Super G+ Tuning
The following are directions for a complete teardown and rebuilding of a Super G+ chassis. There is not much difference for a Viper V1 or BSRT/Scale Auto G3 chassis. Most modifications described here are legal for most HO clubs and are recommended to get your cars competitive. Please note that these tips do not include any parts upgrades. See parts pages for a parts list.
Teardown and clean all parts
-Remove pickup shoes and springs
-Remove rear axle
-Remove traction magnet clip
-Remove traction magnets
-Remove armature/endbell and motor plate assembly
-Remove Endbell from Armature (Special tool needed)
-Remove shoe busses from chassis
-Leave front wheels and guide pin in chassis unless replacing these
Reshape shoe busses
When running O-ring and independent front ends, the chassis sits considerably lower on the track. This usually results in the bottom part of the busses to scrape the power rails. File or bend these “squealer tabs” so they don’t contact the track. CAUTION: do not bend these tabs back or the pickup shoes will fall out constantly and you’ll lose your springs.
– Fold window section over backward to allow shoes to float
– Bend window frame (squealer tab) forward
Busses serve 3 purposes in the car. They: a) hold the back ends of the pickup shoes, b) act as top caps for the shoe springs and c) transfer power from the shoe springs to the end bell. The stock busses don’t do any of these tasks well due to their sloppy fit in the chassis. Reshape the busses so they stay in one position. An added bonus to this is that you can adjust pickup spring pressure by lifting the tips of the busses up slightly.
– Straighten top side of busses (flat pointing forward)
– Re-bend top side so that it follows the contour of the chassis
Bend Endbell Tabs
Bend end bell tabs to improve the electrical connection to the busses. When pickup shoes snag kinks in the rack, they will slam the busses against the end bell tabs. This sloppy area causes the end bell tabs to squish up and break contact to the busses.
– Bend just the tips of the end bell tabs forward
– Bend the bottom corners back in to make reinstalling the motor easier
Flatten Pickup Shoes
Increase the contact surface of the pickup shoes by flattening them out. Stock shoes offer the greatest length but getting them flat can be tricky.
– Flatten shoes from tip to toe for maximum contact with track rails
– Bend tops of shoes back to increase retention
Shim Rear Axle
Install shims between crown gear and the chassis to remove lateral movement of the axle. This procedure eliminates the need for a gear spacer and doesn’t cause any drag on the armature.
– Remove wheels from axle
– Remove gear spacer
– Trim plastic around axle holes in chassis
– Install shims until axle has only .005” lateral movement
Shorten Guide Pin For Tyco Track
Tyco track has a much shallower slot than AFX track. If you run a BSRT guide pin and O-ring front end, chances are the guide pin is bottoming out in the slot.
– File approx 1/32” off the end of the guide pin
– Round the front edge slightly to reduce snagging in joints
Install shims on the commutator end of the armature to reduce the endplay in the motor. This helps keep the armature in the center of the magnetic field as well as keeps the pinion gear in the same position on the crown gear.
– Remove clear plastic shim (leave the red one)
– Install .010″ steel shim
– Reassemble endbell and motor plate
– Reinstall armature assembly in chassis without the motor magnets
– Check armature end play and add shims until there’s only .005″ clearance
The Super G+ chassis have a rear bushing cap built into the traction magnet clip. This bushing cap does not secure the rear bushing properly and will allow it to spin along with the armature. Adding a small shim on top of the bushing will usually keep it secure and stop it from chewing up your chassis. (Not needed on G3 chassis)
– Cut a small 1/16” x ¼” shim out of .015” brass plate
– Bend the ends of the shim down
– Install shim on top of rear bushing
Expand Timing Adjustment
To get maximum range of adjustment in timing, make sure the end bell moves through 4 clicks (5 positions) on the motor plate. Trim the stops on the motor plate to obtain full adjustment.
– Rotate end bell on motor plate and inspect casting flaw restrictions
– Trim the limiting areas of the motor plate
Bend the arms inside the end bell to adjust the timing of the motor. Shorter arms advance timing thus lowering torque and increasing rpm and operating temperature. Rather than advancing timing, it’s highly recommended to just “hook” the ends of the brush holders so that they grab the commutator better. CAUTION: advancing timing and hooking the arms will shorten the life of your armature and commutator. Bending the arms is usually a ‘one time’ operation. They don’t bend back well and retain proper tension.
– Remove end bell from armature
– Bend brush arms with tweezers until you feel lucky
True and Polish Commutator
Remove grooves and pits in the commutator to stop brushes from bouncing and arcing.
– Remove shims from armature
– Install commutator end in rotary tool
– Cut 1/8” wide strips of emery cloth
– Use 400, 600 and 800 grit to smooth and polish the commutator
** Note: Break-in armature with 3V battery with no axle installed
Shim Traction Magnets
Some Super G+ chassis castings are terrible. #2’s especially have traction magnet areas crooked or higher on one side. In order to level the magnets with the bottom of the chassis, trim the excess casting in the magnet area and add a shim to keep the magnet secure. (Not needed on G3 chassis)
– Trim magnet area with sharp knife
– Cut shims from .015” brass plate
– Install shims under traction magnets
– Check that magnets are level with chassis bottom
Rear Axle Retainer
Hard crashes may pop the rear axle out of the car. If this goes unnoticed and the car is placed back on the track, the crown gear is sure to be mangled. To prevent this, drill and install keeper pins in the chassis just below the axle.
– Carefully drill a .030” hole just beneath the axle holes
– Bend wire into a staple that fits into both holes
– Trim excess so that the center section fits up against the back of the chassis
If you don’t want to do any of these modifications but still want to have a good car, that’s why I’m here. All my built cars incorporate many, if not all, of the basic tune-up steps. If you get stuck doing any of these steps, just call me and I can probably talk you through it.