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post #1 of 15 (permalink) Old 04-23-2019, 04:03 PM Thread Starter
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Clutch slip?

Hi,
So I've noticed a new, worrying issue with my bike.
'55 plate sprint st 1050, 18k miles.
When I went to over take some dawdling drivers earlier, as the bike got to 7k rpm in 4th gear, the revs ran away with no noticeable increase in speed, almost like a slipping clutch.
Oil is fairly low mileage (1k) bit been in there for a year. Was last serviced by triumph dealer so the oil's good.
Can't replicate the issue in lower revs (pulling up hill at full throttle from 2-3k rpm).
I'm running a custom ECU map which hasn't given me any issues like this before.
Bike has been standing for a lot of its life, courtesy of my job being away from it a lot of the time, however it's just had a lovely run from Glasgow to Manchester on good Friday with no issues at all.
Any ideas?
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post #2 of 15 (permalink) Old 04-23-2019, 06:04 PM
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Hi Max

I'm no mechanic but that certainly sounds like a slipping clutch to me.
I can't think of anything else with that symptom.

These clutches are very robust under normal conditions and to my knowledge do not give problems like that at a relatively low mileage.

Have you checked all the clutch adjustments are correct?
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post #3 of 15 (permalink) Old 04-24-2019, 01:17 AM Thread Starter
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As far as I can see, it's all good. The biting point is about 40% of travel when moving off, and I can pull the lever a little bit with no opening of the clutch plates when moving, so as far as I can tell the cable is all set up properly.
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post #4 of 15 (permalink) Old 04-24-2019, 02:17 PM
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Is it related to the engine temp?
I guess that as the service was done at the dealer there's no "energy conserving" oil in the engine.


I can't think of anything apart from clutch sleeping. I can't think of any broken part that would not show additional symptoms (noise...).


If the clutch sleeping is confirmed and if the oil is ok (doesn't cost much to change the oil though) that means that:
-either the clutch stack thickness is too low, then one of the 1.6mm steel plate must be replaced w/ a 2.1mm one. EBC provides heavy duty clutch springs for the sprint.

-or the friction plates are damaged, burnt or the like,
-or there is something that prevent the clutch pin to be released completely.


So I would try first to change the oil and if the symptoms are still here, I would take the clutch apart and check it thouroughly (colors steel plates, worn out/burnt friction plates).


Fred
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post #5 of 15 (permalink) Old 04-24-2019, 06:54 PM
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As speed increases so does clutch clamp load. If you accelerate hard and revs rise with no speed increase,clutch it is. No oil can fix it. 18k on clutch is overdue. Cheap and easy.

When all else fails, get a bigger hammer!
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post #6 of 15 (permalink) Old 04-24-2019, 09:52 PM
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Quote:
Originally Posted by fredsprint View Post
-either the clutch stack thickness is too low, then one of the 1.6mm steel plate must be replaced w/ a 2.1mm one. EBC provides heavy duty clutch springs for the sprint.
I agree however allow me to make a slight correction, should read "replaced with a 2.0mm one."

And rather than EBC springs I would use Triumph's own heavy duty springs courtesy of the old 1200cc T300 series Daytona and Trophy.
Pt # T1170047. Be prepared for a markedly heavier clutch pull though.

Last edited by Terry Colley; 04-25-2019 at 12:32 AM.
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post #7 of 15 (permalink) Old 04-25-2019, 01:45 AM Thread Starter
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Thanks for the input.
I reviewed some video footage I had of one of the times of did it and it appears to have slipped right after I changed up, almost as if it hadn't re-bound properly.
I'll have another look at my cable this weekend and see if that makes a difference.
Also, isn't 18k a bit low for a clutch to start playing up like this?
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post #8 of 15 (permalink) Old 04-25-2019, 01:55 AM
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Hi Max yes it is way too early unless it was abused.

I traded my '04 Sprint ST 955i at 75,000kms and this was ridden very hard and often very hard two up.

When I traded it for my 2011 Sprint GT the old 955i still ran like a top, zero clutch slip and very minor oil use, 200ml per 5000kms.
I only have ever run all my Triumph Triples on good quality semi synthetic oils and change this out at 5000kms.

But that is what your symptoms sound like.

If it were my bike I would not bother fitting any clutch components that require more lever pull than the bike has as stock.
The Sprint 955i gen 2 clutch works just fine with the standard components and lasts a very long time under a lot of hard work. This is my opinion.

But that is just me, I am not a weakling and am built like a bull and wear size XXXL motorcycle gloves.
You do not need heavier clutch components for normal road or the odd track day use.
I believe a heaver clutch pull would become annoying especially if you do much city riding like commuting.

cheers
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post #9 of 15 (permalink) Old 04-25-2019, 01:25 PM
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Quote:
Originally Posted by Terry Colley View Post
I agree however allow me to make a slight correction, should read "replaced with a 2.0mm one."
That's correct.



Fred
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post #10 of 15 (permalink) Old 04-25-2019, 01:30 PM
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Quote:
Originally Posted by Max2ksr View Post
Hi,
So I've noticed a new, worrying issue with my bike.
'55 plate sprint st 1050, 18k miles.
When I went to over take some dawdling drivers earlier, as the bike got to 7k rpm in 4th gear, the revs ran away with no noticeable increase in speed, almost like a slipping clutch.
Oil is fairly low mileage (1k) bit been in there for a year. Was last serviced by triumph dealer so the oil's good.
Can't replicate the issue in lower revs (pulling up hill at full throttle from 2-3k rpm).
I'm running a custom ECU map which hasn't given me any issues like this before.
Bike has been standing for a lot of its life, courtesy of my job being away from it a lot of the time, however it's just had a lovely run from Glasgow to Manchester on good Friday with no issues at all.
Any ideas?
Wheel spin?

As mentioned by others, an oil change is cheap. As mentioned by others, make sure the oil is designed for wet clutches. If you've found a trustworthy dealer then that's good news.

Possible that the clutch plates have been contaminated by old oil due to lack of use.

Can always place the front wheel against a (solid) wall and try and spin the rear wheel. Please post video!
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