XRAY - Model racing cars

Hi!

I just completed building the superb T3 2011 Specs. However, one thing causes me a headache. During the central transmission installation I noticed the 2x12mm pins (98 1212) are too short for the gaps in the Composite Fixed Pulley (30 5577). The pins keep on giving a clicking sound when the spur gear is rotating.

The pins are 11.6mm in length and the gaps are 13mm in length. Thus there is a 1.4mm additional gap that causes the pins to move and give the clicking sound.

Do I have faulty parts or what?

I have had a similar problem in the past. This should not affect performance!

Clearly something is moving or making contact with each rotation.

Take the pinion off and rotate the transmission, then move the car around near your ear while rotating the wheels etc to try and narrow down where the sound is coming from.

I have had this before sometime ago but can't remember what is was.

Skiddins

I noticed the same phenomenon on my T2'08 and spent a while experimenting with longer pins (to better fit the slot in the pulley).
I found that the longer pin made no improvement and reasoned that the noise was coming from the pulley moving on the layshaft (due to pulley being slightly oversized or layshaft undersized). When the layshaft is rotated such that the pin is lined up with the centres of the layshaft and rear diff then the pulley moves (towards the rear diff) due to rear belt tension. As the layshaft rotates, the orientation of the pin prevents the pulley moving until the layshaft has completed a 1/2 rotation ... at which point the pulley quickly moves again ... and creates the clicking noise.
The solution was to remove the slop between the pulley and layshaft with a small cutting from your average X-Ray spare part bag (i.e. to act as a thin sleeve between the layshaft and pulley).

Man I have lived with that for years: I always thought is was a design feature so that you could tell the transmission was going around No doubt XRAY would have designed it out if it were a problem

You wont hear it when racing as those parts will be under tension during acceleration, and under tension the other way when off power

I would say you would be classed as gifted of someone with "special needs" if you could hear the clicking noise while going round on track