classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: Marky on October 29, 2010, 06:12:46 PM
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Hi- After a good few years of pure pleasure on the bike I am attempting a rebuild which began with kickstart problems. Now down to the crankshaft bush and found the woodruff key was not locked in(new key needed), the bush was not tight on the shaft(new bush) but more worrying the bush came off without heat which makes me believe the case is worn from the bush turning on the shaft. Its fits in too loosely and I wondered if its possible to get a slieve put in the case rather than have to now look for a new /old crankcase. I had thought of locktite but this bush has oil lines and the thought of some locktite either blocking lines or coming loose is not the way I want to go. Has anyone any ideas on this please?
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Presumably you are talking about the timing case bush.
You said the bush "was not tight on the shaft". Nor should it be. It should be a good hand-sliding fit with no perceptible "rock". Too often though the crankshaft end is worn, which will lower oil pressure. That would probably mean a new shaft if they are case-hardened, which I am not sure of, or if not taking the shaft to be machined and a new bush made.
If the shaft is ok it might be possible to tin the outside of a new bush with tinmans solder so that it is a hard push in fit in the casing. Oil slots can be easily scraped out.
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You can buy oversize bushes for when the crank is reground. It used to be Triumph standard practice that the two big-ends and the crank nose were all reground at the same time, but things change over time.
Tinning the bush sounds good, but there are some excellent Loctite prodicts now for just this purpose, and there's no reason why the oil 'ole should get plugged when you do it either.
Don't get the woodruff key bit, though. Do you mean the half-moon tab + self-tapper used to secure the bush?
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Im helping Marky on this project the is on the timing side and is completly shot. It has been turning in the casing and has caused considerable wear. Marky is refering to the half moon key held in by a self tapper.
Wondering if the casing could be machined and a slieve put in.
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Wondering if the casing could be machined and a slieve put in.
I expect that's possible, or maybe an oversize bush could be made up to fit?
You need to find a good engineering shop, preferably somebody who specialises in Triumph or British bike repairs.
You could try:
SEP http://www.sep-kegworth.co.uk/
Or
MRC http://www.motorcyclerestorationcompany.com/
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Thanks LAB I have a friend with a small workshop and foundary who makes minature steam engines he offered to do it. I was more wondering if anybody had heard of it being done before.
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Never seen wear that bad I must admit. He could always try Kent Daytonas as he's both a good machinist and knows the Triumph C range.
Doesn't sound a huge problem though.
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Not only heard of it being done, I have done it so I expect have lots of others, you will need to ensure that that the bush is slightly smaller than the crankshaft journal after it has been ground, the bush is an interference fit in the case (heat the cases to fit the bush), after fitting the the bush should be line reamed with the case halves bolted together to ensure the hole lines up correctly.
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There is a local firm which has done some work for us which seem to remember the name name from my biking days but we will follow up the links if we have no joy there.
Just about every bush and bearing in the engine is shot but surprisingly no play in the big end the play is probably being taken up by all the alluminium and bronze from all the other bearings. I think the problems have been caused by the oil pump it, and we havent even looked at the rockers yet which I know were running very dry a year ago because the feeder pipe was blocked but I'm sure that will become a knew thread.
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Thanks Rev at the moment no intention of grinding the crank it looks ok but hope to get a micrometer on it tomorrow Just dont want to give Marky more bad knews
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Hey Guys -Thanks for all the input-brightened up what was looking like a dark few days!! Will 'solder''on with great help from Duppy and your advice and get more pleasure from the maintenance! Sorry for delay in replying but BT Internet here in NI was down until tonight.Cheers for now.
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Ok Loctite has been suggested and will be used to fit the new timing side bush.The crank does need reground goin to get that done and the big ends looked at well its hard ta grind the crank with the conrods flyin round so that should be the bottom end sorted. Apart from that half moon shape retainer which isnt half moon shaped but more rugby ball shaped is held in by a self tapper so worry about loctite bearing fit or self tapper falling out.
On the inside of the bush where the shoulder on it hits against the inside of the crankcase there is slot which looks like it should have slotted into a pin. Did triumph just go cheapskate here
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Had a look at the Loctite site. I cannot find anywhere where they mention fitting bushes with their product.
They do "bearing fit" stuff, but I would not think they would envisage the amount of clearance/wear you are talking about. And they are also dealing with ferrous to ferrous components not (probably) phosphor bronze to aluminium alloy. For which it might not be suitable. Contact with engine oil (additives) rather than grease might also be a factor.
I am not a chemist, but mixing different materials and chemicals is chemistry. Which can turn out good or bad!
There is an advisory link on the website worth checking out.
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Hi Folks - thanks for your advice and interest. I have fired off the very same query you highlighted to Loctite and will see what they come up with. I'm a bit unsure to the degree of ''play'' with this crankshaft bush and how much is accepted. Opinions and my estimations seem to vary from 'needing a 'hand sliding fit'' which it borders on (in my opinion)- to too loose (Duppy) and the engineering workshop I talk to saying reground shaft, new sized bush with small bit of loctite and turning the half moon over will do the job (in their opinion). Want to get it right but costs (as always) are mounting! Next concern is the tappets which show a ''little'' wear across the top and a ''small'' amount of play in the guides! Any directions on what is acceptable here or not would be usefull so I can get to the bottom of things! Thank You
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Hi Marky
"Want to get it right but costs (as always) are mounting!"
Yes I have to agree costs do mount, but, if you get it wrong the cost will be far greater.
This bush is used to not only support the end of the shaft but also feed the oil to the big ends, any loose fit here starves the big ends of oil, the results I think you can guess, if you check with specialized Triumph parts suppliers you may find one with a bush with the centre undersize to fit the ground shaft and the outer oversize to compensate for the worn case, if not get one made, you know it makes sense, do the job right and you only do it once.
As for the tappets I guess the wear you ask about is on the face which runs on the cam, slight wear here is no problem also they should be a fairly loose fit in the guides.
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Right Rev-I'll go talk to the engineers!
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Reverse the valves in the guides, so the head touching the seat is not a problem. If you can feel ANY rock the valves and/or guides need replacing (most probably guides).
Too much inlet wear will increase oil consumption by burning. Too much exhaust wear will increase oil contamination and increase oil consumption by loss through the breather.
As for the bush, Tinning was offered as a possibly acceptable solution depending on damage/wear. Replacing the bush with a new one carefully sized is obviously the better solution and is so obvious that comment is really unnecessary.
It will be interesting to view the Loctite response. By the way there is a short video on the loctite site about re-fitting a key to a worn keyway. It looks though as if once fitted, it is there for good, which might compromise future dismantling. Reversing a woodruff (half moon) key will not work.
Addition.
Sorry I misread your post about tappet wear thinking the part about "guide wear" referred to valves. My apologies.
Any tappet face wear or rock will affect valve timing. Some wear is inevitable. The only way to determine what is too much is to refer to a valve timing diagram for that engine and to check using a timing disc and Dial Test Indicator (DTI). Rather awkward with the engine incomplete because allowance has to be made for rocker clearance.
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OK I have re read your post regarding worn tappets, and now after Twolitre's comment I am not sure if you actually mean the tappets or the valves and guides, if the tappets then my previous comment applies but if you mean the valves and guides then Twolitre is correct.
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I've been around the C range Triumphs for many years now, and as I've previously said, I've never yet encountered a main bearing bush which as nipped up so tight that it's turned in the cases. The bush is usually lubed enough/loose enough that that wouldn't happen, but should there be some total oil failure, the harder-working D/S big end would be suffering too.
Not saying it hasn't or can't happen, just that it must be rare, so that said, if it's happened to you and you don't feel comfortable with a suitable repair, I'd let a machine shop have a look at it for you.
A bush like this turning in the soft ally cases could have done a lot of damage, and Loctite or tinning may be unsuitable for this level of repair. Never heard of any over-sized O/D bushes for this application either; it's not a usual wear problem, but a damage repair issue.
Any eventual replacement bush will need line-reaming to suit too. It's possible to get away without reaming (sometimes) if it's just new bush going in, but if your cases need machining to take a custom-made bush it'll be essential, and that's something else a machine could do relatively easily, but you couldn't do at all without the proper tool.
I don't get the bit about "hand sliding fit" though. The bush is a very tight fit in the case, and needs lots of heat to expand the cases to remove it. We are talking about the same bush here, aren't we?
Equally "turning the half-moon over".... eh?
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I have to agree fully with Rex's comments, this is no place to compromise, a full and correct repair is essential.
I have in the past had experience of this bush turning in the case on this occasion I line reamed the case as the hole had worn centrally and evenly I then turned up a new bush allowing two thousands of an inch oversize for the interferance fit, this bike has done 15000 miles since the repair and it is fine.
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Hi guys it would would be madness notto do the job properly we are at present waiting for the new bush to arrive in the meantime we we will be trying to get some quotes for the work from the engineering firms mentioned at the start of this thread
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ok this post was originaly about end float it it is 25 thou the new bush is goin to make it 17 coz the shoulder on the the bush is 8 thou thicker than the old one.
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Hi Duppy
It is your other thread which is regarding end float, get's confusing with more than one doesn't it?.
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ok this post was originaly about end float it it is 25 thou the new bush is goin to make it 17 coz the shoulder on the the bush is 8 thou thicker than the old one.
Shouldn't be any problem with that, but how did you repair the bush location in the end?
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The bush hasn't been fitted yet. It is still out off the case till the crankshaft has been reground but the diameter of the new bush is 4 thou up on the old one and wasn't going to go into the case without some force, the machine shop that is doing the other work is going to fit it and make a slieive to fit if they think that the new bush is not a tight enough fit. I full confidence in them they jave been working on bikes since I was in my teens and the guy's eyes lit up when we brought are box of bits up so I dont think they will do a botched job, should know with in a week.
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I'm confused again... ???
If the new bush is 4 thou up on the old one and won't go in "without some force" why would the other machine shop need to make a sleeve if it isn't tight enough?
Sounds more like they'll be reducing the O/D of the new sleeve, but that would be an easy job.
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A sleeve hasnt been made just talked about as a possibility, when we got the new one it wouldn't go in without heating the case up I assumed it would be lose like the old one.
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As Rex says, this is becoming one confusing discussion,
It appears that you have now bought a proprietary bush and not had one made, if this is the case the bush will need to be two thou bigger on the outside diameter than the hole in the case, to fit the bush no force is used, the case should be heated in an oven to 180-200 degrees C and the bush should be left in a freezer to cool, the bush will then drop straight into the hole and should be left alone till the case cools.
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Ok when I said "force" I meant the old bush can be taken in and out quite easily at room temp. Under the same conditions the new but the new bus wont, so the case needs to be heated to get it in so that looks like a good fit to me. I may have been a bit alarmist over how bad things are and probably tried to paint the worst scenario. Like wnen I posted about endfloat it started out a mile but was only 25 thou. and for some reason I can't understand why the wear on the bush, as a whole seams to be more than the aluminium the shoulder on the old bush is worn eonugh to give 25 thou. endfloat but the new one brings it down to 17 thou. on measuring the two shoulders with a mic. same for the od of the bush 4 thou. more than the old one.
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Duppy
It's a strange fact of life but when a hard and a softer metal are rubbing together it is always the hard metal which wears.
A good example is the Gudgeon pin or wrist pin as our American friends call them, the pin always wears before the little end.
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Sounds like you're all good to go to me.
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Duppy
It's a strange fact of life but when a hard and a softer metal are rubbing together it is always the hard metal which wears.
A good example is the Gudgeon pin or wrist pin as our American friends call them, the pin always wears before the little end.
True Rex we have were going to replace the small ends but the same guy in the machine shop told us the wear was on the gudgeon pin so we are waiting for them now.
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They "usually" come as part of a piston package. Are you reboring too?
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Hi - no rebore deemed necessary at this stage ! The bore,rings and pistons all look ok so probably going to build it up and see how she fairs once I get the crankshaft finished . New bearings/bush all round amongst other parts which came up - seals,spindle,gudgeon pins,sludge trap, valve guides(+seat cut),stator....cams polished, just waiting for crankshaft to be ground and may need big ends which the workshop is going to sort before I get it back. Few other minor issues still to sort but nearly there now!
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No planns to rebore at the minute the bore looks fine its already bored out to +30. The whole bottom end is new bar the big ends but that may change depending on what things look like when the con rods are taken off to grind the crank, Question if things look fine is it a good idea to replace the big end shells anyway or leave well alone?
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If the big end journals are in good order and unworn and the shells are also undamaged and unworn then they will not have to be replaced just ensure that they are refitted in the same place as they are now, but correct measurement is essential as no wear is acceptable here.
The big end bolts should be replaced as a matter of course, these are fitted and tightened to a measured amount of stretch and should only be used once.
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The big end bolts should be replaced as a matter of course, these are fitted and tightened to a measured amount of stretch and should only be used once.
Hmm, in the ideal world when Meriden was still extant, maybe.
Obviously check the bolts for waisting and other damage, but a used genuine Meriden bolt is still a far better bet than a Taiwan sweat-shop bolt of uncertain metallurgy.
I have fitted newies from a reputable Midlands TriBSA parts dealer and the nuts were as soft as butter. Unless you envisage afternoons on the Santa Pod strip I'd advise refitting the old bolts and nuts if at all possible.
I'd also advise reusing the big end shells (obviously if they're not worn) in the SAME locations, rather than regrind as a matter of course, too.
As you may discern, "tried and tested" beats "new pattern" with me every time.
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Rex
Wilemans in Derby still have a supply of original bolts, I can see your point regarding inferior bolts but thankfully in the years I have been working on these 350/500 twins I have only ever known one big end bolt fail and that was a reused original, waisting is difficult to detect on these bolts as they are made with a waist.
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Ok assuming all bearings and such has have been replaced and the rebuild is starting anything in particular to watch as reguards oil leaks just the bottom end at the moment, new oil seals will be put in all round. The drain plug on the chain case has about 2 good threads left so that needs to be sorted, so tap it out or is there a heli coil or modern equivelent.
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Personally I would helicoil it to use the original plug. Normally there's cheap helicoil kits on the Bay of Fools, and also firms like Tracy Tools do cheap kits too.
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Rex I think we would just get the same firm to do it for us with a heilicoil one cant keep retaping casings