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Author Topic: 1954 Bullet Crankshaft  (Read 1110 times)

SRL790

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  • 1954 350
1954 Bullet Crankshaft
« on: May 24, 2009, 08:59:31 PM »
Hi everyone,

I have not visited here for some time since SRL790 has been in pieces all over my garage and I haven't had the time to work on her which makes Andy an unhappy boy.

Last year I had a main bearing fail and it took out the drive side shaft and the drive side flywheel (the shaft came loose in the taper).

I recently obtained a used flywheel from Hitchcock's but am having trouble truing the crank (I have assembled and disassembled twice already and inspected closely and am reaching the conclusion that the used flywheel is not running true) so now I am looking at other options, namely fitting a later model crankshaft.

My question for the group is:

Does anyone know the differences between the early (pre 1955) crankshaft and the Indian built crankshaft?  Stroke is the same at 90mm and I know the crankpin is the same because I fitted the roller bearing conversion to my crank.  Obvious difference is the extension on the drive side shaft for the alternator, but if the taper is the same in the flywheel, I could install my shaft.  Also, is there a difference between the 350 and the 500 crank, or more specifically, the flywheels (SRL790 is a 350)?

Does anyone have one available that they could measure and/or lend me to compare or, better yet, does anyone who has perhaps installed a stroker kit, have one they would be willing to part with?

I'll take all the help I can get on this one.

Andy
Andy Wiltshire
54 350 Bullet, 62 Jaguar MK II, 68 BSA Spitfire, 69 BSA Starfire
70 Bonneville, 71 Bonneville, 71 BSA B25T, 74 Jensen Healey
74 Honda XR75, 81 Yamaha MX80, 82 Suzuki GS1100G

Jon

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Re: 1954 Bullet Crankshaft
« Reply #1 on: May 26, 2009, 06:49:27 PM »
Andy

I believe the 350 has lighter flywheels and there are apparently some other differences between the early brit 350 crank and the brit 500 crank and I think
there may be a mention of this in the Osprey book, I think the 350 crank
was" beefed-up" around the time the 500 was introduced 1952?

Have you tried taking your crank to a crankshaft specialist? I know from
experiance that truing a crank even in a well equiped workshop can
be a real nightmare,especially when said item is fifty years old.

It's also possible that the flywheels on an india crank may not be quite as
good quality as the original item.

Best of luck

SRL790

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  • 1954 350
Re: 1954 Bullet Crankshaft
« Reply #2 on: May 30, 2009, 09:14:04 PM »
Well I disassembled the crank again today and, following Phil Irving's advice (Tuning for Speed), I gently lapped the tapers on the drive and timing shafts into the flywheels with some fine lapping compound.  After reassembly, mounting beween centers and a few well placed whacks with a brass hammer, I'm reading 0.001" runout on the drive side and 0.007" on the timing side.

My (1954) workshop manual states true to 0.0005", which is darn near perfect.  Could anyone out there with a newer manual look up the specs for me and, if anyone else has done this, how close were you able to get it?

Andy
Andy Wiltshire
54 350 Bullet, 62 Jaguar MK II, 68 BSA Spitfire, 69 BSA Starfire
70 Bonneville, 71 Bonneville, 71 BSA B25T, 74 Jensen Healey
74 Honda XR75, 81 Yamaha MX80, 82 Suzuki GS1100G