Why not a belt drive ?

[TampaJim]

All of these spline/driveshaft problems got me to wondering.

 

Harley, most of the newer high torque metric cruisers, and BMW of it's F bikes (including the new 800 ) all use belt drive. So power transfer is not the answer.

 

Belt drives have only three parts so they must be less expensive to manufacture and install. They are simple to maintain and repair. I should think a periodic belt replacement would be easier than a spine lube ( and cheaper).

 

In the event of a failure in the middle of nowhere, you could get a belt replaced at any garage, but the shaft drive has to go back to a specialized shop. Cost difference : $350 vs $3000.

 

Belts are clean and quiet. No oiling as in chains no lash as in shafts.

 

I know BMW has used shaft drive since forever and that other sporttouring bikes also use it, so is there something I'm missing ?

[Guest]

All of these spline/driveshaft problems got me to wondering.

 

Harley, most of the newer high torque metric cruisers, and BMW of it's F bikes (including the new 800 ) all use belt drive. So power transfer is not the answer.

 

Belt drives have only three parts so they must be less expensive to manufacture and install. They are simple to maintain and repair. I should think a periodic belt replacement would be easier than a spine lube ( and cheaper).

 

In the event of a failure in the middle of nowhere, you could get a belt replaced at any garage, but the shaft drive has to go back to a specialized shop. Cost difference : $350 vs $3000.

 

Belts are clean and quiet. No oiling as in chains no lash as in shafts.

 

I know BMW has used shaft drive since forever and that other sporttouring bikes also use it, so is there something I'm missing ?

 

The driveshaft/final drive isn't the big problem. The problem lies with the transmission input shaft and dry clutch. The new K bikes from BMW have gone to a wet clutch configuration and who knows what will be in store for the next big revision of the boxer.

[TPadden]

The driveshaft/final drive isn't the big problem. The problem lies with the transmission input shaft and dry clutch....

 

You're mixing problems Both K and R's have a known rear drive crown bearing problem with failures sometimes destroying the rear drive. As far as belts go, and everything else for that matter, there are both pluses and minuses. Changing one isn't anywhere as easy as replacing a chain - it is one piece so the swingarm has to be removed to replace.

[Joe Frickin' Friday]

All of these spline/driveshaft problems got me to wondering.

 

Harley, most of the newer high torque metric cruisers, and BMW of it's F bikes (including the new 800 ) all use belt drive. So power transfer is not the answer.

 

Belt drives have only three parts so they must be less expensive to manufacture and install. They are simple to maintain and repair. I should think a periodic belt replacement would be easier than a spine lube ( and cheaper).

 

In the event of a failure in the middle of nowhere, you could get a belt replaced at any garage, but the shaft drive has to go back to a specialized shop. Cost difference : $350 vs $3000.

 

Belts are clean and quiet. No oiling as in chains no lash as in shafts.

 

I know BMW has used shaft drive since forever and that other sporttouring bikes also use it, so is there something I'm missing ?

 

As Richard notes, the spline problem is at the input of the gearbox, not the output, so belt drive wouldn't affect that; you'd still have input shaft splines to deal with.

 

"belt drive" and "boxer engine" are a difficult combination. The crankshaft on a boxer is oriented longitudinally, which facilitates a longitudinal gearbox orientation. A belt drive wants a transverse shaft orientation; you could do it with a right-angle drive mechanism on the input or output of the gearbox - and that might even make for less unsprung weight at the rear wheel (by getting rid of that heavy final drive mechanism) - but it'd be tough to package all that behind the boxer engine.

 

Belt drive would not be popular on GS's, which are expected go go off-road occasionally. Rocks/gravel and belt drives are not good friends; a rock caught between belt and pulley can ruin your day. (Note that F650-GS bikes are chain drive.)

 

Other bikes with a longitudinal-crankshaft engine:

 

-Honda ST1300

-Honda Goldwing

-Motoguzzi

-BMW K-bikes

 

All of these bikes - different models, from different manufacturers are shaft drive (instead of belt or chain); it seems that a longitudinal crankshaft and a shaft drive were made for each other.

 

-Yamaha FJR-1300

[RPG]

Three reasons why I wouldn't want a belt:

 

1) Endless belt is a hassle to change without removing "a lot of stuff". A chain at least has a master link. Or are the new ones endless as well?

2) As Mitch said, not a good thing when rocks get stuck between pulleys. Most times, the belt breaks. Happened to my buddy's Harley last year. I got a call and had to bring my trailer. He doesn't make fun of my 166k mile /5 anymore.

3) Pulley's and belts need replacing periodically, and all those parts are exposed to the elements. Shaft drive if nothing else is always clean and tidy.

4) When auto manufacturer's go back to chain or belt, I might be convinced to give it a try again. Ok, that's four reasons.

 

Rick G.

[James Clark]

1) Endless belt is a hassle to change without removing "a lot of stuff".

 

 

Go check out what is required to replace a belt on a VRod or Buell XB - the two Harleys that were designed after the switch to belts - or even a Sportster. Sportsters and VRods run the belt outside of the frame and require swinging the drive side shock out of the way. The XB belt can be replaced while the bike is parked on the sidestand.

[TampaJim]

Thanks for the response guys--I must confess I had not thought about the BMW driveshaft alignment when I posted this question and I can see how spline problems are not neccessarly final drive related.

 

What got me started was some leaking seals and subsequent rear drive failure at 12k last September. The repair bill (warrenty) was something like $1,800. I was really wondering why so many expensive, complex parts were used instead of a simpler solution.

[Paul Mihalka]

I'm looking forward to the F800 series bikes. ROTAX motor, simple ABS, belt drive. What's not to like? If it fits me (or I fit it) I might end up with a F800ST

[TampaJim]

"belt drive" and "boxer engine" are a difficult combination. The crankshaft on a boxer is oriented longitudinally, which facilitates a longitudinal gearbox orientation. A belt drive wants a transverse shaft orientation; you could do it with a right-angle drive mechanism on the input or output of the gearbox - and that might even make for less unsprung weight at the rear wheel (by getting rid of that heavy final drive mechanism) - but it'd be tough to package all that behind the boxer engine.

 

 

One would think that "shaft drive" and "v-twin engine"would be just as difficult to do but the Japanese have been building inexpensive crusiers that way for 25 years. Granted these bikes do not accumulate the miles some BMW's do but I have never heard much about reliability problems with them.

[SAAB93driver]

"belt drive" and "boxer engine" are a difficult combination. The crankshaft on a boxer is oriented longitudinally, which facilitates a longitudinal gearbox orientation. A belt drive wants a transverse shaft orientation; you could do it with a right-angle drive mechanism on the input or output of the gearbox - and that might even make for less unsprung weight at the rear wheel (by getting rid of that heavy final drive mechanism) - but it'd be tough to package all that behind the boxer engine.

 

 

One would think that "shaft drive" and "v-twin engine"would be just as difficult to do but the Japanese have been building inexpensive crusiers that way for 25 years. Granted these bikes do not accumulate the miles some BMW's do but I have never heard much about reliability problems with them.

 

In the case of the japanese cruiser bikes you are adding width to an already narrow profile or to a profile where the width of g/b is not the overriding factor (ie transverse 4 cylinder). With a Boxer or similar longitudinal installation you end up adding length to an already long package - not impossible but it starts to become impractical when compared to using a shaft.

[ShovelStrokeEd]

Jim,

The metric bikes with V-twin engines and shaft drive use a gearbox at the output of the transmission to give another 90 degree turn to the drive train. The added complexity doesn't seem to cause much of a problem as generally, performance is limited and riders seem to be pretty conservative in terms of using that performance. There is a performance penalty with the extra gears of around 3% at best to deal with as well.

 

As has been stated, the packaging problem would preclude such an arrangement on the boxer and brick engines. In addition to the added length, they would have to give up their single sided swing arm, a long standing tradition with BMW, causing the process of a simple tire change to become a good deal more complex.

[TPadden]

.... In addition to the added length, they would have to give up their single sided swing arm, a long standing tradition with BMW, causing the process of a simple tire change to become a good deal more complex.

 

Not necessarily - The 2002 F650CS was the first motorcycle in the world to utilise a single sided swingarm in conjunction with a toothed belt drive system.

[peterbulgar]

What got me started was some leaking seals and subsequent rear drive failure at 12k last September. The repair bill (warrenty) was something like $1,800. I was really wondering why so many expensive, complex parts were used instead of a simpler solution.

Having ridden a chain-drive motorcycle across the country in the bad old days, when you sprayed your chain with sticky lube at every other gas stop (and adjusted the slack every night), and having ridden my shaft-drive R75/5 across the same country a couple years later, the benefits of shaft drive were obvious to me. Modern O and X ring chains and belt drive have lessened the shaft's low-maintenance advantage. However, I'd still pay the cost, weight, and slight power loss penalty of a well-designed shaft drive over a chain or belt just for the very simple and infrequent maintenance. The key is that "well-designed" qualifier. There have been enough reports of rear end seal failures and crown bearing failures on recent BMWs that you have to wonder if they are under-designed, poorly inspected, or built of inadequate materials. Or maybe the final drives just didn't keep up with the yearly increases in power. In any case someone rightly pointed out that there are any number of shaft-drive motorcycles on the market that feature trouble-free final drives. I hope that your unfortunate experience was an anomaly that is not repeated.

 

The weak spot on the early (/5) airhead BMW's driveline was the final drive splines that connected to the rear wheel hub, and those would typically last over 100K miles. The hub was beefed up beginning with the /6 series and the splines would usually go 150K miles or more on those and later models.

 

As far as I know, the only motorcycle with a really inadequate shaft drive was the British Sunbeam S7, an inline twin with one cylinder behind the other (and thus a longitudinal crank). And, just for the sake of historical accuracy, the British Douglas, built in the middle of the last century, was a horizontally opposed twin, like the BMW, that had a chain final drive.

peter '73 R75/5, '04 R1150RA

[waverider]

I agree with the XB comment. I've changed the belt on mine before... waaaay easy. I have the lifetime warranty belt now and no issues and if I did I'd get a new one free.

[Matts_12GS]

Having ridden great numbers of miles on shaft driven cruisers, that trend is starting to change, more companies are going to belt drives, Yamaha and Kawasaki among them. There are also aftermarket belt conversions for the VMAX and some of the Honda cruisers.

The Buell Uly also uses a chain, and is ostensibly designed to go wherever the GS goes using a) a lifetime belt and b) an intelligent belt guard. I've only read what the magazines say, but it seems to work. Why not?

[SAAB93driver]

Having ridden great numbers of miles on shaft driven cruisers, that trend is starting to change, more companies are going to belt drives, Yamaha and Kawasaki among them. There are also aftermarket belt conversions for the VMAX and some of the Honda cruisers.

The Buell Uly also uses a chain, and is ostensibly designed to go wherever the GS goes using a) a lifetime belt and b) an intelligent belt guard. I've only read what the magazines say, but it seems to work. Why not?

 

All the bikes mentioned have a tranverse mounted engine and would benefit from a belt or chain drive so the trend away from a shaft drive would make a certain amount sense from a technical stanpoint. .

 

One aspect that seems little considered is the emotional aspect. Few will argure with a non Boxer BMW with a chain or belt, ie F650, F800, and perhaps some would embrace the new K1200 layout with a belt but the target market for the Boxer would have a hard time swallowing a BMW Boxer with anything other than a shaft drive. They would risk alienating the current clientele and the possibility of attracting replacement clients for the new shaftless Boxers might not be so positive. I'd be surprised if they haven't thought about it, well I guess they did when they brought the first K bikes out that would kill off the Boxer. Maybe they are waiting for all of us to die off first?

[No_Twilight]

However, I'd still pay the cost, weight, and slight power loss penalty of a well-designed shaft drive over a chain or belt just for the very simple and infrequent maintenance. The key is that "well-designed" qualifier. There have been enough reports of rear end seal failures and crown bearing failures on recent BMWs that you have to wonder if they are under-designed, poorly inspected, or built of inadequate materials. Or maybe the final drives just didn't keep up with the yearly increases in power.

 

As a newbie, I bought the BMW for the shaft drive. I wanted the low maintenance and clean design. My only complaint now about shaft drive is that it is heavier.

 

This discussion board is getting a bit of a negative attitude toward the BMW design in general because there are so many members posting thier problems. It is great that we have such a bunch of knowledgable people here to help us out with our problems but just because we only discuss problems and fixes, don't assume every BMW out there is broke and yours is next. Many people find this discussion board only after they have something broken so even if you do statistics of failures vs total members your numberw will still be skewed toward too many failures. Relax, enjoy your BMW and have confidence that there is a very small chance that it will have the problems described in such great (or grusome) detail here.

 

Cheers,

Jerry

[peterbulgar]

This discussion board is getting a bit of a negative attitude toward the BMW design in general because there are so many members posting thier problems.

I bought my '04 R1150RA because I'd had very positive experiences with two BMW airheads, because I have a great local dealer, and because of BMW's reputation for building motorcycles that are completely reliable. And because of shaft drive.

 

BMW has been building horizontally opposed twin-cylinder, air-cooled, shaft drive motorcycles for over 80 years and I'd think that all the bugs would be worked out by now, so one report of a mechanical failure anywhere in the driveline is really one too many.

 

Given the high expectations that most BMW owners have for their motorcycles, I'm not surprised that a few problems get posted and discussed and revisited, and I wouldn't want it any other way. That is one of the valuable benefits of this forum - sharing experiences, positive and negative.

 

I've owned my bike long enough that the few annoying quirks have become endearing character traits. I love the power, brakes, and handling, and I'm planning to take another long trip this summer. It has been dead reliable so far and will probably remain so - I'm counting on it.

 

Personally, I see the BMW abandonment of shaft-drive for some of their models as part of a gradual shift from motorcycles as transportation to motorcycles as toys. But, I'm not in marketing, so I'll have to take it on faith that the company knows what it is doing.

peter '73 R75/5, '04 R1150RA

[Redbrick]

Quote from Paul..........

 

 

"I'm looking forward to the F800 series bikes. ROTAX motor, simple ABS, belt drive. What's not to like? If it fits me (or I fit it) I might end up with a F800ST"

 

Exactly what I'm thinking Paul ...I even have an F800ST as my desktop display right now...According to the F800 website it will cost $250.00 to change the belt and it will need to be done at 25,000 miles...I don't consider that a bad thing...I don't know (you do I'm sure)but the F650's probably are on that kind of schedule.......I like the idea of the belt drive, mid-cc type, lighter sport tourer and am looking forward to some owner feedback from Europe on these new bikes.......It looks great and the power to weight ratio is better than the RT......

 

Phil...........Redbrick

[steveknapp]

I agree with the XB comment. I've changed the belt on mine before... waaaay easy. I have the lifetime warranty belt now and no issues and if I did I'd get a new one free.

 

I've only seen "no scheduled replacement interval". Which to me means that you look at it, and at some point replace it. Similar to the BMW splines have "no scheduled lubrication interval". I didn't think it was warrantied beyond the normal factory 2yr coverage.

 

Anyone thinking changing is tough should look at a XB Buell. Or at least the service manual. Same goes for a tire change. Both look VERY easy.

 

And as far as rocks and whatnot, I'm not sure how much of that is true anymore. The Uly is often thrown flack for that, but Buell claims they've done their homework. Stories of testing where the belt drive was run at high speed and fed a bunch of crap like rocks, sticks, bolts, whatnot...and survived. You can break a chain too ya know.

 

Pros and cons of every system. Everyone has their own preference.