Shaft drive Q&A

[Zooks]

As a lot of you will know I recently purchased a GS1100GK. I come from a mechanical background but have never worked on or owned a shaft drive bike. As this is my first shaft drive I have a few questions. When decelerating there is a slight whining noise coming from the gearbox. I have just put the shaft etc back together after the PO damaged it. I re-filled the gearbox using the specified oil but am wondering if it may still be a little low.

Here are the questions -

• Apart from emptying and refilling the gearbox completely is there anyway to know how much is in it?
• Do shafties always make a little noise? I am presuming that they make a whine as opposed to a chain drive. Yes or no?
• Could this be backlash? I put the same amount of shims back in when I put the cog back in the rear of the box.
• It seems to be a little less noisy when I pull the clutch in. I might be imagining it though. This would presumably be the clutch basket rattling as well?

It only seems to do it at higher RPM's (above 5K) as I drop through the gears coming to a stop. Any thoughts, ideas etc appreciated.

If anyone else wants to use this thread for shafty questions - feel free. I enjoy a good hijacking.

[chiphead]

There is a level screw for the primary drive box located under the shift lever cover. It is a phillips head bolt with a 10 mm head size. You fill the primary case with hypoid gear oil until it begins to run out of that hole with the bike on the center stand.
I'm not familiar with any whine form the shafties but my high frequency hearing isn't that good.
In my experience, clutch baskets rattle,not whine.

[seuadr]

i don't know much about shafts opperation either, but let me just say " welcome to the dark side " :twisted: we have cookies! \\/

[Zooks]

There is a level screw for the primary drive box located under the shift lever cover. It is a phillips head bolt with a 10 mm head size. You fill the primary case with hypoid gear oil until it begins to run out of that hole with the bike on the center stand.

Thank you. I thought I might be missing something. It's night time here now but I will check that first thing in the morning.

[doctorgonzo]

Thank you. I thought I might be missing something. It's night time here now but I will check that first thing in the morning.

And the shaft itself, I guess it's the differential, the part connected to the wheel, you just fill to the top. I haven't noticed a while from mine.

[82Shafty]

As a lot of you will know I recently purchased a GS1100GK. I come from a mechanical background but have never worked on or owned a shaft drive bike. As this is my first shaft drive I have a few questions. When decelerating there is a slight whining noise coming from the gearbox. I have just put the shaft etc back together after the PO damaged it. I re-filled the gearbox using the specified oil but am wondering if it may still be a little low.

Here are the questions -

• Apart from emptying and refilling the gearbox completely is there anyway to know how much is in it?
• Do shafties always make a little noise? I am presuming that they make a whine as opposed to a chain drive. Yes or no?
• Could this be backlash? I put the same amount of shims back in when I put the cog back in the rear of the box.
• It seems to be a little less noisy when I pull the clutch in. I might be imagining it though. This would presumably be the clutch basket rattling as well?

It only seems to do it at higher RPM's (above 5K) as I drop through the gears coming to a stop. Any thoughts, ideas etc appreciated.

If anyone else wants to use this thread for shafty questions - feel free. I enjoy a good hijacking.

What, so what your saying is when you are not using the brake and using the engine as a brake and dropping down through the gears, it whines?

Contact pattern and backlash need to be set according to spec. I've also known slightly-galled bearings to whine as well.

[Zooks]

What, so what your saying is when you are not using the brake and using the engine as a brake and dropping down through the gears, it whines?

Yes, exactly. It makes no noticable nosie whilst accelerating but as soon as I let off the throttle I can hear the whine. It gets a little louder when I drop down the gears (and RPM's jump) as I am slowing down.

[Nessism]

Did you check the contact pattern on the gears when you put them in? Might be off. Also, not sure but I always thought the gears are matched pairs, or they wear in together, so mixing and matching is to be avoided. Not sure exactly but something to consider.

[Zooks]

They are the original pair. You are right they should be kept together because they 'wear' together. You can get them lapped if you really need to (like they do on crown wheel & pinion sets in diffs) by an engineer.

I didn't check the contact pattern. I put it back in as it had come out (or so I thought).

[82Shafty]

http://www.tpub.com/content/construction/14273/css/14273_198.htm

http://www.usgear.com/ring__pinion_installation.htm

My GS by nature has a bit of a whine in under acceleration, more noticeable in second gear. This has been the same as my dad's who has had it since it was new.

[emjay]

If you haven't also replaced the final gear (differential) oil then you should.

[BassCliff]

I'm talkin' 'bout Shaft! We can dig it!

Hi Mr. Zooks,

I cover bevel gear and final drive fluid changes on my little BikeCliff website. (Note: Don't overfill your bevel gear case like I do in the pictorial guide. Use the "level screw".) I've noticed that if I downshift too soon (at too high an rpm) Jessie will whine a little. If I blip the throttle a little as I downshift it helps. Or I just wait to downshift at a lower rpm. I downshift into first only just before coming to a stop. Otherwise I get a big "clunk" instead of a nice "snick".

Thank you for your indulgence,

BassCliff

[49er]

As a lot of you will know I recently purchased a GS1100GK. I come from a mechanical background but have never worked on or owned a shaft drive bike. As this is my first shaft drive I have a few questions. When decelerating there is a slight whining noise coming from the gearbox. I have just put the shaft etc back together after the PO damaged it. I re-filled the gearbox using the specified oil but am wondering if it may still be a little low.

Here are the questions -

• Apart from emptying and refilling the gearbox completely is there anyway to know how much is in it?
• Do shafties always make a little noise? I am presuming that they make a whine as opposed to a chain drive. Yes or no?
• Could this be backlash? I put the same amount of shims back in when I put the cog back in the rear of the box.
• It seems to be a little less noisy when I pull the clutch in. I might be imagining it though. This would presumably be the clutch basket rattling as well?

It only seems to do it at higher RPM's (above 5K) as I drop through the gears coming to a stop. Any thoughts, ideas etc appreciated.

If anyone else wants to use this thread for shafty questions - feel free. I enjoy a good hijacking.

There should be no noise coming from your diff or your gearbox, unless the bike has been abused or has extremely high Kms.
As 82Shafty said, you should recheck the tooth contact pattern and backlash. The whine you mention on decel will be caused by excessive backlash/incorrect tooth contact.
It is still necesary to check clearances, even though you have replaced the original shims in their correct positions. It is also important to loosen the adjacent crankcase bolts before setting up the clearance as this area will act as a "crush zone" affecting reliable readings when setting backlash.
I presume that you didn't dis-assemble the driven gear assembly. If you did, the right bearing preload and tooth contact is achieved by applying the correct torque to the driven gear nut.
There's no quick fix. Using a dial indicator and bearing blue, re-shim until you get 0.003" -0.005" backlash and central contact tooth patterns. It can be a time consuming exercise.

[bwringer]

Here's a view of a dead GS850 engine showing the drain, fill, and level plugs for the secondary gears:




For the rear, just fill it until it reaches the fill hole. Basically, squeeze the bottle until it starts to run out the same hole you're filling it through. Let it finish dripping, then replace the fill plug and go riding.

Do NOT "fill it to the top".


Sitting here in front of my computer discussing a bike I've never even seen, it's very hard to tell where your particular whine is coming from. When you spin the rear wheel with the bike on the centerstand, can you hear anything that would help you narrow down the source of the noise to the front or rear gearbox?

[Zooks]

Thanks guys. It will definitely be backlash and / or 'contact' that is making the noise. As I said, I grew up working on vintage / race cars but have never worked on a shaft bike before. I was sure the noise was coming form the bevel gears at the engine end though.

I will do all the necessary adjustments ASAP.