The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: SimonHolyfield on 21.02. 2019 23:38
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What do we think of this pitting chaps? This journal and its partner measure 1.656"...
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looks nice magnified, like rain drops and a dead spider *spider*, but I would say its an A 50 or A 65 on its worn third grind, I am having a guess someone will know more than me, PUB tomorrow *beer* *beer* *beer* put it this way it does look like oil will sit nicely in the pitting ;)
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Bergs is right. Looks to be a big journal A10 or A65 Crank, with a pretty good set of drive splines.
The pitting is of minor consequence, as the journals are effectively smooth, rather than deeply scored or worn in ridges.
Standard size is 1.6865"/!.6870", so it is already on its 3rd regrind at 1.656" and on the lower published tolerence. Providing the journals are truly circular rather than worn oval, (2 thou was the limit) they should be OK with just a very light polish and a new set of shells....plus the ever popular clean of the sludge trap.
Swarfy.
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Thanks for the reassurance guys. I've only measured in one place on each journal so far, so I'll have to go back for a proper survey.
The plugs have had it - I'll be welding a bit of thick sheet to each of them to get them out. I've got a new trap to go in.
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Well it turns out that dimensionally these big ends are in good shape - but the t/s main measures 1.242"!
This is hugely undersized - the oil way is almost gone. I have a bush that fits it well, but I've never heard of one of these being 120 thou undersize.
Scrap I think.
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Maybe not. someone may have started setting it up for a roller conversion.
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G'day ironhead.
You could be right. Mine is 30mm = 1.181". They could have been using a different bearing.
Cheers
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I guess roller conversion would be an option - I wasn't going to do it, as I have three bikes and the mileage on one probably wouldn't justify the expense.
What do you think?
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Simon, If you have a bush to fit, you may as well use it. Providing it is a solid one, even machining a circular oilway to replace the lost depth of the oilway on the crank. How the oil gets into the crank as the holes flash past beats me. Anyone thought of drilling additional holes in the bush to feed the crank? Or even something in the crank oilway next to the hole to act as a scoop!
Swarfy.
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I went out to walk the dog and think.
The bush I have fits the small 1.242" journal very well. If we think the journal is big enough to carry the running loads without cracking, I will machine the oil way as an annular groove in the thick wall of the bush, not the journal - this will have the same affect as the original groove in the journal.
I guess when SRM sleeve the journal for the needle roller conversion, the shaft is a bit smaller than stock, for the roller sleeve to fit over it - and as Muskrat says, he has a 1.181" t/s journal - which I guess is performing OK, so maybe mine is not fit for scrap just yet.
I have three alternatives - my home grown approach described above; asking SRM to resleeve the journal at £107, or thirdly got for the full needle conversion at about £550.
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Simon Sleeving the crank will not add any appreciable strength, Muskys smaller shaft is OK. The crank is already on its 3rd grind of a possible 4, so to my cheapskate way of thinking ....better to spend the minimum on it, give the sludge trap a clinical clearout and just build into a running unit. Unless a round the world trip is planned, most of these bikes do minimal miles and are just as reliable if treated to regular oils and not hammered. I find it hard to justify the high cost of precision engineering compared to the actual use enjoyed. But that's me.
Swarfy.
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I like your thinking. I guess as the drive side journal is 1.18", with all the bending load that is subject to from the primary along with the cyclic loads from the power stroke then a 1.242" timing side journal will always be OK.
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G'day Simon.
I agree, make the bush. Make sure the bore in the case is round, it may need a skim. A light interference fit of 1-1/2 thou into the case and leave a few thou in the bore for line reaming. The thrust face may take some measuring to work out it's thickness.
Have a good look at the radius on the shaft, you don't want a sharp corner.
Cheers
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Thanks guys.
As an A10 newbie, can someone explain how the end float is controlled? Shims under the drive side bearing?
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Thanks guys.
As an A10 newbie, can someone explain how the end float is controlled? Shims under the drive side bearing?
Yes, and it’s better to have one thick shim (washer) not several thin ones.
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G'day Simon.
Can you give us a close up picture of the t/s crank journal please. Is it machined all the way to the web or does it have a step about 1/8" from the web? You may be able to make your new bush with a thrust face the correct thickness to eliminate the need for shims under the d/s inner race.
Cheers
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It's machined all the way to the web. Notice how the oil holes only partially line up with the oil way in the journal! I'm going to turn a groove in the bush, connecting the bush oil holes with the oil ways in the journal.
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G'day Simon,
Don't loose any sleep over the timing side journal size. Trihards use a near identical crank with 30mm ( 1.181")
timing side & 1 1/8" ( 1.125") drive side . The T140's put out a bit more poke than most A10's.
I've never heard of one braking in normal use.
As Musky suggested, you need to check the blending radius where the journal meets the cheek (a sharp corner here will almost certainly lead to a breakage.)
The crank pin radius mentioned in the service sheets ( 0.090" ??) may be something to aim at.
If you were here in oz I'd offer a swap for a standard crank, it would save me some machining on a roller project in the pipeline. Postage is an absolute killer though.
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I'll suggest that at least one benefit of a larger diameter journal would be increased surface/ oil film area, the Triumphs have the ball race bearing to support theirs....
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Hi All,
I don't like the look of the rust and crap on the outside of that bush housing *sad2*
If it's an original outer has the bush sleeve been pinned to it? It needs to be!
In an awful lot of cases the original bush has lost its proper interference fit
John
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Good point, I have not had a look at that yet.
I'll be sure to clean and measure it before I go any further with that bush.
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G'day Simon.
There still looks to be a small ridge on the thrust face of the crank web. This will "eat" into the bush thrust face and give excessive end float after a while.
I don't trust those steel bodied bush's, and if the bore in the case isn't round and true to size a new bush will need to be made to suit.
Cheers
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It looks like an A65 crank to me (top one)
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A wider camera shot would be good. Can't see the alternator section.
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I'm recording everything here:
http://ariel-square-four.blogspot.com/2019/02/fh-crankshaft-review.html
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looks like a65 even more now, whats the stroke?
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I'll go and measure it. What are the features of A65? This was supposed to be a large journal A10...
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Not A65, that would have a plain section and keyway on the primary side for the alternator rotor.
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apologies my mistake i had to go and check myself, julian is as usual correct.
pics show A10 and A65 cranks
*smile*
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Excellent thanks Julian.
Next thing is, I found there's about 0.5 mm run out at the end of the thread. What's the best way to sort that out?
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Hi Simon,
I would move the steady back onto the main journal position
Have you the drive side clocked up in a 4 jaw chuck?
A 3 jaw will tell lies *eek*
Only then can you assess if / how much the end is running out
Small errors could maybe be trued up by
Fitting a drilled to suit bar over the there's end and "tweaking"
The more I see of what is going on with that crank the more i think its junk *sad2*
John
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Hi Simon,
I would move the steady back onto the main journal position
Have you the drive side clocked up in a 4 jaw chuck?
A 3 jaw will tell lies *eek*
Only then can you assess if / how much the end is running out
Small errors could maybe be trued up by
Fitting a drilled to suit bar over the there's end and "tweaking"
John
I agree with John, it can be tweaked once the crank is set up right.
Remove the step on the thrust face and make a new bush. Job done.
Cheers
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Hi Simon,
I would move the steady back onto the main journal position
Have you the drive side clocked up in a 4 jaw chuck?
A 3 jaw will tell lies *eek*
Only then can you assess if / how much the end is running out
Small errors could maybe be trued up by
Fitting a drilled to suit bar over the there's end and "tweaking"
The more I see of what is going on with that crank the more i think its junk *sad2*
John
If I end up doing anything to this crank, I'm going to set it up in my ER40 collet chuck. Before I do that, I need to modify the steady - unfortunately the crank web hits the foot of the steady at the moment.
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Hi All,
I don't like the look of the rust and crap on the outside of that bush housing *sad2*
If it's an original outer has the bush sleeve been pinned to it? It needs to be!
In an awful lot of cases the original bush has lost its proper interference fit
John
No evidence of any pinning. How are they usually done? Just something to stop the inner bush spinning?
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the two steel backed ones I found in the shed have a stepped steel pin of about 1/8th diameter on the outer reduced to about 3/32 in the bush inbetween the flanged end and the oil groove , you might find one if its cleaned up. yours looks different to my two, also the oil holes are drilled at an angle from the steel back into the bush , drilled towards the flanged end which I think then gets the oil ways lined up better , I have the witness marks in the bush from the crank groove and it is perfectly inline with the angled drilled holes
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Excellent. So the stepped pin is radial to the bush axis?
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yes simon --, when you mentioned oil groove alignment I think I have answered your problem and your steel bit is drilled in the middle of the groove, mine are drilled right on the edge of the groove nearest to the flange at an angle into the bush which then gets everything in line
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G'day Simon,
Probably the best thing to do with the 2 piece bush is "bin" it.
Make sure the hole in the crankcase is bored true ( round & straight) then make a solid bush to suit.
I've done this many times & works fine. I think this was discussed recently somewhere on here.
With the thread clean up, the way I have done the "bashed THOR ends" *rant* in the past is mounting the crank in the lathe. 4 jaw drive side , fixed steady on the existing R/H main journal & chasing the thread via single point tool (60 degree) & gearbox setting ( 20 tpi) . Its also a good time to re-instate the centre drilling with a fine pointed tool for future use.
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Simon That bush looks to have started life as a standard steel backed composite bush, from which someone has removed the inner thin walled bearing material and pressed in a custom bush. Alas, while allowing reclaimation of the well worn crank, the oil holes appear to be not quite right, and as you have found, the bush is not pegged.
I'd go with the sound advice from Ironhead, bin the bush, start afresh and add some oil ways and oil drillings in the right place. Line boring the case to clean it up, install the bush then line bore again to the crank running clearance gives the best result. The outer end of the main journal is usually flush with the outer face of the bush, so bear this in mind if you decide to make a new one. The thread run out is the deal breaker here......maybe it is just too much hassle to turn the pig's ear into a thing of beauty.
Swarfy.
Swarfy.
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This looks very much like the bush I have:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F132949674892
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G'day Simon.
That one is pinned. The smaller hole at 10 O'clock.
Cheers
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I've done a bit more work on the crankshaft today. There are a few pictures, so I have documented progress here:
https://ariel-square-four.blogspot.com/2019/03/fh-crankshaft-2-cleanup.html
Comments & encouragement gratefully received as always!
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Simon.... The most luxurious backyard engineering I have ever seen. I await the sludge trap extravaganza.
Swarfy.
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Easy!
https://ariel-square-four.blogspot.com/2019/01/small-journal-crankshaft.html?m=1
This is one of the small journal cranks.
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Enjoying this now, keep it coming ...
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Enjoying this now, keep it coming ...
I've just learned that you have to heat the flywheel to get it on...
I'll be asking for help on that - but not yet, we have a way to go first. I haven't even looked at the rods yet.
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After a lot of measuring, a little machining and a lot of adjusting, I have about 0.6mm run out at the very end of the oil pump worm.
Good enough? The crankshaft timing pinion run out is about 0.05 mm.
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After a lot of measuring, a little machining and a lot of adjusting, I have about 0.6mm run out at the very end of the oil pump worm.
Good enough? The crankshaft timing pinion run out is about 0.05 mm.
Is the run out caused by a “bent” crank? Or the worm itself. 0.6 mm sounds a lot....
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2 thou to 24 thou seems like your end is bent *eek*pardon the pun ,or as kiwi has said is that with the worm gear on and that's throwing it out- 24 is a lot of bend on your end *whistle*
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Plugs out!
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G'day Simon.
Now you know why we always ask "Did you clean the sludge trap out?" I've seen a lot worse.
Cheers
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Next question. The big end oil ways are just 3/32" holes. On their own twin, the 500 cc KG/KH, Ariel issued a service bulletin advising owners to grind a 'teardrop' into these holes to distribute oil into the bearing.
Is this advised with the BSA engine?
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Simon... Before having a crank ground, I always Dremel Grind a shallow cup across the journal to enlarge the oilway width slightly and restore the wider oil film where oil enters the bearing surface. New cranks had a teardrop or similar cutaway machined in production, but successive regrinds narrow the width of the teardrop cup, until it almost disappears, leaving a very sharp edge to cut a nice central groove in your new shells. Grind the shallow cup first, before grinding the crank, have it ground if necessary, then finally polish the edge again to ensure a smooth transition from oilway to journal surface.
I have already posted my thoughts on this in the thread about the drive side conrod oil bleed hole. It is to do with the reduction of surface area with depth of a shallow cone, like why your vintage Martini Glass seems to empty rather quickly.
Top Quality Sludge, you make it look easy.
Swarfy.
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G'day Simon.
I agree 110% with Swarfy.
By enlarging the hole it ends up wider (across the journal) than long (circumferential (thank god for spellcheck)). I double (3/16") it's width with a Dremell.
Cheers
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G'day Musky. Proof indeed that telepathy exists. Or that great minds truly think alike. More a case of necessity is a Mother.
Crack another Stubby.
Swarfy.
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Thanks chaps, watch this space.
I've cleaned up the flywheel threads now, and I might put it on in the next few days. Any top tips?
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Get all the planned machining, grinding etc done first. Put the crank in the freezer and wait.....either until you have free and secret access to the domestic oven or it is barbecue time and either way you can warm that flywheel up nice and gently, til the spit dances, creep up on the cold crank and just drop it together.
Swarfy.
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Get all the planned machining, grinding etc done first. Put the crank in the freezer and wait.....either until you have free and secret access to the domestic oven or it is barbecue time and either way you can warm that flywheel up nice and gently, til the spit dances, creep up on the cold crank and just drop it together.
Swarfy.
Got it, thanks.
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I am going to the pub, *beer* deserve it after brain work on the yokes , stem etc for the featherybed- long story for another day. swarfy creep up on it sounds good but not like my mate who had his triumph crank case heated up and got the outer bearing race in at an angle and he couldn't centre it up-- it was a swine to get out again once everything was hot *eek*
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I had the misfortune to have one of the radial flywheel bolts sheer off and completely wreck the crankcases.
In my opinion it is worth changing the existing bolts for new ones whilst you have it in bits..
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OK?
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Beautiful mate. Now polish the edges to leave no burs. *clap*
Cheers
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Nicely done, looks to have just come from Small Heath. Could be even a little wider and deeper, just a touch. Blend that nasty sharp edge into a smooth entry to the journal surface, drawing the edge away from the oil hole fore and aft, but still aiming for an elliptical cup. Like musky says, get polishing. Job's a good 'un......just a few more to do.
Swarfy.