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Clutch plates thickness requirements?

12K views 29 replies 8 participants last post by  sonicboom 
#1 ·
Can anyone tell me what the thickness should be for the clutch plates and when the service manual says they should be replaced at? I see online that there are 4 types in the clutch stack, total of 13 plates. The outer most friction plate and steel plate, then 6 other friction plates that are all the same, and 5 other steel plates that are all the same. I plan on taking the clutch apart and checking the thickness on all the plates tomorrow because I'm pretty sure some are worn out beyond what they should be. I just want to get an idea because I'm hoping I don't have to replace all of them. Bike Bandit sells everything individually and most times it's just the friction plates that need replacing but I want to check all to make sure.
 
#3 ·
I'm afraid this is too specific question for this forum ... there are maybe 3 active people that come to mind, that could maybe answer the question, and you are one of them ... best bet would be probably to order one of each plate, so you have a reference and just measure and compare ...
 
#4 ·
I can give a gander through my service manual tonight to see. The last I checked and remember, I think it just mentioned grabbing the set directly from Honda. Which is expensive.
 
#5 ·
Please do if you have the service manual. It would be very helpful! I took them all out and measured, I just want to have a reference. They seemed to be in good shape though, didn't notice and odd wear. I took some pictures and plan on posting a how-to write-up after I'm done for future reference if others are looking to do this.
 
#6 ·
Disc thickness 2.30- 2.50 (.091- .098)

You should measure each of the frictions in three places each.

You can pretty much see the condition of the steels by eye. The manual does not give the specs but you van measure one to the other. You should be able to stack the steels on top of each other without any air gaps in between to check for warpage.
The steels have a rounded edge and a sharp edge and they must all go back in the same direction.

By the diagram in the manual it appears there is at least one odd size either a cork or friction so be careful. The manual calls it 'clutch disc B'. Also I see a 'Clutch plate B'. Which appear to be different from the rest.

I'll snap a pic of the manual diagram.
 

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#8 ·
Much appreciated blipco! I wouldn't think the steel plates are worn out...takes a lot to do that. I've never had to replace steel plates on any bike so far, but I'm surprised the manual doesn't give a spec for those. Is there anything about total stack height by chance?

I measured all the plates, multiple measurements for each one and took an average, although they were all pretty consistent. All the steels came out to be around 2.04-2.05 mm and all the friction plates came out to be 2.39 - 2.42. I did see before that the first friction plate was different from the rest and supposedly the first steel plate is different from the rest, although I can't really tell the difference with that one. Looks the same to me :confused2

Anyway...if they call out for 2.30 - 2.50 range, then it looks like mine are right in the middle. Not sure what to do then. Based on my experience from earlier this season with my zx6r in which the clutch was slipping, I've learned that it doesn't take much to make it slip. With my zx6r it was just a couple of plates that were out of spec by like 0.10 or so and that made all the difference I guess because I put a new set of friction plates in and that solved my problem.

However I'm having different symptoms on the 500. My clutch isn't slipping in high gears and at higher RPM like it was on the zx6r, it's slipping in the beginning when I launch the bike. At first I thought it was simply the clutch cable not being adjusted right, but no matter how much I played with it and re-adjusted, it was still slipping.
 
#9 ·
well then seems like the obvious solution would be stiffer springs that can hold the initial pull ... but that would obviously come whit a price of more force required to pull the clutch in ... i guess if you could find something slightly stronger, it would work, but i guess you already thought about this
 
#12 ·
Yeah, thought about that, but I'm not holding my breath on finding stronger springs for this. Seems like there aren't very many performance parts made for these bikes. Don't know what the spring rate is for the stock springs, or what would work better.

But part of me thinks that's not the problem, because for 1) I haven't heard anyone else have this issue, and 2) I have a friend who used to race a CBR500 this season and a bit last year and he never had this problem on launches. He even wheelied his bike off the line once (have it on video lol), whereas mine just spins the clutch like crazy even if I'm pretty aggressive with letting out the clutch lever. Any quicker and then it just drops the revs all the way down. Guess I've never ridden another 500 to be able to compare, but I've ridden a bunch of Ninja 300s and I can launch those **** near perfectly every time. Huge difference! I get no excessive clutch slip with those.
 
#13 ·
Lubed, no. Never seen anyone put lube on a clutch cable before :confused2

In good shape...yeah I would think so. I mean you can only see the ends, which look to be in great shape, so I can only assume the rest of it is good too. Bike only has about 4700 miles, so I can't imagine the cable being in bad shape. The plates shouldn't either normally, but my thought was that maybe the previous owner had the cable adjusted wrong (it was actually a bit loose when I got the bike) and so maybe he abused the clutch a bit too much causing premature wear. But now I see that mine are right in the middle of the manual's range, so I'll probably just leave them as is. My oil level wasn't too high either.
 
#15 ·
I've owned lots of older, high mileage bikes and rarely had to get a new clutch.
As long as it hasn't been abused, it should last a very long time. On a bike with <20K km I wouldn't worry.
If the clutch slips, I'd check the adjustment first, maybe somebody tightened it up too much.
There must be something seriously wrong before I pull the clutch and start checking the thickness.
 
#16 ·
For most bikes yes, I agree, but with race bikes it's different. Race starts are very hard on clutches. On bigger bikes like 600s and 1000s, it's not uncommon for racers to get new friction plates once a year, which might come out to be only about 1500-2000 miles. On little low powered bikes I'm not sure. I don't know enough about these, but if it's like with anything else, they shouldn't be as hard on parts.

My zx6r had only about 3500 miles on it when I had to replace the friction plates earlier this year....although I think part of that was the previous owner having the lever adjusted too tight and I didn't notice it quick enough. For the last 4 years I've had a bike with a hydraulic clutch so I was used to the feel of that, which feels basically like a 600 with the clutch cable adjusted too tight lol
 
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#18 · (Edited)
I've rebuilt a couple clutches on some old Triumph's, Learn the steel plates almost never wear out. All you do is throw those on a concrete floor and rub them around with your foot to take the glaze off of those.

The friction plates, I never replace those until I get to the point the clutch slips. Most often it will slip throttle roll on in the higher gears.

Taking a clutch apart that is not slipping to measure the friction plates, nothing but a waste of time.

Making something out of nothing.

When I worked as a tech at a Honda shop all those years ago, I don't ever remember taking a clutch apart to measure the friction plates, just simply never did that ever take place. Stupid is as stupid do.
 
#20 ·
But it was slipping...read the posts before.

You've never taken clutch plates apart to measure?? There's a reason why they have that info in the service manual. They do wear out in time and there are standards set for when it's time to replace them based on amount of wear. I guess for you it's better to be ignorant and pretend all is well....sure glad you're not a tech anymore! :rolleyes
 
#19 ·
@sbk1198 the spring doesn't have to be for this bike ... maybe some other models / brands use something similar ... but yes as you have said, i have no problems pulling a wheelie in first or from more aggressive start so, if everything is adjusted correctly and nothing "hangs" that would cause a clutch slip, only one more thing comes to my mind ... what oil do you use, is it possible it was contaminated by something? (and i know this sounds stupid, but you didn't use one of those "energy saving" oils, right? that could cause a clutch to slip as mentioned in this video about slipper clutches: )
 
#21 · (Edited)
@sbk1198 the spring doesn't have to be for this bike ... maybe some other models / brands use something similar ... but yes as you have said, i have no problems pulling a wheelie in first or from more aggressive start so, if everything is adjusted correctly and nothing "hangs" that would cause a clutch slip, only one more thing comes to my mind ... what oil do you use, is it possible it was contaminated by something? (and i know this sounds stupid, but you didn't use one of those "energy saving" oils, right? that could cause a clutch to slip as mentioned in this video about slipper clutches: https://www.youtube.com/watch?v=wJOGKCbvMo8)
I can't say for sure but i doubt it was contaminated by anything. Throughout this year I've changed the oil 2 or 3 times and the clutch behaved the same every time. No, I didn't use any energy savings oil. I've used Motul 300V synthetic, which is what I've used in other bikes in the past as well as my zx6r.

And good call on the springs. I found some EBC spring packs online that are the same size. No idea if the spring rate is different though.
 
#25 ·
I bet mine would be more like 3-4 seconds for 60 ft lol. All my race starts with this bike have been **** because of this slippage issue. With any other bike I've ridden, no problem.

I put it back together now. It was worth checking. Sure didn't hurt anything and only takes about 30-40 minutes to take it all apart, measure, and put back together. Pretty simple on this bike. Maybe when it gets warmer at the start of spring I might just take the bike over to some empty parking lot nearby on a sunday and do a bunch of race start practices. I'll take some tools with me and fiddle with cable adjustment as needed.

Based on the symptoms it really just feels like being an issue of the clutch springs being too soft, but everyone else I've raced with has the same OEM springs too and no such issue. If I can't figure it out by the time our season starts, I'll have one or two of our instructors give it a try and see what they think. I probably should've done that this summer.
 
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#24 ·
Another thing to look for is the cable routing to see that it's not pinched or bent too sharp.

I had a Kawi Versys 650 and one of the problems that a few magazines commented on was that the clutch slipped on take off during 1/4 mile and 0-60 testing.
Also owners were having to change their frayed clutch cables at relatively low miles.

As it turned out there was nothing wrong with the clutch. What happened was that Kawasaki, in an attempt to hide the cable on the naked bike they routed the cable with a sharp bend.
All that was needed was to unhook the cable from one or two clips near the head and all was fine with the world. No more slippy.
 
#29 · (Edited)
I never did call you stupid, You put that on yourself. Was your name ever mention in that post. It was meant as a very generic statement. GO back and read it. Sounds to me like you have a thin skin. I have nothing against you at all. You are making it that way

If you read everything I put up I even put up the fix for your problem....but somehow you probably let that fly over your head.

I'm not a perfect person, nobody is a perfect person.

I was the only one that really gave you the best information on those steel plates glazing over, which is probably most likely what the issue is with the clutch slipping. When I was a tech that often all we ever did to clutches especially with the 750 Honda back in the day. THAT WAS ALMOST ALWAYS THE ISSUE IF THE BIKE HAD LESS THEN 50,000 MILES ON IT.

When you do track days it can be very common to glaze the steel plates. Especially with the newer full syn oils, the friction plates hold up much better, but the issue becomes the steel plates get a build up of glaze on them.

So try to be a little less thin skin, and you may even start to enjoy my humor. The problem with posting you can't see the person and that can cause a great deal of misunderstandings.

Good day sir. PEACE brother.
 
#30 · (Edited)
So back to trying help you guys out.

When you take the clutch apart and those friction plates look good. Just take those steel plates and rub them on the cement floor to ruff them up. Will not take much, just some fine scratches on the surface, that's how they look when new, then they go smooth and then the glaze build up which can be almost invisible, but it's on the surface of those plates.

You want a surface on that steel that looks something like honing marks on a cylinder wall. Nothing works better then a cement floor and circular motion with your foot.

After you do that, that clutch will grab strong as when new. Right now you don't have enough friction under a load.
 
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