Always adjusting the Steering Trim

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KnightAzul

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RC Driving Style
Hi,

It seems that I am always adjusting the steering trim. I set it up so that it tracks an almost perfect straight line then about 10mins later the steering is off again, and it's back to the trim again.

Is this normal? How long would you expect it to track a straight line after setting the trim?

If the answers to the above are no it's not normal, and a long time, then what could be wrong?

Thanks for any help!
KnightAzul
 
i wouldnt use the steering trim on the remote. i would take the servo saver off the steering servo, center the servo(make sure the steering trim is at zero), make sure the tires are straight, then put the servo saver back on. if u got a cheapy servo, sometimes the servo doesn't center itself when u are driving. Also another thing to check out is the chamber links. they can be a factor on if ur vehical stays straight or not.

later
 
As far as I aware I don't have a servo saver installed. The servo is a HiTec HS-325HB which is not top notch by any means, but also is not bottom of the range (I stand to be corrected on this one!).

I followed the process as you described when I installed the servo: centering the servo and connecting the servo when the tires are straight. However, the trim was still required. Infact I seem to remember reading on this forum that it is practically impossible to get the steering spot on without using the trim.

KnightAzul
 
what i mean by the servo saver is the servo hornt hat goes on the steering servo. has a spring inside of it, to keep from stripping gears.

is the chamber adjusted correctly?

What kind of R/C do u have?

On my t-maxx, when i drag it down my road, seeing how straight it goes, it usually drifts a little to one side or the other, but it doesn't bother me though, because i just bash with my t-maxx, going perfectly straight doesn't bother me. But i could see if u race on-road cars then yeah, its important. here is a article about adjusting chamber. http://rcnitro.com/rn/articles/ht_camber.asp

later
 
Hi Maxx Trooper,

I have a RTR Thunder Tiger TS-4n. I've noticed that the right shock is leaking a little oil. This may not be the reason why my steering constantly needs correcting, but given this, coupled with the fact that I don't have much clue about how the steering is put together (horns, springs, etc) I'm going to do a rebuilt of the front steering and suspension (this does bring into question whether an RTR was the right way to go in the first place!).

Are there any good webpages which explain how it's all put together - complete with nice diagrams and hints and tips, as the manual which came with the car is as user friendly as a cornered rat.

Any good recommendations for hop-ups in this area? since I'll probably be breaking some things on the way ...

Thanks,
KnightAzul
 
Is anything loose in your front end. Without engaging your servos can you turn your wheels? Is so you might have a few loose screws which are your cause.
 
I'm not really fimiliar witht he Thunder Tiger. so I'm gona have to pass on this and have someone else help u, cuz i ran out of ideas that could be wrong.

later
 
Originally posted by El Pirata
Is anything loose in your front end. Without engaging your servos can you turn your wheels? Is so you might have a few loose screws which are your cause.

I can turn the wheels (by hand) easily from full lock to full lock without engaging the servo. I take it you mean that the servo is not engaged when it has no power? Any particular screws in mind?

Too add a little more info ...

Being a relative novice I was a little trigger happy and sent the car head on into a kerb (not too fast mind!). The steering was then off centre by a long way, however centering the wheels by hand the servo seemed to find it's centre position correctly again and has not been a problem since.

How can I tell if the servo is shot?

KnightAzul
 
If you are constantly having to adjust your steering trim, there could be a number of issues that cause this.

1. The leaky shock could point to softer suspension on that side and a tendancy to steer to that side.
2. Weak servo could be going. As servos die they tend to lose their alignment and drift. This would cause the phenomena you describe.
3. Any other number of loose parts in the front steering assembly could also cause this problem.
4. Are the tires evenly weighted and secured to their rims? Just like full size cars, RC tires that are out of balance will affect steering. If one is waterlogged and the other is dry, the steering will pull to the heavier tire (the waterlogged one).
 
Last night I finally plucked up the courage to start dismantling the front steering and suspension ... and it looks like I've opened Pandora's box!

- One of the front suspension arms was leaking oil like there was no tomorrow. I can't really tell why though. After taking it completely apart there doesn't seem to be any seal to replace. Looks like I may have to buy new ones.

- The upper arms were not of exactly the same length (the arms with the ball cups at the end). Upon further investigation, the wheels supports were at slightly different distances from the struts. Aparently there should a gap of 3mm on both sides, which was not the case. (tut tut ... RTR indeed!)

How do I accurately measure a 3mm gap? Do you guys use feeler gauges or someother mechanism for accurate (largish) gap measurements.

Thanks for any help,
KnightAzul
 
You could use a credit card and go just a hair larger. A credit card thickness is between 1 and 2mm.

Or you could get your hands on a micrometer.
 
It took some time, but the end result of fixing all of the following items is that my steering still never seems to track a straight line:

- Fixed front shock leaking oil, and at the same time took the opportunity to replace the oil in all 4 shocks.
- Replaced the steering servo with a brand new one.
- Aligned everything on the front steering and wheels.
- Fixed any loose parts in the front steering assembly.

It still veers one way or the other depending on the trim, but never a straight line. One odd thing is that sometimes it seems to track a straight line after a trim adjustment, I then turn her around and immediately on the way back it veers to one side. Argh!
I have tried swapping the wheels also which didn't seem to do very much. BTW: How can I test that the tires evenly weighted?

I have noticed that the front wheels when turning seem to be wonky, especially on the right side (this also could be an illusion with the tires being stuck onto the rim slightly misaligned). Why could this be?

- Could it be that the plastic rim somehow has become deformed? I would have thought that it would snap being plastic, rather than deform.
- A sign of tire wear (the tread is still more or less ok)?
- Could this be a bad toe, camber, etc setting.

Desperately in need of help ...
KnightAzul
 
What kind of toe settings do you use? What kind of alighnment?

I had a big problem with keeping my stadium truck pointed straight on high speed runs.

What I did was to add a bit of toe in on the front suspension (very little) my front tires point like this (very subtle)
Code:
 /------\
   |  |
   |  |
|-------|

MY front tires also lean in at the top (camber?)

This lets my front tires "self center" meaning that if their is a little slop in the front end, both the front tires pull toward the center. This makes the tires return to the same position after turn.

It may not be pefectly alighned but at least I can keep the trim in the same spot for at least one run. It also helps handling for my driving style.

If your trying oto get the tires perfectly vertical, and perfectly alighned, I think you will have troubles. Due to the inherent slop in a r/c, and the rough terrain pounding the front end.


Hopefully others will chime in, my stadium truck is two wheel drive. It may not work the same for a four wheel drive buggy.
 
Actually lykan you have hit the nail on the head. I was trying to get the tires perfectly vertical, and perfectly aligned ... which I guess as you say is practically impossible.

I have a 4 wheel drive touring RC car (Thunder Tiger TS-4n RTR) which I run only on tarmac. However, the setup you suggest with the toe in for the front wheels makes good sense.

Anyone can confirm this for a 4 wheel drive??

Thanks!
KnightAzul
 
Just to let you know, the toe in will also mprove your steering response. How did I find out about it you ask (heheh). I mention this because you say your running on a tarmac.

I couldn't turn for Sheeit! The tires would turn, but instead of tight turns, it was king wide sweeping turns at anything over a snails pace. I mean big 6 foot circles instead of sharp 90's .

I found that little bit of toe in made it very responsive. Too much toei in, and your car will 180 with a 1/4 turn of the wheel.
 
After reading an excellent article: http://www.rcnitro.com/rn/articles/tweak.asp

It would appear that a "Hudy Setup Board" is an essential for toe, camber, caster, etc setup.

Is this what you guys use, or is there a DIY approach which would be sufficient for a newbie ...

Thanks,
KnightAzul
 
The saga continues and my motivation has taken a sharp nose dive ... it still veers of to one side no matter what I do/change.

On hard acceleration it tracks a straight line more or less. However, coasting and constant speed the problem is a lot more evident.

I poured even more money into the car, investing a Huddy Board so that I could accurately set Toe, Camber, Caster etc. I have setup that car with the following which goes along the lines of the manufacturers recommendations:

Ride Height:
Front 5 mm
Rear 6.5 mm

Front Caster: Maximum caster (20º) on R + L with all clips forward
Front Camber: -2º R + L
Front Toe: -1º R + L (toe-in)

Rear Camber: -2º R + L
Rear Toe: -2º R + L (toe-in)

The only things that I have left to do which may solve this problem, are the following:

- The guy at the shop recommended setting the front toe to toe-out by 1º. I am hesitant to do this since everywhere I have read that toe-in is for straight line stability and not toe-out. Is this true?
- The front suspension is a little suspect in that when I lift the car up and put it back down again the suspension remains above the point at which it would be if I was to press down and let it push back up by itself. I.e with the current setting the weight of the car is not enough to compress the spring. I look into this, this evening ... could this be the cause of my problem?

Any advice would be greatly appreciately as I coming to the end my patience!!

KnightAzul
 
Well, the spring thing you mentioned. This is the nature of the beast.

Your camber I thnk (tilt in and out of vertical) will change with suspension travel. Meaning if you hit the gas, the front lifts.

This means the A-arms drop downward. The further the A-arms drop, the more evident the problem becomes.

When at full articulation they end up like this \----/ The bottom of the tire pointing drastically inward.

Thos happens whe you throttle hard, the front lifts, the A-arms drop. If your buggy is not heavy enough to reset the suspension to its correct (depends on your preference) ride height, thnen yo;re gong to be way our of whack.

When you set the buggy up it will look like this |---| the second

you hit the gas the front lifts you end up with this \----/

If you hit a jump .. and the springs compress and dont rebound you end up with this /----\



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.
 
Bit of a newbie here but thought I would throw in my 2 cents.
Did you happen to pull apart the sterring servo.
When I bought my original T-Maxx the first thing I broke were teeth inside the servo.

Later
Whistlre
 
I had the luxury of being able to swap between two new servos on the steering and the problem is exactly the same on both.

I'm gonna bet my bottom dollar too that as lykan says it's the suspension setup. I'll look into this tonight.

What is recommended for the front for straight line stability - toe-in or toe-out - I have read various conflicting posts, so this may be a car/track specific question ...

The good thing to come out of all this is that I have nearly completely dismantled the RTR car and put is back together again, and learnt a hell of a lot along the way ...

KnightAzul
 

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