Author Topic: Disaster  (Read 2150 times)

Offline mark

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Disaster
« on: 18.07. 2011 04:05 »
Finally got the 55 Road Rocket registered after a 2 year restoration, Took it around the block a couple of times, made sure that there were no obvious issues then took off on its first trip. With 10 miles showing on the speedo an ominous knocking noise was heard from the engine and the bike was trailered home. Upon stripping the engine it was found that one big end journal had peeled away its surface, destroying the bearing  and circulating a fair bit of material through the engine. It appears that the journal had been built up some time in its past, the chap that did the machining on the crank commented at the time that it looked like it had been built up but thought that it would be fine. I am now trying to source a big journal crank and have put a few feelers out but if any forum members here in Australia can assist it would be much appreciated
Regards
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Online muskrat

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Re: Disaster
« Reply #1 on: 23.07. 2011 22:06 »
G'day Mark,
                any luck finding a crank yet ? Don't often see them here but do turn up on ebay in the US now and then. Expect to pay around the $250 + mark and post from US would be another $150 or so. This one just finished but didn't reach reserve 220814899707 .
 Might be worth grinding yours back and building back up properly.
Cheers.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Hubie

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Re: Disaster
« Reply #2 on: 24.07. 2011 00:59 »
G'day mate,

I bought one of Terry Kennedy (forum member here) a while ago.  First class item from a first class bloke, he informed me that he's only doing plunger and rigid frame BSA'a now but does has some swingarm stuff.  Might be worth sending him a PM.  Where in Melbourne are you mate?  I thought I was the only one on the forum from Melbourne!

Cheers,
Hubie.
1959 BSA Golden Flash
1956 Royal Enfield Super Meteor
1955 Royal Enfield 350 Bullet
2007 Harley Davidson Sportster 1200 Custom

The early bird gets the worm, but the second mouse get's the cheese!

Offline mark

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Re: Disaster
« Reply #3 on: 24.07. 2011 07:36 »
Hi there Muskrat and Hubie, I have tracked down a couple of cranks but both have the timing side main already ground down 20thou and I'm hanging out for one that will clean up to suit my "new" bush at 1.3665". I am waiting for Mike Reilly to get back from overseas to see what he has and then I will get the one that best suits me. Another one available has standard big ends but the timing side is -40 thou, this wouldn't matter if I was going to replace the bush but I'm trying not to as it is new. As far as building it up, I'm a bit wary as it looks like that is what failed and the 2 people I have contacted about a possible repair have both had reservations. I will try to contact Terry as well.  Hubie, I am at Hurstbridge.
Regards
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Offline terryk

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Re: Disaster
« Reply #4 on: 24.07. 2011 08:15 »
I sold a couple of LJ cranks a while back with some swingarm A10 stuff but they were on last grind. I only have one LJ crank left but its with a super rocket basket case. I do have swingarm A10 parts that I'm selling if you are chasing anything email me. I also have bits for BSA bantam,M20/21,B31/33, A7/10.

Put BSA parts in the email subject or I could junk it.
gflash11@hotmail.com
1950-53 A10 rigid/plungers, 1958-61 A10 super rockets, 1947-50 A7 longstrokes, 1949 Star twin,
1951-54 A7 plungers, 1940s M21, WDM20s,
1948-50s B33s rigid/plunger/swingarm, 1948-50s b31s rigid/plunger/swingarm

Offline mark

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Re: Disaster
« Reply #5 on: 03.08. 2011 07:06 »
Got a Crank from Mike, standard big ends and timing side which means I won't have to replace the bush. Hopefully it will be back on the road in a couple of weeks.
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Offline A10Boy

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Re: Disaster
« Reply #6 on: 03.08. 2011 15:58 »
Mark
Quote
standard big ends and timing side which means I won't have to replace the bush
Presumably you have an undersize bush and there is enough meat there to line bore back to STD?
Regards

Andy

1958 Super Rocket
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Yam XJR 1300

Offline mark

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Re: Disaster
« Reply #7 on: 04.08. 2011 01:44 »
The ruined crank was ground to -8 thou and the bush machined accordingly, that is why I was hanging out for one that could be machined to the same dimensions. Hopefully this one will do the job.
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

Offline A10Boy

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Re: Disaster
« Reply #8 on: 04.08. 2011 11:58 »
Yes, but you're not going to machine the crank to fit the bush, you're going to machine the bush to fit the crank right? The crank journal might need a slight grind to clean it up of course.
Regards

Andy

1958 Super Rocket
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Online muskrat

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Re: Disaster
« Reply #9 on: 04.08. 2011 13:24 »
Mark I tend to agree with Andy. Why waste the extra life of your new crank just for the sake of a bush. Throw a new std bush in and get another 50K out of her.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline mark

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Re: Disaster
« Reply #10 on: 14.08. 2011 07:52 »
Sorry for the delay in replying but I've just done a 10 day jaunt to Birdsville and back (only us Aussies will know where that is). I never really expected to get a crank that was still standard size but wanted one that would at least clean up to the same size as the other. When I said standard I meant that it hadn't been machined before but it will need to be machined true and it seems that there will only be a couple of thou difference between it and the original one, so there isn't much point in machining a new bush for such a small saving. 
regards
Mark
55 road rocket




71 Norton Commando Roadster 750


Australia

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Re: Disaster
« Reply #11 on: 14.08. 2011 12:19 »
Hi Mark,
Are you intending to use the existing timing bush (the one that was installed when the crank failed)?

Richard

Offline mark

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Re: Disaster
« Reply #12 on: 15.08. 2011 00:28 »
Richard, yes the intention is to use the existing bush as it is new and doesn't appear to have suffered whan the crank failed. As I mentioned earlier, it has only done 10 miles. The engineer doing the work for me has measured it all and has said that the new crank will machine up to suit the existing bush and will have needed to be machined fairly closely to that size (-8 thou) anyway. The original bush was machined to suit the original crank after it had been cleaned up but I feel that it will be easier to only get the crank machined rather than take the minimum off the crank and machine a new bush as well. Do you see a problem?

Mark
55 road rocket




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Australia

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Re: Disaster
« Reply #13 on: 15.08. 2011 05:04 »
Mark,
It is possible that the new bush is now out of shape (oval) or the bore (surface) is damaged because of the crankshaft journal failure. I would be surprised if it wasn't.

The required clearance between bush and journal is 0.0015", with 0.003" being the wear limit. I have dismantled running engines with a lot more clearance (up to 0.008"), but oil pressure will be lost at the greater clearances, and the risk of throwing a rod is increased.

If you have enough material on the crankshaft journal, I would be tempted to get the machinist to clean up the bore (take a lick out) so that you know it is concentric, and has a very fine finish. THEN grind the crank to 0.0015" clearance.

Richard

Offline mark

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Re: Disaster
« Reply #14 on: 15.08. 2011 06:57 »
Excellent suggestion Richard. I will speak to him tonight.

Mark
55 road rocket




71 Norton Commando Roadster 750


Australia