Author Topic: Help Needed with Primary Drive Alignment  (Read 466 times)

Offline tilly

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Help Needed with Primary Drive Alignment
« on: 23.12. 2018 00:55 »
I'm after some help trying to align the primary drive on my '58 A10.  Having recently rebuilt the engine and reassembled it all iaw the Haynes manual, the drive sprocket protrudes about 8 to 10 mm further than the Clutch chainwheel which obviously leads to misalignment of the chain.  I've checked it all several times iaw the diagrams in the Spares Catalogue and can't work out what's wrong.  It's running a four spring clutch.  I've enclosed photos of the crankshaft with and without the 'Distance Piece' (11967-1138) fitted (why is it tapered internally?) and wondered if anyone can tell whether it appeared to be correctly aligned for depth against the oil seal on the crankcase.  I'm hoping to avoid taking the Clutch Chainwheel off again.  Those 20 rollers are a pain to insert!
Thanks in advance for any advice on what the check. Regards,
Tilly
Canberra, Australia

Offline muskrat

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Re: Help Needed with Primary Drive Alignment
« Reply #1 on: 23.12. 2018 09:53 »
G'day Tilly,  *welcome*
The adapter on the mainshaft may be wrong for the A10.
The distance piece is tapered so it doesn't foul on the bearing or shaft.
As long as the chain won't foul the cases a new distance piece could be turned up.
There's a couple of forum members over there. Hope one picks up on this topic.
Don't think pictures work on first post.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline BSA_54A10

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Re: Help Needed with Primary Drive Alignment
« Reply #2 on: 23.12. 2018 10:26 »
Have a close look at your cush drive hub.
Some are flat on the back & sit on the spacer while others have a spacer already on the back.

There was a thread on it some time ago called Cush drive hub or something similar.
Think it was Trev ( not me ) who posted the photos of the different types.
All pre-unit drive shafts have the same spline & are the same diameter but they all use different cush drive hubs.
In fact I think the bolt on box & swing arm A series also used different hubs.
Bike Beesa
Trevor

Offline Swarfcut

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Re: Help Needed with Primary Drive Alignment
« Reply #3 on: 23.12. 2018 10:51 »
G'Day Tilly... Yes there are variations in the type of drive sleeve, some run directly on the oilseal, others (like yours) have the distance piece spacer.  In this case the drive sleeve is shorter, but the overall length is the same as the one piece drive sleeve with the smooth oilseal track.  Assuming you have the right parts, assemble the spacer onto the crankshaft with the inner chamfer/internal taper towards the flywheel. This will allow the spacer to clear the change in diameter on the crank, and press against the inner race track of the main bearing. Assemble the drive sleeve and big nut onto the crank and tighten the nut, pushing the drive sleeve and spacer against the inner race. This will ensure the inner bearing race is seated against the flywheel cheek. At this stage there should be only the very slightest amount of end float on the crank. If it moves in and out at all you have a further problem to address.  There is lots of information on the forum about finally assembling the cush drive and the need to tighten the big nut trucking tight.

   Chain misalignment can be usually down to the variable  pattern part quality of the clutch adaptor on the gearbox mainshaft, incorrect assembly of the gearbox is unlikely, but distorted mounting plates and incorrect gearbox  position are possible. After all the time these bikes have been around mis matched, damaged, abused and spurious parts are to be expected. Luckily for you, the parts diagrams are available on this forum via the main header page. Haynes is a reasonable start, but does not have the depth of detail we sometimes need.

  As Musky says, as long as the chain does not foul, your quickest option is probably a custom spacer.

 The earlier plunger engine  has the same dimensions on the crank splines, but has a completely different duplex chain, drive sleeve and cush drive/ sprocket and clutch assembly from the swing arm. Plunger gearboxes have a splined mainshaft in contrast to the tapered input mainshaft of the S/A box.

 Swarfy

Online berger

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Re: Help Needed with Primary Drive Alignment
« Reply #4 on: 23.12. 2018 14:51 »
i have not been to the pub, so because I am bored I will jump in before some of the others do *whistle* . WELCOME to this excellent forum TILLY *welcome* now please go to pictures stories introductions and say something about  yourself  *thanks*  PUB tomorrow  *beer*

Online chaterlea25

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Re: Help Needed with Primary Drive Alignment
« Reply #5 on: 23.12. 2018 17:10 »
Hi and Welcome Tilly,
Some time ago I posted this thread on primary alignment,

https://www.a7a10.net/forum/index.php?topic=9646.msg70166;topicseen#msg70166

Lots of variables to check out  *eek*
The radiused side of the crank collar goes against the crank !!

John
1961 Super Rocket
1963 RGS (ongoing)

Offline tilly

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Re: Help Needed with Primary Drive Alignment
« Reply #6 on: 05.01. 2019 09:06 »
Thanks to all for the advice. Rightly or wrongly I have taken 3.5 mm from the splined drive,retaining the original spacer (note my mistake from my earlier post where I estimated 8 to 10 mm). It is now aligned and seems to run well. It appears a previous owner fitted the 4 spring clutch without bothering to align the chain.

Offline Colsbeeza

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Re: Help Needed with Primary Drive Alignment
« Reply #7 on: 06.01. 2019 09:01 »
G'Day Tilly, I had this same problem last year.
I eventually had to machine 3.0mm from the "splined drive", or sleeve. I believe there were at least two thicknesses for the flange on this item, and I concluded that My bike had the thicker one. I will look up the reference on this forum and post it if I can find it.
Col
Colsbeeza
Australia

Offline Colsbeeza

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Re: Help Needed with Primary Drive Alignment
« Reply #8 on: 06.01. 2019 09:14 »
Hi Tilly,
Here is the reference. I machined 2mm from the flange.

https://www.a7a10.net/forum/index.php?topic=12517.0

Col
Colsbeeza
Australia