Pylon80 4148 Posted September 11, 2021 I doubt diff setups cause cars to randomly veer off to the side I do remember starting off with a beautiful 30$ trackstar servo that would act completely randomly if you were giving quick input left-right-left for instance. Not that it would be the same problem that you have of course. Did you check how the steering responds when you're static? Then with the car in your hand or on some support block, when adding power would the servo move on it's own? I would check that first. The best would be to make a simple video as others have suggested. Can you find a wide open space with nothing to crash into? Also I'm assuming "crash" here doesn't mean traction rolling? Traction rolling is a different problem that you can sort out in due time when the car stops turning on it's one Best of luck! Share this post Link to post Share on other sites
Original Jardasius 97 Posted September 11, 2021 12 minutes ago, alvinlwh said: Yes, brand new with 4 other cars on it as well, without such a problem. All my cars seem to drift right somewhat when freshly built but can be sorted out by trim and finer adjustments. Definitely not a strong pull though! I had a servo that when I go from full lock to neutral, will go to the opposite lock before going to center, that servo is in the bin now obviously. EPA is set up, 85% IIRC. However, this is happening not during any manoeuvre, but a straight line speed test with no steering input. If the EPA's are setup correctly and a hard pull in a straight line from a dead stop it darts to one side or another is 95% of the time a diffirential problem>>> I would firsst yankout that diff flush out the ceramic grease and find a thick heavier grease... When the grease is too thin the grease can heatup and have a nasty effect of havin one wheel spin much faster then the other very smiliar to a limited slip in a car when you hit the gas and one wheel just spins like crazy..... 1 Share this post Link to post Share on other sites
Juggular 5111 Posted September 11, 2021 lol... I just noticed that the advices are all over the place, just like @alvinlwh's car. We all are trying to help, but I'm afraid we are not helping. Sorry @alvinlwh! 1 Share this post Link to post Share on other sites
Big Jon 704 Posted September 11, 2021 Sorry @alvinlwh! A spool is locked differential, with no way to compensate for different wheelspeed. The front wheels will be solidly locked together. Putty is very tight, provides for some shock absorption, but doesn't provide 100% solid locking. 1 Share this post Link to post Share on other sites
Fabia130vRS 2098 Posted September 11, 2021 To me it sound like torque steer. seting up the car geometry is badword of important. Also balnce weight. but probably torque steer and bad geometry with a loose diff (standard grease or too little) if you just have build it… take you time to adjust and measure things. if you dampers are soft that can also be a reason on smoothe surface I prefer harder springs. and in general I like to gear high my cars since I run brushless. So with little throttle I can drive it easy bust fast. I own a M05ver2. also… remove slop on steering and lower arms 1 Share this post Link to post Share on other sites
TurnipJF 10597 Posted September 11, 2021 3 hours ago, alvinlwh said: If it is binding, will it not be difficult to return to neutral after a right move? This is when moving straight ahead with no right command from the tx. Meaning it goes right with no command input. I doubt that it is the steering binding. I had a car doing something very similar to that when one of the wheel bearings was on the way out and and was binding under load. At low throttle the effect was not particularly noticeable, and at full throttle there was enough power being put through to overcome the binding, but at medium throttle the one wheel would bind causing the car to veer off in that direction. 2 1 Share this post Link to post Share on other sites
djmcnz 755 Posted September 11, 2021 Don't buy any new parts until you know what the problem is, especially a gyro which is surely unnecessary on a M chassis with a reasonable motor. As somebody mentioned on the first page, put it on a work stand and eyeball it under various throttle conditions, if as you say it happens regularly you should be able to see it happen. Prop the suspension arms up to normal ride height. Set your phone up to video the front wheels (on the stand) at 60+ FPS so you can slow it down if necessary. Swap everything left to right and try it again, does it veer left instead now? Everything that's not asymmetric e.g., shocks, links, bearings, wheels, tyres, everything. An unbalanced wheel might be impossible to diagnose unless you swap it to the other side and observe erratic behaviour following it (for example). That will eliminate said components which will allow you to narrow your focus. What about slop? Is it the same on both sides? Can you add shims if you do have some slop (which is almost inevitable on an M05)? Don't buy any new parts until you know what the problem is. 2 Share this post Link to post Share on other sites
dannymulder 1072 Posted September 11, 2021 If I where you I would look at the diff and rebuild it , I had that on a xv-01 that pulled always to one side rebuild the diff and the problem was gone, if thats not the problem then use another esc with an bec in it and if that does not work try another servo, yeh you have to try things to know what is wrong. I don't believe it is torque steer because you running a mild brushed motor in it, I am running an 4300kv brushless motor in mine and it goes as straight as an arrow and is very easy to drive, the only thing is that I have to be gentle on the throttle on startup to avoid a lot of wheelspin, but even with a lot of wheelspin it goes straight. 1 1 Share this post Link to post Share on other sites
Fabia130vRS 2098 Posted September 11, 2021 Also you can use touring car wheels on that body and get a much greater grip and over all handling Share this post Link to post Share on other sites
Matty36 267 Posted September 11, 2021 Also just in case it's not been mentioned, make sure the suspension is free in its travel, I had a lower spring cup on a buggy that was touching the wishbone and wouldn't allow the correct travel, and kept that side a bit lower so wouldn't centre itself. Make sure the mounting screws are not too tight, the top and bottom needs to pivot a bit. Share this post Link to post Share on other sites
Willy iine 18842 Posted September 11, 2021 I did not read the thread in detail, but sudden and random hard pull to the right/left is usually caused by glitching from either RF interference or unstable BEC power. I would replace the ESC first and if that does not help replace the receiver/transmitter. Share this post Link to post Share on other sites
Willy iine 18842 Posted September 11, 2021 Is that an open bevel diff? If so, that could be an axle, bearing problem on the right side (?). Anyway might be a good time to rebuild it...! Share this post Link to post Share on other sites
Original Jardasius 97 Posted September 11, 2021 Thats the diff for sure... Yank it and rebuild it a gear is prob binding check to make sure all flashing is totally removed its that or a chunk of somethin fell into the grease 1 Share this post Link to post Share on other sites
TurnipJF 10597 Posted September 11, 2021 Hard to say for certain without feeling how things are moving, but looking at how the wheel and CV appear to be moving slightly relative to the upright even when the wheel isn't rotating, I'd guess the diff itself is okay, but the bearing in which the right outdrive sits may be binding. That or the CV joint itself is stiff. Please let us know the outcome! Share this post Link to post Share on other sites
Willy iine 18842 Posted September 11, 2021 6 minutes ago, alvinlwh said: It is the stock diff (is that open or closed? Sorry still new at this) filled with "toothpaste like" ceramic grease (because I did not have AW grease when I built it). Open diff is basically a non-limited-slip-like action diff. But since you applied some grease to give the diff some resistance it's no longer an open diff. It's functioning more like a ball diff with simulated limited slip action. I don't know how much your grease is giving resistance, but there is definitely something odd going on outside the diff because that's quite a bit of resistance your right axle is giving. 1 Share this post Link to post Share on other sites
Original Jardasius 97 Posted September 11, 2021 6 minutes ago, alvinlwh said: One question about that CV joint, it came with AW grease, but most will say it is stupid to put that thick grease on the exposed drive train. Should I not grease it up then? Without grease it will seize and snap it in two... To properly grease it fully pull it out of the car and rotate it while you fold it to its max and slowly rotate it till you see the small gap and add a small dab into the gap, rotate it around a good bit then wipeoff the excess 1 Share this post Link to post Share on other sites