does anybody know the reason why my truck does this?
 

when im going less than 15mph, my truck will go straight down the path, but as soon as i hit the throttle, itll veer to either the left or right. ive asked this before, but maybe some others out there know the fix for this.
BUT besides that ok, even say i cant fix that problem, another funny thing it does is, so say it veers to the right, i would turn my wheel on my controller to the left a little bit, usually this would center the truck so that i can go straight, but no, my trucks then starts veering to the left!! why in the world??
please someone have the answer to my nightmare
just to let you guys know, ive put heavier diff oil and got true tracks, stiff springs but didnt solve this issue.

My best guess would be a sluggish servo. :yes:

You need a better servo, or a stronger servo saver spring!

is bad servo the cause for problems one or two? hmm..maybe ill try compressing the saver spring to that its stiffer and see if thatll help.
man , i spent lots and lots of hours trying to figure this out but now im totally stumped. like i dont even know what to replace even if i wanted to. dude ill even send $20 to the person that can solve my 2 probs. haha

Is it only when accelerating or while at a steady speed?
Does it do it on all types of surfaces?
It's an e-maxx is it? What tires?

Check for the ultra-obvious also, be sure you have no stripped hexdrives or missing drive pins.

It sounds to me like your steering servos are not syncing, which might be as simple as a faulty position sensor in one of them? Just a guess. I would remove one servo temporarily and see if the problem persists.

The 3905 rx has 2 outputs for steering servos, right?

If so, then try running one of each servo, with one horn or complete st. servo temporarily removed, but try the one connected servo in both of the rx steering outputs to rule out a bad rx/ rx connection.

its not really accelerating, but when accelerating at higher speeds. when i accelerate and stay under 15 mph...no problem but as soon as i wot or even half throttle, then itll start to veer to one side. yes it does this on all types of surfaces. its a emaxx with losi zombie maxx tires.
red shift thats funny how you said about trying one server and disconnecting it from the rx, cus my fren just offered me that advice like 2 hours before you said it. im going to try it out when i get a chance. i ruled out the obvious and the not obvious. i think i pretty much checked everything possible (that i know of) other than the servo issue, but i did check the inside of the servers to make sure theres no broken gears.
so far, it looks like everyone is saying its the servos fault.i really hope you guys are right. any other suggestions just so i have more options to look at?

this happened to me on my tc4...

mid to low speeds it would go fine..pull the trigger hard and it would veer off. I tried messing with my steering trim and everything, nothing was working.

a guy at the track come up to me and says "you need a new dogbone?, I got one if you need it" I was like "what?"

...He was talking about the cvd's/driveshafts.

I had popped a pin out of one of my front ones(broken it) and it would work at slow speeds but at high speeds it wouldn't spin as fast as the other...causing me to veer into the rails.
When I would pick the car up in the air, and pull the trigger, all four tires spun without issue. It wasn't until I started grabbing one wheel at a time that I found out the front one was busted. I could tell because the shaft kept spinning when I helt the wheel.....Frustrating as ****!

check to see if that might be it. if your'e running the stock sliders...one may be stripped

my truck has plastic driveshafts, its not cvds or metal dogbones. but ill try holding the tires to see if one still spins. so i just have my truck upside down, then hold one tire at a time, and the tire that im holding, the driveshaft is not suppose to spin right, only the remaining 3? will this twist my driveshafts though?

Well the best way is to take off all the wheels and give it a visual inspection. But if removing 4 wheel nuts is too much, then the way to do it is have it upside down on your lap and gently grasp both fronts, then both rears while someone else bumps the throttle slightly with the transmitter. This way you'll be certain all 4 are getting power.

If in all this you've never checked all the drive pins - its time.

While its upside down, take your 2mm driver and find the small half moon cutouts in the skids. There are 2 on each end, one on each side. This is the hole you tighten the drive axle drive pins through. Get a light and rotate wheel until you have the socket end of the drive pin lined up with the hole, make sure each one is tight.

I don't use these plastic 3.3 cvds for center drives, but now that you see what's involved, make sure you check them as well. I check my driveline prob every 6 or 8 runs, I might over do it, but its peace of mind.

so when i hold the two front tires and give it gas, what is it suppose to do? are the driveshafts suppose to still spin or be stuck? am i basically just trying to feel both tires trying to turn?

and i just checked all 4 drive pins...all were snug. thats another thing i didnt inspect (i thought i looked everywhere possible almost at least which is why im aksin you guys)

yeah.

I guess my main point was to see if all 4 tires were giving the same about of torque under load. I suggest putting the truck up on something with the wheels suspended(free to spin). While the trigger is being pulled (lightly...if you are by yourself you can try to turn up your throttle on your transmitter till the wheels just start to spin)anyway--if one wheel is easier to stop than the other three, then that is the wheel that is spinning slower and causing you to veer off under throttle.

by the way..don't hold the wheels so tight that you break anything...i merely meant for you to find a part that may already be broken

Is it the amount of throttle you apply, or the speed? If it's a speed-related issue, check your toe and camber settings. At high speeds, a little bit off makes it act funny. I just had to return my Slash suspension for this very reason.

just checked. all four giving same power. plus i just realized it cant be one tire not spinning as fast, cus if that was the case, it prolly would veer off to the same side everytime, but its actually random. and say if it was to veer off to the right, when i turn left on my remote and i mean just a little bit, instead of centering out like it should, now my truck would veer off to the left...sooo annoying! impossible to drive pretty much, but at low speeds it does not do this. and if it does veer off at low speeds i can just counter turn and itll center out.
brian- im pretty sure its at high speeds and not at the amount of throttle i apply. because if i applied a good amount of throttle from the start, my truck will wheelie and take off but itll still go fairly straight. i think its more of as the truck is going in higher speeds.
you maybe right about the toe in/camber but i had it running straight before. and i wasnt even accurate with my toe in/camber..i just eyed it.
but now, i made sure theres the same amount of thread showing on both sides so its pretty accurate.
and the front tires are even more toe in now so i thought that would help but nope. i mean i can try toeing them in like a crazy amount but the fact is, i didnt need toe in before so i know it doesnt need it. i mean worse comes to worse ill just toe in like 5 degrees haha. and still im not even sure if thatll fix my problem.

Generally, you toe IN the rear and toe OUT the fronts. And if this was the case, you'd most likely be veering in the same direction.

Also, check the foams in the tires. They can break up over time and get unbalanced. Also check the glue bonding the tire to the rim. It doesn't take much to mess up with tires spinning at high rpms.

That is how mine re-acted. It didn't correct itself if i counter-steered, it OVER-corrected itself. Even if I barely touched it.

...The difference is, Mine always steered to the right when I accellerated past 15-20 mph and when I countersteered to the left, it over compensated. It drove me nuts because I couldn't duplicate it at slow speeds to see what was happening.

Have you tried holding the truck up in the air and pulling the throttle to see if you have excessive wobble in the wheels. Or to see if one wheel balloons up more than the other? Or to see if the wheels turn?
Have you moved your steering while throttling the truck with the wheels in the air?

i have done this before. and now im traumatized lol. one day i flipped my truck and it was on its lid. so i decided to give it some gas just to see how much my tires ballooned. to my surprise, it ballooned a decent amount and i ductd tape my tires. i noticed that one tire ballooned alot more than the others and then....pop!! that tire got all unbalanced! unglued the tires to see that the foam had ripped in half. this all happened before my problems started.
since then, i replaced that one tire with new tires and foams.
so now when you tell me to do what i did awhile ago, im scared haha. i mean i can take it easy on the throtttle but i dont know when is too much, cus when i did it the first time, i wasnt even gassing too hard.
im really starting to think you guys are right, it miiiiight be the tires unbalanced. cus i just turned my truck over and i gassed it, all tires spinning good and balanced. but i didnt really gass too hard, the more i gassed it, my truck started shaking, but the tires were still straight. but this is no where as much throttle as i would give it if the truck was on the ground. so maybe if there was more throttle, i could maybe see some flaws with my tires...hmmmm.kinda worried to check that out. but we might got a good idea now...it could be the tires.

Thats easy to test - if it is the tires, swap sides with them - put LF on the right front and the LF on the right. Same for the back. Now it should pull left. Simple to test, should take little time.

I don't think its tires, as badly out of balance as some of what I've run have been, I've never had one act this way. More possible is BrianG's suggestion that toe is off. Unless trx has changed, they come with 0deg toe on front and 1deg toe in on the rear. Caster is set with caster blocks or spacers, are they still there and in the same place on both sides? Camber is the angle the tire makes with the vertical viewed dead on. These would have to be pretty far out of whack to cause your prob, so it should be readily apparent.

Drive pins - there is enough tension on wheel axles to drive a wheel until you reach enough speed that a missing pin will prevent that wheel from staying in synch with the others - then it will veer off straight line. Pins are all or nothing. If one starts to back out while running, it usually hits bulkhead and you'll def know it. I have seem then fly out and not touch anything, pin's just all of a sudden gone. Again, an easy thing to check and eliminate as a possibility. Have you checked all wheel bearings? Another easy thing to check that could be causing this.

innitally, it pulls to any side randomly, then which ever way i turn the wheel, itll pull to that side. so even if i switched the tires around, itll act the same way again, because it was not always pulling to that same side anyways.
i have the rpm arms in the front so i dont have caster adjusted. and the camber is showing the same amount of threads on my pillow bals so it should be the same on both sides. and the toe in showing the same threads on the turnbuckle.
and all drive pins are snug. ill trying adding alot of toe in on the fronts to see if that works. kinda sucks in a way cus i didnt have to use toe in before and it went straight. but id be happy that it goes straght again. out of curiousity, why wouldnt everyone run their trucks with alot of toe in. isnt it the more toe in the better steering? or does adding too much toe in decrease speed?

Increasing toe-in - increases straight line stability, decreases strg response, and increases strg mid corner and on-power corner exits.

Maybe important for racing, not much significance for bashing unless your straightline stability is poor the way its setup. My E and 2 Tmaxxes all run stock toe which is zero deg.

Are you still using the stock dual strg servo arrangement? Sounds like its time to call TRX and see what advice their CS folks have. I wouldn't be running it with both anyway - I never ran dual strg servos in my G2R. I 'd plug a 200inlb single servo in there, epa it properly and eliminate servo synch as any kind of poss prob. The way this sounds, this should be something simple, not some prob from hades that can't be solved. Its just not that complicated.

ill try the toe in for the fronts anyways. i also did this steering mod and i have yet to try it out. i ll be able to run my truck tomorrow. the mod i did was unscrew the screw in the reciever box for the servo saver side, then push down on the servo saver so that the spring compresses, not fully or your servo saver will not work but just a tad bit. and then screw back the screw in the reciver box while compressing the spring.
its prolly harder on my servos now cus it takes more effort for the servo saver to work, but less slop by like 30%.
and i also replaced the bushing on the left side to a ball bearing. im hoping it was just the sloppy steering.
if this fails then it is about that time to call traxxas CS. i will report back here with my findings.

I would recheck your alignment in back and front. This is for an emaxx right? I noticed w/ my Revo that since you have tie rods in both F and R, I had the F just a little misaligned to the L and the R a little misaligned to the Right, it would pull to different directions depending on the power/weight to what wheels. I'd use the trim to center it one way, and it would sometimes be straight... but then at other times it would pull.

it wasn't until I finally put it on a setup board and got it right did it ever track reliably for me. Eyeball method was never quite good enough for me.

test ran the truck again with toe in like -5 degrees in the front and -2 in the back because of the true tracks. still same problem. im starting to think its the servo saver. can you guys do me a favor, turn your truck over and look at the servo saver, the part that breaks in two, does it break/move around at all when you turn your tires from left to right. does it move as one piece? i mean just turn your wheels left to right to show the slop, not enough to actually turn the servo.

ok... I might be reaching here...

did you recently remove any of the arms?

I'm wondering if maybe you forgot to replace your caster adjustment shims.
Or if you changed the caster adjustment at all. You should have two shims in each front upper suspension arm.

If you have not messed with them, maybe try adjusting them to have 2 shims towards the rear of each arm. (they go on the inside to push the arm as far back as it will go)
...this should increase your caster angle to 10 degrees, making your truck want to stay in a straight line more. Also give more traction to the front wheels etc...
Stock is 1 front 1 rear giving you 7 deg. if you put them in the front you get 3 degrees
If you don't know what the heck I'm talking about ...look at pg20 in the manual; http://www.traxxas.com/PDF-Library/3905_manual.pdf
...they explain it better than I can.

its traxxas part # 5134


anyway....what i was thinking was that if you were missing them...maybe when you accelerate the arms are sliding around on the pins and messing with your steering control.

If I understood him correctly the other day, he's running RPM arms and they fill the spaces at the bulks and don't use caster shims. WIth RPM arms, you run what they built into the arms.

I may be reaching here...how about removing the stock plastic servo saver set and replacing with an aluminum set and heavy spring....

yea i have rpm arms and they dont require those shims. but i have the old rpm arms and they fit very snug onto the bulks. so what i did was dremel the part where it fits into the bulkhead (the hinge pins go through them as well).
if your saying that the shim is that important and will cause steering probs. i might have sanded one side more than the other! but then again, if this was the prob, i should have never been able to go top speed in a straight line, which i was able to like a month ago.
hmmm..i just checked my front arms and the top left arm do have some play. the other 3 are snug, but still free moving. i must have sanded that one a bit too much. dude, i wonder if this is the reason!! now how can i fix this? put a washer inbetween somewhere? the play is so minimal that the thinnest washer wont fit i dont think. but say it does, how would i know what side to put it on?
azjc-i decided last 9 that i was gonna get a new servo saver..but not a aluminum one cus i dont know anybody that makes a good one. i found some but people are telling me that will just bend, not good aluminum. this was gonna be my last straw, if the new servo saver fails, i was just gonna give up. i even called traxxas but he was no help at all, told me nothing i didnt know already, plus he sounded rude. i called again but same dude answered so i hung up on him haha.

I've put 2 sets of rpm arms on, a Tmaxx and Emaxx. I fitted them like you did - I used a drum sander on dremel until the arms were free to move under their own weight. Both sets have no back and forth play in the bulks .

If you have taken too much off one arm, get some washers and shim out the play. I would push arm forward and shim play out play in that direction. I think tyhat will come closest to matching the camber of the other arm. Ultimately, if its bad enough to be the cause of all this, need to replace that arm.

Sorry the trx jerk was a waste of time. I've had some good luck and some poor - ity depends on who you connet with and what kind of day he's been having, it can be hit or miss, some are incredibly helpful, knowledgeable, and patient. Maybe it was his day off??

What radio are you using? Sounds like a neutral resolution problem to me.

ill try and see if any shims/washers would even fit, if not, i can use some electrical tape. as funny as it sounds, ive used electrical tape on some jobs and it holds up great hahah.
ill just poke the hinge pins through the tape. ill report back when the results.
im using a old fm radio. it had no problems with my other vechicles with it though. what do i do to check the neutral resolution? i tried the steering trim, sub trim, and the epa

nope that wasnt the problem. i tried putting the washer front and back and didnt work.
i wanna say its the tires that is doing all this cus when i have the truck in the air, and give it throttle, my truck shakes a pretty good amount. so theyre pretty unbalanced. but someone said they have had some bad unbalanced tires in their days, and he never had this problem.
oh well, i guess ill have to live with this. thanks to everybody that contributed any help. i really do apppreciate the great tips and info, maybe it will help somebody else down the line.
BUT if you guys happen to think of something else, please post back on here.