mads
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| posted on 10/2/09 at 01:22 PM |
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Upgrading clutches
Reading on from Wheels244 post re: barnett clutch conversion and other people's posts, I have a couple of questions:
1) Why do people upgrade their clutches?
2) Is Barnett's the best one or are there alternatives? (Barnett seems to be the only one I ever see)
3) Where can I get the above from for a R1 at a good price?
thanks all,
mads
We gain knowledge faster than we do wisdom!
Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in
sideways, thoroughly used, totally worn out and loudly proclaiming... "f*ck, what a trip!"
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Dangle_kt
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| posted on 10/2/09 at 01:31 PM |
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a bike clutch is built to shift about 200kgs, maybe a touch more, when you put it in a BEC you double the weight the clutch has to move.
The standard springs can't be too firm, as they have to be soft enough so the riders left hand can compress all 8 (or however many the model
has) springs.
If the springs don't force the plates together with enough UMPHH then the clutch will slip, which is wasted power and leads to very quick wear
of the fibres and even blueing of the steels. which then need replacing.
barnett springs are just a bit firmer than standard ones
To be honest, its a pretty simple job, you take the side cover off, free the actuation arm, remove the clutch pack, swap the springs and reverse the
process to resassemble - the only bugger is the different ways some clutch baskets are secured, locking tabs etc.
Barnett is the best known, I have never heard of any others personally. But I bet they exist. Its worth swapping the clutch plates over too whilst
your in there - although my personal understanding is that people are usually just referring to springs.
The phrase barnett clutch converstion is classic sales speak, trying to make it sound more than it is. Although it is a very worthwhile exercise by
all accounts.
[Edited on 10/2/09 by Dangle_kt]
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dinosaurjuice
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| posted on 10/2/09 at 01:42 PM |
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quote:
Originally posted by Dangle_kt
a bike clutch is built to shift about 200kgs, maybe a touch more, when you put it in a BEC you double the weight the clutch has to move.
[Edited on 10/2/09 by Dangle_kt]
clutches are designed to transfer torque - not weight or power etc.
the clutch can either handle the max torque the engine produces or it cant. slip may be more noticeable in a BEC however...
in my experience using fully synthetic oil can cause some bike clutches to slip. best to use semi.
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cd.thomson
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| posted on 10/2/09 at 01:49 PM |
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hmm surely weight does have some bearing?
the bikes clutch has to transfer a set amount of torque from the engine to the wheels and get the wheels turning.
If you do this in something that weighs nothing/theres no friction on the wheels then the clutch will engage immediately and the wheels will spin,
causing very little clutch wear. If you engage the clutch on a vehicle with infinite mass then the clutch will be forced to continously slip and
quickly be destroyed.
And everything in between.
right?
Craig
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Dangle_kt
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| posted on 10/2/09 at 02:01 PM |
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You might want to rethink your logic on that, I'm pretty confident that weight does effect the amount of clutch slip.
And changing from mineral to semi or fully synth can in fact cause clutch slip in a bike. You want to keep the same oil as has been used on the fibres
before - changing can make clutch slip worse.
The only reason I can see the type of oil making clutch slip better is if you are currently running car oil, which have additives that reducing the
effectivness of the clutch plates that bikes use.
quote:
Originally posted by eight dinosaurjuice
quote:
Originally posted by Dangle_kt
a bike clutch is built to shift about 200kgs, maybe a touch more, when you put it in a BEC you double the weight the clutch has to move.
[Edited on 10/2/09 by Dangle_kt]
clutches are designed to transfer torque - not weight or power etc.
the clutch can either handle the max torque the engine produces or it cant. slip may be more noticeable in a BEC however...
in my experience using fully synthetic oil can cause some bike clutches to slip. best to use semi.
[Edited on 10/2/09 by Dangle_kt]
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Mr Whippy
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| posted on 10/2/09 at 02:02 PM |
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It’s rather like frying the clutch on a car towing a caravan, sitting at a constant speed its fine.
It's the clutches ability to drag the two moving surfaces together rather than simply holding them that stresses a clutch and causes all that
heat.
Once the plates aren’t moving relative to each other friction fully can take over. Think about the difference compared to skidding your feet on the
floor (how little friction there is) compared to initially getting your foot moving.
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dinosaurjuice
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| posted on 10/2/09 at 02:04 PM |
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if the clutch is designed to handle the torque the engine produces it would stall the engine.
in the real world the enertia of the crank would probably cause a few revolutions of slip and that would be it.
it would seem bike clutches cant handle the peak torque, but its just not noticeable on the bike.
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Dangle_kt
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| posted on 10/2/09 at 02:11 PM |
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eh?
How does that work? Are you seriously suggesting that all the bike manufactures in the world are happy to use a clutch which can't handle the
torque their motors produce?
So every BHP/Torque curve I've looked at for a bike is actually an assesment of the clutch, not the abilitity of the engine?
Weight does influence it.
quote:
Originally posted by dinosaurjuice
if the clutch is designed to handle the torque the engine produces it would stall the engine.
in the real world the enertia of the crank would probably cause a few revolutions of slip and that would be it.
it would seem bike clutches cant handle the peak torque, but its just not noticeable on the bike.
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Mr Whippy
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| posted on 10/2/09 at 02:32 PM |
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We’ll as an experiment to see if weight affects a clutch, chain your car to a house and see how long the clutch lasts trying to tow it 
Mind though as your clutch start to get rather hot from all that slipping it will start to fade and loose grip…just like brakes do, next thing will be
smoke and a nasty burning smell  then oh deary me its on fire! 
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dinosaurjuice
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| posted on 10/2/09 at 02:51 PM |
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i think theres some confusion here between pulling away intially (riding the clutch) and fully engaged acceleration.
trying to pull away in a BEC will require the user to purposefully ride/slip the clutch more than on a bike. it will take longer for the BEC to
accelerate upto idle speed+.
spring weight wont affect pulling away as the driver is purposefully reducing pressure to allow slip.
once in gear and the clutch fully engaged there should be no reason for the clutch to slip no matter how heavy the vehicle is.
the clutch can either handle the engines torque or it cant. simple as.
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02GF74
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| posted on 10/2/09 at 03:21 PM |
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quote:
Originally posted by Mr Whippy
We’ll as an experiment to see if weight affects a clutch, chain your car to a house and see how long the clutch lasts trying to tow it
Surely the engine would stall before the clutch starts to slip?
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afj
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| posted on 10/2/09 at 03:44 PM |
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when the clutch is working the bike weighs far more than 200ish kg, if a 2003 r1 is round 180kg dry its maybe 185kg wet plus my weight 75kg
plus leathers helmit ect 15 kg plus a pilian and gear maybe 90 kg = 365kg ish bec weight is around 480kg plus driver =570kg
eerrrrrrrrrrrrrrrr
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Paul TigerB6
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| posted on 10/2/09 at 03:47 PM |
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quote:
Originally posted by dinosaurjuice
trying to pull away in a BEC will require the user to purposefully ride/slip the clutch more than on a bike. it will take longer for the BEC to
accelerate upto idle speed+.
spring weight wont affect pulling away as the driver is purposefully reducing pressure to allow slip.
once in gear and the clutch fully engaged there should be no reason for the clutch to slip no matter how heavy the vehicle is.
the clutch can either handle the engines torque or it cant. simple as.
I'm with the others on this. The bike has a very small contact patch on its rear tyre with which to transfer the engine torque to the road and
so the clutch springs only need to a limited clamping force to overcome this grip.
A BEC has two big fat generally sticky tyres and so will be more liable to slip the clutch before spining its tyres which is heavier duty springing is
used in BEC's. I also agree weight will come into the equation too (ie the clutch in a heavier BEC will have a harder time than in a lighter
BEC, which in turn gets a harder time than that in its "donor vehicle" .
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gingerprince
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| posted on 10/2/09 at 05:46 PM |
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Another for the "with them" crew. So long as the clutch is designed such that it has a higher friction than the driven road tyres in
their grippiest conditions (i.e. dry with sticky rubber) then it's fine, and they'll design that based on a bikes grip.
Put it in a car with twice as many driven wheels, and more rubber on the road in any case then you're outside the design parameters of the bike
clutch.
Fit stronger springs
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cloudy
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| posted on 10/2/09 at 07:06 PM |
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dinosaurjuice is right on this one guys, consider the bike and the car in 5th gear at say 100mph, both are able to throttle fully open without
spinning the tyres - the torque being transmitted through the clutch in both cases is EXACTLY the same - even if it was a lorry it would still be the
same torque.
The part where stiffer springs will help is overcoming the extra time a larger mass will cause the clutch to slip changing gear or pulling away....
In short, harder springs will increase the amount of torque available and reduce wear - which is a good idea, but it's not because it's in
a car rather than the bike...
[Edited on 10/2/09 by cloudy]
www.warnercars.com
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roadrunner
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| posted on 10/2/09 at 07:19 PM |
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I have noticed with my zx9 engine that the clutch slips when pushing on at extreme high revs, say around 11000, but i get no slip at all when setting
off or lower down the rev range, is my clutch on its way out then.
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Paul TigerB6
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| posted on 10/2/09 at 07:23 PM |
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quote:
Originally posted by cloudy
The part where stiffer springs will help is overcoming the extra time a larger mass will cause the clutch to slip changing gear or pulling away....
In short, harder springs will increase the amount of torque available and reduce wear - which is a good idea, but it's not because it's in
a car rather than the bike...
[Edited on 10/2/09 by cloudy]
Having changed an R1 clutch friction plates as well as fitting 3 of the heavier duty Barnett springs just over a week ago to a car i agree with the
above statement but fail to see how the majority are wrong on this one. The increased rate springs generally fitted to BECs and tuned bikes basically
force the friction plates and plain plates together with greater force and so increase friction, which results in less slip for any given situation
over the standard springs (and so reducing wear etc) - think we are all agreed on that one right??
The reason the clutch slips though (with standard springs) is down to the greater traction and weight of the car installation though right?? It stands
to reason (to me at least) that if you are trying to push a mass forwards with x amount of torque, that the weakest link with slip first - be that the
tyres or clutch. Increase the spring rates in the clutch and the tyres are more likely to slip first.
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Paul TigerB6
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| posted on 10/2/09 at 07:27 PM |
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quote:
Originally posted by roadrunner
I have noticed with my zx9 engine that the clutch slips when pushing on at extreme high revs, say around 11000, but i get no slip at all when setting
off or lower down the rev range, is my clutch on its way out then.
It'll be that dodgy engine you bought mate - go and kill the seller!!
Ben (001Ben) had his clutch slipping on the rollers at 9000rpm simply due to the loading of the rolling road according to the operator (hence the new
clutch plates we fitted). His advice was change the friction plates anyway so it was done (and the old ones looked very worse for wear)
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cloudy
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| posted on 10/2/09 at 07:37 PM |
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quote:
Originally posted by Paul TigerB6
The reason the clutch slips though (with standard springs) is down to the greater traction and weight of the car installation though right?? It stands
to reason (to me at least) that if you are trying to push a mass forwards with x amount of torque, that the weakest link with slip first - be that the
tyres or clutch. Increase the spring rates in the clutch and the tyres are more likely to slip first.
Superbikes cannot put anything like full throttle down in any low gear, so the effect is masked - if they had infinite grip I think you would see
exactly the same slip...
www.warnercars.com
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Paul TigerB6
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| posted on 10/2/09 at 07:43 PM |
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quote:
Originally posted by cloudy
Superbikes cannot put anything like full throttle down in any low gear, so the effect is masked - if they had infinite grip I think you would see
exactly the same slip...
Agree with this - and allows for very light springs to be fitted as heavier ones simply arent needed (which helps with the clutch being hand
operated), and hence the clutch slip often seen without any mods when fitted in a car instalation with the engine being under increased load??
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cloudy
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| posted on 10/2/09 at 07:50 PM |
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Increased load - but only down to the higher grip levels and increased drivetrain mass - nowt to do with the mass of the car itself...
James
www.warnercars.com
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roadrunner
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| posted on 10/2/09 at 07:53 PM |
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I can see both arguments here, the weight of the car makes you ride the clutch more while setting off, but if the clutch was fully released then the
engine would stall before the clutch slipped.
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dean100yz
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| posted on 10/2/09 at 07:55 PM |
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quote:
Originally posted by Mr Whippy
It’s rather like frying the clutch on a car towing a caravan, sitting at a constant speed its fine.
It's the clutches ability to drag the two moving surfaces together rather than simply holding them that stresses a clutch and causes all that
heat.
Once the plates aren’t moving relative to each other friction fully can take over. Think about the difference compared to skidding your feet on the
floor (how little friction there is) compared to initially getting your foot moving.
Yep 100%. I dont know kitcars too well yet (learning) but been with bike engines for years. Will def say though semi synth. oil. Better to change more
often using a quality semi synth oil then change less using fully.
Even with my clutch fully disengaged on my Race CRF450 when ridden hard over a 20 min moto it would gain massive freeplay and would start slipping
when on full gas.
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roadrunner
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| posted on 10/2/09 at 07:56 PM |
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Are the Barnett springs stiffer than the ones you can get off Fleebay, just thought i would ask as i have fitted Fleebay ones.
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dean100yz
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| posted on 10/2/09 at 07:58 PM |
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quote:
Originally posted by roadrunner
I have noticed with my zx9 engine that the clutch slips when pushing on at extreme high revs, say around 11000, but i get no slip at all when setting
off or lower down the rev range, is my clutch on its way out then.
What oil do you use? The additives can make this happen semi or fully.
Your springs could be weak too not fully disengaging. Its pretty easy to check plates. If it smells rank (eggy) when you open her up then oils been
cooked!
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