9 replies to this topic

[Rob]

Ive noticed particularly some of the higher powered slot cars which are inline an issue where there seems to poor engagement between the motor shaft and where it runs in the groove in the crown wheel. Evidence of brass or aluminium from continual wear and slop increasing between the motor shaft and groove.

It looks like to me the motor shaft needs to be deeper in the groove to provide a better bearing surface which would help the situation. What have people done to counteract this?

Hope what im asking makes sence!

[FLY in the wall]

Rob,

What I would do is to get a Chupa Chup stick. Cut a section about 1/4" long (5-6mm if metric) to make a spacer. Slit it length ways and then slide it over the axle inside the bushings. Hot water makes them softer.

Set the gear mesh with a piece of plastic shopping bag between the crown and pinion, push the Chup Chup tube on the crown gear side of the axle against the bushing and then push the 2nd spacer on the opposite side of the axle against its bushing.

Run the car stationary to check the mesh. If you are not happy with the mesh you can adjust very carefully the position of the the spacers. Without feeler gauges you need enough play to be able to feel some play but not be able to see the axle move.

When happy put a tiny (on the end of a pin) drop of superglue into the slit of each spacer to hold them in place.

I have a noisy car but it has removable metal wheels so I am going to do similar but with brass tube over the axle on the outside of the bushings. Inside is easier because the is no messing with wheel track width, but my axles are 2.5 and Chup Chups fit better on 3/32 or 2.38 axles.

Edited by FLY in the wall, 26 July 2010 - 11:36 PM.

[Rob]

Had to read that more than once, but the penny dropped and makes sence, good solution.

[rick1776]

Just use two slotit axle stoppers on the inside of the bearings to stop the side lash. Anyone thats tried to run a proxy series with an Al centred crown gear gear will tell you its a recipe for disaster.

[munter]

I have never liked the idea that the motor shaft controls rear axle side play.
If the rules allow I usually use axle spacers on the inside of the rim and the outside of the bearing.
These might be small washers(professor motor does nylon, Slick7 does steel) or tube.
I have used K & B brass or alloy tubing for this.
regards

[Rob]

rick1776, on Jul 26 2010, 11:56 PM, said:

Just use two slotit axle stoppers on the inside of the bearings to stop the side lash. Anyone thats tried to run a proxy series with an Al centred crown gear gear will tell you its a recipe for disaster.

I tried running a 2 hour enduro earlier this year and destroyed a brand new crown wheel in the process from this.

[lenny broke]

G'Day Rob.
I use a piece of 1/8" OD brass tubing- 1/32'' ID. Measure the distance between the back of the crown wheel and the inside of the bearing with a vernier caliper and mark the brass tube to this measurement. You could use the caliper tynes to scribe a small mark on the tube. cut the tube to length and check for fit on the axle. you can them remove and file off the required amount of material to get the desired backlash in the gear set. You can also do another spacer on the other side to to maintain the lash clearance when cornering put load back onto the mesh in the other direction

Cheers Alan

Edited by lenny broke, 27 July 2010 - 11:58 AM.

[FLY in the wall]

Lenny,

I'm going on the outside of the bushing because my bushings are glued in.

[Rob]

Hey thanks Lenny, seems most of the methods achieve the same result without relying on the motor spindle engaging the crown wheel .

[Rob]

I thought Id share this you can pay 9 bucks for each slot it axle stopper sipa 25 or by a pack of 12 Du-Bro collars for 3/32 axles for 7 dollars in hobbie shops. Now I have plenty of axle stoppers!