Corally differential adjustm ent and m aintenance.
To test the differential hold both rear w heels then try to turn the spur gear w ith your right thum b. If
the gear turns w ithout extrem e force then tighten the diff nut in the centre of the right w heel a
sm all am ount. Repeat this process until the gear cannot be easily rotated w hen both w heels are
being held.
Servicing the differential.
Unscrew the diff nut and carefully rem ove each com ponent, m aking careful note of the order in
w hich they are fitted (refer to the sectional draw ings if necessary). Check the bearings in the centre
of the spur gear and the drive plate, clean if necessary. Clean the 1/8" balls, the diff w ashers, the
spur gear, and thrust bearing. W orn diff balls are often the cause of poor differential action, so if
they are old or if the diff has been slipping a great deal, then try a new set. If you suspect that the
diff w ashers are w orn then firstly try building the diff w ith the w ashers turned over so that the balls
run on the other face of the w ashers. If you have already done this once or if the diff still feels rough
then they w ill need to be replaced.
Now clean and degrease all the diff w ashers. Corally differentials often use O-rings w here the large
diff w ashers sit on, these O-rings grip the w ashers to prevent slip and ensure an even pressure on
each diff ball, thus m aking sure the spur gear runs true. It is critical that these O-rings are free from
grease otherw ise they cannot grip the w ashers and the diff w ill slip under acceleration. Degrease
these O-rings and fit the cleaned w ashers. Put a sm all am ount of ball diff lubricant on the exposed
surface of these w ashers, w here the spur gear and thrust bearings w ill run. Reassem ble the com plete
diff in the reverse order to that detailed above. Be careful not to get any grease on the O-rings or
the back of the w ashers, if you do - STOP, and go through the degreasing process again. Ideally use
Corally m otor cleaner to degrease and allow the residue to evaporate before continuing.
Ball pivot servicing.
The 12X utilises sim ple, but highly effective ball pivots on the T-bar. It is im portant that the
m ovem ent of these pivots is free and sm ooth. To rem ove the T-bar or to service the ball pivots
sim ply rem ove the large rubber O-ring and the T-bar can be lift aw ay. The plastic socket can then be
rem oved in tw o pieces. Please note that at the Corally factory these ball pivots are m atched in sets
to ensure that sm ooth, play free m ovem ent is m aintained. Do not m ix the ball and socket sets.
Check the system for play or binding, if the pivot system is w orn or dam aged then replace. If there is
play betw een the m oulded socket / O-ring and the T-bar, then fit a carbon spacer (optionally
available). There are also plastic T-bar pivot clips available as an alternative for the O-rings. It is not
usual for play to be evident unless a m uch thinner T-bar is fitted.
Basic chassis set-up.
M ost chassis tuning is to be done to give a good balance betw een front and rear traction. Too m uch
front end traction w ill cause the car to turn too fiercely or even spin, this is referred to as
oversteer. Too m uch rear end traction w ill cause the car to turn far less than the front w heels are
actually asking it to do. The car w ill push or understeer w ide in the turns. The car w ill also scrub
off speed due to the extra lock on the turned front w heels. It is critical that you tune your car to
give a good balance betw een front and rear grip. The ideal situation is for the car to negotiate the
turns w ithout under or oversteering. The m inim um am ount of steering lock should be used as this
w ill ensure that the car carries its speed through the turns.
Corally cars are designed to give m axim um traction, w ith neutral and stable handling. This is a good
starting point on m ost tracks, but not all tracks or conditions are the sam e.
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