Tranny Trouble AHHHHHHHHHH

[Scoooter]

Ok guys a few weeks ago I noticed that my 82 gs 750t was making a popping sound and the chain had alot of vibration in it. So I ordered new sprockets and a new chain from denniskirk.com. Last night I installed the new parts including brakes. When I left the shop I noticed the vibration was still present. Put the bike on the belly stand and rolled the back wheel, you could feel the vibr. and you could also feel a small knock. So I assumed it was the back wheel bearings. I took the wheel back off a few minutes ago and checked the bearings, they were fine. Also checked the swingarm, it is also solid. I reinstalled the back wheel with the chain on, it rolled fine with no sounds or vibr. I reinstalled the chain, and took the front sprocket cover off to make sure it was turning true, it was, I started the bike and put it in 1st gear, the chain jumps like crazy and it has a rather loud knocking sound without the cover on. I then went through all 5 gears and just idleing it knocks and the chain jumps, when you rev the bike to say 3000 rpm's the knocking goes away but the chain still vibrates badly. What would you think the problem is. Is the tranny fixable without taking the motor off the bike? I am thinking it is something with the main shaft since it does this in all 5 gears. HELP PLEASEEEEEEE!!! btw the bike only has 11000 miles on it. Thx for the help, Scott

[tfb]

Sounds crazy.

What do you mean by "a popping sound"?

Is your output shaft bearing broken or worn?

Something in your gearbox might have broken -- you could try pulling off the sump plate off the bottom of the engine (not a huge job, but will probably involve the removal of the exhaust system also) and see if there are any broken teeth which have made it to the bottom.

[Scoooter]

By popping sound I mean at low speeds it knocks like it has a monkey with a hammer inside it. I haven't checked the main bearing yet but that is what I am thinking it may be. I have never worked on a bike tranny before so I am a little worried about the situation. I am going to remove the front sprocket tonight and see if I can tell if the bearing is bad. Can this tranny come apart without motor removal?

[chef1366]

You have to split the cases to get any transmission out of a bike.

[tfb]

Check things out the best you can by removing the sump plate (bottom of engine first), and visually inspecting what you can from underneath.

[Scoooter]

Ok I removed the front sprocket and the main bearing seems ok. I then took off the sump plate expecting teeth and bearings to come falling out, it is sppotless inside the plate, no shavings, teeth and not even built up sludge. I looked up inside the case and my cousin spun the main shaft very slowly, all the teeth that I could see looked like brand new. I had him go throuth the gears and they sounded great except for 1st gear, it makes a really loud clanking sound going into 1st, I would say three to four times louder than when you shift throuth the other gears. So I have no idea what the problem is unless it is an internal bearing. Any ideas???? I am making plans to go ahead and pull the motor this weekend. Thx for the suggestions and help, it is very appreciated, Scott

[tfb]

Well, first gear can be a bit more 'clunky' than the other gears... but not by a huge amount.

There are three other basic areas I would check before you consider splitting the cases looking for the problem:

1. Check that the rotor (on the left-hand end of the crank) hasn't become loose on its spline.
2. Check that the starter clutch hasn't become loose on the three bolts that mount it onto the back of the rotor.
3. Check that your clutch (under the right-hand cover on the engine) is all OK, ie. centre nut is tight, back plate isn't fractured, teeth for the primary drive from the crankshaft are all OK, etc.

Basically any one of these things could be causing the noise & vibration etc. that you are experiencing. It still could easily be a gearbox problem, but check the three things above first, as they don't require removing the engine and splitting the crankcase...

... which you don't want to do unless you really need to, OK?! ;-)

[Clone]

Whoa, stop talking about spitting cases so early in the diagnostic phase.
Start simple and get more complex. FIRST check the alignment of the chain and sprockets. SECOND check the tension of the chain. THIRD check that your front sprocket doesn't have a boss side and needs to be mounted a certain way. FOURTH it may sound stupid but are the chain and sprockets of the same pitch.
If the drive shaft doesn't have play in it, I wouldn't be too sure the transmission is trashed.

[DimitriT]

How is your rear wheel alignment?

[Scoooter]

Whoa, stop talking about spitting cases so early in the diagnostic phase.
Start simple and get more complex. FIRST check the alignment of the chain and sprockets. SECOND check the tension of the chain. THIRD check that your front sprocket doesn't have a boss side and needs to be mounted a certain way. FOURTH it may sound stupid but are the chain and sprockets of the same pitch.
If the drive shaft doesn't have play in it, I wouldn't be too sure the transmission is trashed.

The alignment is fine, and has been checked several times, chain tension makes no difference in the problem, it does it wether it is tight or loose, sprockets and chain are same pitch, this is a new set of chain and sprockets, it was doing it with the old sprockets as well, thats why i changed them, thought that was the problem. The drive shaft has no play at all, but could it still be 1 of the other 3 remaining bearings? Believe me I DO NOT want to pull this motor and preform surgery on the tranny.

[Scoooter]

The thing that still has me puzzled is the fact the knocking stops and the vibration lessens after it gets a little speed on it. If the bike is on center stand and you place it in gear and let off the cluth it sounds horrible and jerks and shakes violently.:?

[BadBillyB]

I would suggest pulling the clutch basket out and inspecting the damper springs on the back. With the basket out, you can turn the input shaft by hand and feel for a binding spot. You could even drive the input shaft with a drill motor coupled with maybe a piece of 3/4 heater hose with a bolt stuffed into it. Leave the countershaft sprocket off and feel for a vibration right on the shaft. You can even run it in different gears like this with the engine off......BadBillyB

[Jethro]

It sounds to me like you have the typical GS clutch rattle at idle. When you give it gas the knock goes away? This is typical of older GS bikes, and often we bump up the idle to lessen the knock. It is causing no problems. It is very rare for the overbuilt gearbox in these bikes to give up the ghost at 11,000 miles, even if you flog it like a red headed step-child.

About the chain, do you only notice this problem when there is no load on the wheel? Only on the centerstand? My chain jumps all over the place when the bike is on the stand and idleing in gear.

How did you align the rear wheel?

[Scoooter]

Ok I removed the clutch cover and the shaft that comes straight out of the clutch basket moves around in all directions, in, out in a full circle, is this supposed to do that? I can also hear a metalic sound when I am moving the shaft around. There were no shavings or anything else in the bottom of the housing, Thx Scott

[Carter Turk]

Are you talking about the rack release? It has an E-clip holding it in place?

By your description, it sounds like you have not removed the clutch springs, inner clutch hub and basket to reveal the actual shaft the clutch is riding on?