Tight crank bearing

Information relating to the Matchless G9 or AJS Model 20 500cc twin
theEagle
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Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

rubber bands on bearing rollers to try to fit down into race
IMG_5060.JPG
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theEagle
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Joined: Thu Jul 27, 2017 2:18 pm
Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

ajsph: this is good to know!! ALso this is what I am afraid of here, that some things are not as they should .....
theEagle
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Re: Tight crank bearing

Post by theEagle »

General summary of the last attempt to fit the case by putting rubberbands on the bearing to keep rollers in:

Bearing rollers seemed to keep well into the cage by the rubber bands. However, when trying to fit the timing case it stops some 10-15 mm (just approx, did not measure) from the other case halve. It seem to "hang" on the bearing, and it is possible to wiggle it a bit even if I put in the Al centering rings where the cams will be (to know I am aligning itcorrectly)

With hand force it does not go further down.
Trying to heat for 1-2 min with a gas burner have no effect.
Hitting it quite softly (not "tapping" but hitting with only little force) with a rubber hammer it probably sets down 1mm or something as the wiggle disappears and it quickly tightens and need some relatively forceful strokes to make the halves split again.

Thoughts?
Anders
theEagle
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Re: Tight crank bearing

Post by theEagle »

alanengineer: I did not put the race in , the crankcase was assembled when i got it. You can see what it looks like on the first image. In my opinion that is square i place.
Only real reason for splitting the case in the first place was to asses status and also because it looked quite dirty inside(and it was!). The overall sense of the bike is that someone have not treated the bike very well.. but also it is old, it has obviously been imported to sweden in 1970 so some threads/bolts have been "converted" to metric...
I have found some interesting washers on the cam follower axle that i dont think is original.. as pointed out there is some wierd disc inside the bearing on teh shaft..etc etc..

just trying to see if it can run, recording the issues on the way, and trying not to do anything that brake anything...(I am still not sure if I have all parts..)
anders
alanengineer
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Re: Tight crank bearing

Post by alanengineer »

when you try and get the two sides together, are you turning the crankshaft as you push the halves together. 2nd pair of hands might come in useful. never used rubber bands as the rollers and race have good lead in angles, sound as if it would work if you could retrieve the bits
dodger
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Re: Tight crank bearing

Post by dodger »

Are you sure the problem is not the cam follower spindles, they act like dowls and must be spot on. I had a similar problem once, turned out one of these spindles was slightly bent.
alanengineer
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Re: Tight crank bearing

Post by alanengineer »

To confirm my last posting.
Turn the crankshaft as you put the cases together and dont use rubber bands.
Rubber bands are another thing that can introduce problems.
Dodger has a point, are you sure the interference is around the crankshaft
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1608
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Re: Tight crank bearing

Post by 1608 »

I think the 'weird' washer is an oil thrower.
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Duncan
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Re: Tight crank bearing

Post by Duncan »

Just to clarify, the rubber band was to gain the confidence that the rollers would go inside the outer race rather than starting to remove them from the crankcase, it was never intended to used them for the final assembly.
alanengineer
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Re: Tight crank bearing

Post by alanengineer »

Hi Duncan
surely the rollers hold themselves in place whist you assemble. surely also, once you have the rollers entering the race, you cant get to the rubber band to remove it. We havnt heard from Eagle for a while, so maybe he has fixed it
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