In need of help. my car wont drive straight
05-30-2014, 12:09 AM
#16
05-30-2014, 12:19 AM
#17
I have toe-in on the front end.. And i was told at the hobby shop to run -3 camber all the way around..I wil post a pic asap
05-30-2014, 12:25 AM
#18
M 2 pennies worth. Disassemble the entire car, clean and inspect every part. Anything cracked, broken, or stripped out gets replaced. Check the bearings to see if they are gritty. Slowly rebuild the car, ensure screws arent over-tight and everything moves freely, but doesnt have slop. Check servonlike mentioned above. If these steps are followed, and issue still persist, then you just have a ghost in the machine.
05-30-2014, 12:35 AM
#19
If it pulls to one side under acceleration only, it has to be unequal power distribution. IE one wheel is getting more power than the other.
This might be caused by
Differential
CVD's or Dogbones
Binding of CVD or bearings
uneven tire wear
Body rubbing against a tire
Disconnect your driveshafts from the differential. Do both turns spin freely?
With driveshafts connected place a piece of tape on top of each wheel on that axle and turn over the belt/driveshaft. Do the wheels stay in sync or is one going faster than the other? IF so it might be diff.
Something as simple as putting your tire on too tight can cause this.
This might be caused by
Differential
CVD's or Dogbones
Binding of CVD or bearings
uneven tire wear
Body rubbing against a tire
Disconnect your driveshafts from the differential. Do both turns spin freely?
With driveshafts connected place a piece of tape on top of each wheel on that axle and turn over the belt/driveshaft. Do the wheels stay in sync or is one going faster than the other? IF so it might be diff.
Something as simple as putting your tire on too tight can cause this.
05-30-2014, 01:01 AM
#20
05-30-2014, 02:55 AM
#21
Tech Regular
To add the list that the other guys already gave you, check toe on your rear. If toe-in on left rear is 2 degrees and toe-in on right rear is 2.3 degrees, this can cause the problems you are facing. Re-align your toe on the rear. Very important in your case!
Also, check toe on the front, if the toe value is quite extreme (beyond 1 deg or -1 degree) your car start to "search"...
Check the servo horn and see if some gears are stripped. In case of servo saver; replace your saver and install a good quality saver.
Also, CLEAN your RECEIVER with a clean brush. It may occur that there is some glitch in the receiver and it can cause strange/unexpected behaviour of your servo.
Make sure the wheel hexes move free and do not rub any hubs or bearings. If there is too little space between the wheel hex and hub, the hex will rub against the hub and will cause problems you won't notice easily.
Just make a list of all the things the guys before me have said and I am sure your problem will be solved.
So:
Equal size tires
Bearings
Binding parts
Equal shock lenght
Equal filled shocks (rebuild completely)
downstops
GLUE the tires all around!
check steering linkage
Check diff (do not use too much grease on your ball diff)
CVD/dogbones
Front or rear belt stripped or skipping
Front belt too loose compared to rear belt
Replace broken bulkhead/parts
And all above I recommended.
Also, check toe on the front, if the toe value is quite extreme (beyond 1 deg or -1 degree) your car start to "search"...
Check the servo horn and see if some gears are stripped. In case of servo saver; replace your saver and install a good quality saver.
Also, CLEAN your RECEIVER with a clean brush. It may occur that there is some glitch in the receiver and it can cause strange/unexpected behaviour of your servo.
Make sure the wheel hexes move free and do not rub any hubs or bearings. If there is too little space between the wheel hex and hub, the hex will rub against the hub and will cause problems you won't notice easily.
Just make a list of all the things the guys before me have said and I am sure your problem will be solved.
So:
Equal size tires
Bearings
Binding parts
Equal shock lenght
Equal filled shocks (rebuild completely)
downstops
GLUE the tires all around!
check steering linkage
Check diff (do not use too much grease on your ball diff)
CVD/dogbones
Front or rear belt stripped or skipping
Front belt too loose compared to rear belt
Replace broken bulkhead/parts
And all above I recommended.
05-30-2014, 04:54 AM
#22
What do you mean power or coasting? When I drive at a costing speed it gradually will pull left. Then if I gun it,it will slam me to the right...
I have toe-in on the front end.. And i was told at the hobby shop to run -3 camber all the way around..I wil post a pic asap
I have toe-in on the front end.. And i was told at the hobby shop to run -3 camber all the way around..I wil post a pic asap
05-30-2014, 07:52 AM
#23
What weight oil or grease you got in the diffs?
05-30-2014, 07:53 AM
#24
http://www.rctech.net/forum/electric...-sows-ear.html
You should take a look at this thread for HPI Sprint 2 help, there was so much covered!!
You should take a look at this thread for HPI Sprint 2 help, there was so much covered!!
05-30-2014, 04:18 PM
#25
All of the above mentioned should be checked. There's really no way of telling until somebody knowledgeable looks at the car. But As Geezatec mentioned, you should tell us when it happens first. It sounds like it starts turning to left as you pull the throttle from the dead stop and, as you put more throttle, it starts turning right. Am I correct?
If so, it sounds like the car deserves a total tear down and rebuilding. The veering to one side at the beginning of throttle, so called "torque steer", usually happens to one side and as the speed goes up to almost or full throttle, it starts going to a certain direction as the the front tires are heading (unless there's some sort of binding in one axle where the car goes to left when the front tires are heading to right in an extreme situation).
As gentlemen mentioned, I would check all drive trains first for binding such as bearing, diffs, belts, tires, dog bones, etc,.
Tweak is not something you can just see by looking at the car. And it does cause torque steering. If the chassis is bent already, you will have to get a new chassis. To find out, 1. Take off tires 2. Lay the car on setting board or something very flat like glass 3. Gently push down each 4 corners of the car to see if there's any tipping. If there is, 4. As mentioned above, unscrew all screws at bottom of lower chassis and upper chassis and tighten them in pentagram order (i.g. left front->right rear->left rear -> right front) 5. then check again for tipping. 6. If it continues, possible irreversible tweak on chassis.
Before deciding to purchase a new chassis, you gotta check for drive trains to eliminate other causes cuz, well, buying a new chassis is more money right?
Then check droops as well since it can also cause torque steering. 1. With tires attached, lay the car on set up board 2. Grab the middle of front shock tower and slowly lift the car 3. If both Lt and Rt leave the floor at the same time, then you're good. If not, adjust droops to make it happen. And do the same in the rear. One perk of this.. You need to check for the tweak on the chassis and weight between Lt and Rt before this.
Lastly, set up the car. Camber, toes, right height, etc.. They don't need to be optimal setting for the track. Just make them equal between left and right. If you don't have set up tools, just eyeball them for now. Make'em at least look similar to each other.
Do all of these in repetition until everything is right. Then run the car to check. Like a gentleman said above, the best bet is to take it to local track and ask around if you can't resolve the issue. Hobbyshops, especially the big franchises, won't help you much even if they know the answer. They won't invest that much time on your car unless you pay them for it.
If so, it sounds like the car deserves a total tear down and rebuilding. The veering to one side at the beginning of throttle, so called "torque steer", usually happens to one side and as the speed goes up to almost or full throttle, it starts going to a certain direction as the the front tires are heading (unless there's some sort of binding in one axle where the car goes to left when the front tires are heading to right in an extreme situation).
As gentlemen mentioned, I would check all drive trains first for binding such as bearing, diffs, belts, tires, dog bones, etc,.
Tweak is not something you can just see by looking at the car. And it does cause torque steering. If the chassis is bent already, you will have to get a new chassis. To find out, 1. Take off tires 2. Lay the car on setting board or something very flat like glass 3. Gently push down each 4 corners of the car to see if there's any tipping. If there is, 4. As mentioned above, unscrew all screws at bottom of lower chassis and upper chassis and tighten them in pentagram order (i.g. left front->right rear->left rear -> right front) 5. then check again for tipping. 6. If it continues, possible irreversible tweak on chassis.
Before deciding to purchase a new chassis, you gotta check for drive trains to eliminate other causes cuz, well, buying a new chassis is more money right?
Then check droops as well since it can also cause torque steering. 1. With tires attached, lay the car on set up board 2. Grab the middle of front shock tower and slowly lift the car 3. If both Lt and Rt leave the floor at the same time, then you're good. If not, adjust droops to make it happen. And do the same in the rear. One perk of this.. You need to check for the tweak on the chassis and weight between Lt and Rt before this.
Lastly, set up the car. Camber, toes, right height, etc.. They don't need to be optimal setting for the track. Just make them equal between left and right. If you don't have set up tools, just eyeball them for now. Make'em at least look similar to each other.
Do all of these in repetition until everything is right. Then run the car to check. Like a gentleman said above, the best bet is to take it to local track and ask around if you can't resolve the issue. Hobbyshops, especially the big franchises, won't help you much even if they know the answer. They won't invest that much time on your car unless you pay them for it.
05-30-2014, 08:18 PM
#26
There's 2 common ways to do that. 1 way is to use a piece of a plastic bag and put it on the ball stud before you snap the rod end on over it then trim away the excess. My favorite only works with closed rod ends like the Sprint 2 comes with...use a little bit of cotton inside the ball cup. Keep adding cotton until the slop is gone but the ball cup does not bind.
05-30-2014, 08:38 PM
#27
You had posted enough, Now post some photos.
05-31-2014, 05:19 PM
#28
One other suggestion. Ditch the plastic bushings in the steering assembly for ball bearings. There's LOT slop of introduced as those plastic bushings wear over time. Your looking for bearings with the following dimensions...
Inner diameter: 4mm
Outer diameter: 8mm
Thickness: 3mm
http://www.bocabearings.com/bearing-...9/4x8x3-MR84ZZ
Inner diameter: 4mm
Outer diameter: 8mm
Thickness: 3mm
http://www.bocabearings.com/bearing-...9/4x8x3-MR84ZZ
06-01-2014, 04:54 AM
#29
Dude, you're confused big time. You flip flop from asking guys at hobby shops and then coming here and then going back and so on. This isn't working. You have to stick to one algorithm and take it step by step, otherwise you'll bve chasing your tail forever.
Best way to do it is to work on the car yourself and take out variables one by one. All the possibilities have been covered already. Now you have to think about things and figure out a way to experiment at each step to see if you're going in the right direction or shooting in the dark. Just to let you know, posting pictures here won't help you either because it's very unlikely we're going to see anything at that scale.
But here's a suggestion. When I have a problem like that, I take out the drivetrain from the equation by disconnecting the motor (take the pinion out) then with the radio on and the steering straight, I roll the car along to see if it goes straight. If it doesn't there's obviously a problem not to do with the drive train (you can take the belts and diffs out as well, but I would be pretty confident to say the problem would be elsewhere). If the car does go straight, then you have to look at diffs, bearings, etc.
Back to the car not going straight with the motor disconnected, I would swap wheels left to right first to see if they're the same diameter. One end of the car at a time. You're not going to see with the naked eye the difference if there is one. But if now the car veers the other way, you nailed it. Get some new wheels and tires.
If the car still goes to the same side, check you toe left to right both front and rear, and make sure the servo is centralised correctly, tie rods equal left to right (this is actually adjusted first, then you add some toe out as needed, keeping the tie rods equal).
And no, I don't think tight tires can do much. I have wheels which are badly damaged and the car still goes straight as an arrow.
Also, get rid of the tow in on the front. your car will wander like crazy at speed. Get some toe out , a degree or two per side should be plenty. At the rear, you will see most people run about 3 degrees overall, max 3 degrees per side. That's enough.
About camber, I would say give it up for the time being, run zero until you figure out the problem and then you can tune to the track.
Last point, if you have crap tools to set all these, you're going to have a hard time achieving anything. A Hudy or similar setup station is expensive but worth the money. I guess if you had one, you'd have figured the problem on your own by now. Maybe you can borrow one and the owner can help you use it.
My experience shows that twak and all that stuff, suspension, etc is very important but you can dial it out without actually fixing the problem. By that I mean it will never be a serious problem (unless it's really serious, and then you can see with the naked eye the problem). The crucial points to cover are wheels, wheel bearings, transmission (diffs/diff bearings).
And yes, someone already pointed this out, pinching your hub bearings is easy and it will result exactly in this problem you have plus it will ruin your brand new bearings. Perhaps start by replacing (again) the wheel bearings and don't be ham fisted when you do up the wheels. Or better still, use aluminum clamps, check there is a bit of longitudinal play in the axles (bearings not pressed against), and even use bearing spacers in the the hub (my preferred method).
Good luck.
Best way to do it is to work on the car yourself and take out variables one by one. All the possibilities have been covered already. Now you have to think about things and figure out a way to experiment at each step to see if you're going in the right direction or shooting in the dark. Just to let you know, posting pictures here won't help you either because it's very unlikely we're going to see anything at that scale.
But here's a suggestion. When I have a problem like that, I take out the drivetrain from the equation by disconnecting the motor (take the pinion out) then with the radio on and the steering straight, I roll the car along to see if it goes straight. If it doesn't there's obviously a problem not to do with the drive train (you can take the belts and diffs out as well, but I would be pretty confident to say the problem would be elsewhere). If the car does go straight, then you have to look at diffs, bearings, etc.
Back to the car not going straight with the motor disconnected, I would swap wheels left to right first to see if they're the same diameter. One end of the car at a time. You're not going to see with the naked eye the difference if there is one. But if now the car veers the other way, you nailed it. Get some new wheels and tires.
If the car still goes to the same side, check you toe left to right both front and rear, and make sure the servo is centralised correctly, tie rods equal left to right (this is actually adjusted first, then you add some toe out as needed, keeping the tie rods equal).
And no, I don't think tight tires can do much. I have wheels which are badly damaged and the car still goes straight as an arrow.
Also, get rid of the tow in on the front. your car will wander like crazy at speed. Get some toe out , a degree or two per side should be plenty. At the rear, you will see most people run about 3 degrees overall, max 3 degrees per side. That's enough.
About camber, I would say give it up for the time being, run zero until you figure out the problem and then you can tune to the track.
Last point, if you have crap tools to set all these, you're going to have a hard time achieving anything. A Hudy or similar setup station is expensive but worth the money. I guess if you had one, you'd have figured the problem on your own by now. Maybe you can borrow one and the owner can help you use it.
My experience shows that twak and all that stuff, suspension, etc is very important but you can dial it out without actually fixing the problem. By that I mean it will never be a serious problem (unless it's really serious, and then you can see with the naked eye the problem). The crucial points to cover are wheels, wheel bearings, transmission (diffs/diff bearings).
And yes, someone already pointed this out, pinching your hub bearings is easy and it will result exactly in this problem you have plus it will ruin your brand new bearings. Perhaps start by replacing (again) the wheel bearings and don't be ham fisted when you do up the wheels. Or better still, use aluminum clamps, check there is a bit of longitudinal play in the axles (bearings not pressed against), and even use bearing spacers in the the hub (my preferred method).
Good luck.
06-01-2014, 04:55 AM
#30
double post
Last edited by niznai; 06-06-2014 at 12:49 AM.
