[MuteVibes]

Hey everyone!

I'm pretty new to the Vulcan "club", so I registered to this forum. Mainly because I love this bike, especially my own, but also becauseI have a problem I keep pulling my hair out with.

I got this bike from a friend for free, he knew I love his bike a lot, he bought a 2000cc Vulcan, so I got his older '94 750 for free. However it had a grinding noise when shifted in gear. It idles fine, revs up great with a little pop when i close the throttle after a short rev. but whenever I tried to put it in gear, it started grinding, and would not go in gear at all. not even on the stand with the wheel clear off the ground.

After that I started digging, and eventually found that the final drive at the rear wheel was grinding. So I replaced it with a used part, since new they're (not quite) in my budget at the moment. (new starting at about 1100 euro) . I drove the bike a few meters and everything was fine, shifted into all gears, drove really amazing, my legs were shaking of excitement.

Today, a few weeks later, I installed some new exhausts since the old ones were rusted and gone, I wanted to drive it again. So I went a few meters. about 200meters i think, and it started grinding again.. What could it be? I'm not in the position to spend 1100 euro on it at the moment.

The noise is definitely coming from past the shaft, or atleast at the rear wheel-height.

any tips I could check, replace, lube, fix?

I'm a car mechanic with a passion for bikes, so I'm quite handy with tools

 

[Spockster]

Those splines need 60% moly paste. See my reply in your introduction thread. Sounds like the splines are gone on the driveshaft.

eBay is one of the best places for parts, though shipping will be high to your location if there's nothing locally.

Edit.... There's also the Marketplace here in the forum.

 

[MuteVibes]

Those splines need 60% moly paste. See my reply in your introduction thread. Sounds like the splines are gone on the driveshaft.

eBay is one of the best places for parts, though shipping will be high to your location if there's nothing locally.

Edit.... There's also the Marketplace here in the forum.

well, the bad part is, I already replaced that part, and put the recommended oil in (asked at a Kawa-dealer for the oil). Also used common engine-bearring grease for the splines used for axles on cars. Maybe that's where it went bad. It just feels so bad to know I can't ride it again.I want to have it fixed at my own power

 

[Spockster]

well, the bad part is, I already replaced that part, and put the recommended oil in (asked at a Kawa-dealer for the oil). Also used common engine-bearring grease for the splines used for axles on cars. Maybe that's where it went bad. It just feels so bad to know I can't ride it again.I want to have it fixed at my own power

Examine the splines on the coupler and the input shaft on the rear gear.

 

[Thorn]

Yeah, both parts wear on each other, so the splines on the drive shaft coupler (female) and the final drive hub *male) both need to be changed at the same time if there has been damage.

 

[Spockster]

Yeah, both parts wear on each other, so the splines on the drive shaft coupler (female) and the final drive hub *male) both need to be changed at the same time if there has been damage.

That's true. If you put a good part on a worn part, the splines will begin destroying each other.

So look to see if the teeth are mostly squared with sharp edges. If they're rounded over and have a peak in the middle they're most likely shot. Red dust is a bad sign, but not always terminal.

Post a pic if you're not sure.

 

[MuteVibes]

Been a while since I had time to work on the bike. But here are some pictures of how it looks..

First 2 are from the wheel splines. To me, they look okay, and not really worn out. Anything I could check aswell without taking the whole bridge off?

 

[Spockster]

Been a while since I had time to work on the bike. But here are some pictures of how it looks..

First 2 are from the wheel splines. To me, they look okay, and not really worn out. Anything I could check aswell without taking the whole bridge off?

Those hub/wheel splines are not the splines that cause the most problem, and you have to go easy on the lube there because it will sling out onto the wheel, but they should get greased.

The problems happen on the left side, where the driveshaft coupler meets the final drive assembly. The final drive is held on by four bolts into the swingarm.

When you take the final drive off, check the splines on the driveshaft coupler and the shaft on the final drive.

The driveshaft will stay in the swingarm.

 

[MuteVibes]

I'm trying to get the final drive* off. But the shaft got loose so that's causing some issues. The final drive seems to be stuck on the shaft or something. Is there a clip that I should undo?

 

[Jason Pittenger]

I'm trying to get the final drive* off. But the shaft got loose so that's causing some issues. The final drive seems to be stuck on the shaft or something. Is there a clip that I should undo?

It should slide right out. If one or the other is warn, it might have jammed against the other. Try putting some torque on it by putting it in gear and rotating the rear wheel forwards/backwards to see if you can get it unstuck.

 

[Spockster]

It should slide right out. If one or the other is warn, it might have jammed against the other. Try putting some torque on it by putting it in gear and rotating the rear wheel forwards/backwards to see if you can get it unstuck.

Yes. I would try slapping the wheel backwards in gear, since it probably jammed while pulling forward.

You might also be able to use the final drive like a slide hammer. Push the gearcase up tight against the swingarm and then yank it toward the rear. Or if you have a slide hammer, try that.

At best you'll probably need a new coupler, at worst you'll also need another final drive.

 

[Jason Pittenger]

Yes. I would try slapping the wheel backwards in gear, since it probably jammed while pulling forward.

I had to think about this for a minute, but I think you want to rotate it forward while in gear. This would be similar to engine braking.
But I've already reversed it three times in my head.....so.....

 

[Spockster]

I had to think about this for a minute, but I think you want to rotate it forward while in gear. This would be similar to engine braking.
But I've already reversed it three times in my head.....so.....

Got me thinking about it. I think it's correct if you put backward pressure on it. Because that will reverse the rotation of the final gear shaft, pushing against the engine in gear.

Wasn't sure there for a minute, had to use my hands.

On the other hand if the splines slipped under engine braking or hard downshift, they could be slipped in the other direction.

It was already slipping, if you could make it slip just one spline (or half a spline) and stop, it could slip apart.

 

[Spockster]

Should tie the centerstand forward so it doesn't slip off and fall over while you're yanking on it.

 

[MuteVibes]

Well I think I found the problem, took the whole swingarm off for inspection on the bench but the shaft is stuck in the rear drive. I checked the old rear drive I have laying around, and the splines look very nice (on the old one).

However on the new(er) one, it's just stuck, so I think the splines slipped and bit stuck.. any tips on how to get it loose?

Heat maybe?

 

[MuteVibes]

I got the shaft out. And it looks like the shaft is game-over.. so I think it means I should get another shaft?

 

[Spockster]

I got the shaft out. And it looks like the shaft is game-over.. so I think it means I should get another shaft?

The splines don't look so bad in the pictures, but if they were slipping and stuck together they must be worn out .

You'll have to check and adjust the swingarm alignment when you put it back together.

 

[mmart]

The male end of the coupling looks better than mine did, but I can’t tell on the female end if they’re chewed from the pic.

 

[MuteVibes]

It looks like the female end, of the driveshaft, are quite shaved off. Luckily a second hand shaft is not that expensive, so I'll give that a shot. Also, the spring was full of grease and did not really "spring" anymore. The splines were stuck, and locked on eachother on the higher parts, so I assume that they were slipping a lot. How can I prevent that, is there any part that I may be missing?

I'll definitely adjust the swingarm to center it perfectly, because it seemed to be off-centred when I got the bike. Maybe I'll just get it to a shop for that.

So far thank you all for the help and input! It makes this job a lot easier

 

[Thorn]

Hard to tell without my 3d glasses on, but it seems like the middle section of the splines is worn completely away, even though the tips still have a crisp profile. There is some damage to the male splines on the final drive, but not horrible. The female part of the drive shaft is actually a coupler, which you can pull off the end of the drive shaft with a pair of snap ring pliers. Sometimes it is easier to find a drive shaft with a coupler still attached, and sometimes you can find just the coupler.