Gear Drive vs. Chain Drive Cams

[sportygordy]

Got my Jim's out of the closet and plan on a cam change. Wanted to go with an S&S 640G but a lot of folks telling me to stay with the new style chain drive set up.. So this raised a good question, Is there really any benefit  with Gear Drive Cams now that we have a good chain drive system? I got out a paper and pencil and proceeded to write down the pros and cost with a chain drive.. here is what i got:

Pros:
no hassle with shoe maintenance


Cons:
$$$$$ and lots of $$$$$
run out spec and concern with maintaining spec.
nosier

[mayor]

I think hi-lift long duration cams can still benefit from being gear drive, I would guess that bolt-in stuff has less of a benefit with gears compared to the hydro system.  The S&S 640's aren't exactly bolt-in.   

[05FLHTC]

Is the 640 available in the new style?

[Horizonmech]

On the old board tuners used to report the difference between gear and chain drives was approx 4hp, measured in the 95ci.......that was the old style chains.....

[wavlovr1]

I went with gear drives on my2002 when the chains exploded in my 95 taking out both cams and oil pump. I will never go back. On my 2009 Street Glide, I have the 255 cams with the stock chains. The only reason I have not changed to gear drive there is a 7 year warrenty. You can bet I'll change to a gear driven cam when the warrenty runs out. Noyze, what noyze? I can hear a slight whine but most people who listen to it say they don't even hear it. In my mind, the slight whine does not compare to the sounds of a chain exploding in the primary while crusing down the highway....

jb

[05FLHTC]

I went with gear drives on my2002 when the chains exploded in my 95 taking out both cams and oil pump. I will never go back. On my 2009 Street Glide, I have the 255 cams with the stock chains. The only reason I have not changed to gear drive there is a 7 year warrenty. You can bet I'll change to a gear driven cam when the warrenty runs out. Noyze, what noyze? I can hear a slight whine but most people who listen to it say they don't even hear it. In my mind, the slight whine does not compare to the sounds of a chain exploding in the primary while crusing down the highway....

jb

You are comparing apples to a grapefruit between 2002 & 2009 models. Do what ya want but there is NO way I would ever consider installing gear drives into an OEM setup without 1ST having the crank plugged. 

[05FLHTC]

On the old board tuners used to report the difference between gear and chain drives was approx 4hp, measured in the 95ci.......that was the old style chains.....

This info was BS & a tactic only used for a sales pitch...

Back before we had the new style hydraulic tensioner setup, the gear drive was the only game in town. We have more experience now with OEM cranks that DO NOT provide the required tolerances that gear drives mandate/require. 

[sportygordy]

You are comparing apples to a grapefruit between 2002 & 2009 models. Do what ya want but there is NO way I would ever consider installing gear drives into an OEM setup without 1ST having the crank plugged.
[/quote]

The 131 went 'into' the closet due to bad crank run out. The coming out party involves the crank trued & plugged and some head work by Charlie. The S&S 640 cam is offered both in chain and gear. The comparison is between the new style cam tensioner plate and a gear drive set up.. 

[Sonny S.]

>>>Is there really any benefit  with Gear Drive Cams now that we have a good chain drive system? <<<

We have a decent chain drive system that works well with a mild motor, and the valve spring pressure of the 06 & up stock heads.

The key to building a radical motor that hopefully holds together is to eliminate the weak links.
Don't install parts that were never intended for your application, then blame the manufacturer when the break.
IMHO if you are going in to the Hi Performance world with both feet ( ie 131 ) you can't be cheap or take the easy way out. Gonna do it...do it right.

Weld the crank, support the cams with bearings, and install a gear drive.

[Big Dan]

Gears provide more accurate valve timing, without doubt. How important that really is in most of these motors I couldn't say. But with that much motor and a welded crank, I can't see running anything but gears.

[mayor]

On the old board tuners used to report the difference between gear and chain drives was approx 4hp, measured in the 95ci.......that was the old style chains.....

This info was BS & a tactic only used for a sales pitch...

the supporting data just isn't there.  like '05 said, this might have been the best option when this was the only option, but the hydra-chains are a much better system than the old spring loaded tensioner system.  With that said, I would think there is a limit to their (hydro) affectiveness when it comes to hi-lift, long duration cams using hi-pressure valve springs. 

>>>Is there really any benefit  with Gear Drive Cams now that we have a good chain drive system? <<<

We have a decent chain drive system that works well with a mild motor, and the valve spring pressure of the 06 & up stock heads.

The key to building a radical motor that hopefully holds together is to eliminate the weak links.
Don't install parts that were never intended for your application, then blame the manufacturer when the break.
IMHO if you are going in to the Hi Performance world with both feet ( ie 131 ) you can't be cheap or take the easy way out. Gonna do it...do it right.

Weld the crank, support the cams with bearings, and install a gear drive.

that is a lot of cam to control, gear drive would probably be best. 

[Admiral Akbar]

Wanted to go with an S&S 640G but a lot of folks telling me to stay with the new style chain drive set up..

Go gears.. If you have a motor that can support that cam, you'd better have a true crank or you'll tear the motor up.. Not just the gears... but main bearings.. chains are a waste here..

Max

[05FLHTC]

You got some great replies here...

The gears are great when they are setup & installed correctly with the needed upgrades done to the crank.

My gear drives 598's are very quiet running in my 103 with the Hoban crank...   

[02FYRFTR]

Weld the crank, support the cams with bearings, and install a gear drive.
  I agree one hundred percent.  If you can't do it right then leave it alone.  If you want a 640G setup complete I got one brand new at a price you can afford.

[dave629]

If you trust your crank to stay true and solid, go with gears but I don't see the significant advantage over hydro-chain to warrant the excessive cost of gear drive. Some like the whine but I choose to leave her home.

[ORork]

I could understand a high lift/long duration cam pulling the slack out of the chain (on the tensioner side) while on the closing ramp of the cam with enough valve spring pressure, hence screwing with the valve timing. Anybody ever put a scope on an EFI cam sensor and see that?

[lupe]

I could understand a high lift/long duration cam pulling the slack out of the chain (on the tensioner side) while on the closing ramp of the cam with enough valve spring pressure, hence screwing with the valve timing. Anybody ever put a scope on an EFI cam sensor and see that?

head,s up on your scope point sir,  Not dead sure if u mean a timing light and/or a genuine oscilloscope, . BUT, its a darn good adviso in my nobody op, no matter what the level of tool. -the mechanical  principal you speak of. that is what i would like to speak to, Was in radio shack, many year,s ago, For look see at relay,s etc etc. Bought a stupid cheap old disco type strobe light with a built in rheostat that allowed adjust for strobe flash change in any given time frame. It is amazing what that can show a man who put,s it to, Valvetrain, inner primary, secondary drive, belt or chain etc etc. anything that moves in any plane on our hog,s.  . just plain open,s your eye,s at time,s..  Hey, sorry member. i know you know this. was to  show support and got to be fun ya know, anyway. very cool advise . that,s my real intent grin. tx for ear.

[les]

Gear drive will give you the most precise cam timing because there is no variation introduced by the (even small) slack in the chains.