GS1100GK: noise & vibration in 4th / 5th gear - gear box? transmission? drive train?

[Guest]

My 20,000 miles GS1100GK is giving me transmission (I suspect) problems. I am fine in gears 1, 2, & 3. About 40mph, if I go into 4th I get a vibration like a wheel out of balance. Same in 5th at highway speeds. I suspected the tire balance but that isn't the issue. Why? 1) I checked the balance 2) With the bike on the center stand, I can shift through the gears and there is a noticeable clunking and vibration in 4th and 5th. I suspect the transmission, but with mileage this low I am surprised. I checked the front and rear drive oil (which I had changed when I got a bike just a couple of thousand miles ago). The back was still like new. The front was black and the magnetic tip drain plug was covered with bits.

I've done lots of work on bikes, but never transmission gears. Is that the likely problem or something else? What is the fix and how hard is it to do? I'm concerned that I might do the gears ($100 on eBay) but then find out it is something like where the shaft the gears sit on connects to the bike that is out of round so it will just happen again.

I need some advice / help. I don't know why this would happen at such low miles. I'm not even sure if it is the transmission or drive ... but it is currently only happening in 4th and 5th gears.

[Larry D]

Sounds like the drive spline gear is about to go. Let me see if I can find some pictures to clarify....

Okay, the drive spline gear resides within the hub on the rear wheel. It is sacrificial and will fail over time, it is meant to wear vs. the gear the drives it, which is much harder material. Here are a couple pics of the one that came out of my GK. You can see that they were on the verge of failing. Also, there's a couple pics of the new one. There are plenty of threads concerning this topic, just use the search feature and you will find them.

[bwringer]

Put the bike on the centerstand in neutral and peel back the rubber boot at the left front of the swingarm (don't worry, nothing is going to jump out at you). See if there's fresh-ish oil in there. Check to see if the secondary drive u-joint has any side-to-side play or is otherwise wonky. The u-joints rarely, if ever, go bad, but sometimes the bearings and gears on the engine side have issues.

Make sure your fingers are out of the way, then CAREFULLY rotate the rear wheel. See whether the flange rotates smoothly.

Take the rear wheel off and check the rear spline as Larry said, too -- this can whack back and forth just before it goes blooey. (Sorry for throwing all these highly technical terms at you... )

[hjfisk]

Again check the rear sline on the wheel. Very common

[londonboards]

If it was the rear spline or any component south of the engine/gearbox, why would it only mis-behave in 4th or 5th?

I'm would be thinking something amiss in the gearbox. But what do I know?

[tano1980]

Richard - I had the same question.... why would the rear tire differential gears, or the front end of the drive-shaft U-joint only matter in 4th or 5th gear? ... especially when up on the center stand?

In any event, I have removed the rear tire and looked at the male and female gears. They look good to me. (pictures below). I'll be on to the U-joint next, but not likely today. I guess in re-reading this I should have done the U-joint first. So, while I'm on that part.... I'm assuming that I undo the boot clamp, and then peel back the rubber boot as best as possible since the frame is pretty much in the way. Any hints?

Thank you.
Randy (.... and how do I get multiple pictures into a single post?)

GS1100GK Rear Drive Gears.jpg

[londonboards]

Rear hub teeth look good.

I'm suspecting something inside your gearbox (I'm sorry to say). Running the bike on the main stand, you should be able to eliminate the U joints and so on, just by narrowing down where the noise is coming from.

If you are able, disconnect at the U joint and run the bike with no power going to the read wheel. That will tell you for sure that it's something in the gear box.

[Grimly]

Are you sure they're ok? The wear happens at the back of the visible end.
That's a silver-coloured one, which are notorious for early wear.

(.... and how do I get multiple pictures into a single post?)

[ATTACH=CONFIG]45185[/ATTACH]

Link to a pic hosting site - like imgur (but not photobucket, it's dog slow) and put the link in the box that pops up (deselect the "store as local reference" or whatever it is). You can also trim out the majority of the imgur link to leave the pure image link.

[tano1980]

Ok.. Dave's post got me thinking whether the teeth were really good or not (even though they looked good to me). I figured I'd combine Dave's suspicion with Richard's "run the bike now" to determine if the sound still existed. My theory being that with the rear wheel off, there are no gears at the back-end to mesh and make the noise. ... Correct. The noise is still present. It sounds like it is coming from directly under the center of the bike and now I hear it in every gear (the garage is a lot quieter since my son is also working on a bike today). It increases in noise *and* vibration in each gear and is certainly most noticeable in 4th and 5th. However, as I said, THIS time when putting it into first I heard the noise immediately, just at less volume.

I also just tested it again because I thought I heard it whether the clutch was in or out.... but it is ONLY when the clutch is out (so the shaft/wheel are spinning). I don't know if that helps with the diagnosis or not, but I wanted to provide as complete a set of new information as possible.

Continued thanks....

[londonboards]

Sounds like a gearbox bearing then. There is nothing else to do than to have the engine out and strip it right down IMHO.

Perhaps drop the sump and look in the oil strainer and oil filter. You will most likely see some detritus either from a damaged bearing or the metal particles that have caused a bearing to become damaged. Either way, that will be your final cue to strip the engine.

Perhaps take a video and post that up for us or get another opinion from someone local that can come and see it.

I suppose it could just be something silly that we have overlooked but your options are getting slimmer at this point.

Hate to bring you bad news but I wouldn't ride this bike until you know exactly what's going on.

[tano1980]

Ok, i just got back to this today after lots of other summer bike projects that had me riding. I'd done some more debugging with my son and here is what we've done/found. I'd really appreciate any "next steps" or "guides" that can be suggested....

1) back wheel is off, top of shocks are disconnected, bike on center stand, shaft drive hanging down
2) start bike and have the noise in every gear (not neutral)
3) put back of shaft drive (normally where the wheel is) on top of a milk crate to raise it up
4) start bike and have the noise only in 4th and 5th starting around 3000 rpm
5) get out a stethoscope
6) rev bike to 3000 rpm in 5th and listen with stethoscope to A) rear drive shaft housing at the wheel (rear wheel is off, housing up on milk crate); B) front of shaft drive near the engine; C) engine near where the shaft drive exits; D) clutch cover
7) the sound is DEFINITELY at B ... just to the rear of the rubber cover (which let some oil out when we tried to peel it back but were unable to see anything)

So.. does that mean the shaft or universal needs to be replaced? If so, how is that done? I have the shop manual but it doesn't talk about removing the shaft. The manual does talk a LOT about shims for preload and backlash.. which looks intimidating to me, so hopefully I don't need to get into any of that.

Thank you!

[AMK]

Do a search on "secondary drive", alot of issues with the sounds of this.

Also take a look at this link: http://www.thegsresources.com/_forum...ng-Replacement,

If it is the transmission these gears will come out too. Do them first and it may save you from pulling the engine.

[tano1980]

FINALLY got back to this.. actually, I took it to a shop. The Secondary Gear shaft (Bevel Gear Shaft?) snapped off... just like it twisted too hard and sheared. So, the splines still let everything spin and the shaft piece was still there but bouncing around inside the housing.

Now the question... any idea how common this is? I have a donor bike that I can get a replacement from but I see that Suzuki made updates to the part twice.. but PRICEY! I'm wondering if this is a rare occurrence and I can use the donor (same model year) part or I should upgrade (ouch!) because "it will just happen again".

Thanks!

[tom203]

Your donor bike parts should work...hopefully, they are in decent shape. These big guys can torture the secondary drive

[Wingsconsin]

HOLY MOLY ----

From Sept 2016 to May 2019 and you're finally getting back to this ..?
I thought I was going OCD and ADD while reading this thread.

Best of luck getting it going --
See you in 2022