Weird clutch "grabbing" on 2000 VFR

I've had this bike for ~9 months now, drive it daily and its had the issue I'm about to describe the whole time. I'm not necessarily looking to fix it, mainly just curious what it might be.

The problem existed with the previous owner as well (he told me about it before the sale, to his credit). He describes the problem as the clutch sometime "grabbing" and causing you to lurch forward. That's not the word I would choose (but it's at least partially accurate). He said he had a mechanic look at it and he believed it was an issue with some pin in the clutch. They tried sanding/grinding it back to smooth (I think) and said that if that doesn't fix it more drastic measures (a clutch rebuild? I don't really know) would have to be taken.

I, on the other hand, am convinced (even though I'm not particularly mechanically adept) that it's a bubble in the hydraulic line. Here's what it does:

It ONLY happens when you're giving it a fair amount of revs (at least above 4K, probably less) as your releasing the clutch. You can emulate it in higher gears, but it real life it never happens anywhere but 1st. Shortly after the clutch begins to engage it will -- on its own -- *completely* engage. It may sound like that's a terrible thing causing you to stall (best case scenario) or lurch into traffic or whatever (worst case scenario), but the next thing that happens happens so quickly that it's over instantly. All resistance on the lever disappears completely and since there is still pressure applied against the lever as it is released (to keep it from being released the whole way) and that causes the lever to go the whole way back to the bar; clutch disengaged. All that happens is a very startling but very very short lived small lurch forward.

This NEVER happens when you pull out gently, which is why I've reached the conclusion that there's a bubble in the line. Of course, that may be the most idiotic diagnosis ever. I figure that with the revs higher there is more pressure against the plates which in turn puts more pressure on the fluid and causes the bubble to collapse. At low revs there isn't enough pressure and the air bubble doesn't compress.

I adapted to the style of not pulling out aggressively almost immediately (I'm an adult, I don't need to be doing drag race starts) and after these 9 months it's become a complete non-issue to me. I've never tried to bleed the clutch lines because I would have no idea even where to start and I suspect its probably a giant PITA, but of so little consequence to me that I can't see paying a mechanic to do it. Still, it wouldn't hurt to get it sorted out if it's easy/cheap.

Thanks in advance for any thoughts you might have.

 

When was the clutch fluid last replaced? What color is it (does it look like used deep fryer oil?)?

I'm guessing one of the following possibly:

1. Old Fluid / High Moisture in system.
2. Air in system.
3. Worn / Bad Springs
4. Oxidization on push rod.

I would start with replacing the fluid and bleeding it .. then check the push rod .. then pull and inspect the clutch basket and components.

 

I'm with Jeff. Change and bleed the system. Its not too difficult. Have a friend keep an eye on the resevoir for you to ease the anguish. Consult your manual if unsure, but its not bad. Good luck.

 

Mine has always done the same. But it's an 07 with low miles that was meticulously maintained by the PO, so I figured it was just a quirk of the VFR. I'm just careful to partially engage the clutch below 3k rpm, then roll on the throttle as I let out the last bit of clutch. But I was actually planning on replacing the stock clutch springs with some stiffer Barnett ones tomorrow in an effort to increase the RPM's at which I can launch without the clutch "bucking me".

 

It's a thing that happens with some late 5th gens and early 6th gens (same clutch assembly).
Its not a bubble or anything to do with the fluid.
The only thing that fixes it is new clutch springs and plates.
Not expensive, and easy to do.
Make sure you get a gasket before you start, and make sure you check basket bolts for stretch.

 

I'm not going to try and guess the cause of this one, but I will answer Otter's question about how to bleed a clutch (or other hydraulic system). Basic maintenance is always a good place to start.

Get yourself a nice heavy glass bottle (I use a square Jim Beam bottle) and a piece of plastic tube about 2-3 feet long that is a snug fit on the bleed nipple (at the clutch slave). You'll also need some nice new DOT 4 brake fluid, a phillips head screwdriver (for the master cylinder cap) and an 8mm wrench (for the bleed nipple), plus rags or paper towels.

Put the wrench onto the bleed nipple, the fit the tube, put the other end into the bottle. Clean any gunge away from the master cylinder cap, then remove it carefully, don't drip brake fluid on paint or plastic (a towel can be useful). Under the alloy cap is a plastic spacer, then the rubber diaphragm, take these out too. You can now look into the fluid, it should be a clear yellow/amber. If it is really ghastly/dirty, probably best to suction that out and mop any crud up with paper towels. Top up with clean fluid.

Now crack loose the bleed nipple, pump the clutch lever and fluid should come out of the hose (just a little at a time). Lightly close the bleed nipple, release the clutch lever and let the master piston refill. Repeat as needed until clean fluid comes out the bleed. Refill the master reservoir as needed, making sure you don't let the fluid level go low enough to draw air into the master piston. Any air bubbles should be pumped out in this process.

When you are done, tighten the bleed nipple firmly, and remove the drain tube. Top off the reservoir, clean the rim and refit the diaphragm and spacer, then the cap. If you've spilt any brake fluid, hose it off with water.

It is worthwhile finishing the job by by greasing the lever pivot. If you want to go a little further, pull off the clutch master (3x8mm bolts) and slide the pushrod out. Take some fine sandpaper (1200 or so) and polish the rod, grease it and reinstall. You may find the clutch slave piston has crept out a little while off the engine, you may need to push it back in by hand, but in any case this will happen as you nip up the bolts during re-installation.

 

Thanks for that info Cadbury64! I had always assumed that since there wasn't anything as solid as a brake rotor to push against that pumping the lever with the bleed valve open wouldn't do much of anything. Sounds like bleeding the clutch isn't much different than bleeding brakes which I've done a fair amount of times.

 

on my 94 the clutch "fluid" was a brown gel like substance.
Flushing it made an incredible difference.

 

I have delt with this on my 2007. I tried everything to fix it. Polished the push rod, bled the lines a million times, debured the plates and basket, adjusted the lever and even gave the steels and frictions a light sanding. Nothing helped until I tried upgraded springs from barnett. Their standard drop in springs helped a good deal and brought the grab point from say 4000 rpms to about 5000 rpms. It was around this point in time when member Toecutter was doing his torocharger build. He was tinkering with his clutch, not because of grabbiness, but due to the supercharged vfrs 200 hp, it was slipping in higher gears and high load. He was experimenting with different plates and springs and found that 99 pound barnett springs with the oem plates was the best combo and he recommended me to try this, not because I needed anymore torque holding capacity, but the higher spring pressure actually stabilizes the clutch pack and eliminates the clutch chatter that you are describing. If you have a weak left hand I would recommend going with the standard drop in barnett spring. If you are a strong guy, I would highly recommend the 99 pound springs, as they will eliminate the clutch chatter and grabiness. I am normal build guy and I would say the clutch lever effort with the 99 pounds springs is fine for everyday riding, but can get annoying if you get stuck in rush hour traffic for a prolonged amount of time. But due to the fact that I can now launch at 10,000 rpms easily, it is totally worth it.

 

This same topic pops up about once a month, (if only there was a search button... lol) Here is my last post from 24 days ago on the same topic:

"Most VFR800's experience high rpm clutch engagement chatter. I am willing to bet that those who have not experienced it, have not left from a stop at above 5000 rpms. Anyways the usual VFR clutch chatter is caused by too little spring pressure for too much clutch friction plate surface area. Honda did this, to create a nice light lever for touring, while still being able to manage a relatively heavy and torquey bike. Unfortunately the side effect is an unstable clutch pack at high rpm engagement. It is a relatively easy fix, if you don't mind a heavier clutch lever. The standard drop in barnett springs help raise the chatter point up a thousand or two rpms, but did not totally fix the issue. A set of

Barnett 99lb #MT-91 Springs

totally cured the chatter. Launching at 10,000 rpms is a breeze now. The lever is pretty heavy though lol."

 

"My 2007 has had clutch chatter since day one. I tried bleeding the clutch lines a million times, adjusting the lever, polishing the push rod, deburing the steels, giving the friction plates a light sanding, nothing worked. Only after installing the heavier springs, did the chatter go away. FYI, I am at 70,000 miles on the oem plates now, with most of those miles having heavy abuse on the clutch and 20 or 30 thousand miles having the 100 pound springs. The clutch is still doing great."

 

Sorry about teaching you to suck eggs then! If you need more resistance when bleeding the clutch slave, you could pull the slave off the engine and clamp the piston in with a g-clamp. I've never needed that, the clutch springs have enough resistance to make the process work.

 

Mine just started doing a weird "grabbing" also, just not as dramatic. It's a 2001, new clutch disks (5 months ago, stock) synthetic oil, and EBC springs. According to EBC, their springs are 10% heavier than stock. The first time it did it, I thought it was me. When the bike is coldish, 2nd or third leaving from a stop sign (slowly), the clutch grabs and jerks me forward. Almost pulled my hands off the bars but I pulled the clutch in and saved it. Now I'm out into traffic with the clutch in. Second time, thought it was me again, figured I would be more careful next time (same stop sign, same distance from my house). 3rd time was today. Different stop sign, but same amount of stop/go. Leave driveway, go through one stop sign, next stop sign does it. This time I was going slower and it grabbed and had a weird vibration through the whole bike. Pulled in the clutch and released, same thing. Did it 3 times in a row. I was on a residential street so I pulled over to the side and tried it again. All normal. Tried half a dozen times but all normal. Rest of the ride, all normal.
I'm not one to leave something like this alone, so I will pull it apart at some point and have a look at the disks and basket. I'll report on my findings. The vibration was the weird part, never felt anything like that before.

 

Is it possible there's a burr in the basket causing the plates to not slide well?

 

That was my thought, but it only happens cold and only once. Oil level is a bit high so I siphoned some out to make it just under full. I know it's a long shot, but I'll ride it tomorrow and see what happens. Also, there was some very slight notching on the basket when I changed the plates, so I filed them all smooth.

 

How does your clutch lever feel when the grabbing occurs Jim? Does it lose pressure?

 

Lever feels normal. I just pull it back in, and release it normally again. Doesn't feel any different before or after.

 

Maybe you have some grit stopping the clutch pushrod from easing into the slave piston as you release the clutch, so when you release the lever a bit more it suddenly jumps in and causes the grab? Have you cleaned around the slave and pushrod, it's a grotty area due to all the chain gloop. With the slave cylinder cylinder removed, you should be able to pull the pushrod right out and polish that up, then grease it on reinstallation.

I can't imagine that engine oil level plays any part in this as when running the level will be well below the clutch, and it sounds like you have dealt with any burrs on the basket. I installed EBC fibre discs and springs two months ago, and my clutch is awesome (95000km on the bike).

 

The grab happens 1/2 way to being fully released. The bike is part way around the corner when it grabs. That's why I thought it was me doing it. Fluid was changed and bled at the same time the plates were changed. Rod is shiny and smooth, no burrs, and lubed on the ends. It moves smoothly in and out. I've ridden it the last 5 months without a problem until a couple of weeks ago.

 

Yeah, that would be the next thing I'd suggest as well - checking the clutch push rod and the seal on the slave that it rides in and out of for some grit.