V7 drive shaft spline alignment/wear issue: advice needed

[lewisham_phil]

This is the first time I've dismantled the rear end, as a new tyre is on order, and I'm rather shocked to see the state of the rear shaft and splined socket on my 2012 V7. It's only done under 20,000 miles, although through many salty winters. See images for the glorious chocolaty mess:









 

Bad water ingress clearly, the likely cause being the rubber boot: the inner clip seems ridiculously short, causing a crease in the rubber, which I hadn't previously noticed. Also as can be seen on the last image, the seal on the rear of the bevel drive case is leaking, so this oil is mixing with the water and rust making a right mess.
Fortunately the main bevel drive and bearings all look good.
Firstly: Do we think those splines are shot? I'm minded to think so, but it's my first Guzzi, so I'll ask the experts.
As can be seen, the main drive shaft splines have only been engaging 3/4 of their length in the  splined socket; the rear splined connector has been engaging properly, as evidenced by the wear pattern. This seems to be a common issue, which leads me to my second question: is there a recognised method of ensuring that the main shaft engages far enough into the socket? I am thinking of a washer/spacer at the rear of the splined socket, to shift it forward a few mm; enough to catch all of the (shorter) splines on the main shaft, while still engaging the rear splines fully. Maybe combined with a spacer at the gearbox end, to push the drive shaft backward a few mm.Note that the circlip and disc have been removed from the splined socket in the images.
I'm assuming the depth of engagement of the splines will vary slightly depending on suspension deflection, due to the disparity in position of the kardan joint centre of rotation and the the swing arm pivot. I might sketch this up and work out the variation. Whatever, the current set-up is not right, as most of the wear is occurring with the shaft splines not fully engaged.
I'd appreciate anyone's experience on this, while I shop around for eventual replacement parts. (A new shaft from Fowlers is £840!!)

[DoubleGuzzi]

Yikes!
 

[faffi]

I do not have enough experience, either, but I would not expect the minor pitting to be of concern and long as you get everything absolutely clean and use good quality moly grease when assembling. As to the main drive splines, they are quite long and I would expect that they leave some margin for movement - the shaft will move lengthwise on the splines as the wheel travel up and down - and to make sure the graded portion never comes into contact with the coupler.

Hopefully, someone with longtime experience will chime in and give knowledge-based information to you.

[Huzo]

I do not have enough experience, either, but I would not expect the minor pitting to be of concern and long as you get everything absolutely clean and use good quality moly grease when assembling. As to the main drive splines, they are quite long and I would expect that they leave some margin for movement - the shaft will move lengthwise on the splines as the wheel travel up and down - and to make sure the graded portion never comes into contact with the coupler.

Hopefully, someone with longtime experience will chime in and give knowledge-based information to you.

If the mating surfaces are up to scratch, then the rest is just going along for the ride.
I’ll agree that it looks bad, have you considered cleaning it all up and painting the non mating surfaces with something good.
As mentioned, as long as the mating surfaces have not suffered, I’d just clean the whole lot and smother it with grease, just to keep the surface rust away.
Use good molybdenum grease on the splines and make sure the sealing rings are good, then go and ride…
Well spotted though..

[Dirk_S]

Everytime I read about driveshaft rust on a motorcycle or car, it’s mentioned that it’s normally just surface rust. So, structural integrity doesn’t seem to be too affected, I don’t think. Clean those splines well and see how they mate up, keeping in mind that the rust removed has now revealed the next layer and thus will allow a hair more slop. Be curious to see a quick video of the splines fitted once cleaned.

[SIR REAL ED]

I do not have enough experience, either, but I would not expect the minor pitting to be of concern and long as you get everything absolutely clean and use good quality moly grease when assembling. As to the main drive splines, they are quite long and I would expect that they leave some margin for movement - the shaft will move lengthwise on the splines as the wheel travel up and down - and to make sure the graded portion never comes into contact with the coupler.

Hopefully, someone with longtime experience will chime in and give knowledge-based information to you.

Right you are!   

[SIR REAL ED]

If the mating surfaces are up to scratch, then the rest is just going along for the ride.
I’ll agree that it looks bad, have you considered cleaning it all up and painting the non mating surfaces with something good.
As mentioned, as long as the mating surfaces have not suffered, I’d just clean the whole lot and smother it with grease, just to keep the surface rust away.
Use good molybdenum grease on the splines and make sure the sealing rings are good, then go and ride…
Well spotted though..

Agreed.

But if this was an engine oil thread, someone would have to chime in with "If the Engineers wanted that drive shaft painted and lubricated, they would have done so at the factory!!!  I wouldn't second guess the Moto Guzzi Engineers!  No telling how many driveshafts have been destroyed by too much paint and too much grease!!"

 

Better engine oil solves ALL mechanical issues!

[Kev m]

Everytime I read about driveshaft rust on a motorcycle or car, it’s mentioned that it’s normally just surface rust. So, structural integrity doesn’t seem to be too affected, I don’t think. Clean those splines well and see how they mate up, keeping in mind that the rust removed has now revealed the next layer and thus will allow a hair more slop. Be curious to see a pic of the splines fitted once cleaned.

Yup! I was gonna ask when was the last time he saw the driveshaft on a RWD car or truck.

[rocker59]

Clean it up.

Grease it up.

Ride.

[Dirk_S]

As an additional ‘probably good’ pat on the back, here are some pics some may find amusing. Originally posted in one of my sidecar threads. Granted, this is not rust but instead due to an overloaded sidecar with over 700 miles of gravel and rocky forest roads—including some rock garden climbing—and an extra 2,000+ miles of pavement before and after the rougher terrain. You can see the wearing area is O THANK GOD at the rear end of the driveshaft and coupler. And no—it had not begun slipping just yet.

[Moparnut72]

Yikes. I don't think I have ever seen chain drive motorcycle sprockets worn that badly. I don't do chain drive bikes anymore.
kk

[SIR REAL ED]

As an additional ‘probably good’ pat on the back, here are some pics some may find amusing. Originally posted in one of my sidecar threads. Granted, this is not rust but instead due to an overloaded sidecar with over 700 miles of gravel and rocky forest roads—including some rock garden climbing—and an extra 2,000+ miles of pavement before and after the rougher terrain. You can see the wearing area is O THANK GOD at the rear end of the driveshaft and coupler. And no—it had not begun slipping just yet.

That is impressive.  How many miles total on that bike?

I wonder if a good portion of that wear was due to improper heat treating/hardening.

[Dirk_S]

That is impressive.  How many miles total on that bike?

I wonder if a good portion of that wear was due to improper heat treating/hardening.

40,000 miles when I sold it last year, but that driveshaft wasn’t the original. Original driveshaft’s u-joint began losing its free play the previous year, observed during the first attempt of the same trip (Mid-Atlantic BDR). Similarly, I’m chalking up that failing UJ to a combination of sidecar load (this first sidecar was the custom-built one that was much heavier than my current Sputnik) and the rear shocks with extra length.

[John A]

On drive splines I degrease them and spray them with molybdenum dry film. I cure that with heat and use Wurth sticky grease on top of that. Sounds like overkill but it sure works.

[SmithSwede]

As mentioned in another current thread, my 2013 V7 Stone drive shaft couplings and shaft were totally shot at about 60,000 miles.  I had to hammer the components apart.  I posted a thread on this years ago if you want to look or see photos. 

Since new I had tried to lubricate all this stuff with Guard Dog 50% moly paste every time I changed the rear tire (about 10k miles per tire).

Maybe I didn’t clean off the old grease and crud before adding the new grease. Or maybe these components have a surface hardening that only lasts about 60k, then wears severely. 

I didn’t have the surface rust, but just because I slathered grease on all those surfaces.  I think I used that really thick Wurth grease. 

If you see this issue on a small block, I highly recommend checking on the input shaft bearing to the transmission.  Mine was totally shot at this mileage—the ball bearings were barely contained in the race.  Easy enough to replace, but dang!

And sure enough—at about 120k, I again replaced the transmission bearing

Mike Haven down in Houston told me that bearing was a known weak spot on small blocks.  All the other transmission bearings seemed fine.

[rocker59]

my 2013 V7 Stone drive shaft couplings and shaft were totally shot at about 60,000 miles.   

Out of curiosity, what is the recommended replacement interval in the owners' manual?

It should be on the periodic maintenance table.

[Dirk_S]

Out of curiosity, what is the recommended replacement interval in the owners' manual?

It should be on the periodic maintenance table.

Changing out a driveshaft? That would be like changing fork internals or piston rings. Sure, one day…but Guzzi ain’t got time to play Nostradamus.

[Alfetta]

I don't have much Guzzi experience, as I'm on my first one ever.  However i do know a bit about passing power through a splined joint.

splines that slide actually require a given amount of clearance, and therefore will suffer from torque reversal. Reducing the clearance can an will increase life but comes at a manufacturing cost based on tolerance requirements.

splines that are transferring torque while moving axially need to have a good high pressure lubricant and the proper surface hardness. In a good design, one of the components should be harder that the other, this does mean the one component should be considered the "wear" side. as a simple example, consider a glass shaft pressing onto a wood shaft, if the force is high enough, the wood will yield as the glass remains un changed. but if a glass shaft presses onto another glass shaft, there is no material to yield and both components shatter.

As space is limited in the Guzzi spline design, it would be cumbersome to increase the spline diameter to reduce the pressures seen at the pitch line. so this limits the joint capability right from the start. Another cavoite would be the actual material selected for the joint components, material such as S7 are specifically formulated to accept high impact loading. (like a jack-hammer piston). I have no clue what material Guzzi is using on any of the coupling pieces, so it is hard to say that they are a good choice or not.

but based on my vintage tractor PTO shaft experience, splines can look like shite and still do the intended job.

[John A]

Out of curiosity, what is the recommended replacement interval in the owners' manual?

It should be on the periodic maintenance table.

It’s “ on condition “ meaning it should be inspected at intervals which should be in the owner’s manual. Time replacement goes on calendar time or hours or miles , which is too subjective for a manufacturer to recommend unless it’ll fall out of the sky and be on the five o’clock news.

[faffi]

I don't have much Guzzi experience, as I'm on my first one ever.  However i do know a bit about passing power through a splined joint.

splines that slide actually require a given amount of clearance, and therefore will suffer from torque reversal. Reducing the clearance can an will increase life but comes at a manufacturing cost based on tolerance requirements.

splines that are transferring torque while moving axially need to have a good high pressure lubricant and the proper surface hardness. In a good design, one of the components should be harder that the other, this does mean the one component should be considered the "wear" side. as a simple example, consider a glass shaft pressing onto a wood shaft, if the force is high enough, the wood will yield as the glass remains un changed. but if a glass shaft presses onto another glass shaft, there is no material to yield and both components shatter.

As space is limited in the Guzzi spline design, it would be cumbersome to increase the spline diameter to reduce the pressures seen at the pitch line. so this limits the joint capability right from the start. Another cavoite would be the actual material selected for the joint components, material such as S7 are specifically formulated to accept high impact loading. (like a jack-hammer piston). I have no clue what material Guzzi is using on any of the coupling pieces, so it is hard to say that they are a good choice or not.

but based on my vintage tractor PTO shaft experience, splines can look like shite and still do the intended job.

Interesting read, thank you. I guess machines with 4 or 6 cylinders will put less stress on the splines than a single or twin due to their smoother running? Yet bikes like the Yamaha XVs and Honda VTs and Suzuki VSs rarely suffer from shaft wear or failure despite being twins ranging from 400 to 1800cc. Kawasaki VNs, though, do have a reputation for failures, allegedly a result of being fitted dry from the factory. For instance, the final drive on my VT500FT looked factory fresh after 55k miles, despite minimal maintenance. The final drives I have inspected on one XVS650, one XV750, one XV1000 and one XV1100 that have/does all belong(ed) to me have not shown any sign of wear. Then again, these are just tiny samples that does not prove much.

Another example that can suggest the Guzzi final drives being of inferior design and/or quality can be found in the old BMW airhead models. Despite rather short swingarms, combined with soft suspension offering 5 inches of travel, it is unusual for their shafts to fail. The final drive units can break prematurely, but the shaft and U-joints usually lasts a long time from what I have gathered.

Then again, you are guaranteed to find anomalies from every brand and model that goes against "average".

[Dirk_S]

…Another example that can suggest the Guzzi final drives being of inferior design and/or quality can be found in the old BMW airhead models. Despite rather short swingarms, combined with soft suspension offering 5 inches of travel, it is unusual for their shafts to fail. The final drive units can break prematurely, but the shaft and U-joints usually lasts a long time from what I have gathered.

Seek ye information on airhead GSes and their driveshaft woes. It’s not just the oil heads that had failures.

[rocker59]

It’s “ on condition “ meaning it should be inspected at intervals which should be in the owner’s manual. Time replacement goes on calendar time or hours or miles , which is too subjective for a manufacturer to recommend unless it’ll fall out of the sky and be on the five o’clock news.

Changing out a driveshaft? That would be like changing fork internals or piston rings. Sure, one day…but Guzzi ain’t got time to play Nostradamus.

There was a time when drive shaft replacement was listed.  It was listed on my Sport 1100 owners' manual maintenance table.

Just curious if they still have it listed.

[Alfetta]

Another example that can suggest the Guzzi final drives being of inferior design and/or quality can be found in the old BMW airhead models. Despite rather short swingarms, combined with soft suspension offering 5 inches of travel, it is unusual for their shafts to fail. The final drive units can break prematurely, but the shaft and U-joints usually lasts a long time from what I have gathered.

my BMW R75/5 does not have a spline where the axle connects to the tranny. The boxer has a flange that fits on a tapered output shaft and the u-joint bolts directly to this flange.
There is a spline joint at the input to the BMW's wheel end gearbox and mine looks rather good despite the age. I think that this is due to the fact that the swingarm tube on the boxer actually receives an amount of gear oil and can be changed without disassembly.
However, the boxer also has a spline on the output of the wheel gear box and it is typically bad on older machines.  Torque reversal is damaging...

I will not judge what machine is better, but i do like BMW using the swing arm tube as an oil bath. It must be stated though that repairing damaged splines on the BMW involves both the gearbox and the wheel is a real chore. and IMHO typically German...

[SmithSwede]

Out of curiosity, what is the recommended replacement interval in the owners' manual?

It should be on the periodic maintenance table.

I don't think drive shaft life span is expressly referenced in any of the Owner's Manuals or Service Manuals.  I think it is like the clutch---you are supposed to know the clutch will eventually wear out, but who knows exactly when that will occur. 

[SmithSwede]

Maybe this is a topic for a separate thread, but I have to say I've been mighty impressed with the service life of the O-ring chain that came stock on my 2019 Kawasaki Z900RS. 

I am coming up on 60,000 miles on the original chain.  I got nervous after about 25,000 miles, and bought a good chain wear gauge.  Even at 59,300 miles, I'm not even close to the 1% wear indicator on the gauge.  No kinked links, no rust, no missing O-rings, no hooked sprockets--everything looks great. 

So, ponder that a bit.  Back in the 1970s and 1980s when I ran the old non-O ring chains, you were doing good to get 7,000 to 10,000 miles from a chain. 

I had a BMW F800S with a belt drive, and it would regularly shred the belt at about 20,000 miles.  With no warning.  Everything would look great, no cracking or other obvious problems, and then one day you are riding home and the teeth on the belt are spitting off.  Once one tooth goes, the others follow quickly.

On my 2013 Guzzi V7, at around this same mileage, I am hammering apart and replacing the drive shaft, the couplings, and the input bearing on the transmission.   

In comparison, the chain on the Kawasaki inline 4 is still fine. 

I never clean that chain.  Just regularly use a paint brush to apply a noticeable coating of old 85-90 gear hypoid oil on the chain.  Yes, it slings oil a bit . . .

but dang---I'm liking these modern chains as a final drive solution !!!

The other thing I like is that if I ever do have a problem with the chain in East NoWhere, I can probably get a 530 chain pretty easily.  Which is not the case for some coupling on a V7 Moto Guzzi, or a BMW belt drive system. 

[Kiwi_Roy]

the problem may be the clip that holds the rubber boot to the gearbox, my V7 III was fitted with something like a Q strap.
Q straps have a natural weak point where the tail enters the ratchet part. Water sprayed up from the front wheel hits this weak point and enters the shaft tunnel.
I upgraded to a worm drive clip, that seems to have solved the water problem.

[Dirk_S]

A few folks have drilled a hole into their swingarm near the final drive for water to escape, right? Be curious if there’s a proper writeup for this mod if true.

[faffi]

Seek ye information on airhead GSes and their driveshaft woes. It’s not just the oil heads that had failures.

I see I should have been more specific than just mentioning airheads, as the airheads featuring Paralever definitely had their issues. Still does - currently, BMW list shafts as wear items to be replaced after 25 to 40k miles IIRC.

[SIR REAL ED]

Interesting read, thank you. I guess machines with 4 or 6 cylinders will put less stress on the splines than a single or twin due to their smoother running? Yet bikes like the Yamaha XVs and Honda VTs and Suzuki VSs rarely suffer from shaft wear or failure despite being twins ranging from 400 to 1800cc. Kawasaki VNs, though, do have a reputation for failures, allegedly a result of being fitted dry from the factory. For instance, the final drive on my VT500FT looked factory fresh after 55k miles, despite minimal maintenance. The final drives I have inspected on one XVS650, one XV750, one XV1000 and one XV1100 that have/does all belong(ed) to me have not shown any sign of wear. Then again, these are just tiny samples that does not prove much.

Another example that can suggest the Guzzi final drives being of inferior design and/or quality can be found in the old BMW airhead models. Despite rather short swingarms, combined with soft suspension offering 5 inches of travel, it is unusual for their shafts to fail. The final drive units can break prematurely, but the shaft and U-joints usually lasts a long time from what I have gathered.

Then again, you are guaranteed to find anomalies from every brand and model that goes against "average".

 
Some shaft drive motorcycles (second generation Suzuki GS shaft drive models starting with the GS650G, IIRC) had spring loaded ramps and cams incorporated into their driveshafts to cushion shock loads.

I suspect they were effective.

You are right.  Smaller pistons means smaller shock loads.

Shirley, it is no more difficult to incorporate cushions into the rear hub of a shaft drive bike that it is to do the same on a chain drive bike.

Do no shaft drive models do this?

[faffi]

Sir Real Ed, I believe every shaft drive bike have some sort of shock cushioning. The Virago have one on the output shaft, two ramps pushed together with a stiff spring. If the load is too high, the ramps will try and climb up on each others shoulder, compressing the spring in the process. Some bikes have this feature on the shaft itself, some have both systems. Also, it is quite common to have springs in the clutch basket on shaft drive bikes as well as on chain drive bikes.

My V9 and the modern V7 - at least - have rubber cushions in the rear final drive similar to most chain driven bikes. The second generation of Viragos also have these.

You can see the Virago system here https://www.cmsnl.com/yamaha-xv1000-virago-1984-e-usa_model9062/partslist/C-11.html