Clutch toast at 24k?

My 06 XB12Ss required its first clutch adjustment about a month ago at ~23,000km (14,500mi) after it began slipping badly in heavy traffic on a hot day. While I had the cover off, I noted that moisture had infiltrated the primary so I replaced the primary oil with 80w90 conventional gear oil as I have always done every 5000km (3000mi).

Over the last month, the clutch performed flawlessly for another 1000km (600mi)

Yesterday, also a hot day, I was stuck in traffic again and the clutch started slipping badly again. This time, no amount of adjustment will fix the slip. The slip is now so bad that the bike is essentially immobile.

The clutch lever action and gear selection are fine so I don't think the spring is broken. The oil does not smell burned. I haven't torn into the clutch basket yet to confirm but the only thing I can think of is that the clutch plates are worn out.

I've ridden over 1/4 million kilometres on bikes with wet, dry, unit, & primary clutches, I have NEVER worn out a clutch before. I ride hard but I don't abuse my clutches either (no burnouts or wheelies).

Anyone else have experience with a clutch that needed replacing at such a low mileage? We all have our preferences when it comes to lubricants, but does anyone have first-hand experience with gear oil (which is exactly what HD Formula+ is) causing excessive clutch wear?

Assuming I am needing to replace the clutch pack, any thoughts on the Barnett kit?

dont know where the info about formula+ being the same as gear fluid came from, but it is for sure not the same.

i switched from formula+ to gear oil to try it and i ended up with some serious clutch shutter up on the mountain. switched back that night back on the mountain and shutter was gone. they are not the same. 20w50 engine oil and gear oil 80w90 are about the same viscosity, this is because gear oil is tested an rated differently than engine oil. but regardless. clutches go bad, coulda been from last time it slipped glazed the clutches and has rapidly worn cause of that. my clutch is on its way out as well 25K i think cause i miss adjusted it and glazed them on a 1200 miles trip

i switched from formula+ to gear oil to try it and i ended up with some serious clutch shutter up on the mountain

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Some gear oils dont have the friction modifiers for use with clutches and is likely what caused your clutch shudder. Some have them for use with elsd rear ends. I run the lucas gear oil in my primary and it has worked really well for me lately.

dont know where the info about formula+ being the same as gear fluid came from, but it is for sure not the same.

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Ya, perhaps "same" is too strong a word, but certainly "similar" and "equivalent" are words I have heard used by a Harley mechanic I am friends with, and over on BobIsTheOilGuy.
Regardless, I don't believe there's anything in good old 80w90 gear oil that would be harmful to clutch plates, is there? As Kona pointed out, it's designed for use in LSDs, which are essentially wet clutches too...

I am just going over my maintenance logs and I am noting that on the last two primary oil changes I did, I used GL5 rated oil as opposed to the GL4 I had previously been using. I didn't give this much thought at the time (assuming that GL5 supersedes GL4) but as I do a little research, I am finding conflicting information on whether GL5 is backwards compatible with GL4. 

There are those who claim that the additional wear additives in GL5 are corrosive to yellow metals like bronze & copper. On the other hand, there are those who claim GL5 also contains corrosion inhibitors so there's nothing to worry about using GL5. 

It's confusing to say the least and at this point I think I'm about ready to swallow my pride & just start using the recommended HD Formula +! 

Anyone have any sustantiated information on whether GL5 could burn out a clutch and whether it's compatible in our XB primary cases or not?

The mileage you can get out of a clutch heavily depends on how much you abuse it, burnouts and clutch wheelies can shorten a clutches life dramatically as well as drag racing.
I am running an Energy One clutch (plates and spring) with ATF in the primary and couldn't be happier with it.

At this point (if you suspect you have caused the problem with the type of oil you used) it would be best to take a couple hours and pull your clutch plates to clean them to remove any residual fluid and soak them in the correct oil. While you have it apart you can check the friction plates for thickness and glazing and the steel plates for bluing.

Thanks stopie, I plan to pull the clutch pack apart once I get a clutch spring tool.

I have heard good things about ATF in the XB primary. Perhaps I'll give it a try. I like the thought of lubricants specifically intended for gear boxes (like ATF or gear oil) because of the extra sheer that regular engine oil isn't necessarily designed for...

it would be best to take a couple hours and pull your clutch plates to...check the friction plates for thickness and glazing and the steel plates for bluing

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I purchased the Barnett diaphragm spring compressor and pulled the clutch pack (image below). All friction plates check out between .690" & .785". The minimum specified in the manual is .661" so I should be OK. A visual inspection shows no obvious signs of glazing or scoring. I did note however that the recesses in the clutch shell, and the spaces in between the friction pads, were a bit gummed-up with a black sludge. I also noted a light rust on some of the tabs on the steel plates (obviously from water infiltration documented here).
Given my observations in the clutch pack and the relatively low mileage on the bike, I remain confused regarding the SEVERE slipping I began experiencing. I plan to just replace the plates with a new Barnett set while I have it apart, so hopefully that resolves things, but in the meantime I'd appreciate any more thoughts on possible causes of my clutch slipping (yes, I did first try adjusting the clutch, several times ).

As I clean the afore-mentioned sludge out of the clutch shell, I'm wondering if some how it's the cause of the slipping. It's thick, like axle grease. The accumulation of it between the friction pads may have been preventing positive engagement of the plates? Anyone else ever find this inside the clutch?

That's bad stuff right there. If it all checks out, I would clean, reassemble, and adjust the clutch then run the ATF that I had mentioned earlier (at least for a while). This should take care of any slipping.
That goop could definitely be the cause of the slipping. I do like Barnett stuff, but I didn't go with Barnett in my Buell for some reason... cant remember why...
Is that dimension the thickness of the friction plate? Its been a while, but I don't remember the (or any) friction plates being over half an inch thick

Is that dimension the thickness of the friction plate? Its been a while, but I don't remember the (or any) friction plates being over half an inch thick

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Yes, friction plates, but I'm sorry I skipped a decimal in my measurements; US imperial is my 'second language'! [confused]

Oh, one more thing to do, as you reassemble the clutch scuff the steel plates in two patterns (first a cross hash then a light circular). Do this with a piece of 320 grit sandpaper that you tape to a mirror or other piece of glass. If you have a granite gauge block this is best, but most people do not so I recommend glass. The glass will ensure that you only remove material evenly and help keep the flatness of the steel plates. Remember though, only scuff, this will also give you an indication if any of the plates have any distortion by "reading" the pattern left my the scuffing.

After a month-long delay due to a mix up whereby American Sportbike mistakenly sent me a voltage regulator, I finally received the Barnett clutch pack I ordered from them.

It's interesting to note that the Barnett friction pads are larger than those on the stock plates, providing more overall contact area.

A little note accompanied the kit which specifically warns NOT to use Harley's Formula+ fluid. It states that ATF should instead be used. I am comfortable following this recommendation considering that there's nothing in our XB's primary case that isn't also found in an automatic transmission (wet clutch pack, chain drive, gears etc), but does anyone know why Barnett would recommend against Formula+?

To bring closure to this thread, I got the new Barnett clutch pack in without incident. The only pieces which caught my attention were the adjustment screw assembly and ramp assembly, both of which seemed to have a bit more play in them that I expected, but I guess since they are held together with clips, this is normal (?).

Regardless, it's all buttoned back up and operating exactly as it should. I am now running ATF in the primary per Barnett's instructions. I cycled through a sacrificial litre (diluted 20% with kerosene) just to be sure any residual gear oil and/or sludge got flushed out, then refilled with a fresh litre of ATF. The ATF makes a NOTICEABLE improvement in cold shifting action, and so far I am pleased with the Barnett pack.

In retrospect, I am still a little confused about what the problem was in the first place. I am reasonably confident that it was the sludge noted above that caused the slipping. I am also speculating that the sludge itself was caused by the water which recently infiltrated my primary case documented here. Any agreements or rebuttals to my thoughts are appreciated.