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Primary Chain scraping
#803625 04/01/20 3:34 am
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Spidy Offline OP
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I was in the prosses of rebuilding my clutch on my 1977 t140 and I notice the chain marks on the bottom of my crank case. The Primary chain’s tension is correct, and there is no play in either of the shafts. I did find some small metal shavings at the bottom of the crank case, but there were no shavings in the rest of the engine oil when I did the oil change. Is this a major concern? Thanks.

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Re: Primary Chain scraping
Spidy #803629 04/01/20 5:01 am
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No, happens all the time. Haven't seen a Triumph without it.

Re: Primary Chain scraping
Spidy #803634 04/01/20 5:58 am
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Hi Spidy, My '73 Tiger 750 has that. Pretty much they all do that as was reported above.

I find the chain can rub alternator tube also. Does yours have rub marks there also?

I tension chain in loosest spot to where it just cannot touch tube no matter how hard I push. But also check chain in many points as you would a rear chain. Too tight of primary chain puts great pressure on crank & trans bearings as well as tensioner. Too loose it rubs.

Book says 3/8 in one place 1/2" in another. I don't know.

I usually shoot for about 1/2" at loosest place using ruler in filler hole. Pulling down firmly on chain, take reading, push up firmly, take reading & subtract difference. Actually I use wood dowel I marked in 1/8" increments. I bent a wire hook to pull up on chain. So with cover on I push down on dowel & then pull up to read. Motor heat soaked I can still feel some play at tightest spot. So I think I'm ok.

Make sure clutch plates are in & springs tensioned before checking chain tension.

You know how slot in tensioner blade chews up end of adjuster tube nut? I took a thin flat washer & bent to match curve of blade. Filed 1/2 round end of adjuster tube to match washer profile. Adjuster tube holds washer tight to blade so it doesn't spin. Now adjuster turns easily without binding, no damage to end & you can accurately feel it notch on every 1/2 turn.

PM me your email if you want photos. I can't post here.
Don


1973 Tiger 750
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Re: Primary Chain scraping
Spidy #803714 04/02/20 4:20 am
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That’s a relief, I just wanted to make sure I’m not making mountains out of ant hills. My front top stator stud has some chain wear on it as well. Once I get everything back together, I will double check my tension and try out that washer trick. Thanks

Re: Primary Chain scraping
TR7RVMan #803716 04/02/20 4:37 am
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please send me pictures. [email protected]

Re: Primary Chain scraping
Spidy #803805 04/03/20 12:35 am
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[quote=Spidy My front top stator stud has some chain wear on it as well. [/quote]

That shouldn't happen!!! something not right there.

Re: Primary Chain scraping
Spidy #803807 04/03/20 12:55 am
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Time to check the chain for stretch. It's in the shop manual.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: Primary Chain scraping
Spidy #803808 04/03/20 1:18 am
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Hi TR7RVMan; may you explain a bit more about that? I cannot visualize it right.

Thanks

Re: Primary Chain scraping
Spidy #803809 04/03/20 1:28 am
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I notice Spidy's comment:
" I notice the chain marks on the bottom of my crank case."

I assume Spidy means "on the bottom of his chaincase".

If so, there is absolutely no way that there can be any chain marks on the bottom of the chaincase.

For some reason 2 experienced folk have said that is normal,

it is not. The lower chain run is over the tensioner blade, how does the chain make contact with the bottom of the chaincase, even if the chain has some free play?

Even with some slack, the chain will not hit alternator mounting studs. I'm sure. It would be a disastrous situation leading to rapid chain failure.

Do TR7RV and T150V accept this as a usual occurrence?

Re: Primary Chain scraping
koan58 #803812 04/03/20 2:08 am
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it may not be desirable
but
its typical chaincase damage ... behind the tensioner blade , under the clutch hub .

the same slop in the chain can move to the front sprocket and hit the stator stub under hard deceleration .

it means the chain is worn and or misadjusted ... or was ... at some time in the past .
2 samples from fleabay's current offerings ;
[Linked Image from i.ebayimg.com]
[Linked Image from i.ebayimg.com]

Last edited by quinten; 04/03/20 2:18 am.
Re: Primary Chain scraping
Spidy #803817 04/03/20 3:35 am
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Next stop: The chain breaks, piles up just behind the left cylinder, and blows the top of the crankcase out.

I've seen several of these disasters over the years.

Change that worn-out primary chain NOW, before it happens.

Re: Primary Chain scraping
Spidy #803823 04/03/20 6:46 am
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Hi All, Thanks for pointing out that the rubbing is NOT GOOD.

I didn't mean to imply it was good. It should be corrected. What I stand by is every single primary cover I've had off, I've seen marks there.

Speaking of chain wear. I've measured a few chains in the last few years.... Interestingly I've found that things start going wrong at about 50% of the wear the shop manual states as maximum. Tensioner slipper wear is part of the mix also.

I can't be sure of this, but when the blade gets curved upwards very far odd things start to happen. I'm thinking the sharper angle of the chain run feeding into clutch basket teeth have a tendency to force the chain downwards more than an unworn chain with a lower tensioner arch. This is with the same free play measured at top of chain.

I may be totally full of bull on this, but it seems things change from what I've observed with fairly small wear on chain.

Correct me if I'm wrong. Any thoughts or observations from your experience. Seriously is there more to it than just tension that makes chain want to rub?

How do you guys adjust primary tension? Meaning test the play so it's just right. Is play of 2 & 3 row chains the same? Seems it would be??

I purchased new Renold primary chain. Did not have same smooth finish on the side plate edges or rollers. Did not have full circle riveting on pins. Will see how this wears. Got Wassell tensioner. Slipper was glued on crooked & end loops were crooked. Exchanged it for LF Harris. Much better. Almost as good as original.
Don


1973 Tiger 750
Re: Primary Chain scraping
Spidy #803824 04/03/20 6:55 am
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Hi Russrudolph, reverb, I emailed you photos. You can repost here if you want.
Don


1973 Tiger 750
Re: Primary Chain scraping
Spidy #803928 04/04/20 3:34 am
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I've always seen wear on the primary side of the cases just behind the tensioner …..as others have also stated and seen. Its not a perfect world, things get hot/older/misused/ misaligned/loose etc etc etc. No its not good...I never said it was good. But it happens and tbh its a Triumph design fault, they would have seen it countless times and did nothing about it. But generally once its happened and the metal is gone - and this will be in the first few thousand km - then it stops and the problem is sort of self solved until you change the mix ie new clutch, new chain, new front sprocket etc then it will 'trim' or 'settle' in and its problem solved again. It doesn't really hurt anything as long as the metal removal is normal or not excessive. I'd also advocate frequently changing the primary oil to help with material removal....the oil in the primary will have metal, both alloy and steel, as well as clutch material in it when you install new parts.
On a another note, I have seen the slipper/tensioner with grooves in it as well on twins....rarely [maybe never??]seen this in later triples. Again a design issue.

I have also seem wear on the stator studs...….this is a different animal altogether. This needs addressing asap. Failure here can be disastrous. As I stated, "That shouldn't happen!!! something not right there"

Re: Primary Chain scraping
Spidy #803930 04/04/20 3:45 am
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BTW, I check my chain tension through the inspection hole while applying downward tension on the kickstarter. I err on the slack side, I prefer this to too much tension.....and never had an issue.

Re: Primary Chain scraping
Spidy #803934 04/04/20 4:52 am
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Does this just mean that T140 owners are not quite as anal about triplex chain alignment as Trident owners?
Or that the factory was not quite as anal about getting the shims correct in the first place?


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Primary Chain scraping
Spidy #804193 04/06/20 12:00 am
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Hello; here are the photos that gently TR7RVMan sent:


[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

[Linked Image from i.postimg.cc]

Re: Primary Chain scraping
DavidP #804219 04/06/20 5:51 am
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Originally Posted by DavidP
Does this just mean that T140 owners are not quite as anal about triplex chain alignment as Trident owners?
Or that the factory was not quite as anal about getting the shims correct in the first place?
I think its more to do with the chaincase design plus the way the slipper tensioner is adjusted on the triples.

Re: Primary Chain scraping
Spidy #804224 04/06/20 6:53 am
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Hi, The chain alignment on T140 is probably not so critical as on triple from what I've read, However, I've never worked on or even ridden a triple.

T140 I have some experience/practice setting primary chain line. Sprockets are not perfectly straight, especially the clutch basket. Aftermarket clutch baskets may not be machined same as original. If replacing the keyed hub on main shaft, aftermarket ones are often not machined the same so don't have same depth after nut torque. Thrust washer thickness in part of calculation. Basically you have to fully assemble clutch. Install crank sprocket, no chain & torque bolts. Take several measurements, marking sprocket & basket as you go. Average to best measurements. Install shims to give figure you want. Recheck. What about thrust washer wear?? It's a fast wearing part so to speak. I like to bias basket outward to the limit so as washer wears alignment stays in spec longer. Again the best you can given the sizes of washers. Plan on spending several hours on this. Does it really matter that much? I don't know. I do it though.

The 3 row chain has basically the same chain path as 2 row. The inside row is very close to 650 with the outer row extending outwards on 3 row. The tensioner & adjuster are basically the same, but slipper & blade holder is wider of course on 3 row.

Alternator wire tube on T140 is same as 650, so chain wants to hit boot easily & also the wire itself. I made longer skinner tube so chain cannot touch wire. Factory should have done that. Don't use inner boot. Use black silicon sealant on outside boot. Works good.

The outside row of links are mostly outside the gasket surface. So the gasket has to be trimmed very thin on bottom & back. Real T140 gaskets are available, but costly, so most trim 650 gasket.

This also means changes to primary cover, even though casting # remained the same. Chain will also hit the top oil cup cast into primary cover. Again on 2 row chain, the chain is inwards of entire primary cover. So T140 cover is machined thinner on bottom & around the rear bolt circle or chain will rub casting around bolt holes. Also primary cover can contact stator in some cases as stator is moved out.

So 3 row has even more places for chain to rub than 2 row.

Primary cover is machined out at rotor area for clearance & the pointer is much shortened on the '73-75 versions.

At this time not one seller in world that I could find is selling new primary cover to fit T140! NONE! LF Harris is no longer selling one that may have fit. Photos on sellers web sites shows it might, but that version is not actually sold or made now, meaning part sold may not match photo. Many photos are what they sell, but the cover won't fit. Better getting used T140 or modifying 650. Was unable to find even one good used T140! Didn't realize how bad the repro T140 covers were until too late. New cover was .007" out of flat too. Plus.... had hairline crack at edge of bolt hole to oil space.

Notice special shape of washer I put under head of tensioner rod. The chain runs very close. I wanted large of surface as possible, but not rub & it could not spin. Washer has hole that fits the rod. I drove swaging on rod through hole in washer. It worked good & didn't deform washer much. So far this has worked quite well at both ends after 1000mi.

So the primary chain is a bit of a bother sometimes. Just what we have to live with & do the best we can.
Don


1973 Tiger 750
Re: Primary Chain scraping
Spidy #804225 04/06/20 6:55 am
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Hi Tridentt150, On 650 or T140, I get how tension on kicker puts chain slack in top run. How to you measure the slack? Meaning for a newbie how would they what was good?
Don


1973 Tiger 750
Re: Primary Chain scraping
Spidy #804243 04/06/20 12:30 pm
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I never measure it Don, if you can push it below the inspection hole or above it then I'd adjust, if its somewhere in between then I'd leave it alone. I found that if I adjusted any tighter [even to specs] then the chain only stretched back to how it was anyway. Then you found yourself in a constant cycle.

Re: Primary Chain scraping
Spidy #804290 04/06/20 7:07 pm
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Hi tridentt150, I don’t understand. On twins the inspection hole is on top of primary case. Could you please clarify that? Thanks.
Don


1973 Tiger 750
Re: Primary Chain scraping
Spidy #804294 04/06/20 7:18 pm
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the chain adjustment isn't tensioned ... it is de-slacked .

the running tension is supplied by the front driving sprocket .
if the engine is running , the tension is on top ... as the front sprocket pulls the chain counterclockwise .

if the tension is supplied through the clutch sprocket , with the kickstarter .
the chain is pulled at the bottom ... clockwise ... and the slack moves to the top ...


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