Clutch grabbing (throttle it in neutral and the bike moves)

[GS750]

I previously posted this on 14 March 2005.

Ive had my clutch done on my GS750 B about 3000Km ago.

Ive done 2 oil changes since (and filters) because I thought it might be an oil issue.

Im using mobil1 20W50 non synthetic, and it states "SUITABLE FOR WET CLUTCH"

Ive noticed since I had my clutch done (they said they replaced the metals and fibres, as well as the springs) that if I blip the throttle in gear with the clutch held in, it will creep forward.

Ive ensured the clutch is adjusted correctly, and the cable is too, it has about 2mm free play in the lever as shown in the book.

any ideas?

The suggestions were that I run 10W40 oil.

Since reading the replies I have ran the mobil 1 non synthetic and I do my oilchanges (including filter) religiously at 5000Km, but the problem still exists, even when its got fresh oil in it.

I was wondering if its possible that they didnt actually replace the springs?

I am extremely suspicious of this large bike shoppe because they told me when I rang to see if it was done, that they had a problem with the fibre clutch plates they ordered, and that they were much smaller than the ones installed in my bike ( I suspect they ordered either for a later model GS or a GSX perhaps).

Well, I figured, ok, anyone can order or receive the wrong parts......


Anyway, when I collected it, the bike definately had alot more clutch than it did when I took it in for the repair, which I only had done because I was working 12hr dayshifts, 1500Km from home and had no tools to do it myself, and the clutch was slipping reeeeeeealy badly on the way to work, and had no more adjustments left anywhere (either end of the clutch cable, nor on the mechanism inside the LEFT ENGINE COVER)

It simply had to be done before I could get home.


Now, 2 years on and it still creeps forward when you blip the throttle in neutral, and it also clunks heavily when it goes from neutral to 1st.

Without an autopsy (or X-ray vision,) I only know what they told me (that the basket was machined, and had new fibres and metals, as well as the springs).

Ps: Ive now racked up another 30000Km on it since that "repair")
Any ideas or suggestions??

 

[nabrams]

This is one of those instances where you only have a chance of figuring out what's going on if you actually open it up and see with your own two eyes - even then, it might take a while. If anything in there deviates from the stock set-up then obviously all bets are off.

 

[Calvin Blackmore]

My Bike has alwyas clunked neutral to 1st when cold

The oil on the plates is more viscous cold than when at normal operating temperature so it makes for a lot of drag. On the order of a viscous coupling form transmission of old.

what ambient temps do you start up in?
open it up and spec out the fibre and metal plate thicknesses

did you own this bike form the day it was new? If not you may have no way of knowing if this is normal behaviour for its model\ year

 

[lecroy]

I previously posted this on 14 March 2005.
Now, 2 years on and it still creeps forward when you blip the throttle in neutral, and it also clunks heavily when it goes from neutral to 1st.

Without an autopsy (or X-ray vision,) I only know what they told me (that the basket was machined, and had new fibres and metals, as well as the springs).

Ps: Ive now racked up another 30000Km on it since that "repair")
Any ideas or suggestions??

If what your saying is true and that it's in neutral and still moves.

I am betting that they did not clearance the basket correctly. You said they did some machine work on the basket which seems very suspect to begin with. If the clearance is set too tight, the basket will drag on the input shaft and turn, even if you take all the plates out of the bike. It's not a oil brand or plate problem.

If you want to know, put the bike in neutral. Remove the clutch cover and then remove the clutch hat (six 10mm bolts?). Pull out all the plates and try to turn the inner hub. It it seems tight and does not spin freely, there's your problem. When I say free, I mean free. If the bike is wanting to move, it's going to be tight as all. You will be able to tell.

First step, order all the shims. Suzuki made several sizes. Just get them all and be done with it. With you running it so long with it being tight like this, you better make sure nothing else was damaged. If it were me I would replace the needle bearings.

Once you have the shims get yourself a nut, bolt and some large washers. Pull the basket and bolt the assembly together using the largest shim and all the new parts. Take a measurement (I just use a feeler gauge) and put the right shim in. Bolt it back together outside the bike and recheck it. If it falls in spec, put it back in the bike using some assembly lube on all the parts. Check the hub and make sure it spins freely after the nut was torqued. Make sure you torque it right and use that locking tab. You should be good to go.

I posted some pictures on how to do this in the HP area afgter someone asked. Maybe do a search.

Good luck with it.

 

[Guest]

sounds normal enough to me, I'd just ride it til it breaks again

 

[endlessGSgeek]

IN NEUTRAL?? Could be even more serious than shims.

IN NEUTRAL?? Could be even more serious than shims.

"Now, 2 years on and it still creeps forward when you blip the throttle in neutral, and it also clunks heavily when it goes from neutral to 1st."

Did you really mean that it pulls forward even in NEUTRAL???

I hear what Lecroy is saying about shims, but I don't know what he means. The same symptoms that Lecroy describes (inner hub hard or impossible to turn with human hand) can also be caused by a much more serious problem. There is a chance that you have a partially seized gear on the countershaft. The countershaft is exposed at the end of the inner hub in the clutch, and if it is in neutral, it should spin freely as LeCroy says. The engine diagram helps (http://www.thegsresources.com/garage/gs_engine.htm). A partially seized gear(s) on the countershaft (or driven shaft... the third shaft), will make the wheel spin when in neutral. In fact, it makes more sense to me than shims. If the problem is a seized (partially seized) gear on the countershaft, nothing short of cracking the crankcase halves and replacing the countershaft and any damaged (seized) gears on it.

I've done this repair on an old 1975 Suzuki TS250 that my buddy rode without CCI oil in the injection tank. I forgave him, cause he didn't know. A bigger job on the 750. I hope Lecroy is right, but be prepared to break it down this winter if you can't fix it out at the clutch. You'll have to buy lots of new shaft end seals, and not a bad time to replace ALL of the shaft end bearings (Why the heck not). Not ready to deal with this type of engine rebuild, and you'll sell it for $400 and someone else will have to do it. There is no way out. Best of luck on this problem.

 

[lecroy]

Good point. If you can not spin the inner hub freely by hand, next step is to loosen the hub nut. If it still will not spin, the problem is not the shim. Still needs to be checked, but there is something else wrong.



This was what I had wrote before. Sorry no pictures, but it is in the manual.



I was talking about setting the stackup in the clutch and someone has asked how to do it. I am pretty old school about this stuff so if you have a better way fill us in....

Ok, lets start by explaining what I am talking about. The newer (83 and up) GS used different parts in the clutch bearing assembly than the older types and requires shims to get the stackup. Say you buy a new basket with a Falicon SC gear and put it into your 82. It's going to fit just fine, except if you measure it, it would be way out of spec. This is the problem I ran into with that little street bike I am working on. So I ditched the old 82 parts and put some 84 parts in.

Timing was good for this. I had torqued the street bike, but my engine is still waiting on a few parts so the clutch is out. Picture time....

This first picture shows all the parts that make up the clutch. They are mounted left to right. If we call these A - L (left to right), E being the basket, G is really the only part that changes. The older GS's had a wider bearing. Part H is the shim. Notice there is a paper bag of shims just above it. These are all stock OEM parts you can buy. I think there are 5 sizes. Or you can grind your own.


The manuals used to talk about placing the parts on a table to make the measurement. I never did it this way. Instead I run a bolt through the assembly.



Here you can see the shim.


There is no reason to put any more parts once the larger bearing has been installed. Yes, that is a buffer wheel washer. Helps to keep things in the center....


From the backside, I slide the feeler gauge between the oil pump gear and the basket. This is supposed to be 0.08mm (I think) max. I always try to get this around 0.06mm. Shims are hard to tell apart unless you mark them. I don't so I use the calipers to figure out which one is which. I start with the thickest shim. See how sloppy it is then pick the one I want to use. I take it back apart, put the new shim in and remeasure it.

I just finger tighten the nut/bolt that holds the assembly together.

I guess that's it. Hope this helps.