Author Topic: Another noise question -A7SS  (Read 4811 times)

Offline BSA500

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Re: Another noise question -A7SS
« Reply #45 on: 20.05. 2016 20:47 »
Well folks bad news. She had started to vibrate really badly I suspected the float had returned along with a knocking noise. Just split her down to the crankcases and yes the float has returned  *conf* *conf* *conf*. Crank nut(srm) was nice and tight. Bigger problem was the ever so sloppy timing side big end-FFS. These are new shells from last years rebuild what's going on. Nearly beer time.

Offline muskrat

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Re: Another noise question -A7SS
« Reply #46 on: 20.05. 2016 22:47 »
Bugga *ex*.
Something not right in there. Are the cases a matched pair? Was the new t/s bush line bored to size? Did you use new big end bolts? The old ones may have stretched causing big end failure (lucky you caught it) and tensioned correctly. Are the rods dead straight? When checking the end float for shimming are you doing the cush nut up tight? Dive side bearing should be a shrink fit into the cases and a tight fit on the crank (a pain to get on & off for shim replacement).
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Offline BSA500

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Re: Another noise question -A7SS
« Reply #47 on: 20.05. 2016 23:37 »
Bugga *ex*.
Something not right in there. Are the cases a matched pair? Was the new t/s bush line bored to size? Did you use new big end bolts? The old ones may have stretched causing big end failure (lucky you caught it) and tensioned correctly. Are the rods dead straight? When checking the end float for shimming are you doing the cush nut up tight? Dive side bearing should be a shrink fit into the cases and a tight fit on the crank (a pain to get on & off for shim replacement).
Cheers
Yes matched pair,New bush line bored,Not new bolts,rods ok,cush nut srm type 65 ft/pounds and bearing has always slipped on th ecrank but has never given this much grief

Offline Scott and Jay

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Re: Another noise question -A7SS
« Reply #48 on: 20.05. 2016 23:49 »
People in our club have had a problem where the drive side bearing appeared to be seated properly but was not

Offline BSA500

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Re: Another noise question -A7SS
« Reply #49 on: 21.05. 2016 09:46 »
People in our club have had a problem where the drive side bearing appeared to be seated properly but was not
Yes thats an area I will be having a close look at. Also the last attempts were with the oil pump still on so it will be removed when I set the float again

Offline BSA500

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Re: Another noise question -A7SS
« Reply #50 on: 21.05. 2016 12:31 »
  It just seem to skip around the law of physics. You shim to a given thickness you ride it the gap increases but no shim loss or any other metal, the crankshaft doesn't grow. All crankcase bolts tight, shock assembly well tight???WTF

Offline muskrat

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Re: Another noise question -A7SS
« Reply #51 on: 21.05. 2016 22:06 »
Is there any wear marks on the thrust face of the timing bush? If every thing is done correctly that's the only place that can create end float. That or the outer drive side race wasn't fully home when you took the measurement. Then when the engine heats up the outer race could move deeper into the casing to make more end float.
Silly question time. Where are you placing the shims?
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
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Online bsa-bill

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Re: Another noise question -A7SS
« Reply #52 on: 22.05. 2016 09:43 »
If the timing side bush was not line bored accurately then the crank will not travel through the bush as far as it should but will feel as if it has ( will go through as far as the slight taper of inaccuracy will allow)  so shimming the other side will give you the clearance required, then as the timing bush beds in the crank will travel through a bit further and your end float will increase.

I'm speaking from experience as this happened to me, although I never got as far as the engine running due to it being so far offline the crank actually nipped up when tightening the cases fully, the line boring inaccuracies could be very small but enough,  took it back to the shop with a new bush and they got it second time, they could offer no reason for the first one being off but agreed that was the problem
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 BSA500

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Re: Another noise question -A7SS
« Reply #53 on: 22.05. 2016 19:46 »
I have yet to pull the crank out of the cases. It was line bored and has been running without any obvious issues. No sign of brass glitter in the oil etc. I am thinking towards the drive side bearing not being fully home but I will check all the suggestions.
Thanks so far

Offline BSA500

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Re: Another noise question -A7SS
« Reply #54 on: 23.05. 2016 21:48 »
Here are the some pics of the big end shells. Bear in mind they have just over a thousand miles on them. Not quite sure what they show as the conrods appeared tight but the bolts are not new. Measured the journals at 1.441 inch using +20 shells,plenty of oil around the crank etc.
 While inside checked the timing bush and that looks fine no obvious shaving by the crank and no brass glitter. Roller bearing was still on the crank(loctite) and I could slip a 6 thou feeler gauge behind it. So I shall reheat the drive side case drop out the bearing outer clean up and put it back again. Any suggestions on the crank beyond cleaning oilways,new shells,conrod bolts and nuts ???

http://i11.photobucket.com/albums/a170/bsa500/DSC05018_zpsdxzjblj8.jpg

http://i11.photobucket.com/albums/a170/bsa500/DSC05016_zpswsnmp9xp.jpg

adm edit: removed photobucket links, added as attachment

Online chaterlea25

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Re: Another noise question -A7SS
« Reply #55 on: 23.05. 2016 22:02 »
Hi,
Clean the oil tank!! Clean the oil tank!! Clean the oil tank!!

Buy and fit new big end bolts,  (ARP) beware of cheapies  *eek*, have the rod  big ends measured

Re con the oil pump or buy a new one,

Check and /or replace the PRV

Good luck
1961 Super Rocket
1963 RGS (ongoing)

Offline BSA500

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Re: Another noise question -A7SS
« Reply #56 on: 23.05. 2016 22:12 »
Hi,
Clean the oil tank!! Clean the oil tank!! Clean the oil tank!!

Buy and fit new big end bolts,  (ARP) beware of cheapies  *eek*, have the rod  big ends measured

Re con the oil pump or buy a new one,

Check and /or replace the PRV

Good luck

Cleaned the oil tank last time-will do again
Yes new bolts.The rods were measured last rebuild and even though the beezer badly needed a rebore last time the big ends had no play so thats why this is a pain
Oil pump is a iron bodied SRM pump
Will clean and check PRV and while I am there the anti syphon valve

Online Greybeard

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Re: Another noise question -A7SS
« Reply #57 on: 23.05. 2016 22:38 »
What about cleaning the crankshaft sludge trap?

Offline BSA500

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Re: Another noise question -A7SS
« Reply #58 on: 23.05. 2016 22:48 »
I did last time but will again *smile*

Offline cableguide

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Re: Another noise question -A7SS
« Reply #59 on: 24.05. 2016 07:59 »
++1 on clean the oil tank..and sludge trap!
And its how u do it that matters. No good just swilling a bit of paraffin around and hoping for the best, you've got to dislodge every bit of muck.  I fill with Jizer and then leave for a week, longer if u can. Then take the tank to a garage lay it on an old plumped up curtain or similiar and power wash it for five mins until every nook and cranny is left bare shiny metal and nothing else....then an immediate soaking in WD40 to stop rust, its a filthy awful job but seems to work.

Are you using lots of thin shims?..I've never beleived the bearing inner can squash a fist full of shims down to the desired thickness unless the race is so tight as to need a 100 ton press to push it on which most wont...There is just not enough interference on most shafts to stop the bearing moving around and messing up the shim measurement. On my last build I turned up a single thick shim/spacer. So far so good.
Have fun.