Author Topic: I'm about ready to split the cases,  (Read 352 times)

Online Minto

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I'm about ready to split the cases,
« on: 27.04. 2020 23:51 »
Well, I've been doing a bit here and there over the last week and tonight made a couple of extension legs for a little two leg gear puller to get the crank pinion off, worked a treat. So now (apart from the valium) I think I'm ready to separate the case halves and have a look at the crank etc. Anything I need to be aware of or is it a case of just undoing the bolts and pulling the two halves apart? Is anything likely to boing out and dispear into the darkest corner of my monkeys nest of a garage, never to be seen again?
I've had a search and read old posts til I'm cross eyed, but I still don't get how the main bearing works. Is it, as it seems from what I've read in two pieces (inner and outer) that separate, then fit back together? Can anyone point me in the direction of a picture of the bearing in both complete and separated states. How does this bearing come apart and go back together. The pics of replacement bearings from SRM just look like any other roller bearings I've come across, so as is often the way, I'm confused.
Sorry for the daft questions.
52 A10 plunger
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Offline Swarfcut

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Re: I'm about ready to split the cases,
« Reply #1 on: 28.04. 2020 09:08 »
 Before splitting the cases, with just the crank assembly in the cases, see how much in and out movement "crank end float" you can detect, and mentally decide whether when running there was anything you thought was amiss. Also see how much up and down movement there is in the timing bush.

 What I am trying to say is that in an ideal world the float  and lift will be just a working clearance.  Some play is expected, but unless you want a wallet busting experience and the engine is running fine, some wear may be considered acceptable. Hope for the best, but be prepared for the worst case. What you don't want is bits of mysterious metal particles embedded in greasy sludge in the crankcase nooks and crannies.

 To split the cases, make sure all the  fixing nuts are removed, the one inside the cases by the cam trough is often forgotten.

 A little bit of heat from a hot air gun will soften the joint between the cases. From experience, lay the motor on its timing side, work on the joint with a craft knife, keeping movement matched each side.   Keeping it equal  all the way round is the secret.

  Once you have a sign of movement, continue with only blunt instruments and avoid damage. Look for signs of previous abuse.  Once the joint is apart, you can wiggle and lift away the drive side case, keeping it square. The drive side bearing simply slides apart.

 All will be revealed, it really is far simpler than it sounds. Then turn the crank and timing case over, support firmly on the crank web and squarely lift away the timing case from the crank, trying to avoid gouging the timing bush with the relatively sharp outer edge of the crank journal. Wear on this bush can be roughly gauged by comparison of the unworn central portion where the crank oilway runs. In bad cases there is a definite step which can make removal of the timing case from the crank a bit of a juggle.

 

 Swarfy.

Online RichardL

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Re: I'm about ready to split the cases,
« Reply #2 on: 28.04. 2020 11:42 »
Minto,

Unlike conventional bearings, where you're used to seeing the rollers between two lips on the outer race, our main bearing is missing the inside lip. Therefore, the inner race and rollers pull free of the outer race leaving it in the case.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online bsa-bill

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Re: I'm about ready to split the cases,
« Reply #3 on: 28.04. 2020 12:12 »
I guess a lot of us wish for a perfect motor and probably go for "as new" condition after the purchase of our beloved bike, perhaps we should just take a step back and consider that "as new" is what BSA put out in order that their machine would give tens of thousands of miles of use by which time clearances would have changed with use, so 3 thou max is  not 3 thou max for safe use
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Minto

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Re: I'm about ready to split the cases,
« Reply #4 on: 28.04. 2020 13:25 »
Swarfy, Bill and Richard, thank you all for the info, that's everything I think I need to know for now.
The motor was nice and quiet and felt pretty good without unbearable vibration (certainly less than other twins I've ridden, including my Mille), the crank feels nice n tight in the cases with just a tiny amount of end float. There is no discernible verticle movement in the con rods, the camshaft also feels sound. Obviously I'll check the big end shells and journals when the rods come off but it all feels pretty good so far.
The strip down was only really to take care of the sludge trap.
Thanks again all.
52 A10 plunger
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Online orabanda

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Re: I'm about ready to split the cases,
« Reply #5 on: 28.04. 2020 14:54 »
Well done team, on the good advice.
I had an A10 and the B31 out of the shed recently, and took this snap.
Richard

Online bsa-bill

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Re: I'm about ready to split the cases,
« Reply #6 on: 28.04. 2020 15:53 »
are you sure they are two metres apart Richard  *smile*
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Swarfcut

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Re: I'm about ready to split the cases,
« Reply #7 on: 28.04. 2020 21:44 »
   Rich.  Just a couple of thoughts......

 If that's the shed, you live in a Palace.

 Check oil levels before you ride.....might be a bit dry inside.  (Neither bike has market its territory as I can see!)

 Cheers,
 
 Swarfy.

Online Minto

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Re: I'm about ready to split the cases,
« Reply #8 on: 01.05. 2020 02:13 »
Hey all
Just to say I was relieved that the end float measure a little over 2 thou, and once the cases came apart it became apparent that the motor had received attention not too long ago. The sludge plugs, well one of them came out with no protest at all, the other took a little persuasion but there was very little cleaning to be done in there. No nasty sludge or bits in the crank case halves, just nice clean oil. The rods might not be a matched pair, numbers 600 and 645, but both installed as per manual. Shells and journals all look good. Bushes and bearing seem fine on inspection, even the anti wet sumping valve screw came out ok. So an order for bits has been made and reassembly will take place once these arrive. Just some cleaning and stripping the paint from the barrels to be done before repainting them, I thought orange might be nice?
Thanks to everyone who passed on advice and knowledge, this has been a lot less of a drama than I imagined it was going to be... So far.
Much gratitude to all.
Jase
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Online mikeb

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Re: I'm about ready to split the cases,
« Reply #9 on: 01.05. 2020 04:24 »
thats's good new Jase
i think orange barrels would look even better if the tank was lime green and get some of those ape hangers that GB has been posting about recently.

tho seriously, its probably on your list already, but one thing i was glad i did when the cases were apart was replace and 'stamp' the oil return ball bearing to ensure a nice fit. (ie get 2 new balls, clean the area well, tap (light hammer) one into the seat where it is to seal, discard that ball and put the other new one in). result = no wet sumping!
or, next time, i pledge to do this, drill it out and a65-ify it, ie drill through and have that ball-valve assembly replaceable from the timing case under the oil pump. i'm sure you've seen the threads about it.

cheers
New Zealand
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Online chaterlea25

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Online Minto

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Re: I'm about ready to split the cases,
« Reply #11 on: 02.05. 2020 23:48 »
Thanks for that link John.
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