Deceleration Tyre Chatter - Scaley Monte

[Wobble 106]

I have a problem with a Scaley '87 Montecarlo Nascar that chatters quite noisily when slowing for corners etc. It doesn't appear to effect its braking but annoys the whatever out of me 'cos it kinda stuffs up my concentration. It's had BRM Nascar tyres added to it and acceleration is good with nil chatter so I figure the tyres aren't out of round and the motor has been hot glued in 'cos it was as loose as a really loose thing. It's running on wood no magnet so I'm sure some of you guys will have a way better idea of what's happening than I do.

 

I'm open to suggestions so please feel free to add your thoughts so I can fix it.

[terry 36]

Have you tried adjusting the brake setting on your controller?

[munter 153]

I havent seen a plastic chassis that didnt flex....whats the motor/rear axle/pinion/spur rigidity like?

 

Think bracing

[slotmadmac 127]

Yeah. Brace the rear bushes to the motor. I use thin piano wire and JB Weld - which is easy to remove if you need to.

 

[Wobble 106]

Yeah bracing … had another look at the innards and they were worse than I first thought. Thanks guys.

 

[munter 153]

I can see a weak spot from here and I am 750kms away....pretty sure you will fix it.

[Wobble 106]

I recall now, I didn't remove the magnet just in case I busted the chassis in doing so.

[David Carter 84]

Yep as Mac said, that chassis will be twisting to the max

[munter 153]

Yep as Mac said, that chassis will be twisting to the max

 

eh boi.....!!!!

[slotmadmac 127]

If clearance under the interior allows, another trick to stop shudder / longitudinal flex is to fix lengths of plastic tube or square section plastic rod down the length of the chassis between the motor and the front wheels. You can also run guide wires through these tubes for a nice tidy set up. I am doing this more and more these days.

[difinity 27]

I tend to run flat carbon fibre strap from the motor to the guide post with these chassis. Bracing the motor to the rear axle mount helps too.

[dangermouse 95]

photos of all these mods would be appreciated thanks - where do you get carbon fibre strap from?

[slotmadmac 127]

Here is a motor braced to the rear bushes.

 

[slotmadmac 127]

and here is an old pic of the square section tubing in place

 

 

These days I use plastic section and tend to respray / repaint the whole chassis when the tube is in place so it looks nice and tidy.

[Wobble 106]

Thanks for your input guys. I'm going to try a bit of that Mac. Still struggling to understand why it's smooth on acceleration and chatters on deceleration.

Terry I wondered about the brakes but I had knaff all brake wound on and it still did it.

[Slotspeed 14]

Maybe not the same thing but I had very bad chatter with one of my Carrera cars. The standard clearance from axle to bush was way too loose, most noticeable as a horrible chatter on deceleration, so much so I was getting tyre squeal under braking. Perhaps this is what you have? Apart from that I also braced the rear bushes as has already been suggested. What was quite funny is that I spent more than the value of the car replacing the drivetrain with slot.it axle and crown gear for better clearance and less friction. It became apparent however that the chatter was actually helping remarkedly with braking! I ended up putting the original crownwheel back in too! For other Carrera cars with the same problem I have just been using the superglue trick to tighten up the clearance and have only needed to revisit the process once in one year on my most used car, as I keep it well lubricated so to speak hahaha.

[difinity 27]

photos of all these mods would be appreciated thanks - where do you get carbon fibre strap from?

 

The same hobby shop I get metal rod from (in Canberra). Should be available anywhere plastic/metal hobby pieces are. Maybe try your local RC/plane store?

[gordo 0]

gear lash may be the issue. a tad too loose perhaps