Low speed rattles?
There's a few common places that annoying rattles can resonate from on ye olde GS. One of them being the clutch.
It's a heavy unit to be spinning around on the big needle roller bearing and you will always see and feel the [normal] movement when you get hold of the clutch basket. Considering that the huge helical gear around the outside of it is being driven by the crank itself, movement isn't what you want. That sort of freeplay doesn't really matter, for instance, if the clutch is being driven by chain or belt as there is more flex. Gears don't exactly flex, but they will wear.
On top of this, there is a gear sat behind it, driven by the basket, which then drives the oil pump. A lot going on for something that only has one bearing.
Now a couple of the intelligent folks at GSResources forum removed some of the play by machining a little off the bearing hub that runs on the inside of the needle roller bearing. In effect, this removes a little of the end float and holds the basket at the angle it was designed to run. Thereby keeping the gears at the correct angle, and reducing some of the noise inside. Sounds good huh?
That's the back of the clutch basket. The large gear is driven by the crankshaft. The two slots in the back of the clutch centre drive the gear that, in turn, drives the oil pump. The springs you can see are for cushioning take up of drive as you let the clutch out to pull away etc. These sag slightly with age and, ideally, need replacing because they start to rattle. Or, as I was about to do, you can shim them with washers to quieten them down.
So this unit has a few jobs to do. Probably best that it spins as it should instead of flopping under its own weight...
The clutch hub itself is 28mm thick. It is hardened because a needle roller bearing runs on it constantly. We need to know how much end float we have initially before we can take any off it. For this you'll need a dial test indicator.
I found out that the GS1150 actually comes with a 27mm hub and uses shims to get the correct clearance. This could be an option as the bearing is apparently the same for all models.
The only issue with taking a reading from the outer fingers of the clutch basket, as I did, is that you could be reading end float as well as the actual play in the bearing itself. Even a new bearing and hub would have some "flop" in the real world so I'm not concerned about that. I measured 0.020" (0.5mm) with the DTI. Being conservative, and knowing that a little movement is a necessity, I decided to remove 0.016" (0.4mm) and bring the hub down to 27.6mm.
Over to my mate Shane who chucked it on the lathe, but it didn't go the way we wanted. The hub was too hard for the carbide tools he was using. He even tried it on the mill, but that went a little skew-whiff, rendering the hub useless unless we could grind it flat again.
I took it to Paul Gilbert in Southport, who also decked the barrels, machined the head and also took some valve shims down for this bike. I asked if he was able to run the shim grinder over the hub. He disappeared for two minutes and came back with a hub that looked like new! A quick measure with a vernier and I asked him to take the other side down just a smidgeon and he was back with it dead on 27.6mm! Back in the game.
I cannot recommend Paul enough, his knowledge and ability is incredible. If you live on the Gold Coast, Australia, have your cylinder head work sorted there.
I rushed home after work that night and cracked on. Put it back together, torqued up the clutch hub nut and... too tight! The clutch centre didn't turn freely. The end float I'd measured was a false reading due to the side play in the needle roller. Bugger! At least I'm still learning.
Time for a cup of tea, this has been known to fix a few of my fu@k-ups over the years. I either needed a new hub, or I needed to remove metal from somewhere else to give me some clearance. The back of the basket! The drive for the gear behind is very thin. If I rubbed the basket round and round on wet & dry paper with a dose of WD-40, would I be able to gain enough clearance?
The short answer is yes. It worked perfectly. I have a thick piece of steel for this purpose and, as long as you keep changing the position of the work constantly, you will get good results. Hold it in the same position and you will go off at an angle. So every few revolutions, turn the work to a different position in your hand.
Damping Springs.
The other thing I wanted to do was quieten down the rattling springs. There are three heavy, and three lights springs. The only way to gain access though is to grind off the heads of the rivets. Not something i wanted to do as welding is required to finish the job off, but it would be nice to make it quieter and take away some of the backlash in the drivetrain.
Out with the angle grinder and gently as she goes.
Tapping the rivets through, gave access to the springs. Note the large wave washer in the middle.
Backing plate with springs still in place.
There is a thrust washer fitted in between the gear and aluminium basket. The rivets and spacers can be seen too.
Starting to reassemble with washers fitted. I ended up with two on each of the light springs, and one on each heavy spring. This took away all free-play which should make for a quicker take-up of drive too. It always felt as though you couldn't get away fast enough on this bike due to wear in the drivetrain. Anything to remove some of this backlash would be good.
Clamping the backplate together and ensuring the rivets are pushed through fully at all times is uber important here.
I should have let it cool slightly between welds as I ended up with some of the rubber material on the backing plate separating. Nothing I can do about that now but again, we keep learning.
By the time I'd rubbed that slotted drive on the back down on the wet & dry, the tiny marks you can see in the shiny surface were completely gone. Didn't get another pic though as I was busy putting it all back together.
Was there a difference?
The biggest change was clutch adjustment! Before, I'd always had to remove all free-play in the cable when the engine was cold to be able to select a gear. By the time it got hot, there was always free-play. Once cold again, it was gone. Now it remains the same whatever temperature.
Everything feels tighter and gear selection is nicer too. The engine doesn't seem any quieter though, so I will continue on. My next stop is the starter clutch, something I should've checked when the engine was in pieces. However, I didn't have a puller at the time and everything seemed tight.
Starter clutch next...
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