Clutch/gear slippage How 2 diagnose?

[Guest]

Hello, I've got a great running 1980 Gs1000G, but have an issue I am unsure of how to diagnose. I am experiencing what I initially assumed to be clutch slippage, the bike at times seems to have higher RPM without increase in acceleration. The thing that confuses me is that I would think this would be mostly experienced in lower gears/higher torque situations, however it actually seems more prevalent at highway speeds in higher gears. It also seems to be intermitant, but increasing in frequency. It has been a few months since I rode the bike, and I am in process of replacing the battery so I can take it out and refresh my memory of the actual conditions I am noticing this. Can anyone give me an idea of how I might determine if this issue is clutch related, or if it may be a gear slipping? Thank you to anyone who may be able to help!

P.S. I have read through earlier posts, and see that cable adjustment is a frequent problem, but do not believe this is my problem. Though I could be wrong, and will double check this as well.

[Nessism]

Clutches typically slip in higher gears with a large handful of throttle. Most common cause is collapsed springs. The plates typically last the life of the bike but you never know. First step is to pull the clutch cover, measure the plate thickness and compare to the manual spec, then order new springs and plates if they measure too thin. Slam those in and very good chance the slippage goes away.

A couple other random thoughts: don't use automotive grade oil since some additives tend to contaminate clutch plates, and two, the rear wheel splines wear out and when they do it seems like a slipping clutch but with zero torque transfer to the rear end.

[rippledub@gmail.com]

Thanks Nessism,

The large handful of throttle resonates with me, as I seem to remember this problem showing up when trying to pass at highway speed. I will check the clutch, though I did put new springs in the clutch when I rebuilt. though it has been 4 or 5 years, the mileage I have put on is probably in the 10 - 12,000 mile range, would this be normal to need new springs already?

As far as oil . . . I have exclusively used Rotella T 15-40 Diesel oil. This was per recommendations from this forum, is this an acceptable oil in your view?

Thanks again!
rippledub

[Nessism]

Rotella is fine, and the springs should be fine as well. Maybe the plates have become petrified from age? This can happen.

[rippledub@gmail.com]

thanks!

[Steve]

Your springs should still be fine at 4 or 5 years and 10-12,000 miles, but it would still be prudent to take the advice in Nessism's signature:
"To measure is to know."

It will only cost about $10 for a clutch cover gasket. Pull the springs, measure their length. While the springs are out, measure the clutch disks, but be sure to note which side was OUT, put it back the same way. Since you have to take the steel plates out to get all the fiber plates out, check them, too. They typically don't wear, but they might get warped or glazed.

If you do choose to replace the springs, get OEM Suzuki springs only. There is no need for "heavy duty" springs unless you have a monster motor that rapidray has built up for you.

If you do this with the bike on the side stand, you won't even have to drain the oil.

When you get it all together, you will have to verify cable adjustment. For just a few bucks more, why not change the cable, too? Again, get a Suzuki cable. They all feel good when new, the Suzuki cables tend to last a bit longer. In fact, you might want to verify that a tight clutch cable is not the cause of your problem now. If it is not fully released, it would be easy for it to slip.

One way to check that is to put the bike up against something that will NOT move. Put the wheel up against a wall, tree, truck bumper, anything SOLID. Have the engine running, put the transmission in top gear. Start revving the engine while letting out the clutch. Do your best to let the clutch out completely, while also doing your best to apply throttle to keep the engine running. If you can't kill the engine, you WILL need to do some work. Don't do an extended torture test, this whole process should take less than 5 seconds.

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[rippledub@gmail.com]

Hey! Thanks Steve!

[bobgroger]

My GS850 accelerated from 6k-9k with no increase in speed. Springs were new and HD. Replacement of the fibers, which looked great, fixed it. It is possible someone ran car oil in it, but it was parked since 1995 and I don't think they had invented friction modifiers by then. So yes, sometimes you need to replace the clutch plates. I roughed up the steels with a DA since they weren't burnt. It was a half hour job or so. Make sure you replace the clutch cover screw at 9 o'clock with the right length one, if it is too long it rubs on the clutch basket.

[Steve]

It is possible someone ran car oil in it, but it was parked since 1995 and I don't think they had invented friction modifiers by then.

No idea when the modifiers appeared, but I have not seen any of them in anything thicker than 30-weight oil. Since Suzuki specified 10w-40 or 20w-50, you shouldn't be putting any 30 in there, anyway.

Make sure you replace the clutch cover screw at 9 o'clock with the right length one, if it is too long it rubs on the clutch basket.

I'm not going to bother asking how you know about that, I'm just going to say "that is GOOD to know".

I have several pieces of cardboard on the shelf that have diagrams on them of various engine covers. When bolts are removed, they get put into the holes around those diagrams so they get put back exactly where they came out. Because I have always done that, I had no idea that the 9 o'clock bolt length was critical.

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[rippledub@gmail.com]

So It sounds like I can just replace the fiber plates if the steel ones are within tolerance, and not warped? Or is there good reason to replace all together? It sure would be cheaper to re-use the steel plates!
Thanks again for all the advice!

P.S. Thanks for the heads up regarding using the side stand to avoid oil change . . . great tip!

[Steve]

Yes, you can replace just the fibers, but my money says you will only need to replace the springs, gasket and maybe a cable.

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