Wet Clutch Question

[l0ckman]

OK google is my friend, YouTube also. I now understand old dry clutch, wet clutch sort-of. They are the same just wet or dry i get that. What I do not understand is why engine rpm has to do with it. Either it is engaged, or it is not, or your feathering or slipping the clutch. Slipping or feathering the clutch I understand causes undo wear, heat, and all the bad things. But as long as you release the clutch and fully engage it what difference does the engine rpm have on it? Why would a clutch that is fully engaged slip just because the engine rpm is under a certain rpm? I do not get that part. Why would it slip at 3000 rpm, and not at 4000 rpm? Any and all info welcome, and video's even more welcome, i am a visual guy.

Michael

 

[gypsy_100]

OK google is my friend, YouTube also. I now understand old dry clutch, wet clutch sort-of. They are the same just wet or dry i get that. What I do not understand is why engine rpm has to do with it. Either it is engaged, or it is not, or your feathering or slipping the clutch. Slipping or feathering the clutch I understand causes undo wear, heat, and all the bad things. But as long as you release the clutch and fully engage it what difference does the engine rpm have on it? Why would a clutch that is fully engaged slip just because the engine rpm is under a certain rpm? I do not get that part. Why would it slip at 3000 rpm, and not at 4000 rpm? Any and all info welcome, and video's even more welcome, i am a visual guy.

Michael

Your understanding is correct for a "typical" clutch arrangement in a motorcycle. And it is correct for the SM (manual shifting) versions of the Spyders. However, for the SE's, there is a centrifugal mechanism that disengages the clutch as the rev's drop so that when you come to a stop the clutch is fully disengaged and the engine rev's can drop to idle. Otherwise you would stall the engine. As the rev's then increase from idle, the centrifugal mechanism gradually and smoothly engages the clutch. Apparently, this mechanism starts to disengage the clutch at rev's high enough that people who kept their RT's in higher gears as the road speed dropped and lugged the engine along were unknowingly causing the clutch to slip a little. Eventually there were problems. One of BRP's computer updates for the SE's was to raise the rpm that would initiate an automatic downshift so the downshifts would occur sooner as the engine speed and road speed dropped.

 

[l0ckman]

Mine is a manual. So I still do no get.

Michael

 

[gypsy_100]

Mine is a manual. So I still do no get.

Michael

So you are in control of the clutch. The rpm's are irrelevant. Where and what are you reading that shows rpm's affect the manual-transmission clutch?

 

[NancysToy]

Mine is a manual. So I still do no get.

Michael

What you don't get is that line of hooey that your dealer gave you. You were right, they were wrong...period. If they did not check your clutch assist solenoid, I would point to that as the root of your problem. If it is OK, your clutch engagement procedures might be in question. For a manual clutch, those are about the only choices if the clutch fully disengages. A bad slave cylinder (or master cylinder) would enter into the equation if the clutch is dragging. Low RPM usage is not a factor.

 

[l0ckman]

So you are in control of the clutch. The rpm's are irrelevant. Where and what are you reading that shows rpm's affect the manual-transmission clutch?

My clutch on my manual RT just had to be replaced. I posted about it earlier. The tech told me I did not shift at high enough rpm's. I just do not get it, does not make sense to me.

Michael

 

[jthornton]

My clutch on my manual RT just had to be replaced. I posted about it earlier. The tech told me I did not shift at high enough rpm's. I just do not get it, does not make sense to me.

Michael

On a manual transmission that is a bunch of s**t, unless something is/was keeping the clutch from engaging the RPM has nothing to do with it AFAIK. I even looked at the parts breakdown on the manual clutch and it looks like a normal motorcycle clutch to me... if you dump the clutch it kills the engine right?

John

 

[gypsy_100]

My clutch on my manual RT just had to be replaced. I posted about it earlier. The tech told me I did not shift at high enough rpm's. I just do not get it, does not make sense to me.

Michael

Scotty and Jthornton are absolutely correct. The rpm for the manual clutch are irrelevant. Your manual clutch does have a vacuum assist to make it easier to pull the lever. Did you ever try holding the lever disengaged with the engine off? Pretty hard pull is required on the lever and sitting at a stop sign or red light would get pretty tiring. So BRP put in a vacuum assist to make the pull easier. When you start to pull the lever and disengage the clutch, the computer is notified and it tells the vacuum assist solenoid to apply some vacuum assistance. Now, the amount of assistance provided is a function of rpm. At idle, the computer provides max assistance to make it easy to hold at a red light, for example. As the rev's increase, the computer applies less assistance. Above 4,000 rpm, the computer provides no assistance -- at those rev's you are just quickly shifting gears and no assistance is needed. Bottom line -- while the vacuum assist is determined in part by the engine rpm, the rpm has no effect on clutch slippage. Low rpm just allow vacuum assist to make it easier to pull the clutch lever.

Now, what Scotty is referring to is that if the vacuum assist solenoid goes wacko (technical term), the shop manual says that it could lead to burnt and damaged clutch plates. If the solenoid were applying assist constantly, the vacuum must be strong enough that it is slightly disengaging the clutch, causing slippage even though you are not pulling on the lever. Again, rpm would have nothing to do with it. The problem would be a faulty solenoid/check valve that is constantly applying vacuum when it should not be.

 

[BajaRon]

The only thing I can possibly extrapolate from this Dealer's explanation (or excuse depending on how you look at it) is as follows.

If you were to take off and or shift at very low RPM you may tend to slip the clutch for an inordinate length of time so as not to lug or kill the engine. I don't see how this is likely in anything but 1st gear from a stop, but I suppose it is possible in other gears as well.

The only thing that is going to prematurely ruin a manual clutch (other than mechanical failure) is slipping the clutch too much.

But I have to agree with Scotty here. Most likely the dealer is giving you the mushroom treatment...

 

[mcaccamise]

Wish i had vacume assist on my RSS LOL

 

[gypsy_100]

As long as we're grasping at straws here, what kind of oil do you use? If you are using super-slippery automotive oil, it is too slippery for wet clutches and will cause them to slip. I would think you would have noticed the slipping long before any damage was done but maybe not. Just looking for possible explanations here. You should always be using dedicated motorcycle oil suitable for wet clutches; look for the JASO MA or better yet JASO MA2 on the back of the bottle. There's numerous threads here on that subject!

Otherwise, we're back to no explanation. Your dealer really should have checked out the vacuum assist solenoid and check valve as the shop manual explains that could cause clutch slipping, as explained in an earlier post. If that is the cause, you'll be looking at another clutch job at some point.

To give the dealer's tech the benefit of the doubt, perhaps when he told you about keeping the engine rev's up, he had mentally slipped a gear (pun intended) and was thinking of the bulletin and reprogramming of the SE's to keep the rev's higher and simply forgot that would not apply to the SM's.

Keep us posted on any further developments.