Visit The Dirt Forum for More Information

Author Topic:   double roller chain or gear to gear timing sets
posted June 06, 2003 06:52 PM
I want to know the advantages and disadvantages of gear to gear drive on a racing motor that will turn anywhere from 5000 to 7000 rpm.

rico 08
posted June 07, 2003 09:56 AM
I've heard that gear to gear may transfer too many harmonics to the cam but i've never ran one,i'd save my money for a true roller setup like everyone else uses or should be.

posted June 07, 2003 12:17 PM
i have heard the same thing about the vibes plus the sound of a gear drive will drive you nuts lol

posted June 07, 2003 05:10 PM
again most tracks don't allow gear drives.
I don't know how you hear a gear drive over an open exaust anyway.
But then again I could hear the rear gear bearing howling from the far end of the track so I guess maybe you could hear the gears if you dont buy the quiet kind.

Jason Boivin

rico 08
posted June 07, 2003 09:53 PM
You can swap the gears around and they are quiet,a buddy of mine tore down his motor and his dad secretly switched the gears around so his would be quiet,needless to say he tore back into it to make it sound off.

posted June 08, 2003 07:14 PM
We've never ran a gear drive but as a kid I remember going to the races with my old man and a couple of sportman cars were running a gear can here them for sure over the noise. They HOWL!!

posted June 10, 2003 03:42 PM
it takes energy to make noise, right? Why run something that takes power away?

posted June 10, 2003 06:53 PM
The way it was 'splained to me :
Belt Drive is the best and most expensive.
A good gear drive is next, like a Shaver Westmar or a similar unit, then a good roller chain, then the cheapo noisey gear drives. That was judged by how steady the timing stayed over the rpm range.

posted June 10, 2003 07:15 PM
mod4 is correct.

1) belt drive
2) fixed idler gear drive
3) true roller timing chain, billet gears
4) everything else not mentioned
5) last and least....dual idler gear drive, noisey or quiet, they're junk!

posted June 10, 2003 07:26 PM
Also from what I read the double idler gear setup has a tendency to try and push the cam and crank away from each other.Which would put more wear on parts

posted June 11, 2003 12:14 AM
We run a single idler gear drive in our late model engine but it is held together with a steel frame rather than an aluminium one (for strength).
I have a spare engine that runs a dual idler gear drive, & yes it is noisey but who really cares, it is a racing car, & as soon as you start running solid lifters (roller or flat) the valve train is going to be noisey anyway. They are agricultural but reliable.
Alot of the Gearte built engines use the sommers bros units. I don't know for sure but I think they are a dual idler.
Shaver/Wesmar made there own (single idler) unit because they didn't like an of the others. Works for them.
If your going to use a roller chain, make sure you get the "premium" roll master item as the others are junk. These are the most expensive versions of roller chains and are quite good. You do get what you pay for.
I guess it all depends on the rest of the valve train. Big roller cams with rev kits and heavy valve springs re going to be hard on the drive system at big revs.

posted June 11, 2003 01:07 AM
The Sommers Bros. gear drive is identical to the Shaver/Wesmar drive . Both are 100% reliable , and the best you can buy . Unfortunately Sommers Bros. is no longer in the gear drive business . Everyone is right about the duel idler's ! These thing's are total junk , and are basically designed for the average high school kid who wants his Camaro to sound "cool" . Though I can't figure out why in the H*ll anyone would want to listen to those thing's whine


Hendren Racing Engines
Rutherfordton , NC

Back to the Archives