Custardpants
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| posted on 14/4/13 at 03:52 PM |
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Clutch slip when hot, argh!
Hi Guys - know there has just been another thread on the westfield megabusa but unfortunately I'm still looking for what's causing this on
my Indy.(hayabusa engined)
At oil temp around 80degrees C and early on in my drive the clutch is absolutely fine. However after a few more accelerations with my oil approaching
100degrees my clutch starts to badly slip in the higher rpms, respecially 6th. It seems to be the same whether I clutchlessly change or not. The
engine also has uprated clutch springs(although unsure what age they are). When the problem manifested itself the clutch was only slightly slipping,
prompting a change of plates which if anything, has only made the problem worse, despite me measuring the whole pack to be 1mm thicker and within
suzuki limits too.
It has had the following with no effect
New clutch plates and motul 300V full synth oil
Slipper clutch ramp reinstalled to standard spec.
New master cylinder
New slave cylinder
The only thing I have left to try is
Go back to silkolene semi synth
install a new set of uprated springs.
Increase the clutch pack thickness by substituting in some thicker steels from my old set of clutch plates
And lastly spring spacers to increase the spring pressure?
I wonder if I could increase my oil cooling and keep it at around 90 degrees but this will be difficult on track, and surely oil of 105degrees
shouldn't cause this anyway. I have silverstone booked on 6 may and wonder if its worth having a drag lockup clutch ready to put on just in case
in cant fix this in time...argh.
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Andy B
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| posted on 14/4/13 at 04:14 PM |
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Are there any notches starting to show in either the clutch drum or basket. It is common as tey start towear and especially in car applications. If
the notches get to deep plates get stuck and hung up on them so even though you release the clutch the plates hang allowing the clutch to slip.
Regards
Andy
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Custardpants
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| posted on 15/4/13 at 10:26 AM |
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Thanks Andy. Other than the basket prongs is there anywhere else I can check? Would wear in the basket spring beds cause an issue?
The clutch hub itself appeared to have small marks when I last looked at it but still appeared to be although used, fairly smooth. I wonder if the new
plates and steels have sharper edges which are more likely to snag here over the steels which I previously removed. The older clutch plates ironically
had far less clutch slip even on track at the top of fifth gear, and I wonder if this is why. Would a gentle file of the edges of the new steels and
plates where they sit on the hub be a bad idea? I have a new clutch hub on the way from powertec which I can also fit.
Danny from MK kindly suggested checking the pushrod for play when the clutch is released, but both my slave cylinders have internal springs and self
adjust to take up the slack. Otherwise to totally rule out the slave cylinder issue I am sorely tempted to come up with a simple cable clutch
arrangement - at least as the cable stretches it will only increase the slop, and having a heavy clutch isn't really an issue when it's a
foot controlling it! Grateful for any other ideas to try.
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adithorp
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| posted on 15/4/13 at 12:50 PM |
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quote:
Originally posted by Custardpants
Danny from MK kindly suggested checking the pushrod for play when the clutch is released, but both my slave cylinders have internal springs and self
adjust to take up the slack. Otherwise to totally rule out the slave cylinder issue I am sorely tempted to come up with a simple cable clutch
arrangement - at least as the cable stretches it will only increase the slop, and having a heavy clutch isn't really an issue when it's a
foot controlling it! Grateful for any other ideas to try.
Most (all) master cylinders have return springs inside. What Danny means is that there has to be play between the push rod and padal, to ensure the
piston has returned all the way to it's stop and opened the gallery to the resevoir. If there's no play in the push rod, then the piston
can't fully return and release presure. The slave will then return a little bit less with each push and the clutch slip.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Custardpants
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| posted on 15/4/13 at 07:33 PM |
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Thanks, will give that a go!
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:{THC}:YosamiteSam
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| posted on 17/4/13 at 05:06 PM |
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i think you need to make sure that when the clutch pedal is fully released that the clutch plates are fully engaged. you can check this by looking
through the inspection bolt hole and carefully putting your little finger on the plates [engine off of course] operate the clutch pedal and feel the
plates moving with your finger. you should have a little bit of free play on the clutch pedal followed by plenty of movement in the pedal to actually
move master and slave.
start by making sure all air is bled out the system
next adjust pedal maximum lower point and maximum high point [use stops if there fitted]
then check that the slave moves the push rod [only needs to be a couple of millimeters]
if thats still not working youv either got a faulty hydraulic system, or badly adjusted pedals.
if the plates are new theres no problem - are they in the correct sequence of fitting?
as said are the slides showing signs of snagging?
uprated springs should be strong enuff to return the plates
are the plates OEM plates or aftermarket copies? OEM ones are generally regarded as better quality.
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Custardpants
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| posted on 20/4/13 at 12:26 PM |
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Thanks. Apart from sticking my finger through the inspection opening and onto the plates I have done all the above.
When Testing the car today the clutch slipped when clutchlessly changing, but was absolutely fine if I used the clutch when changing gear. Does that
suggest anything? Surely if the plates were snagging then this would be the other way round. There is definitely play in the master pushrod, so apart
from take it all apart and continue to substitute parts I have no idea what the cause is still.
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MikeCapon
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| posted on 20/4/13 at 12:54 PM |
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What oil are you using? You must use a motorcycle oil for a bike engine. Hi spec car oils have friction modifiers that do not mix well with wet
clutches. Big power Suzukis seem particularly prone to this.
www.shock-factory.co.uk
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Custardpants
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| posted on 20/4/13 at 02:23 PM |
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Urm thanks mike it has motul 300v fully synth bike oil. I (id be amazed at anyone who went to the length of fitting a dry sump and then used car oil
lol)
am going to try silkolene 5w40 semi synth though next as I have had great success with this in the past.
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trikerneil
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| posted on 20/4/13 at 02:36 PM |
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I'd agree with MikeCapon, my Yam clutch is hopeless on fully synthetic oil.
Neil
ACE Cafe - Just say No.
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Custardpants
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| posted on 21/4/13 at 10:07 PM |
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Stripped everything down today and fixed it, hooray;
2 steels were backwards(rounded edge facing clutch cover rather than engine), and there was some slight grooving on the clutch hub. The current
springs had also crept 1mm shorter over time. Also looked up that the fully synth 300v oil had moly additives.
Something on this list fixed it.
Change to semi synth silkolene 10W40 comp oil (no moly friction modifiers in this oil)
Two clutch steels round the other way (might have been catching on hub)
New clutch hub (as above)
Nw uprated clutch springs (noticeably stiffer than the older set, despite them too being uprated)
Set of 1mm washers between springs and pressure plate to increase spring pressure
Reinstalled backlash eliminator (the standard ramp action did nothing to help clutch lockup at higher rpm and just added too much backlash to the
drivetrain)
All this fixed my clutch slip, and the clutch seems far more eager to lock, which is exactly what I wanted. The clutch basket springs had some play
but will keep an eye on them and will be the topic of another thread. Thanks very much for the help guys!
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jwhatley
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| posted on 22/4/13 at 06:51 PM |
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That's interesting as to what you have found as I have started to get an issue with mine..
I have a lockup clutch on mine and am also running 300V which is what I've been told to use by holeshot racing in my engine.
But when pulling away I have started to get a slow bouncing motion almost like I have a warped plate, but no cultch slip issues.
I'm told that the backlash eliminator can cause issues too, so I need to do some investigation myself.
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Custardpants
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| posted on 22/4/13 at 07:31 PM |
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Perhaps take a look at your basket springs? If running Gen 1 Busa clutch plates one of the main changes of the Busa 2 plates is an anti judder spring
inside the composite clutch plate closest to the face of the clutch basket. This should be a fairly cheap Suzuki spare if you can buy it with just one
composite plate.
What issues to did hear about the backlash eliminator causing? Would have thought more wear on the basket springs, but mine aren't too bad.
Some slop in the bigger springs but the smaller springs are tight (for now, but a drag billet basket is on the horizon next year I think).
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:{THC}:YosamiteSam
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| posted on 4/5/13 at 01:22 AM |
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the washers behind the springs wont increase the pressure - just make it preloaded - a spring will always have the same pressure throughout its range
of movement.
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Custardpants
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| posted on 4/5/13 at 08:55 AM |
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quote:
Originally posted by :{THC}:YosamiteSam
the washers behind the springs wont increase the pressure - just make it preloaded - a spring will always have the same pressure throughout its range
of movement.
Sorry Sam but I couldn't help but burst out laughing at this. Before going any further I'd suggest filling your car boot up with wood or
similar heavy items and see what happens to the suspension as it compresses. Failing that 'spring rate' in google will suffice. If you
want any further clarification/ debate by all means start another thread on the topic.
Back to the thread I've done some research of some of the bec oils.
Motul 300v has moly content and doesn't have the best Jaso rating.
Motul 5100 has moly content and a comparitively poor performance with oil degradation
Motul 7100 fares better and has little to no moly.
On the other hand all the silkolene oils have the highest Jaso standard and none have moly additives so that's what I will be sticking to from
now on.
Jaso oil standards for all bike oils and grades listed here
http://www.jalos.or.jp/onfile/pdf/4T_EV_LIST.pdf
Motul 5100 datasheet (you will need to register for a free gixxer login)
http://www.gixxer.com/forums/attachment.php?attachmentid=197147&d=1358220243
As above 7100 datasheet
http://www.gixxer.com/forums/attachment.php?attachmentid=197148&d=1358220243
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MikeRJ
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| posted on 4/5/13 at 09:14 AM |
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quote:
Originally posted by :{THC}:YosamiteSam
the washers behind the springs wont increase the pressure - just make it preloaded - a spring will always have the same pressure throughout its range
of movement.
Not quite correct. A spring will still have the same rate irrespective of pre-load (ignoring progressively wound suspension springs) but
adding pre-load will definitely increase the static pressure on the clutch pack.
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