Fitting BT-H Magneto

[Howard]

I don't want to fit .110" of spacers between the pinion and the drive unit because I would end up with very little support for the pinion from the centre of the drive unit.
I am not too keen on removing metal from the front of the BT-H or the rear of the timing chest so I figure I might leave the pinion out of mesh as it is a light load on a nylon pinion...what do you guys think?

Hi Kevin,
I haven’t taken much notice of this thread, because I know nowt about BT-H. I’ve just had a quick scan, so I may be going over old ground, but have you checked the diameter of the tapers. A small difference in diameter will make a relatively big difference to the position along the shaft.
I know it’s a pain in the bum, but If I’d spent that much on new parts, I wouldn’t be settling for incorrect meshing pinions!

H

 

[redbloke1956]

Hi Kevin,
I haven’t taken much notice of this thread, because I know nowt about BT-H. I’ve just had a quick scan, so I may be going over old ground, but have you checked the diameter of the tapers. A small difference in diameter will make a relatively big difference to the position along the shaft.
I know it’s a pain in the bum, but If I’d spent that much on new parts, I wouldn’t be settling for incorrect meshing pinions!

H

Damned good point Howard, thanks mate

 

[davidd]

Kevin,

You have been quite patient slogging up this long learning ramp. I would not give up now. If you have confirmed that everything regarding the engine, the magneto and the mounting hub for the gear are stock and the gear is not aligned then I would modify the gear assembly to align it with the small idler. I would think you could shim under ET 223/1 to get it to the right height. I would like to think that you could get it to the right position and then ride it without fear, or too much fear. I do not think the mag gear is as lightly loaded as you think. I bought a bike once that had a nylon gear on the ATD and I found the teeth plugging the return line to the oil tank.

David

 

[chankly bore]

Dave is right regarding what to do in respect of alignment, but I think the pinion has less load with the BTH than the horrible traditional ATD.Since the picture of your original magneto pinion seems fairly well aligned, I would not expect the taper to be too far out.There is a thread I have already responded to regarding this taper.Doing lockwire on the 2BA bolts, or loctite is a good wheeze.Some early nylon pinions were of a peculiar soft and expanding material; I believe this has now been corrected.

 

[BigEd]

Dear Kevin,
It is often difficult to diagnose problems when you have the bits in front of you never mind when are on the other side of the world.;-) I guess we are all thinking hard to help find a solution. Trying to be logical about things I've made a précis of some of the things that have been said and wonder if they can be used as a starting point to verify and check.

Regarding gears not meshing fully you have said:

1. …. I have just checked my original mag in place and it has the same issue (hadn't noticed it when I first stripped down the very messy timing case) So this has me perturbed:
2. With the original mag and ATD, the gear sits too far into the case, ..
3. The new BTH and old ATD sits in roughly the same place,
4. The new BTH and new pinion assy sits in roughly the same place.
5. I just found a photo that I took of the timing case before I dismantled everything (it was a mess) and the angle is not good but it looks as though the original mag pinion did mesh so I must have stuffed something up?........

So one step at a time:

In "1." above you said when you put the original mag back on you still has the misalignment issue. Was the original magneto back on with your original ATD?
In “5.” above it would appear that maybe the alignment was in order before you started.
Does putting all the original parts back result in correct alignment?

 

[redbloke1956]

Hi Kevin,
I haven’t taken much notice of this thread, because I know nowt about BT-H. I’ve just had a quick scan, so I may be going over old ground, but have you checked the diameter of the tapers. A small difference in diameter will make a relatively big difference to the position along the shaft.
I know it’s a pain in the bum, but If I’d spent that much on new parts, I wouldn’t be settling for incorrect meshing pinions!

H

Thanks Howard, sometimes we don't see the forest for the trees, will check that tomorrow.
Kevin

 

[redbloke1956]

Dear Kevin,
It is often difficult to diagnose problems when you have the bits in front of you never mind when are on the other side of the world.;-) I guess we are all thinking hard to help find a solution. Trying to be logical about things I've made a précis of some of the things that have been said and wonder if they can be used as a starting point to verify and check.

Regarding gears not meshing fully you have said:

1. …. I have just checked my original mag in place and it has the same issue (hadn't noticed it when I first stripped down the very messy timing case) So this has me perturbed:
2. With the original mag and ATD, the gear sits too far into the case, ..
3. The new BTH and old ATD sits in roughly the same place,
4. The new BTH and new pinion assy sits in roughly the same place.
5. I just found a photo that I took of the timing case before I dismantled everything (it was a mess) and the angle is not good but it looks as though the original mag pinion did mesh so I must have stuffed something up?........

So one step at a time:

In "1." above you said when you put the original mag back on you still has the misalignment issue. Was the original magneto back on with your original ATD?
In “5.” above it would appear that maybe the alignment was in order before you started.
Does putting all the original parts back result in correct alignment?

Thanks Eddy, I put original mag back on with the old ATD and with the new pinion/boss assy same result (or close enough), the reason I am questioning myself is that one of the original photos "appears" to show correct alignment?
I will try some in depth measurements of both the BTH and old mag tomorrow.
One interesting point though...I have noticed that the original ATD has had the taper resleeved at some point....there is no (or little) internal taper, previous owner wore a blue and white striped apron I think because everything I have found so far has been butchered.
Kevin

 

[redbloke1956]

Kevin,

You have been quite patient slogging up this long learning ramp. I would not give up now. If you have confirmed that everything regarding the engine, the magneto and the mounting hub for the gear are stock and the gear is not aligned then I would modify the gear assembly to align it with the small idler. I would think you could shim under ET 223/1 to get it to the right height. I would like to think that you could get it to the right position and then ride it without fear, or too much fear. I do not think the mag gear is as lightly loaded as you think. I bought a bike once that had a nylon gear on the ATD and I found the teeth plugging the return line to the oil tank.

David

Thanks David, you are spot on, I have decided to fix the problem one way or another rather than ignore it, don't know where my head was for a while, getting frustrated with fixing the stuff ups of butchers I think, I started this project barely knowing how to spell Vincent but the previous butcher makes me look like PEI

 

[BigEd]

Dear Kevin,
When dealing with old bikes we should always bear in mind that we often don't know what one or more previous owner may have done to the bike. Never assume that something that is "original" is correct. In the 60 + years that these Vincent bikes have been around there has been plenty of opportunity for "original" parts to have been "modified".;-)
Stick at it. There will be a solution, we just haven't found it .... yet.

Thanks Eddy, I put original mag back on with the old ATD and with the new pinion/boss assy same result (or close enough), the reason I am questioning myself is that one of the original photos "appears" to show correct alignment?
I will try some in depth measurements of both the BTH and old mag tomorrow.
One interesting point though...I have noticed that the original ATD has had the taper resleeved at some point....there is no (or little) internal taper, previous owner wore a blue and white striped apron I think because everything I have found so far has been butchered.
Kevin

 

[redbloke1956]

still trying to fit the BTH!!!

In the attached photo you can see a .015" gap between the pinion boss and the face of the BTH magneto, I personally think the gap should be larger, I am basing this on practicalities ...nothing else, being my first Vin I have nothing to compare with.
I THINK it is the cause of my problem....either the taper on the BTH is incorrect (improbable?) or the internal taper in the boss is too large?
I would appreciate any input on this dilemna of mine, I need to gain about .110" to get correct meshing of the mag pinion and small idler.

From a state of confusion
Kevin