Always adjusting the Steering Trim

[lykan]

Well here's my stadium truck.

The tires are alighned in. looking from the top. This helps me in self centering, tires and wheeel sare bound to have slop. It sort of lets the front align itself on straight.

The camber is set with the tires tilted in at te top /---\ The reasonn for this is more sensitve steering onpavement. The front end of my stadium truck is light so it adds more grip.

Every time I hit a jump, or do a hard landing I have to reset the steering trim. If you are looking for being able to do a lap, hit ajump take three hard corners. Then come out heading straight without adjusting the trim, I think you are looking for something that does not exsist.

The nature of off road cars just tells m e that you;re not going to be able to get it perfect and have it stay that way. It shouldn't veer badly that's for sure. Then again it's shouldn't always be perfect either.

One of the rue arts to offroad driving, is to be able to adjust to a cars response, and track conditions on the fly.

On some tracks it will respopn beuatifull, and pull to the left on the back straight. On others the loose dirt makes it less responsive to turns, but goes better in stright line. Being able to drive two laps, then compensate and feel the track is what off road is all about.

Now, My T-maxx thats a different story all together. It torque steers. Hard accel on pavement, and there's no way to get it to go in a straight line without a lot of trim compensation. One more lap, and it's time to re-compensate.

I am wondering what exactly your looking for, and how much? How far off is the steering? How often do you have to adjust? Is it possible to get it set up just right, it just won;t hold an adjustment?

Let us know you've got me curious now

 

[KnightAzul]

This is my first RC car, and I have owned it for a grand total of just over 2 months (it was a christmas present: RTR Thunder Tiger Ts-4n - 4 wheel drive).

I only race on tarmac. I have no point of comparison, with previous RC cars, to know if what the RC car is doing is normal and repeated straight lines really is the holy grail in RC racing!

The situation is:

- On hard acceleration it tracks a straight line more or less. A little torque steer is evident.
- However, coasting and constant low speed the problem is a lot more evident. Basically the car will gradually veer to one side and get progressively worse.
- There is no way to correct the steering at constant low speed, if I adjust the trim (with the smallest possible) change it veers off to the other side!

One small detail which may or may not help is that the arm with the ball-cups which connect the steering linkage to the front wheels are of a slightly different length (2mm difference) on the left and right side.

Any more info you need just let me know ...
Thanks,
KnightAzul

 

[lykan]

Well, seeing as how you are on road
(is tarmac pavement, and flat?)

What kind of tires are you running?

Also, you say one tie rod is shorter than the other. Is it supposed to be that way is that the way the linkage is set up?

One way to tell is to check to see if the tires maintain paralell when you turn them.

When you are on road(flat surafces),the more you tilt the top of the tire in /---\, the more "hook" your going to get.

Meaning a slight turn with the tires tilted like that is really going to whip you around (turn reallly fast). Is it possible you have the steering set up so fine that the slightst ovement, and your turning sharp?

Also, does your conrtoller have dual rate steering? On one of my futaba controllers there's two settings that could cause an issue.

One is steering rate (or sensiitivity) the more steering rate, the faster the tires turn. A little turn of the steering is a big turn of the tires.

The other setting is what I call "the dead spot" The more the dead spot, the more you are allowed to turn the steering without it hving an effect. So you can move the controller back and fortha little bit without turning the tires.

Is it possible you're steering is just way to sensitive?

Good luck, lemme know

By the way, hang in there, It's frusterating I know.

One way I set up my ST, it turns so fast I am doing 360's at 30 mph. The other way it would turn way too wide, and I would hit curbs. It took me along time to get it to where I thought it was just right for me.

 

[KnightAzul]

Originally posted by lykan
So yes, set your suspension so that when you drop it from a jump, or hit the throttle, it returns to the height you have the camber/caster set at. Otherwise your alignment is set ocrrect for a suspension angle your buggy will never see.

I've been try to achieve this with no luck. No matter what I do with the shocks on the front (more pre-load, less pre-load, longer rods, shorter rods, different positions on the lower arm, etc) nothing seems to work. Whenever I push the suspension down it returns back to a certain position, however if I lift the front end a little then it doesn'

Originally posted by lykan
So yes, set your suspension so that when you drop it from a jump, or hit the throttle, it returns to the height you have the camber/caster set at. Otherwise your alignment is set ocrrect for a suspension angle your buggy will never see.

I've been try to achieve this with no luck. No matter what I do with the shocks on the front (more pre-load, less pre-load, longer rods, shorter rods, different positions on the lower arm, etc) nothing seems to work. Whenever I push the suspension down it returns back to a certain position, however if I lift the front end a little then it doesn't go back down again all the way back to the same position :nono: BTW, the screws have not been over tightened at the ends of the shock ...

- Could it be that the spring is too strong for the car (this would be surprising since it is a RTR ... however you never know!)
- Could the viscosity of the shock oil have anything to do with it? I doubt this since as I understand it, this would only affect the rate at which the returns back to a position, but not the actual position.

lykan, to answer some of your questions:

- The tarmac is not perfectly flat.
- The tyres are brand new and pre-glued:
Front Tyres: Medial Pro Touring Class (Glued on rims) Medium
· Rear Tyres: Medial Pro Touring Class (Glued on rims) 35º Shore

Hit "submit reply" before finishing ...

lykan, to continue to answer your questions:

- One tie rod is shorter than the other, it is this way so that the wheels are aligned with each other. If both arms are the same length then there is a visible difference in the toe of each wheel.

- Steering rate is set to 70% which means that slight movement on the steering wheel have little effect - which means that I am in the dead-spot zone. Also the problem is very evident when I am coasting ... this is with my hand away from the steering wheel.

Thanks for the encouragement!!!!

KnightAzul

 

[SkyMaxx]

Originally posted by KnightAzul

...
- One tie rod is shorter than the other, it is this way so that the wheels are aligned with each other. If both arms are the same length then there is a visible difference in the toe of each wheel.
...

This may be your problem right here. Are the turnbuckles physically the same size without rod ends? Are they supposed to be? When you say they are different lengths, is that with the rod ends on one being tightened on further that the other?

I only ask, because I am not 100% familiar with your ride's build.

Back to the issue at hand. If the turnbuckles are noticeably different in length, then you most likely do not have your servo centered properly in the servo horn (the thing the linkage connects to). If this is the case, you are already playing with an unbalanced steering set up.

What needs to occur is the turnbuckles being set at the same length with the steering linkage in a neutral (straight with no steering input) position. With this done, the servo horn should be attached to the servo with the servo set to a neutral position (meaning with power on the receiver, no steering input from the radio...trim or otherwise). From there, you should adjust your toe and trim according to your needs.

If the servo remains unbalanced as it sounds like it is, there will be drift as the servo continues to try and center itself.

If the problem continues, the shocks having differing strength in the dampening action can unbalance the steering.

Beyond that, I'd have to see some pictures...because this issue shouldn't be too difficult to resolve...yet we have been trying for some time.

 

[KnightAzul]

What needs to occur is the turnbuckles being set at the same length with the steering linkage in a neutral (straight with no steering input) position. With this done, the servo horn should be attached to the servo with the servo set to a neutral position (meaning with power on the receiver, no steering input from the radio...trim or otherwise). From there, you should adjust your toe and trim according to your needs

This has now been done and the turnbuckles are both 5.0 cm in length. They had 4 mm difference before: 4.8 and 5.2 respectively.

If the problem continues, the shocks having differing strength in the dampening action can unbalance the steering.

The problem with the front suspension was that whenever I push the suspension down it returns back to a certain position, however if I lift the front end a little then it doesn't go back down again all the way back to the same position. As a test I drained all of the 50 W oil out and installed the shocks again. Now it's ok, so I guess 50 W oil with the original springs is too viscose. I'll go for a lighter oil.

With all these changes hopefully (finger's crossed) things will improve!!
Thanks for all the help, and I'll let you know how it goes ...

KnightAzul