07 S4RT Clutch slip with new Barnett plates

[Heath]

So my clutch basket and plates were getting pretty chewed up. The clutch still had a little life in it but the teeth were getting bad. Decided it was time to change it all out since I was having the 15k service done. I changed out my clutch springs, pack and basket. At first when I installed it was slipping on the low end. I ended up taking the plates out and cleaning them of the factory film they are shipped in. Oops should of done that first. I burped the top end of the master and low end slip is gone.  I didn't really have time to do a full ride check before giving my bike up for its 15k service.

I go and get the 15k service done. Keep in mind this was a half-assed 15k service. A new-to-me mechanic that was recommended to me didn't do a complete 15k service, kept some of my parts, ect..  That's another story though, never going to him again. He did not flush my brake fluid. Said he just topped off and burped it.

I get the bike back and go for a few rides.  What I have noticed now that I have had time to ride it is it is slipping on harder pulls at freeway speeds (60-80mph).  It makes me sound like I don't know how to use my clutch.  For example if I am cruising in a lane about 60-70ish, drop a gear and get on it as I am switching lanes the clutch will slip. It is not a confidence booster at all. Especially if I am trying to cut in and not slow up the person in the next lane.  I have read online people having issues with Barnett plates but this is pretty bad. 
Is there a fix? 
Can I ditch the half plate set up they come with? that feels to be the weak link here.
What else can I check?
Should I flush the whole clutch?

I did go back in and burp the top end of the clutch again. Took all the plates out and cleaned them again too. Still does the same thing.


2007 S4RT
999 Master cylinder
Oberon clutch slave
Barnett clutch basket (new)
Barnett clutch pack (new)
EVR clutch springs (new)

[koko64]

Just to confirm, which pack did you buy from Barnett? Do you need the later pack with extra plates and greater stack height?
Some have had issues with that brand but I never did. Some have had batches of bad friction material.

Consider what the stack height spec is and if you need to use some thicker driven plates from the old stack. Also consider the depth of the spring cap base and compare it to stock. So spring tension and preload is a potential issue. Are EVR springs softer to allow for their plates having a greater stack height? Does that mean you need Barnett springs that are stronger to acvount for a lesser stack height? I would ask Barnett about that. It would be interesting to note the spec of Barnett springs/caps. Are the Barnett springs heavier with a shorter cap height? What about the cap bolt length? Too long for the stack height and they bottom early. Iirc Barnett friction plates were thinner than oem effecting stack height.

Stack height, spring cap depth, cap retaining bolt length and spring weight are genuine clutch tuning issues.

Sorry to make it complex but the dry clutches are tunable race clutches and different brand parts with various spec can effect them. The more power you have the more this matters vs a clapped out stock 900 with 70hp.

If the clutch pull is softer with the new pack then that is an indictation of too short stack height and/or weak spring pressure imo.

[Heath]

I bought Barnett Ducati Clutch Plate Kit- Dry
Part# 306-25-40002
Notes: Includes 7 frictions, 8 steels, 1 damper spring and specific installation instructions.
which is what they say works for the S4RS/S4RT.

According to Motowheels website the EVR springs are the same rate as stock. My springs I took out were barely above spec so it was time. My caps are STM, I think. I painted them a while ago so all markings are gone. My pressure plate is STM so they used to sell the whole kit. I am pretty sure that is what the previous owner did.

Do you know what height I should be going for?

The clutch pull seems about the same as it has always been.

[koko64]

I don't have the spec in front of me. Do you have a manual for your bike? If you havent thrown out the old plates it would be an interesting exercise to measure the old stack height. In theory it should be lower than the new pack, but if it isnt..

Went to the workshop.
My Haynes manual says 49.3 for older dry clutch Ducatis. That would be the dry clutch general spec, that is pre 1100. What gets me is that your bike has a lot more power than a 900.
I've kept old steel plates to tune the stack height over the years. If the issue is not one of the parameters I've mentioned then you may be another disappointed Barnett customer. But in all honesty, I've probably "tuned" every single dry pack I've ever installed from any mfr.

[ducpainter]

No FHE with the Barnett dry clutch plates, but the two best techs in my area won't use them.

The wet clutch plates seem to work.

[Heath]

I don't have the spec in front of me. Do you have a manual for your bike? If you havent thrown out the old plates it would be an interesting exercise to measure the old stack height. In theory it should be lower than the new pack, but if it isnt..
<snip>

Owners manual and workshop don't say an exact height +/-. Just thickness of each plate new vs minimum thickness. If I add that up they say stock height would be 38.5 and min height would be 37.1?  That's just subtracting .2mm from each friction plate.
I do still have my old plates. I will measure them and my Barnett plates when I get a chance.

I would take the bike to my old mechanic, but I am in between jobs right now so I am pinching pennies.

No FHE with the Barnett dry clutch plates, but the two best techs in my area won't use them.

The wet clutch plates seem to work.

Do you know what they do use?

[ducpainter]

<snip>
Do you know what they do use?

OEM.

Like you, everyone wants to save a little. They both tried them. Unfortunately there's no economy in Barnnett dry plates.

This link indicates a total pack thickness of 40.5 mm

IIRC the pack on my Ducati slipper is in the 38mm range.

[koko64]

That Haynes spec must be a bad typo then.
I can't find a pack height spec in the M900 OEM manual, just individual plate specs, warpage, etc.

[Heath]

OEM.

Like you, everyone wants to save a little. They both tried them. Unfortunately there's no economy in Barnnett dry plates.

This link indicates a total pack thickness of 40.5 mm

IIRC the pack on my Ducati slipper is in the 38mm range.

I was going to go with a different brand and then the mechanic said he uses Barnett. Well I found out a lot of what he said was just smoke. I don't know how so many people recommended the guy. I dirgress..

That pack you linked is for a different bike. It looks like someone of the other bikes use 1 more friction and 1 more steel.
Adding up this one though  link is 38.5.  I read on another forum its 38mm =/- 2mm.   Another person said they swapped plates around until they got a height of 37mm and that was the sweet spot for Barnett on an S4RS. So I think you are on to something with the 38mm.  I'll keep messing with it when I get more time. 

[koko64]

The kits for 1100's have more plates. The 1100 drums/hubs are a smidge taller too.

If the clutch slips make the stack taller. If it grabs make it shorter. The spare steel plates are useful for tuning.
I have found the Barnett alloy friction plates of the past to generally be a little thinner than oem alloy plates. I would use some of the thicker oem steel driven plates to raise the stack to stop slipping. Note that all this is to no avail if the fault is in the batch of friction material itself. I haven't handled a Barnett kit in a few years.
If you get the stack height to the max of the spec allowed with good springs and it still slips (the pull will get stiffer), then you have a case for asking Barnett for a refund.

My advice is to buy alloy oem friction plates and use them with your plain plates after giving them a good clean/scuff up. EVR and Ducabike have friction plate kits but I haven't tried them yet.

[ducpainter]

I was going to go with a different brand and then the mechanic said he uses Barnett. Well I found out a lot of what he said was just smoke. I don't know how so many people recommended the guy. I dirgress..

That pack you linked is for a different bike. It looks like someone of the other bikes use 1 more friction and 1 more steel.
Adding up this one though  link is 38.5.  I read on another forum its 38mm =/- 2mm.   Another person said they swapped plates around until they got a height of 37mm and that was the sweet spot for Barnett on an S4RS. So I think you are on to something with the 38mm.  I'll keep messing with it when I get more time. 

The advantage to the kit I linked to is that there are more 2mm plates than in the "correct" kit. Those thicker plates can sometimes help in getting, and keeping, the stack the optimum height.

The price is the same, and the parts are the same, just a different mix, and quantity. The 1100 kit also includes the convex plate, which can help eliminate drag, should that be an issue. If you end up replacing your plates I'd go with the 1100 kit.

[koko64]

Yes, I've used that kit in my worked M900. I got a slightly used set, probably from a forum member. Its true, you get spares and wriggle room for tuning the stack.
I wanted the later kit for the alloy friction plates to go with the alloy basket and billet hub I was running.