Author Topic: A7 End Float and Sludge Traps  (Read 612 times)

Offline bikerbob

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A7 End Float and Sludge Traps
« on: 05.11. 2014 16:30 »
 Have got the A7 dismantled and am just checking. Am I correct in thinking that the early A7 swinging arm does not have the removable  tube in the sludge trap, and the end float at the moment is .012 and should be a max of .005. Also the left hand small end bush has turned in the con rod but must have still been getting enough lubrication as there is no visible scoring and both gudgeon pins are the same size. but I will replace both small end bushes.

Offline muskrat

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Re: A7 End Float and Sludge Traps
« Reply #1 on: 05.11. 2014 18:48 »
G'day Bob.
I don't recall the A7's having a tube, I thought they were only in the LJ A10 cranks.
A 10thou shim behind the drive side roller will fix the end float, but if the timing side bush is if'y it should be replaced and end float calculated afresh.
I'd ask why did the little end bush rotate?  A few things to check there before a new one is pushed in. Alignment of big and little ends, rod twist or bend, fit of bush in the rod.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
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Offline Derby Rob

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Re: A7 End Float and Sludge Traps
« Reply #2 on: 05.11. 2014 19:46 »
yep ,no sludge trap tube in my 61 a7.
61 BSA A7,yamaha rd500 ,suzuki ts250er,suzuki x7,1958 francis barnett cruiser 80

Offline bikerbob

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Re: A7 End Float and Sludge Traps
« Reply #3 on: 05.11. 2014 20:03 »
The previous owner had a problem last year when the timing side bush turned and cut off the oil supply this was repaired along with the camshaft and cam followers and I think the small end bush must have turned then  and was overlooked on the strip down I would not have known till I removed the pistons there was no play on the small end bushes.  I have  removed the sludge plugs and there was very little sludge in there cleaned it out and refitted the plugs and there was no tube in there am now waiting for new shims. I was reading an old service sheet and it said max .005 for A10 and .005-.010 for A7 but on rechecking the service sheet was dated 1948 so must be for the first A7 and A10 not for the swingarm models.

Online duTch

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Re: A7 End Float and Sludge Traps
« Reply #4 on: 06.11. 2014 07:14 »

Quote
The previous owner had a problem last year when the timing side bush turned and cut off the oil supply

 *????* *????*.....I think I suddenly know less than I thought..?....that the T/S bush has locating flats that prohibit it from turning... *????*
 .....and an oil groove around the outside to feed no matter how it's orientated........*dunno*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online bsa-bill

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Re: A7 End Float and Sludge Traps
« Reply #5 on: 06.11. 2014 08:59 »
HI Dutch bikerbob is probably referring to the two part bush where the inner metal bush is pinned to the outer part that has the flat on it , the pins do apparently sometimes shear allowing the inner to revolve with the shaft, not good, I never did like that idea although BSA and many others find it sound enough, I always use the one part bush, get it oversize and have it bored to suit the crank ( should that be undersize?}
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
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Offline muskrat

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Re: A7 End Float and Sludge Traps
« Reply #6 on: 06.11. 2014 09:11 »
Yep, that would do it, but if the t/s bush cut supply to the big ends the oil should be diverted to the cam and the little end gets fed with splash from it. *dunno*
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Re: A7 End Float and Sludge Traps
« Reply #7 on: 06.11. 2014 13:46 »

Quote
the two part bush where the inner metal bush is pinned to the outer part
  Thanks Bill, forgot about them...,and yep I think you mean ' undersize and bore it out'...
Quote
get it oversize and have it bored to suit the crank ( should that be undersize?}

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline bikerbob

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Re: A7 End Float and Sludge Traps
« Reply #8 on: 06.11. 2014 14:01 »
The offending timing side bush was the type with the steel outer and bronze inner but it had not been pinned and had turned I don't know if it caused damage to the camshaft and followers only that on strip down they were found to need attention and were built up and reground to the correct profiles.