Cranks

[Slacker]

This may seem to be a dumb question for most of you. What is the difference between the standard crank and the SG crank. Any advantages one over the other or is it just application.

[Mark Leber]

Slacker,
Here is a standard threaded crank:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXUT05&P=Z

This is a short threaded crank:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBFH6&P=Z

And this one is a "SG" crank
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXDBX7&P=7

The standard threaded style can be adapted to fit most any application by simply using the proper clutch nut and cutting it to the short threaded length if necessary.

The short threaded style is just a cut down version of the standard threaded crank. It is most commonly used in the RC10GT and can pretty much be adapted to fit any other model.

The "SG" crank was origionally designed to fit touring cars but has recently been becoming more popular in purpose built dirt oval cars. There are also conversion mounts available now that allow it to be used in the RC10GT. "SG" stands for surface ground. The main advantage to the "SG" is that the pilot for the clutch bell bearings is machined right onto the crank instead of having the pilot thread on as part of a clutch nut. This allows much better alignment of the clutch assembly which minimizes vibration. The "SG" uses larger more durable clutch bell bearings and allows the use of threaded clutch bells such as the one designed for the NTC3 which make gear changes a snap. The "SG" also eliminates the dreaded "E" clip commonly found on most clutch systems and replaces it with a retaining screw which is much more durable. Both the standard and short styles can be adapted to the "SG".

The "SG" is the preferred crank in my opinion but it does have limited adaptibility. If you can get it to work with your application its the way to go.

Hope this helps!!, Mark leber

[Slacker]

Thanks Very much for the info

[Racinrc14]

Not all engines that are equipped with 'SG' cranks are the same diameter, as I have recently discovered, e.g., the new stock motor in the RC10GT uses an SG style crank, but it is machained to accept s.a.e. (inch) bearings. Most Asian and European .12's, .15's and .18's are machined to accept metric bearings. I have a Collari .12 that I am trying to adapt to my GT (turned EDM), but I'm having trouble finding the right clutch bell that accepts metric bearings and at the same time meshes properly with the Associated spurs. Anybody have a fix for this? Thanks,

Tommy

[DKUBISTARACING]

I have built gas cars out of the gt. try using NTC3 motor mounts and cut slots in the chassis just like the custom works gsx cars have. Then use the NTC3 clutch system, much better clutch then the old GT clutch.

[Mark Leber]

Racinrc14,
The AE .15 RTR crank looks kind of like the real SG cranks but thats where the similarities end. The two are not interchangeable. That style crank is unique only to the GT. However the real SG cranks can be adapted to work in a GT by simply using a Klein SG motor mount and either the Traxxas or NTC3 clutch setup.

Here is the mount:
http://www.kleinrcmotorsports.com/proddetail.php?prod=k8888&cat=8

I prefer to use the Traxxas clutch setup. Here is the list of parts for it:

AE 7618- collet and shims

Traxxas 4142- flywheel

AE 2313- SG nut

Traxxas 4146x- clutch

Racers Edge 14920- 20T clutch bell w/ bearings (substitute the last two digits in the pt# for whatever size gear you need.)

AE 2321- clutch screw and shims

If you would rather run the NTC3 clutch setup just hollar and I will post up a parts list for it as well.

Mark Leber

[Racinrc14]

Why does mounting an SG equipped motor require different mounts? Isn't the flywheel in the same location as a standard crank setup? Also, I like the idea of using the NTC3 spin-on clutch gears, can the FT NTC3 spin on clutch bell be adapted to single-speed use (I am aware of the Klein clutch bell), and what size bearings does it use?

Tommy

[lawtonlosi]

I had to do a lil adaptation to my novamega .12. Its an SG crank. I cutdown a ntc3 sg nut, and then used an ofna shim kit to get the correct alignment. I then used the traxxas clutch setup mentioned above. One note, the revo clutch bells are a different pitch. I got a whole new traxxas clutch for 5 bucks on ebay out of a revo, but the bell was a different pitch. Only took a couple hours of being upset with myself to figure it out lol.

[Mark Leber]

Racinrc14,
The SG motor uses a different mount in the GT because the distance from the center of the pinion gear to the inside of the clutch bell where it meets the flywheel is greater on the Traxxas and the NTC3 bell than it is on the stock GT bell. This requires moving the motor over to the left to get the pinion-spur alignment correct. I have heard of some guys cutting down the clutch nut and grinding off the back of the clutch bell to get the pinion gear back inline but this also requires grinding off the first thread or two on the crank so the inner bearing can slip in further and sanding the clutch down some too. This is in my opinion too much work and means that any replacement parts must be modified in the future as well. The SG mount is only like 30 bucks and everything will bolt right up in unmodded form with minimal shimming.
The NTC3 clutch bell will work fine for a single speed. You just spin on one gear instead of two.
The traxxas uses 5x11 bearings in the stock bells and 5x10 bearings in the Racers Edge bells.
The NTC3 uses a 5x10 inner and a 5x9 flanged outer bearing.


Hope this helps!!
Mark Leber

[Racinrc14]

Outstanding. I appreciate the info. So I'll set my GT/EDM with the NTC3 clutch, mounts and clutch bell. Any tips on clutch shoe setup for foam tires on the Coopers track?