Main Bearings 1955 18s

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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AJSBSA
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Main Bearings 1955 18s

Post by AJSBSA »

Hello
I have just replaced the main bearings (bought from the club) on my bike and I am concerned that they seem a tight fit on the shaft certainly tighter than the ones I took out.
I do not see how I can check end float when they are this tight or am I missing some thing.
Cheers Steve


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silverarrow
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Main Bearings 1955 18s

Post by silverarrow »

Stephen,

i would speak to jim at the club spares and see if anyone else has had this worry. It sounds as if for whatever reason something is too tight. Does the crank rotate freely when the bottom end is assembled? Is there any chance that the bearings and or crankcases are misaligned? Did you try the bearings on the shaft before fitting.

Plain bearings are often supplied so that they are reemed to fit, again check with Jim.

Les Smith (silverarrow397)
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moley
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Main Bearings 1955 18s

Post by moley »

i just fitted main bearings to a Matchless 1955 G80S.. and mine were also extremely tight on the crankshaft. i asked around and was told to lap the shaft gently in with some emery tape - did the job -perfect...

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Tolly
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Main Bearings 1955 18s

Post by Tolly »

Hi Stephen,

I fitted new mains in my G5 a couple of years ago and had to reem the bearing to get a good fit, be careful if you do reem it as it has to be line reemed i.e. a guide put through from the other crank case to make sure it's true.

Regards Mike.

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moley
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Main Bearings 1955 18s

Post by moley »

Hi Stephen

Did any of the above help?

Regards Andy

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AJSBSA
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Main Bearings 1955 18s

Post by AJSBSA »

I rang Jampot spares and they said they should be a tight fit (not a press fit but certianly not a sliding a fit) I asked about end float and was advised that even with a tight fit end float will be present.
This is in deed what I found when I put the cases back together if I tapped the end of the crank with a rubber mallet I did get about 10 to 20 thou of play.
I fired the bike up last night for the first time (second kick) and it sounds very well indeed, the new bearings have fixed the whirring noise so I am a happy camper.
Thanks for all the help also thanks to the people at the Alterative Rally that lent their ears to help track down the cause of the noise.

Steve


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Tolly
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Main Bearings 1955 18s

Post by Tolly »

Hi Stephen,
Glad you had a good result, those chaps at the spares scheme are very knowledgable.
Have many miles of fun riding.

Regards, Mike

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