LL SW-9 Worm gear Swap Out

I have heard of some individuals swapping out the plastic worm gears on the LL SW-9's and replacing them with a brass one. Anyone know what part needs to be had to do this and does it improve performance? Thanks.

jeff

 

Any kato worm gear will do

 

I wouldn't expect it to improve performance in any meaningful way unless the plastic gear is visibly ragged, worn out or broken. While it's not ever recommended practice to run plastic on plastic or brass on brass, at the relatively light loads these parts see it is sometimes done with satisfactory service life.

 

I have done several of these mechanisms and here's my experience fwiw.

Although not absolutely necessary for these to run well, changing the worms to Kato brass does give a few advantages.
1. Some (read some) of the plastic worms were reported to be out of round in conjunction with the motor shaft centerline causing noise. The brass worms seem to be more precise and run more true. Personally, I have not found any of the plastic worms out of round.
Noisy worm to worm gear mesh can also be caused by the worm bottoming out in the worm gear. This can be remedied by shimming the motor in the saddle to give clearance.

2. The small amount of added weight of the brass in my opinion adds to the flywheel effect helping overall smoothness.

3. As pointed out, a brass worm and plastic worm gear is a more desirable condition and again in my opinion, runs smoother.

Replacing the worm is only one part of tuning these mechanisms however. I have found the trucks need to be carefully tuned as in wheel gauge and making sure the muffs are positioned on the axles such that the gears don't rub along side one another.
Make sure there is no flash on the truck gears as well.

The pick up tabs on the shell need to be uniform. I usually adjust them until they are even with the bottom of the jack pad.

(Again) my experience is that these mechs can be all over the road as far as performance right out of the box so there is not one fitzall but general guidelines applied to each individual mech.

Your mileage may vary.

Hope this helps,
Jim

 

Thanks for the responses.