Steering Centering Problem
 

I know that this subject has been beaten to death but I need some help here. I have an HPI RTR 4 /3 Evo and the wheels don't seem to straighten after turning. I though I had a bad servo so I have replaced it with a Hitec high torque servo (analog). Its a little better but not perfect. I adjust the ST trim even a little to center and the wheels seem to point slightly either to left or right after steering depending on which way I adjust the ST trim. Doesn't really look like a big steering problem until I drive this car on a flat surface and it just flys off to left or right and ST trim don't seem to center it perfectly. What can I do? I even loosened the bolt that holds the steering arms to make the wheel turn smoother thinking maybe its not returning to original position because its getting stuck. But still not perfect. Any suggestions would be appreciated.

1st: check out your transmitter setting is not the culprit ie. no bad setup. Make sure your radio equipments are working properly, especially the servos.

2nd: make sure you don't over tighten the Knockle Arm Adjusting Nut. Its silver hexagonal nut that push pivot ball inside the arm.

The best way to check is by removing the steering linkage from servo and check for free steering movement left and right. Ditto with suspension arms moving freely up and down without suspension.

Make sure these :

http://www.3racing.com.hk/Image/V3R/V3R011_s.jpg

Don't push / overtighten these :

http://www.3racing.com.hk/Image/V3R/V3R012_s.jpg

The rs4-3 doesn't have pivot ball suspension so that wouldn't be the problem.

A3, you need to isolate the problem. Disconnect the linkages and rotate the steering bells to make sure they are rotating smoothly. Same with the steering knuckles. Somthing is binding. I am assuming that your servo is working properly although you can check that too. Turn your radio and receiver on and try to turn the servo horn. Does it move? turn the wheel on your radio and make sure the servo is operating smoothly.

Low battery ?

weak servo saver?

No offence to Hitec but Many drivers here in Oz including myself have encounted the same problem. After going through the whole front end we were still having the same problem. In the end we changed the servo to something at the top end of the market and found it was fine. We could only put it down to the hitec servo. After talking to a friend of mine who works in a hobby store he said "your not the only one with the same problem" and suggested to spend a little more on this servo and you will have no probs.

Thank you all for your input. I have tried to isolate the problem. The linkages and steering bells are smooth and it doesn't seem to be binding anywhere and all batteries were even replaced. The horn on the servo doesn't seem to move when pushed by hand while the power is on and I am assuming this is a good indication that the servo gears are not worn already. I tried to see if there was an inexpensive fix for this steering problem but I may try going with a little more expensive servo if all fails. What servo do u guys recommend? Do I go with a high torque or high speed servo for steering? And what are the benefits of digital servos other than just being very accurate? I do not plan on racing anytime soon and right now I am mostly a parking lot basher. =)
Oh and by the way, I have noticed something strange the last time I ran my car. When I try to do small donuts at WOT it doesn't seem to do it anymore. The donut (circle) is not tight and keeps getting larger and larger and no longer tight. Is this an indication that my clutch or my tranny needs replacing? I have checked the teeth on the spur gear and they seem to be intact. What are the visible signs of a worn out clutch? Any input is much appreciated.

Which Hitec servo do you have?

I have the Hitec HS-645MG Ultra torque servo. And it seems to function fine I think. Do you think that this might be the problem?

The HS-645MG is an upgraded basic servo.


If you wish for the performce of the $$$$ servos without the big $$$ checkout:

The HS-5925/HS-5945 or the new Karbonite or Ti servos.

I really don't think its the servo. I use that same steering servo on 2 r40's and they have worked fine. Before that I had them installed in an RS4-2 and a racer2.

drfritz brings up a good point. Reattach all of the steering linkages and put tires on. Turn on the radio and reciever. Then wiggle the front wheels gently and see how much play you have. Now try and turn the wheels left or right harder to see how much force is needed to make the servo saver kick in. You shouldn't have too much play and it should take a good amount of force to make the servo saver kick in.

Are the front toe settings okay?

You guys..the lower end hitech servos are junk..Roy if you have a 645 and dont have centering problems your one of the few,I would go with any mid to top line servo from JR, Futaba,Airtronics,KO,I'm just not sure on the high end hitec stuff,right now I'm trying one of their digtal servos(5925)so far so good,But i have allways had good luck with Airtronics(94357,94358,94359),JR's mid range 590's and 650's,Futaba 9404's and the 9550 digtal.If you have NO binding and the linkage is fine,That leaves two thing..THE servo saver and the servo,I would change the servo saver first(I dont run them my self)I would bet its the servo saver causing most of the centering problems..That and maybe the servo,the 645's are known for their centering issue's..:nod:

Re: Steering Centering Problem
 

Had the same problem with top Hytec servos.
Good digitals will return you to the center position every time. My choices are the Futabas and /or KO Propos.

The other thing is, any sloppiness (play) in the steering linkage will cause an apparent failure to center on the set up gage by the amount of play in the system. Since the front suspension is self centering, this is not apparent when driving, as the wheels will self center to neutral, and the servo also returns to neutral.

Used to suffer the same problem with Hitec servo's thought it was my car... ended up trying three different servo's cause there figures are great for the price... but thats where it stops and still the same problem.

I only run Ko digital servos now, and there is no comparison - you get what you pay for. Even the low budget servo's that come with radio's i found better.

Get yourself some Ko's and Ko the problem ;)

I agree with most of your posts about the durability of Hitec servos. I think mine lasted because they were used for years in light weight cars like the rs4's. I got the R40's a few months ago and have only run in a few races with them. I keep a real close eye on the servos though and have been looking around at the Futaba S9550's. So far the 645's have held up although I have had issues with the micro servos in my micro RS4. The other reason I havn't bought new servos is that one R40 is for me and the other for my son. They are set up pretty much the same, and we race in different classes. So I figure there is always a back up car.

I just think that for A3, the Hitec servos could be a good option. He doesn't race so he won't lose a race because is car wouldn't steer correctly. It really depends on his budget though. I agree that better servos are a good investment. I know when I started, I really needed to get the cheaper servos. Now I have the money (but not time enough to race) to upgrade. Hitec also has a good warranty program. You just gotta wait till they send it back.

I have not used the new futaba digital servo's as i'm on a good thing with the ko-propo digital ones, but i have heard nothing but good things about them so far, and they are cheaper then the ko ones as far as i know.

i dont know if weight is the problem with the hitec servo's, i have a small hitec in my yokomo 1/12th scale and have no end of problems with centering issues especially down the straight aways when the last thing you want to be doing is correcting at 12th scale with a 10 turn motor... almost impossible your hit the wall before you even think about where your going :/ maybe some are good and some are bad... like a lotery, if your one of the lucky 20% that get a good one... keep it lol

The servo saver I have is the one that came with the car. I have not upgraded to a better one since I didn't know this would cause such problems. What kind or brand servo saver should I buy? Any recommendations? I will try this first and if this doesn't solve the centering problem I will look into a new servo. Thanks alot guys for all your responses and keep em' coming....=P

Were you able to check the servo saver? You could just replace the worn one with another stock unit. Kimbro (sp?) is probably your best bet for a combo servo horn/servo saver. Make sure that the servo saver is causing the problem first though. In a pinch, you could put CA in your old servo saver to lock it up. Just don't hit anything! :lol:

I ran JR 590's in a XXXS and never.. I mean never ran a servo saver,just a horn.I never had any problems with the servo(I did keep a spare in the tool box..:lol: )I did hit "things", I race and it happens..:lol:

Well whatever the problem was I think I have fixed it. I was parking lot bashing with my friends the other day and the car got away from me and hit a curb at full throttle. It flew up in the air and I saw parts flying off everywhere. When I checked for damage the whole left side was gone, that piece of plastic crap they call a "tuned pipe" was shattered and the chassis was warped. The engine seemed fine though, just a small piece had chipped off the heat sink. So i went on line and decided since I have to fix all of these things anyway why not upgrade at the same time? So I bought a new chassis (wanted the super chassis but a little more than i wanted to pay), all the parts for the front suspension with titanium turnbuckle set, carbon graphite front, back and mid deck. I also invested in a RD logic tuned pipe (chrome). My RS4 looks really great now and after I rebuilt everything I just adjusted the camber, toe and caster. Now it centers like it's supposed to. I think what it was that caused the not centering problem was the POS plastic linkages that comes with the car. Thanks all for your input.

Taking everything apart, inspecting and then reassembling the car will allow you to fix almost any problem. If you don't take it apart you can't see many of the parts. I used to try to avoid doing this and spent many frustrating hours trying to figure out my problem. If I only had spent 20 minutes taking it apart, I could have found the problem quickly.

Dissasemble, inspect, replace bent, broken, or damages parts and reassemble and 99% of the time, your problem will be solved.

Thanks for posting that you figured out the problem.

Well there you go, I would have put money on it being the Hitec servo. I have had one good one in 5. Futaba all the way.