 gears bought from Holder 5 years ago.
2. The original Vincent drawings would appear to be right in respect of the G7/G10 dogs, but Mr Holder's machinery/machinist may not up to the tolerances required.
3. About a year ago it appears the Vincent supplier(s) were still getting their gears from Mr Holder; made with his (original?) drawings on his machinery.
Time we got the VOC's superior drawings into the hands of a specialist gear manufacturer for a trial run methinks!

Perhaps Dick Wheeldon could comment?

Peter B
Bristol, UK.
 

timetraveller

Well Known and Active Forum Website User
VOC Member
This thread seems to be turning into a critque on the quality of Vincent Spares. In the next MPH, Kent and Sussex Section Review, you will find details about the failure of parts with two of our members. The first had a valve seat fall out of a head that was less than one year and 5,000 miles old. The second fitted new lower guides and valves and then found that one of the new valves was seriously loose in one of the new guides. Several years ago I was given the oportunity to quote for the provision of new spare parts. (Please note that I do not make these parts but source them from machinist of known accuracy). As these are manufactured to Club owned drawing, and the Spares Company guards its privacy carefully, I cannot provide full details but one of the items was H13 which goes behind the brake arms and the gear change lever on twins. I was sent down a sample to show the machinist. The tolerances on the square hole in the middle of this item are quite tight at plus nothing, minus half a thou. The sample was 3 thou overized in one direction and 5 thou oversized in the other. With modern machine tools there is no excuse for such slackness or for valve seats falling out and it looks as though we need to start and chase up the quality control system.
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Some years ago the VOC spares company and other suppliers all obtained gears from the Holder organisation ..... sometimes known as Velocette's ....which own the original Vincent manufacturing drawings.

The VOC drawings project did draw up the gears but as far as I know gears have never been manufactured in accordance with club drawings. Or am I incorrect?

Therefore Trevor, are you saying the original Vincent drawings may be wrong?

Vic
Irrespective of who made them, the Spares Co. have drawings to check them to, so why send out potentially dangerous components, and parts that do not fit, these at premium prices ?
So the question now, is, why go to the expense of producing drawings, if they are not going to be used, in any direction, either for manufacture or for checking purposes. Or maybe they are ?
 

nortonpower

Forum Website User
Non-VOC Member
While talking about quality: had a Vincent 1000 in recently for some work. I noticed the primary chain was tight and a turn later very slack so out went the primary to check what is the cause. I knew where to look as I had the same problem last year on another Vincent twin. The teeth on the big primary sprocket are machined wrong - everything is concentric to a few thou but the teeth are 20 thou out!!!! Exactly as the wheel last year. I did the same to this sprocket as to the last one. Centered it on the mill on the teeth and remachined all other important dimensions, turned oversize bushes, shrunk a sleeve over the center to restore the diameter for the seal, drilled new holes for the clutch and so on. Was nearly a days work to get everything run straight and true. At least one of those sprockets was purchased a while ago by one of my customers from the spares company. They should be advised to check their stock and if there are more to be found I would talk to the makers.....
 
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