gear driven cams

Simply put, they sound cool!

 

No chains or chain tensioners or cam sprockets to wear out, change timing, or break....
more precision, HONDA style!!

 

Off the engine crank are a set of idler gears, that transfer the power up to drive/rotate the cams. Very persise and very little wear. Never have to replace the parts and will have consistant cam timing for the life of the engine. With a chain, they get away with a little less noise. That I believe is the only real advantage. The chains do wear out and stretch over time, and in rare cases, break. If the chain breaks, your cam timing is uncontrolled, and will most likely result in broken/bent valves at the minimum. Due to it's wear and stretch, there are tensioner(s) to keep the chain tight, and need to be replaced every "XX" amount of miles. Personally I'd like to have gear driven cams, but the chain works fine too. I've never messed with it on my 04 vfr, but I have replaced the chain and tensioner before on my yz426f dirt bike.

 

Why don't all bikes use gears?

 

All very true but don't forget that there is also a HP rob from the chain tensioners. May not be much but it's there non the less.

Gear driven... could be considered a more "direct drive" if not a just about solid link. Maybe it could be related to a shaft drive vs chain drive. A more secure and less complicated means of connecting a bunch stuff to run in unison.

What does it mean to me? It means that I need to change out my tensioners when the time comes. There is a good write up here on the process.

Side effect of chain driven = maintenance
Side effect of gear driven = noise

I have no concerns in regards to the 6th gens chain drive reliability at all.

 

This is what you get vs. sprockets, chains & tensioners, it just oozzes relaibilty doesn't it. One end mates to a gear on the crank shaft the other to a gear on the cam shaft.

 

I am liking this question, more to the why and how of it all. I am pretty far from a motorcycle mechanic myself. My thoughts. If the only advantage is to get rid of the gear noise, and the result is more maintenace with chain, tensioner, and potentially a minute HP draw - Then why the heck did the honda engineers make the change? To me, it does not seem like a sensible trade-off. Especially with Hondas rep for reliability. Are the gears really that noisy? Is it possible consumers actually complained?

 

Here's a pic of mine. Sounds cool...although somewhat drowned out now, by my Staintune exhaust :smile:

 

The "noise" gives it soul, like a Pete Jackson "noisy" gear drive on a car engine, it makes it sound like you have a blower(super charger) under the hood when you really don't. It's something unique to the pre VTEC VFR's; the main reason to go back to chain.....COST. Its much cheaper to make chain & sprockets vs. the beefy chunk of iron pictured in my other post. I'm sure emissions played a hand in it as well, as it would be difficult @ best to vary the timing curve to meet emissions w/ a gear drive set up unless of course the ecu & sensor package was amped up quite a bit but that would cost more $$$$ they have figured out how to do it diesel engines so it is possible, but even that industry is going away from this technology & going camless w/ all being controlled electronically.

 

Gear NOISE?? NOISE??
NO WAY, that's Honda MUSIC, my friends!!


And don't forget the (almost) wear-proof set up.... with split, spring-loaded, anti-backlash gears all designed to last about 200,000 miles, i guess.

 

Thanks T-Bone, I'll buy that. You Wisconsin guys are pretty smart!!
(Edit here- as far as the sound is concerned, years ago a buddy of mine had a gpz 750 turbo, you know it sounded really cool. Turbo sound with an actual turbo!!)

 

Another thing that I just thought of that might have played a role in the drop of the "gear drive". Is that with fuel injection and electronically controlled timing. One main sensor is the KNOCK SENSOR, which senses ping or pre-detonation. Which is bad for the motor. The sensor adjust the timing due to this sound created. With cars, you can not install a "gear drive" on a fuel injected vehicle, due to the timing picks up the noise created by the gear drive and tries to adjust the timing. Resulting the the car running like shit.

So maybe this is one of the main reasons, along with emmisions being effected, and who knows, maybe it would some how affect the V-tec? I do know that the 98-01 vfr800 had gear drive, and also was fuel injected, maybe there was no knock sensor, but a more simple electronic timing design.

 

Wait a sec, tbone. I am not sure I buy the bald assertion that the gear drive is more expensive to manufacture than the chain drive. Any citation to back that up?

What about the relative weight of gear drive vs. cam drive? I read a mag article that asserted that the 6th Gen's chain drive saved about 2 lbs. over the 5th Gen gear drive - not that it mattered much, given the overall weight increase of the current generation VFR. Still, as a general matter do people agree that chain drives are lighter?

What are the failure rates of chain drives vs. gear drives? Does anyone know? Or are we all assuming there is a significant difference based on anecdotes or limited personal experience?

I am not trying to be a PITA. I am just curious. Well, and also I am a lawyer.

 

I'm unaware of the failure rate of chain drives. I ride my bike and perform the regular maintence, and don't worry about the chain drive. It's the way they did it and it seems to work just fine. I do have personal experence with the two on cars. Gear drive is the life of the engine, chain drive is usually about 100k. Many new car have belts instead of chains, and the life of those is about 60K-100K depending on the vehicle and right foot. Another thing about the wiegh is that the chains are typiclly lighter, but then Honda added the v-tec to the bike increasing the wieght again. So maybe due to the added weight of the v-tec, they went to the chain drive to loss a few pounds? I love my 04 and it seems to run great. But if I wanted to be picky, I would get a 98-01 vfr 800 with the gear drive and less overall weight, with the same performance and mpg.

 

That is the only bonus, my Gen6 spinned at top end (10K+) quicker and smoother than my current Gen 5 does but don't use that end of the Range enough to worry about loosing it.

That sound is just the coolest, ear plugs out makes my light in traffic but slow in speeds ( 25>45 mph ) 40 minute eachway weekend commute even more enjoyable. Did have a Ricey guy once ask me if it had a blower at a set of lights.

 

I've heard a few 98-01 vfr's pass me one those days I decide to drive on the freeway, and what an amazing and exciting sound.

 

Meh, the sound is interesting, but I don't think that's what Honda engineers were aiming at when they designed the VFR's gear-driven cams. I read that Honda wanted to distance itself from the total "cam disaster" of the chain-driven VF750F/VF700F series, but I don't know the basis of that rumor either. I do know that the cam chain tensioners on the 1st Generation bikes suck. I had to replace mine at 20,000 miles. On the other hand, I don't think that the Honda designers were trying to eliminate the cam gear whine when they engineered the 6th Generation. It would be interesting to dig up some first-hand information on that decision.

 

the gear drive set up is the most reliable and precise set up for a production bike that i can think of. there are some other systems out there for cars but not that im aware of for bikes. with gears there is no need to worry about chain stretch causing slightly altered valve timing. and as far as the noise goes i think it sounds great. it is due to the gears being straight cut instead of a helical cut gear like you find in cars manual transmissions. just think if you hear a car with manual trans back up it has that whine to it[ thats a straight cut gear], but all forward gears are quite because of the helical cut gear. so technically i guess honda could of used that type of gear but i think due to the way they mesh it would be harder to set up the timing. the noise itself , anyone correct me if im wrong, i think is due to the small amount of air that gets trapped between the gears as they start to contact each other getting squeezed out as the gears mesh. this is the same way superchargers on dragster have that sound, due to the air getting sqeezed out between the belt and gears. hope that helps.:smile: