PDA

View Full Version : Car steers hard to the left when accellerating


Tapir
2011.10.14, 05:22 PM
Hi.
My car sometimes steers hard to the left when accelerating.
The biggest problem is from standing still but also sometimes in speed. It goes straight when driving slowly, but if I apply full thorottle it "worms" away.

Tire diameter. Equal left/ right.
Bearings. Good. Replaced with new also.
Differential are right in center.
Motor pod bearing cups. Same height.
Thrust bearing in diff. Good
Diff with or without slip. Same problem.


PN #2 T-plate
Tri damper. Could it be the settings here? I think I have tried everything, but nothing helps.


It drives wonderful, but it annoys me that it suddenly weers of to the left.

Can anyone help me out?

color01
2011.10.14, 07:17 PM
Heh, I often have that issue too. It can be quickly tuned away using the tri-damper, just tighten the left-side spring until the car starts spinning to the right under acceleration, and then back it off a little bit.

Alternatively, the front end can also cause this problem. Does one side have more preload than the other? Equal ride height L/R? Front bearings equal? As a guy trying to drift an MR03, I've found that the front and rear ends are equally important in making sure the car tracks (decently) straight under tire-spinning acceleration.

All things being set properly, RWD Mini-Z's will still tend to prefer spinning to the left, because of the increased rotational mass of the rear left wheel vs. the right.

Rear left: Wheel + tire + bearing + wheel hub + rear axle + diff parts + E-clip + 2 nuts.
Rear right: Wheel + tire + bearing + diff parts.

So if your car turns equally left and right, and handles equally left and right at high speed (i.e. no chassis/suspension tweak) then the rest of the problem is mostly a Mini-Z driveline characteristic and I wouldn't worry too much about fixing it.

Tapir
2011.10.14, 08:58 PM
Thanks again color01.
You are always helpful :)

When there are wheelspin, I see your logic. The only problem here is that I dont think this is isolated to when the wheel spins. It also seems to happen when using less power.

As for front spring preload etc, this should be good as it is. The car has the same amount of steering R/L and spinouts is not a problem to any side.

When driving on a track, the car handles very good, but suddenly out of nowhere, it just takes off to the left.

color01
2011.10.14, 11:53 PM
If the chassis is already well-sorted, then we start looking at the electronics. How old is your servo saver? Does it get stuck? How much steering play do you have (at the wheels) when the car is ON and your steering is centered? My servo saver hasn't been changed out since 2009 when I first got my 03, and it's definitely gone to crap in that time. Newer cars definitely have more precise steering than mine.



You might also want to check your bind between the car and the radio -- a bad bind can cause random "glitching" even though the MR03 is a 2.4GHz ASF car.

Tapir
2011.10.16, 11:53 AM
Tried a new cahssis. Moved over all the parts.
Problem is the same.

Can it be a diff problem? It works well when I spin it in my hands, but when the problem occurs it is almost as it only drives on one rear wheel.

Strange stuff.

cowboysir
2011.10.16, 12:56 PM
Have you tried adding a tooth or two to your pinion gear? It's not the best solution but in the past I've worked out that type of "torque steer" with bigger gears. Be aware of heat issues when you do but it's something of a solution...

color01
2011.10.16, 05:00 PM
It can be a diff problem or a rear axle problem, but if the car dramatically veers off the line randomly (same parts of the track? yes/no?) then I would really suspect an electronics issue. It'd be weird but not impossible for the glitching to occur only to the left.

Mike Keely
2011.10.16, 08:33 PM
I have seen this once but not on my car. I think it was either a brush problem or a small diameter commutator motor issue. We where at a hand out motor race when I saw this same thing happen to many drivers. All the drivers having the problem had 2.4 Mhz boarded cars.

Have you tried to change the motor?

Does it always happen at the same spot on the track? If so it may be a change in the height of the RCP tiles ( if you have a few tracks bought at differant times the track tiles can come with thickness variations )and it does mainly run on one wheel when the one tire is on the taller cut tile.

Tapir
2011.10.17, 07:35 PM
I have changed the electronics, and problem is the same.
I have tried 3 different motors. Problem the same.
Tried another diff. Problem the same.

It happens on the straight, when accelerating hard. problem is that it only happens sometimes.

From standstill it also sometimes happens.
The tiles seem very even.

I can do lap after lap, and everything is smooth. Suddenly. Bam. It shoots off into the wall.

Strange stuff.

littleleon
2011.10.17, 09:40 PM
You mentioned that you have tried different electronics, but have you tried a different transmitter too?