Slipping clutch got worse after overhaul, input wanted.

[fj316]

I've split this from my project thread so as not to derail it and to get a better understanding of the clutch slipping problem. I am studying the clutch files on the forum as I tinker and it got a bit better before it got a lot worse.

My beater gears terribly due to a defective slave and after todays emergency useage it's been totally grounded until the new slave from RPM arrives in the mail.

But as far as I have gathered slippage should worsen through excessive wear if the slave is bad and not as an immediate direct result so I'm wringing my brain to try and locate the whats and whys and I've come to the point where I am in need of expertise to troubleshoot. I'll try to keep it brief and to the point of what's been done and my thoughts. I also want to see if what I know and do is totally in the woods since I do not have a new clutch cover gasket at hand since I changed to a fresh one recently so next time the cover comes off it's for the last time in a long time.

Chronologically as follows:

Took apart the basics, emptied the basket of plates. No notching or other visible wear on the metal.

Changed the fibre friction plates since the existing ones were worn and I want to start fresh as I'm going over the bike. The plates installed came from my local junkyard dog and were not Yamaha OEM due to my slinky budget and delivery time of OEM ones. I am still waiting for an additional wide disc I ordered to replace the rear one with the two springs which will be done next time the cover comes off. The superfluous thin wire is removed and discarded as mentioned in the clutch files. I'm reluctant to throw out the brand new discs but I'm open to reprimand if they infact could contribute to slippage. As far as I noticed the clutch funtioned as it did before and after replacing the fibre with light slipping as it passed 4-5k revs in low gears.

The metal friction discs were removed and cleaned to the best of my ability. Some of them were ok with no aparent glazing, a couple of the others had brown crud that I removed as much as I could without working the plates to hard. I used a stiff nylon brush and fine grit sanding paper on all the metal discs which were not discolored from heat, just from residue of the old clutch plates. Would a round of brake cleaner help me remove the remaining glaze and do I need to be careful in sanding/brushing the discs as long as they are kept within spec and not warped? If the only real reason to change one is warping or below spec thickness I want to do what I can to not have to order and wait for replacements as the bike has gotten enough downtime this season as is.

The spring has been doubled up as described with an EBC spring from Bear at oldbikebarn.com. It resulted in a short alleviation of the slip problem but the clutch pull became so hard that I'm having trouble holding it back when stopped for longer periods of time. After increasing spring pressure however the clutch has started slipping real bad and the tach now jumps visibly as opposed to the odd jolt that could be felt but not observed while riding a constant speed. The second I can afford a Barnett plate I'll get that instead but in the meantime I fear I might drop the original spring and just go with the EBC as it seemed thicker than the original when I installed it and I assume it will perform better than the worn one that has been on the bike for god knows how long.

The oil was also changed to a synthetic one. I will go back to the semi one used before just to be on the safe side but I am aware that it should not cause slippage and it did not affect or worsen clutch-slip in the weeks after oil change before the slave gave out and the new spring got installed and it all got shot to hades.

Also while on the oil train I soaked the discs before installing them but the internet suggested that too much oil directly on the discs could worsen slip, so once coated they should be wiped and installed so that they can get oil from the sump through normal wet clutch operation. Again when dismantling it I will wipe and reinstall the fibres along with other parts if I haven't been grossly misinformed.


I hope this isn't to long winded and that I haven't done anything too moronic on the clutch in trying to learn and work on my bike but I'm stumped as to why the slippage just keeps getting worse as I change parts which are supposed to improve it.

So thanks in advance for any thoughts or reprimands that would come my way.

[skymasteres]

You know, as much as I am a cheep bastard, there are some places where it just pays to buy once.
This is one of those times.  I don't know about the synthetic oil. Every time I have taken a high milage clutch, that wasn't slipping, and put synthetic in it it would start slipping immediately.

You're on the right track with checking the tollerances of the respective parts. The warping and thickness of the steels needs to be checked carefully. If they are out of spec, replace them. If not, use some accetone and wet sand the buggers. You don't need to develop "tooth" on them, it'll wear away anyway, you just need to get them back down to bare metal.

As for the friction disks, I have had fairly good luck washing them down with a good solvent, lightly sanding them by laying them down on a peice of sandpaper over a glass plate, and soaking them in fresh oil. As long as they still have proper thickness, check at like 5 places around the circumference, you should be good to go. Also, the OEM frictions are the way to go. The EBC ones are, in my opinion, made of a harder material that is more prone to glazing once they start to slip. If they start to slip they can sometimes be saved using the sanding proceedure I mentiond. I've used this a few times out of desperation and extreem finantial hardship even reassembling the thing when I had gone beyond manufaturer limits on thickness. It worked for 16k miles on the V-45 till I could do a proper rebuild.

That being said, on the FJ I love the Barnett plate, but I feel like the clutch pull is a lot harder than the original system would be. If you've doubled up on springs and you're still slipping I take all your steels and frictions out, wash/deglaze everything, and put it together with fresh oil. Then just go easy on it till all the frictions have "soaked in" the new oil. In the mean time you can order yourself up the new OEM frictions, and however many steels you need for when the thing starts to slip again down the road.

[Pat Conlon]

A couple of points:
1) You were not specific on what oil you used...Automotive synthetic oil is not what you want to run with a wet clutch..(if that is what you used)
2) There is a reason many of us recommend the use of Yamaha oem fiber plates.
Going by my past memory (meaning: I could be wrong) some aftermarket plates were thinner than the oem fiber plates, thus needing an additional fiber and steel plate added to the clutch pack to give the pack the appropriate overall thickness.

[andyb]

Does the slave bolt onto the bike easily, or do you need a fair bit of work to screw it tight for the last bit?  If it's leaking and otherwise in poor condition, it's possible that it's also not retracting properly and putting a tension on the pushrod even at rest.

I've always liked full synthetic car oil on bikes that I race, but I ensure that I don't get an energy conserving grade.  Dragstrips will clearly show you if you have slippage of the clutch!

Do be sure that it's the clutch slipping, rather than a tire, too.

I'd try to recondition the fibers that you got as described by lightly cleaning them, but there's nothing that will substitute for proper, new, OEM fibers.  I've gone the heavy spring route and still had slippage; after replacing the fibers with absolutely new ones I was able to reduce spring tension a lot, without getting slip.  An FJ clutch pack can be reduced to garbage in 20k miles or less, if the rider is enthusiastic enough, so a used pack could already have the life used up.

Fix the slave. Put in new OEM fibers.  Keep the doubled springs.  If you're not openly abusing things, it should last for quite a long time once it's working well.

[fj316]

Thanks for the good replies.

First and foremost the oil is a motorcycle oil which is designed for wet clutches. I'd be pretty embarrased if I'd in addition to going the cheapo route with the fibres used a motor oil with friction enhancers. Should have stated so in my original post but it got lost in my wall of text. I am long winded by nature.

In the short time since I changed the oil it has become cruddy due to it being the first oil change on the bike in god knows how long so I am still going to change it to flush out the grime it's collected. I'd love to get my hands on some diesel oil that is mentioned here once in a while but I have checked and I can't verify the oil that is available is free from additives so I'll use the semi-synth alternative for the next change and then mabye back to synthetic after that since I plan on frequent changes as long as I have the bike.

The junkyard dog albeit an accurate description of one of the dealers I use might be misleading since they were new in sealed packages. They were thicker than the used ones I pulled off the bike and I'll double check that they are within spec and clean them to make sure they perform as intended. Ordering a full set of OEM sounds like a good plan either way so I'll take that to heart so that I at least have them lying at the ready for an inevietable change if and when I take the kookaloo out of the ones I have on now.

There was some jimmying when bolting the slave back on so it might very well not retract properly. It also doesn't completely disengage and the wheel rotates when in gear on the centre stand. So when I can take some pictures of how ragged it was and then toss it over a cliff I'll be a happy camper. In any case there will be no more riding until that is fixed.

The acetone tip was golden as I have a bottle of it lying around so I can pull out the contents of the basket and check the specs of all the parts and get to cleaning and sanding properly both the metal discs and a light round on the fibres for safe measure. Any idea on what distance miles/km I would need to ease in new oil on the plates?

And even though I'm positive that during the last emergency use of the bike the clutch was indeed slipping at cruising speed I'll keep in mind the tire slip once I report back after new slave is installed and cleaning is done. 

Thanks for the insights, I am now a bit wiser to the ways of the clutch. 

[RichBaker]

The rear wheel rotating with it in gear, on the  CS, is normal.... Even with the clutch disengaged.

[fj316]

Thanks Rich that was my last puzzle piece. It took me two days since I have to do it in open air. But the other day the slave cylinder came from Randy at RPM and gave me a celebratory day of installment and bleeding. Then it started to drizzle so I had to postpone the rest after taking a short ride to test the state of the bike. It got considerably better but was slippin' and grippin' on the clutch still.

Yesterday however I got the last leg of the clutch ordeal in. The acetone tip was the ticket for my success along with 600 wet sanding paper.

Man oh man was that ever long overdue.

Before and after shot, the brush pictured was not used as the sanding paper was most effective.

Cleaned the fibres but did not sand them as I have OEM's on the way in case it should deteriorate.

As of now thoig I took an initially timid ride to get the clutch well oiled and set in place I can now safely say it is buttery smooth and no major jolts or judders while in cruising speed and the tach needle is now rock solid. Currently waiting out some thunder to take a more sprited ride to check the upper reaches of the clutch. But as far as I can tell it's now as good as it gets.

Your input has been very much appreciated and in cases also invaluable to get the grime out and the kookaloo in. Thanks again everyone.

ps. thankfully I had a friend over for a visit so even though it also rained during the evening of disc sanding he was on umbrella duty because I would be damned if I didn't assemble the clutch the same day as I cleaned the innards. We were a hilarious sight indeed but the parts and clutch housing stayed dry and all is now well.

[racerrad8]

FYI, those frictions in the photo are not stock, but some form of aftermarket.

Did all of the steel floaters have the dimples in the plate?

If is too hard to tell how many steel plates are there?

Did you have total of 8 friction disc or 9?

Some of the aftermarket kits use thinner frictions & steel which allows them to use on more of each. The problem with those kits is the steels are too thin and warp causing all kinds of issues.

Glad it is working good up to this point, but if you have stock friction coming in, drop them in your preferred engine oil over night to give them a soak. Then clean the steels one more time and you should be good for a long time.

Randy - RPM

[fj316]

Finally the stock frictions arrived and is awaiting replacement along with sprockets and chain. Will soak with the new oil as advised and clean the steels one more time.

IIRC there are 8 frictions, 6 wide and 2 narrow. Going for 7+1 and removing the dampeners for more grip.

All the floaters had dimples and as far as i know only the frictions are aftermarket as I have not replaced the steels.

Thanks.