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ddaenen1

My TA04 - handling problems

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I have taken my TA04 out for a spin yesterday for the first time in quite a while. Since last time, i changed a serious amount of things: rear diff changed to ball diff, front diff changed to one-way, Savox servo instead of the Futaba and some other small stuff. Now i seem to suffer from some odd behaviour for which i am counting on your expert experience. Here the problems i observed:

1. If i brake, the car makes an uncontrolled spin

2. My left turns are much sharper than my right turns

3. It seems extremely hard to get the car to run straight. It does at low speeds but randomly may pull to the left or the right when i accelerate.

I have checked all the regular things like turnbuckle lengths and i cannot detect any abnormalities there so i am clueless why it behaves like that now.

Some specs. I run a graupner 9.5T on a Turnigy 60A with 2S Lipo. Steering servo Savox = SC1257TG.

Here some pics of the car:

1364464121NIMG_20120625_00177.jpg?psid=1

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Front one-way means only the rear wheels brake (like a hand brake). So obviously the car will spin on brake. Usefull for drifters.

As for steering, check that steering is not binding, has no excessive slop, l/r turnbuckles have the same length, on center servo is also centered, no slop in servo saver, l/r endpoints are the same.

But first, put a glitch buster capacitor (on any free rx channel) or use an external bec, a fast servo needs incredible amounts of peak current (like 7 Amps! on some) which cause brief voltage drops which in turn may cause rx to reset

Check if nothing loose, no cold solder joints or defective connectors between battery and esc. A damaged battery can also lead to voltage drops on acceleration.

Also, I assume you have 2.4ghz radio gear, radio glitches due to interferences can also cause similar behaviour.

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1. If i brake, the car makes an uncontrolled spin

The one way in the front means you only have rear wheel brakes. It's like pulling on the handbrake in the real car. You must brake in a straight line and with accurate amounts of force to prevent the wheels locking up.

2. My left turns are much sharper than my right turns

Servo is not centred correctly.

3. It seems extremely hard to get the car to run straight. It does at low speeds but randomly may pull to the left or the right when i accelerate.

This sounds like lack of traction on one side of the model. The side that still has traction steers the car the opposite way. Tyre compound, damper/spring tune may solve it. Good throttle control and not trying to accelerate too hard too quickly is one thing most people take a bit to learn when going from brushed and Ni-MH power to brushless and Li-Po. With the brushed motor, you just mash the throttle and wait for things to catch up. The brushless will just rev out, whether you have traction or not.

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The one way in the front means you only have rear wheel brakes. It's like pulling on the handbrake in the real car. You must brake in a straight line and with accurate amounts of force to prevent the wheels locking up.

Servo is not centred correctly.

This is an interesting one because i noticed that when i mount the servo saver on the servo, it is not fully centered when the TX trim is on zero. either it is one notch to the left or one to the right. Does this have to do with the TX/RX? I run with a flysky FS-GT3B. Can i program the zero on the TX?

offtopic: why don't the html options show when i post? Used to be fine in the past.

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hi,

front one way is designed and intended to be used with a very smooth driving style , reduce braking power and brake on the straight, get all braking done before you turn and roll the car through turns then get back on the power when half way through the turn to use the one way to pull the car out of the turn ,

check weight bias, get an old bit off wood and stick two wood screws through it at points where they will touch the chassis plate at front and rear , mark the chassis center and set it on the screws,, add weight until the car balances on the screws , you can buy them ready made but the wood and screws does the same job.

check that the roll bars are not binding on either side and check the dampers for air, if one shock has air in and the other side doesnt you will get a tweaked chassis under acceleration and braking

have fun, :)

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When you install the servo saver or horn

- on tx put steering trim to middle

- power on, let the servo center, now mount the saver or horn as straight as possible. It will not be exactly centered, use the closest position

- now compensate from steering trim to get it right

- adjust steering turnbuckles to get all the steering assembly centered and desired front toe angle

- use again tx steering trim to make the final adjustments while running straight at moderate speed

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If your TX setup has sub-trims, use the sub trims to set the servo horn centre before you use the actual normal trim settings. This will leave full motion both directions of the servo while keeping the trim as close to centre as possible. If the TX doesn't have a sub-trim setting, then you must use the normal trim setting which will result in more steering one direction than the other at the extremes of the servo throw.

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offtopic: why don't the html options show when i post? Used to be fine in the past.

Forum update today. Some things in the edit box have changed. I can't even get the cursor to start flashing in the text box half the time so I can start typing until I click around the screen madly and eventually it starts flashing.

The 'quote' system is really horrid in this update.

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I was having similar problems with my TA04-SS. If you are running the stabilizer bars, make sure the end link lengths are equal.

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In addition, check the cars droop / down stop settings and make sure your shock lengths are even. Place car on an even surface. Position yourself where you can view both tyres. grab the front shock tower at dead centre. slowly lift the car and see which tyre if any comes off the surface first. then try the same test on the rear. If one tyre comes up before another, it means that your suspension is binding, droop is set incorrectly or shock lengths are on even. All these things will effect how the car drives in a straight line.

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Two things I didn't see mentioned. On your tx, make sure that your epa's (end point adjustments) are set right. Additionally, it sounds like your rear diff may be set too loose. Keep us updated.

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This may sound nuts, but make sure there aren't any pebbles lodged anywhere that could interfere with your steering. I fought similar steering gremlins recently and when I tore it apart to replace pretty much everything, a pebble was sitting in a suspicious spot (and servo saver needed to be replaced). Someone suggested I check for pebbles and I shrugged them off. I felt like an idiot, might as well check that for your own sanity.

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