nissky

Hello all,

This is my first post here and very new to rc scene....

I picked up a cheap brushless 1/10 buggy to get started on and having a lot of fun! I think I have finally got the thing aligned to a reasonable level for stable handling, it was a mess out of the box.
At the moment it’s set up with;
Negative 2 degree front and rear camber and a tiny amount of front toe.
Filled shocks properly with 35w oil, and ride height on lowest setting (mostly pavement).
Took ages to balance the wheels!
I am at the point where it feels pretty good, and tracks straight and suspension is nice and compliant.
It’s all great up to 50% throttle, if i accelerate a bit harder it pulls consistently to the left. The harder on the throttle the more it pulls. I can easily correct via steering but it’s annoying. I tried alignment settings to compensate but then it doesn’t track straight.
I am using the original off-road tyres which I assume don’t have the best traction on pavement, it will easily break traction even at speed.
Any suggestions for fixing turning under acceleration?

MarkA

iTrader: (21)

Exactly what car?

nissky

It’s a hsp xstr, which looks exactly the same as a redcat tornado epx.
I took it for another run, if I ease on the power I can get to full throttle without too much correction. Was getting a nice rhythm doing laps of a car park and practicing getting power down through corners.
Probably expecting too much and punching throttle too hard....

MarkA

iTrader: (21)

What you are discovering is the torque-steer most shaft-drive 4wd buggies have under high power loads. In your case it's made worse by the less than optimized geometry and less than race-grade smooth motor and esc of the HSP package. You've probably done all you can do to work around it already.

greener74

iTrader: (12)

Those cars wander anyway, but you can look for a tight wheel bearing, sloppy steering rack. Or check the chassis for tweak. Put a screwdriver under the center of the car and lift up the chassis and see if both tires come off the ground at the same time. If one tire lifts off the ground and one is still touching that will throw the balance of the car off. And it will pull one way on power and pull the other way off power. Also I usually toe my cars at 0, but if you want to calm it down you can toe it out .5 to 1 degree.

nissky

It seemed to get more stable after the tires have wore down a little (or maybe im getting use to it!)
I also tightened down the screws on the steering rack, which removed a bit of the play.
The bearings are all good by the way, as i balance the wheels on each hub by removing the shaft. Would notice any binding etc.

nissky

I have pretty much worn through the rear tires , so much fun and cheaper/safer than 1:1 driving
I can't post a picture yet but the rear buggy tires are bald, whereas the fronts are 50% worn at most. Is this because during acceleration the weight transfers to the rear tires causing them to wear faster?

MarkA

iTrader: (21)

The rearward weight transfer should actually prevent the rears from spinning under acceleration, i.e. when 4w buggies fight wheelspin, it's usually the front wheels that do so first and wheelspin is what often equals more tire wear. Uneven wear like that would suggest to me that a bit of drifting has occurred...

nissky

oops double post

nissky

Six or seven 30min runs...pretty uneven.
I think rear camber was a bit out on one side.
Was doing lots of high speed turns, or slow speed in and powering out with wheel spin and opposite lock.

The new tires, I thought they would be a little better, but no they have less traction. They move around heaps and balloon a bit more.

nissky

Some light reading, such as...
Understanding Tuning: Introduction to basic tuning for racing
Tune With Camber Links

And after some experimenting, I am surprised how much suspension settings change the behaviour of an rc car. I didn’t think it would be so significant. I’m getting into this hobby.
I moved the shock mounting locations one hole further out all around, so more inclined.
This made the car massively less twitchy to small steering inputs and more controllable.
Overall steering feels a bit slower, so I added a touch more camber all around. This is getting fun, and feels heaps faster.
Need to borrow the kids soccer cones and great a rough track.

MarkA

iTrader: (21)

Those of us into organized racing can spend hours at a track moving things in single mm increments to tune...

Some really good setup reading here - the gold standard in rc car setup books/explanations: https://www.hudy.net/xhudy/showfile....2bef0706315e0c
Applies to all scales and works even without most of the tools mentioned.

nissky

Thanks mark for the link