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Why? Design flaw?

Old 07-07-2013, 09:06 PM
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Why? Design flaw?

We all know that the SH clutch can't handle high RPM slipping, which really hurts launches at the strip, and can be dangerous at times, but why? I can make many passes and the maximum RPM that the clutch will slip doesn't change. Up to around 6500 pm it will slip. Take it up to 7000 and try to slowly engage the clutch and it instantly grabs, requiring a quick pull back of the clutch lever. I would think that if it had to do with heat, the switch point would vary.

I have read here that this is common to the SH, but I have also seen others that say they don't have the problem.

Is there anyone that can run the motor up to 8-9000, and slowly release the clutch till you can feel it, without it instantly grabbing?

Just curious if this is something I can tune out of the system, or correct.

Bike is a '98 and has done this always, from 2000 miles to 9500, even after flushing with Dot 4.

Just curious.
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Old 07-08-2013, 02:00 PM
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Poor clutch. What gear are you starting in?
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Old 07-08-2013, 02:26 PM
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If your on a drag strip then you best bet is to have a cable clutch conversion and do away with the hydraulics.

(:-})
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Old 07-08-2013, 03:52 PM
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2 Wrong Terms

The issue you describe is not "slippage" but engagement grabiness.

My 1997 with 80k miles has always done this despite the engine oil or slave bleeding. When you let out the clutch at say 6500 it will smoothly engage (drive the trany input shaft) but go 500 higher and it grabs abruptly and the front wheel jumps up which shrinks your sphincter. Just a torquey medium sized 90 degree v-twin letting you know it does what it does in its own way. Not a "design flaw".

Try starting in 2nd gear; and then short-shift 1st, rev 2nd out a bit and staying in 3rd to redline thru the rest of the 1/4...

Maybe others know if different friction plates (EBC, Ferodo, Vesra, etc) and new/bead-blasted drive plates and maybe new OEM or AM springs would reduce the grabiness...
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Old 07-08-2013, 04:47 PM
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Well, with so many people here getting big miles, some over 50,000 miles, from their stock clutch, I wouldn't consider it a poor clutch. In fact, it seems like a great clutch, despite the grabby/snatchiness at high RPM.

In drag racing I start in 1st on the SuperHawk, because I cant launch at high revs, however, the snatchy nature at 7000 RPM happens in all gears.

For comparison, I launch my Bandit at 10,000 RPM and consistently get better results than launching at 6,000 RPM, like 2/10ths better in the 1/8th mile.
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Old 07-08-2013, 07:19 PM
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reread my post about 2nd gear starts etc
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Old 07-08-2013, 07:33 PM
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I've never been on the 1320 with my Superhawk or raced anybody with it yet since I bought it and got it on the road. So, just out of curiousity, and not knowing what kind of clutch my bike has, I tried slipping the clutch from a dig in 1st at 4500 RPMS and I got major clutch chatter. The sound scared the crap out'a me. For a split second, I thought something broke. The bike was hard to control. The front tire was up, then down, then up, then down. Tried it again at 4000 RPMS and got the same result.

Last edited by CruxGNZ; 07-08-2013 at 07:36 PM.
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Old 07-08-2013, 07:48 PM
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There have been others that have had the same problem as yours. Yours can be fixed to where it will slip up to 7000 rpm, which is apparently where they all get snatchy from the factory. Search on "grabby clutch" and you will find some threads on clutch & clutch fluid maintenance.
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Old 07-08-2013, 08:12 PM
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Originally Posted by skokievtr View Post
reread my post about 2nd gear starts etc
Lol, thanks skokie, but the thread here is not about dragracing tips. The scope of this thread is how to make the VTR clutch slip higher than the 7000 limit seen by most people, if that is even possible. It seems to be commonly held that switching to non-Honda plates is not the way to go either.
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Old 07-09-2013, 12:26 AM
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Originally Posted by rz_racer_69 View Post
Lol, thanks skokie, but the thread here is not about dragracing tips. The scope of this thread is how to make the VTR clutch slip higher than the 7000 limit seen by most people, if that is even possible. It seems to be commonly held that switching to non-Honda plates is not the way to go either.
Well... How about this for starters... Where does the Bandit have peak torque? And when you do 10k rpm launches, are you on that peak, or above/below it?

At 7k rpm, you are basically launching at peak torque of the superhawks engine, and you have about 1000-1500 rpm to go until the engine levels of, and stops having usefull power...

So why in the world would you want to launch at 7k or higher? It's completely impractical, and the only possible real world application it could have, is for dragracing... I's not going to matter on a roadcourse if you launch at 7k or 5k... It's not going to matter at a stoplight... So why?

DRAGRACING... It's the only place it matters...

Oh, and once you figure that out, I gave you the answer in the first sentances... Why can't you launch higher than 6000-6500 rpm... Since you are hitting peak torque, which no bike ever is good at launching at... Cable or hydraulic clutch... All will be grabby once you hit that...
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Old 07-09-2013, 11:45 AM
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Originally Posted by Tweety View Post
Since you are hitting peak torque, which no bike ever is good at launching at... Cable or hydraulic clutch... All will be grabby once you hit that...
I'd have to respectfully disagree with you there Tweety. Many, in fact most, bikes will just slip as you let the clutch out until it grabs and not be all grabby/chattery like the SH's seem to be.

Every one I've ridden if you rev it much they get real chattery where it will grab then release then grab and release. It's been awhile since I've been into a clutch on one to verify this but Honda does use some centrifugal assist clutches especially on some of the bigger bikes. I've always assumed that this was the cause of the chatter. As the revs increase the assist increases and it grabs, then it pulls the rpms down and it slips, rpms go up and it grabs, etc. Not a design flaw, but like Tweety did say it's only going to be much of an issue with drag racing so it's not really a focus Honda had when designing the bike.
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Old 07-09-2013, 08:08 PM
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If someone comes up with a real solution to this, let me know. Both my bikes do it. It can be dangerous and I am sure it isn't good for clutch components. I have put an ebc clutch and springs in but to no avial.
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Old 07-10-2013, 01:13 AM
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Originally Posted by GTS View Post
I'd have to respectfully disagree with you there Tweety. Many, in fact most, bikes will just slip as you let the clutch out until it grabs and not be all grabby/chattery like the SH's seem to be.

Every one I've ridden if you rev it much they get real chattery where it will grab then release then grab and release. It's been awhile since I've been into a clutch on one to verify this but Honda does use some centrifugal assist clutches especially on some of the bigger bikes. I've always assumed that this was the cause of the chatter. As the revs increase the assist increases and it grabs, then it pulls the rpms down and it slips, rpms go up and it grabs, etc. Not a design flaw, but like Tweety did say it's only going to be much of an issue with drag racing so it's not really a focus Honda had when designing the bike.
Well, lets disagree then... I can say for sure that ALL the hydraulic clutch operated Honda's do it, bar none... I was farly sure that the cable operated did too, but I could be wrong...
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Old 07-10-2013, 04:56 AM
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So where is the write up on cable conversion. All of my 6 cbrs were free if this issue. You could launch them at a ANY rpm and genty or harshly slip out the clutch.
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Old 07-10-2013, 08:26 AM
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There's no centrifugal assist on the clutch.

It may be due to the time between torque impulses on the VTR, along with an undersized (for dragracing) clutch. Each torque impulse causes the clutch to slip. It then hooks back up between pulses. It's the hooking back up that causes the instability.

Try heavier clutch springs. They were installed on all proper VTR race bikes, to handle the engine torque.
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Old 07-10-2013, 08:37 AM
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The Honda XL1000V (with the same VTR engine) has a cable operated clutch so nab that and install in place of the hydraulic system (see pic below). IIRC the tip was passed on by either a UK track racer or drag racer.

2012-03-10155743.jpg?t=1331396840
http://www.vtr1000.org/phpBB3/viewtopic.php?f=9&t=23016

Originally Posted by smokinjoe73 View Post
So where is the write up on cable conversion. All of my 6 cbrs were free if this issue. You could launch them at a ANY rpm and genty or harshly slip out the clutch.

Last edited by Wicky; 07-10-2013 at 08:43 AM.
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Old 07-11-2013, 06:54 PM
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[QUOTE=smokinjoe73;358634]So where is the write up on cable conversion. All of my 6 cbrs were free if this issue. You could launch them at a ANY rpm and
genty or harshly slip out the clutch.[/
QUOTE]
Had zero clutch issue launching the hell out of my 99 Blackbird. Superhawk scary holeshots

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Old 07-11-2013, 08:03 PM
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Really? The veradero had a cable clutch? Could this really solve the problem?
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Old 07-12-2013, 12:00 AM
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If you read that thread wicky linked, you would have found other interesting things to investigate on your bike... I have... I'll replace parts and try my bike again, long before going to a cable clutch...
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Old 07-12-2013, 03:42 PM
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I've ridden a ton of bikes over the 7+ years I've worked as a tech in dealerships. Not that I went out and beat on every one to see if they do this but the SH is the only one I recall ever doing this. Most any off road bike you can rev the crap out of it and let the clutch out and it'll just grab linearly. Not sure I'd say all the hydraulic clutched Honda's do it either as the above mentioned Blackbird didn't. I don't seem to recall any of the Magnas or Sabers doing it either.
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Old 07-12-2013, 05:22 PM
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When first riding the bike, I fell into my old habits on how I launched my previous bike (VF700F), and it really scared the hell out of me! That bucking due to the clutch releasing and grabbing is unsettling to say the least. Nowadays, I keep the revs low when starting out until the clutch is all the way out. Wish it was otherwise! BZ
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Old 07-12-2013, 09:05 PM
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Originally Posted by RCVTR View Post
Try heavier clutch springs. They were installed on all proper VTR race bikes, to handle the engine torque.
Have you tried this? Or know of anyone that has tried this? I'm very curious to see how or if this helps the problem.
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Old 07-12-2013, 09:31 PM
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Originally Posted by RCVTR View Post
Try heavier clutch springs. They were installed on all proper VTR race bikes, to handle the engine torque.
It's been my experience that heavier springs are a solution to a different problem, and not at all conducive to easier slipping of the clutch, as they are designed to do just the opposite. On my racebikes, when a heavier clutch spring was warranted, launches always suffered. Going back to stock springs on the tuned motors returned the better behavior, but would slip and burn up the clutches.

An interesting thought, I wonder if lighter than stock clutch springs might behave better and still give enough pressure on mostly stock bikes.
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Old 07-13-2013, 01:31 AM
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I have heavier clutch springs... Made no difference to this issue, what so ever... Just saying...

BTW, did anyone read the link wicky gave?
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Old 07-13-2013, 07:44 AM
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Originally Posted by Tweety View Post

BTW, did anyone read the link wicky gave?
Interesting article. My only issue with this is response time. Meaning,
from the moment you release clutch lever, will the mecanism work
instantly, or, have a certain delay due to it's function ?
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Old 07-13-2013, 08:02 AM
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Originally Posted by Tweety View Post
I have heavier clutch springs... Made no difference to this issue, what so ever... Just saying...

BTW, did anyone read the link wicky gave?
In Wicky's link, there was just more possible solutions to the problem. Nobody reported if the changes they made helped or not.

I would like to know if Tony's (on VTR1000 site/Wicky's link) conversion to a semi-hydraulic clutch cable did anything. That would mean that the issue is possibly in the slave cylinder.

Tweety, do you happen to know what rate the springs are that you tried for the clutch? And, do you or anyone else possibly know what the stock spring rate is?

One more question, to anyone that has had this clutch issue, do you have a stock clutch line, or do you have a stainless steel braided clutch line? Just guessing here, but maybe the line is just part of the problem? No way to know for sure, unless enough people chime in. I have the stock clutch line (part metal and part squishy rubber).
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Old 07-13-2013, 10:10 AM
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Theoretcially the clutch line shouldnt have have effect on this issue.

#1- The clutch line pressure is not high enough ( way less than braking where braided lines and hose expansion is an issue) to really need a braided line, the only reason the line is metal and rubber is because of where the line runs, so close to the engine that is could possibly cause a line blow out due to over temp, hence why the metal line is used.

#2 But (and this is a long shot) If the rubber parts of the line were expanding it would cause the clutch to engage due to pressure being lost in the expansion of the line. So in theory switching to a compleatly braided line could cause the clutch to be less grabby durring the high rpm launch, due to the clutch not being able to force expansion of the line.

#3 And I could see this helping would be the clutch chattering, cause part of the chatter could be caused by (what i said in #2) the clutch being able to force the slave in durring the releasing of the clutch causing it to grab too fast and jump back off the slave rod. in turn causing the chatter.

but as I said before clutch line pressure isnt close to braking pressure and it shouldnt have much effect on the clutch. but its all about experiance of people who have tried the braided clutch line.

So just for sh*** and giggles grab your front brake hose and squeeze the lever you can feel the expansion, now grab the rubber section of the clutch line and do the same, little to no expasion, if you have expansion then you need a new line cause that line is shot.

Last edited by sailorjerry; 07-13-2013 at 10:24 AM.
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Old 07-13-2013, 10:26 AM
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I have a braided steel clutch line. It doesn't help with the clutch chattering issue (in my case). BZ
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