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Message started by ohiomoto on 05/25/21 at 04:39:31

Title: Clutch slipping during warm up???
Post by ohiomoto on 05/25/21 at 04:39:31

My bike is stock and has around 25-30k miles on it. (I'm on my third speedometer and forget the exact mileage I had on the first two.)

I recently changed the oil on my bike and now my clutch is slipping under medium acceleration during warm up. Once warm, it has full grip.

I used Rotilla T4 as usual so I don't think it's the oil. I always run a good bit of slack at the lever. But the actuation arm has always been near the upper mark on the case. It sort of sits right on that mark unless I push it down by hand or push the lever out at the bar.

It seems like my clutch needs some thermal expansion for it to reach full clamping force.

Could this be a pushrod issue?

(I'm not seeing how, but I might be overlooking something.)

What's the life expectancy of the plates in these things?

(Seems like it should be more than 30k for a stock bike.)

Title: Re: Clutch slipping during warm up???
Post by Gary_in_NJ on 05/25/21 at 05:29:39

The clutch is so easy to get to I wouldn't bother to guess at the problem. Remove the clutch assembly and measure the friction plates to make sure they are within spec. Also, inspect the steel plates for signs of warpage and over-temp. If you (carefully) lay the bike on it's left side, you don't even have to worry about the new oil you just put in the bike.

Title: Re: Clutch slipping during warm up???
Post by SoC on 05/25/21 at 10:34:12

If you read through the past posts on oil additive, your problem sounds similar to descriptions of need for zink additive.

Before doing too much work, maybe try adding some Redline ZDDP additive. Zinc in oil formulations varies and is necessary for clutch to funtion properly. Since it appears to have come post oil change, I would say to start there, before wrenching too much. If I remember correctly the ZDDP additive is recommended even if using T4. You may need to do a fresh oil flush with new filter and some run time to clean it.

Draining and adding new oil and additive is pretty quick and bike is still in service while you ride it for the quick flush. Drain it again and replace with fresh oil and additive and ride. There has been reference to flushing with diesel, just flush, no starting motor, but that would require at least another oil flush to clean the diesel out and I would not recommend it.

I use T4 and add the Redline ZDDP to it. If after that it is still a problem venture into the clutch housing.

Title: Re: Clutch slipping during warm up???
Post by Gary_in_NJ on 05/25/21 at 12:12:18

I've never had a clutch slipping issue with T4 or T5 in the Savage, or any other motorcycle for that matter. I've used those oils in everything from a 30hp savage to a 120hp GSX1100. It's not the oil.

30,000 miles is a lot of miles for a clutch.

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 05/25/21 at 13:27:11

Is 30k a lot on a clutch that only has to handle ~30 hp??

I don't ride the thing all that hard, but this is the first street bike I've put this many miles on. I was thinking it should last a lot longer even though it's pretty weak.

Title: Re: Clutch slipping during warm up???
Post by Dave on 05/25/21 at 13:39:36

51505547444748554D4F260 wrote:

ZDDP does not help with the clutch function - and you have to be careful what ZDDP additives you use. A lot of them have other friction modifiers included and they are not recommended for a wet clutch.

The senior members of this forum no longer recommend the used of a ZDDP additive - it is far better to buy an oil that already had enough ZDDP included. The Rotella oils have more than 1,000 ppm of ZDDP and keeps the cam and rockers happy.

There was a brief period of time that the formulation of Rotella T6 that came in a white bottle had an increased about of Moly....and it caused a few members to experience clutch issues.

If the clutch has been contaminated with a friction modifier - you pretty much have to take the clutch apart and scrub and scuff up the fiber plates to get rid of it.

If the lever on the side of the engine case is within the marks and you can feel some free play in the lever - the clutch plates are most likely not worn out.

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 05/25/21 at 13:41:08

SOC, it is odd the the issue seemed to rear its head after an oil change, but a) it's the same oil I have been running for years, and b) the clutch works fine after the bike get warmed up. This only happens early in the mornings when I leave for work. Works fine in the afternoons (so far) on the same oil.

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 05/25/21 at 13:49:30

Dave, centerline of the arm is just below the top mark on the case. It will drop a tad lower if I push it down to take up the remaining slack. (Pretty much just like DBM's lever in his DR clutch upgrade thread.) So there is a good bit of slop in the pushrod/actuator assembly.

It acts like when a basket gets grooved and the plates hang, but only when it's cold.

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 05/25/21 at 14:28:06

Okay, it's in the upper 80s here today and but the bike has been sitting since I got home from work yesterday. So I took it out and beat on it!

I ran through the gears hard a few times. I did a few 4th and 5th gear clutch slaps at high different rpms. The clutch grabs pretty good.

The only thing I noticed is that it would slip just a bit and then grab with the clutch slaps. Like I was feathering the clutch, but not slipping like it was doing the past few mornings.

The little bit of slip doesn't happen if I actively push the lever out. Also, it takes almost nothing to get it to the slip. It's like the clutch is strong but it's on the edge of disengagement at all times.

Something is slightly off. It's either near is EOL, or something with the actuator rod or cam. Or it's just being a Savage. :-/

Title: Re: Clutch slipping during warm up???
Post by verslagen1 on 05/25/21 at 17:16:43

6B6C6D6B696B706B040 wrote:

The little bit of slip doesn't happen if I actively push the lever out. Also, it takes almost nothing to get it to the slip. It's like the clutch is strong but it's on the edge of disengagement at all times.

where is the clutch lever on the case in respect to the marks when you take up the slack?

Up towards the top? might mean you need a longer rod.
when you are at the top marks, you don't get the maximum disengagement travel that you get with the lower marks.

Title: Re: Clutch slipping during warm up???
Post by Gary_in_NJ on 05/25/21 at 18:22:37

Could also be cable stretch.

Title: Re: Clutch slipping during warm up???
Post by DragBikeMike on 05/26/21 at 12:25:48

Sounds to me like a wear & tear issue. It's gettin old and things aren't as fresh as they used to be. You want to fix this before it gets out of hand and damages the pressure disc, hub, and steel plates.

Your oil gets thinner as it heats up. The clutch has to squeeze the oil out in order to grab. Those shallow slots in the friction plates are there to provide a path for oil and debris to exit the clutch pack. As the friction plates wear, the slots get shallower and there's less room for oil to exit. There may not be a sufficient flow path for the cold oil to exit, but when the oil heats up the slots can handle.

Springs get weaker with age. They might be strong enough to squeeze the pack together when the oil is hot, but lack sufficient force to squeeze the oil out when it's cold.

I agree with Gary. It's just too darned easy to dig into the clutch. Open it up and inspect it. Fiber plates should be about .115" thick. Spring free length should be about 1.365". If possible, check the spring force at 26mm. It should be 55 to 60 lbs. IMO, the force measurement is way more important than free length. If in doubt, replace the springs. They're cheap ($4.52 a copy).

If you are desperate, you can increase the spring preload .06" by installing an extra steel plate between the innermost fiber plate and the pressure disk. Not my cup-o-tea but it will probably work. The extra plate must go here.

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 05/26/21 at 19:19:30

Didn't think about the lack of oil evacuation on the plates. That's a great point DBM. That fits the EOL theory and makes perfect sense.

I'll just order the parts along with some longer push rods and see what I have when I get it apart. It's not my cup of tea having the bike lying around in the garage when I could be riding it to work. ;)

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 07/15/21 at 18:12:54

I finally dove into this since I had the pipe and left peg off while replacing the broken swingarm on my bike.

The plates checked out between .116" and .117" and the springs measured out to ~1.36". Everything in there looked great except that the nut holding the assembly in place was barely finger tight! The washer was the only thing keeping it from spinning off.

The lever feels a little better now, but it's raining here so I only went up the street. Fingers crossed.

Title: Re: Clutch slipping during warm up???
Post by zevenenergie on 07/16/21 at 01:51:55

I'm looking forward to the sequel, because I have the exact same problem.

Title: Re: Clutch slipping during warm up???
Post by twhitus on 07/17/21 at 12:52:39

could this be a sticky cable when its cooler? like the cable lube is a bit gunked up and its not releasing all the way?

Title: Re: Clutch slipping during warm up???
Post by ohiomoto on 07/18/21 at 11:32:51

Test ride done. Clutch feels better than ever and the transmission "whine" during deceleration has been reduced to 20% of what it had been. I never realized how loud it actually was. I'm thinking that thing has been loose since I got it.

Oh and after giving it some more thought, I think I have closer to 20k on this bike, not the 30k I thought I might have. I'll have to dig up the old speedos to be sure.

And as far as I know, I'm the only one who ever pulled the clutch cover when I replaced the chain tensioner. seems hard to believe but I think the nut might have been installed like that at the factory. :o

Title: Re: Clutch slipping during warm up???
Post by Dave on 07/19/21 at 04:22:30

3037363032302B305F0 wrote:

And as far as I know, I'm the only one who ever pulled the clutch cover when I replaced the chain tensioner. seems hard to believe but I think the nut might have been installed like that at the factory. :o

That is entirely possible. I bought my bike used with only 262 miles on it. At 400 miles it started making a ticking sound and by 1,200 miles it was a horrible knock that sounded like the engine was coming apart. Ultimately it turned out the flywheel nut on the crankshaft was loose......and nobody had ever messed around in there after it left the factory.