Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board crank pinion gear

Hi guys
does anyone have an old unwanted/worn out Triumph 650 crank pinion gear they would like to part with please? I need it to lock the cam gears up for torquing.
Cheers

Put all the gears in place then put some rag in there between the teeth. It’ll do the job and not cause any damage.

I have a few spares but I'd be surprised if a call to almost any Triumph shop near you didn't produce one. I've bought complete T140 sets on eBay for a song. I like them because they're good and heavy and made to a higher spec. That's why I have a few left over of course. I live in Norway so if I send it to you now who knows when it would arrive with Xmas and all...
Allan Gill's method works too, but I just don't like it.

SR

I would advise against the "jamming the rag" method.

The problem is that some of the rag gets very close to, or even between, the cam pinion and idler pinion. This exerts enormous force onto the idler pinion and its shaft, in the direction from the camshaft centre to idler centre (ie to the Southeast with the intake pinion, to the Southwest with the exhaust pinion).

The idler shaft has no direct way of resisting such forces (the crank pinion and other cam pinions are only sideways connected, not in direct opposition, as they are an isosceles triangle surrounding the idler).
The idler shaft is only 1/2" diameter, supported by a short press-fit into the crankcase. It isn't intended to handle large forces (just imagine the the idler would pretty much function between the 3 pinions without a shaft).

I am talking from unpleasant experience. I used the jammed rag a few times over the years, but the last time I didn't get away with it. I ended up with a loose idler spindle (as evidenced by much greater timing chest clatter than is usually found in a Triumph). It only took one ride out to have me removing the timing cover to find it.
Having just rebuilt the engine, now it came back down again to deal with it. And that was a barrel load of larfs. This forum was immensely helpful (I think the threads are still present from about 10 years ago), with suggestions of electroplating, welding/boring using various reference points to reclaim the accuracy of position of the spindle, etc.
Fortunately, I hadn't wallowed the hole in the case very much, just slightly tapered, so a +2thou spindle from Grin sorted it.

But you don't want to go down that road in the first place, don't rag-jam.
I'm not sure that jamming with a spare crank pinion is good for the idler spindle either, though it doesn't exert the extreme force that anything compressed between pinions will.

But the cams need to be locked in some way, to tighten the nuts. The best opportunity is when the top end is still off, so the small ends can be used with a bar through them. But often one is dealing with the timing chest in isolation. What's wrong with holding the crank pinion nut while tightening the cam nuts?

Ebay is a good place to find reasonably cheap spare crankshaft pinions. They do work well for what you are proposing. I don't like the bar through the small ends method - it just seems cruel to me (based on n evidence whatsoever - it is just something that doesn't 'feel' right for me).

As Koan suggests, the best method is to undo all the nuts on crankshaft, camshafts, clutch etc with the engine complete and still in the frame, so that you can use the gearbox and rear brake etc for jamming. But if it's too late for that, using a locking pinion should be a good second best.

Is $50 considered a cheap Triumph timing pinion because that's what they seem to be going for at the moment.

put in a bid



https://www.ebay.com/itm/Camshaft-Crankshaft-Timing-Pinion-Gears-Triumph-750-Bonneville-T140-TR7RV-876/133263008740?hash=item1f071823e4:g:RxoAAOSwfV9d6Y-e

or if you watch for a bit you can see some going for not a lot of maney

Come on guys, it's the 2001 not 1950...I use battery impact wrenches to loosen stuff ....And for tightening on some stuff, but won't admit it here...

i jam the teeth on the gears with mastodon bones, myself

The teeth work but your still applying the same separation forces as if you were putting a rag in between the gears, the idea is you don’t put a rag in such a way that it will pass through all the teeth. Just enough to bite.

If using a cam pinion to jam the teeth you want to go between the idler and the cam pinion, if you go between two cam pinions you chance the whole lot rotating as each gear touches only one each side it. If you drop the crank pinion in there (much smaller) it might rotate a couple of teeth before it all locks up.

I’ve used both. If your kits in good condition then the rag or pinion won’t do any damage, torque values are not that high, least not
High enough to bust something. To distort a housed bush enough to create gap for it to rattle you’d have to be jumping on it, or it was ready for replacing anyway.

Impact wrenches can be fine for tightening, providing you use something with limits the torque, you can get extension shafts which have a torque value on them. Past a certain torque they no longer transmit a force through them. You get a set of them numbered up in Nm or ft/lb

many thanks for your input guys, I went with a 1/4 drive extension bar through the small ends with wrist pins fitted and a wood chock in between both con rods, worked a treat

Tigernuts - "I don't like the bar through the small ends method - it just seems cruel to me (based on n evidence whatsoever - it is just something that doesn't 'feel' right for me)."

I should have been more careful and complete with my statement, especially as we've recently read on this forum of someone using this method, resulting in indentations in the crankcase gasket surface. I wouldn't be at all surprised to find that he had also damaged the upper surfaces of his small-end bushes, or even distorted the small-ends of the rods, because I suspect that simply "a bar that came to hand" may have been used.
To use this method, the bar must be a straight, smooth 11/16ths steel bar, then it will apply force evenly to the small end bush surface, rather than the line contact with a smaller bar diameter.
This method would be improved by using fore/aft rectangular steel bridges over the crankcase mouth, at the centre and sides, say about 1/2" square bar. This would both spread the load on the relatively soft alloy crankcase mouth, support the 11/16" bar properly (avoiding bending in the middle which would also damage the small end bushes), and will also improve the crankshaft orientation away from BDC to nearer mid-position. As we're using the crankshaft as a spanner, this gives that spanner substantially more leverage.
Those are my musings on the subject, if it is done correctly I don't think it is a problem.

Having typed all that claptrap, I've never used that method myself, never found it necessary.
As Tigernuts said, thinking ahead most times you can loosen all shaft nuts before disconnecting rear and primary drive.
You can also leave such tightening to that stage, in reverse order.

I've never torqued the timing nuts myself, I reckon they only need to be "well tight". They haven't the slightest tendency to come loose (never heard of it, have you?) so what's the problem with holding the crank nut while tightening the cam nuts? Bexause the cams are LH and the crank RH, through the idler they tighten against each other. 2 spanners.

If you use the jammed rag technique it relies on the fact that the teeth don't fit together, because there is something being drawn into the space between the teeth that is bigger than that space. That compressive force is enormous anywhere near the junction of the wheels, and in an entirely unsuported direction for the idler spindle.
The use of a crank pinion to lock the cam and idler pinion does at least redirect the force on the idler to nearer to vertical, by which it is contained to some extent by the (exhaust pinion while tightening the inlet nut) or the (crank pinion while tightening the exhast nut).

Ian Gill "The teeth work but your still applying the same separation forces as if you were putting a rag in between the gears, the idea is you don’t put a rag in such a way that it will pass through all the teeth. Just enough to bite."

Not so Ian, if you force a space to take something its not designed for (the tiny clearance between the teeth) something wil have tol give. Imagine a washing mangle (I'm old enough!) that has no gap for the clothes to pass through, it chokes before the garment is even between the rollers. Force that pair of cacks through and you'll break the frame of the mangle or the spindle.
That is what I'm trying to say to you, jamming with a rag between pinions is very different to all of the other options that have been mentioned.
Locking with a pinion locks mainly against rotation, only a small spreading force between pinions is exerted.
Ian Gill "If using a cam pinion to jam the teeth you want to go between the idler and the cam pinion, if you go between two cam pinions you chance the whole lot rotating as each gear touches only one each side it. If you drop the crank pinion in there (much smaller) it might rotate a couple of teeth before it all locks up."
This can only be done on the intake side when the oil pump is removed, under the intake pinion and behind the idler, using a spare crank pinion. I don't think there is room for it anywhere else, and there is certainly no room for a cam pinion at all. The more I read your post the less it makes sense to me.
The thing that you don't want to do, is introduce anything like a wedge between pinions, which a rag is, it will not do you any favours!

Actually, I reckon that if, as Jay999 has done, the gudgeon pins are in the small ends, and if there is adequate protection to the cylinder base deck surface on the crankcases, a bar through the small ends would be fine. There's quite an element of common sense involved and it can be surprising to find how uncommon this is!

Not Ian but Allan but we know what you meant. I did say though that you don’t want the rag in such a way that it will go through the teeth. If it’s rolled up thick enough it will have the same action as the gear.

Tigernuts - "Actually, I reckon that if, as Jay999 has done, the gudgeon pins are in the small ends, and if there is adequate protection to the cylinder base deck surface on the crankcases, a bar through the small ends would be fine. "

Swings and roundabouts maybe. The gudgeon pins will give some comfort to the small ends, but necessitate the use of a much smaller diameter bar.
I would suggest that supporting it in the middle would be even more important. Otherwise when the bar bends under the torquing, even more force will tend to deform/bend the small end.

I still much prefer the traditional method, followed by the crank cog technique (though since my disaster I've stuck with traditionalism, and no more ragging!).

Sorry Allan, I'd been watching some Deep Purple on youtube with a few beers, and I thinnk Ian Gillan was stuck in my brainwaves! I guess we'll beg to differ on this matter, Allan, Allan,Allan - like doing lines at school!