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Old 03-16-2017, 02:27 PM   #136
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Unless your droop is way off, you may want to spend some time balancing the weight bias on your chassis (front/back & left/right).

TC4 was designed with brushed motors and 6 or 7 cell round cell packs in mind. If you are running a heavy motor and a light lipo, you may not have enough static weight on the left rear to balance out the weight of the motor. You can use the shock pre-load collars to get an even chassis ride height, but if the chassis isn't balanced at least one of the shocks is going to have more pre-load.

A quick way to tell if your car isn't balanced left/right is to measure the distance between the shock collars (the top part that the spring touches) and a fixed point on the car like top shock screw. I bet you will find that one side is different than the other.

While torque steer will always be an issue on a shaft drive car, it isn't as big of an issue that some people make it out if you are running a brushless motor. However if your chassis isn't properly balanced, any torque steer that you do get will be magnified.

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As far as drop, there is no magic number. Just make sure that it is the same at each end of the car. The easiest way to check drop (after you have set the right height) is to lift the car at the center line of the car. You can use a hex driver/allen wrench to lift up on the center of the car and watch which wheel lifts off the ground first (at the rear of the car as an example). Just adjust the drop on that end of the car until both wheels lift off the ground at the same time.

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Other things that can cause a car to track poorly:
- Bad bearing(s)
- Aftermarket ball cups rubbing on the wheels.
- Binding suspension parts (bent hinge pins/poor tolerances)
- Uneven steering geometry (make sure the steering turnbuckles are the same length when the car is set at neutral).

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Basically if the car is veering noticeably during a momentum change event, there is something mechanically wrong with the car that needs to be sorted out.
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Old 03-16-2017, 02:44 PM   #137
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Quote:
Originally Posted by IndyRC_Racer View Post
Unless your droop is way off, you may want to spend some time balancing the weight bias on your chassis (front/back & left/right).

TC4 was designed with brushed motors and 6 or 7 cell round cell packs in mind. If you are running a heavy motor and a light lipo, you may not have enough static weight on the left rear to balance out the weight of the motor. You can use the shock pre-load collars to get an even chassis ride height, but if the chassis isn't balanced at least one of the shocks is going to have more pre-load.

A quick way to tell if your car isn't balanced left/right is to measure the distance between the shock collars (the top part that the spring touches) and a fixed point on the car like top shock screw. I bet you will find that one side is different than the other.

While torque steer will always be an issue on a shaft drive car, it isn't as big of an issue that some people make it out if you are running a brushless motor. However if your chassis isn't properly balanced, any torque steer that you do get will be magnified.

---------

As far as drop, there is no magic number. Just make sure that it is the same at each end of the car. The easiest way to check drop (after you have set the right height) is to lift the car at the center line of the car. You can use a hex driver/allen wrench to lift up on the center of the car and watch which wheel lifts off the ground first (at the rear of the car as an example). Just adjust the drop on that end of the car until both wheels lift off the ground at the same time.

----------

Other things that can cause a car to track poorly:
- Bad bearing(s)
- Aftermarket ball cups rubbing on the wheels.
- Binding suspension parts (bent hinge pins/poor tolerances)
- Uneven steering geometry (make sure the steering turnbuckles are the same length when the car is set at neutral).

----------

Basically if the car is veering noticeably during a momentum change event, there is something mechanically wrong with the car that needs to be sorted out.
Thanks for that reply, I will take all of it in my testing consideration. There is definitely something a little off when I turn up the motor. I believe my chassis is pretty balanced already. The lipo is about 600g, really heavy 4s. The motor is huge and weighs about 350+150mm2+50servo. Something I notice is momentum the motor has. When you really push it fast, the car jerks to one side. Its why nic case used a brass weight on his driveshaft. My steering geo is as close as I can tell, must be the suspension. I'll have an update later in the week.
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Old 03-16-2017, 02:45 PM   #138
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Yeah I knew. What should the droop be? I'm about to redo my suspension with 70wt oil and red springs. I run 11mm rear and about 9 to 10mm front ride height.
Make sure the left and right tires land and leave the ground at the same time when you lift the front end and then do the same thing with the rear. Use the droop screws to adjust.
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Old 03-16-2017, 04:31 PM   #139
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Well I just checked the droop. Looks equal to me. I used an allen wrench as like a level on the equal side on the front and back with the battery in. Both tires leave the ground at the same level, hmm. I am getting the feeling its a form of torque steer or my suspension is wrong in another way. I just tried again and it didn't seem different. With that throttle it definitely leans left. When I coast it seems to go straight just fine. Dang you alignment! I may just fiddle with camber or something in the mean time until my shock parts get here.
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Old 03-16-2017, 05:54 PM   #140
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I'd double check the weights of your components. Based on the numbers you posted, your car IS heavier on the left side. You may need to add weight to balance out the car.

Basically what is happening is that under heavy acceleration you are transferring so much weight that it is causing the right front wheel to lift off the ground. If your front has toe out, you are probably pulling to the left. If the front has toe in, you are probably pulling to the right.

Since you are running a lot of ride height here are a few things to check...
- Make sure the steering turnbuckles/inner ball cups aren't rubbing on the chassis. You may need to file down/dremel any areas where could be occurring (not saying it is)
- What is the angle of your front a-arms? At extreme downward angles, you can have problems with the caster block hitting the a-arm screw nubs or the camber link preventing down travel.
- Make sure your front shocks have enough down travel to account for any suspension movement. If you are using the stock TC4 shock "ball cups", you may need to unscrew them a bit to allow full movement. Another option is to use the TC3 shock eyelets which are longer.
- Disconnect the front sway bar if you are using one. It may be causing a bind. At a minimum, you may need to make the sway bar mounts longer due to the taller ride height.

Here are a few simple suggestion to counter the weight transfer issue you are having assuming there is no mechanical issues.
- Move the battery forward in the battery slot. While this may not solve the issue, it could help make the car easier to get up to speed.
- Temporarily add some right side weight, possibly on top of the servo.

Some setup changes that can reduce rear weight transfer include...
- Add rear anti-squat. Check your manual for explanation/settings
- Stand up your rear shocks and/or increase spring weight. This can help the rear from squatting under acceleration
- Make sure your spring rate matches your dampening rate. If you are using light springs with heavy oils, it can make the suspension very lazy.

You are already running the rear higher than the front, which should help keep the car level during acceleration.

----------

The one thing that has me scratching my head is that you say your car is squatting on the left rear during acceleration. Based on the rotation of the motor/shaft, I would have expected the right rear to squat instead if it was a torque issue with the motor.

I will close this post by saying that we tried getting a touring class class going when we were still racing at the Major Taylor Velodrome in Indianapolis. It was easy to get them going at 55-60mph average for a 4 minute race, but beyond that speed every little problem with setup would get magnified.

Hope you find the gremlin in your car and stay safe.
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Old 03-25-2017, 06:53 PM   #141
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I just checked all my droop and caster, toe. Everything looks even to me. I had to adjust a few things but the problem seems to still be present. I would say it is a little less severe, or it could just be my driving. I set my steering dual rate to only 30%, and added some steering negative expo. I think the only thing that isn't "balanced" in the car is the shock oils. I have never been good at refilling them, usually a tiny bit of air is always in them so who knows, that may be it. Wish I could post some pictures, anyways I am going to do some runs.
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Old 03-25-2017, 07:56 PM   #142
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600 gram lipo is probably causing lots of handling issues... My 4S hv tc4 is also very tail happy, eventhough my lipo pack only weighs 370gram... My car weighs 1720gram ready to run....
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Old 03-26-2017, 01:56 PM   #143
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I did some decent runs before I hit a reflector on the road at night. The body made a really loud wubble sound. Nothing broke but my front splitter. Only got up to about 65mph, barely touching the throttle. By droop settings, are we talking just ride height? When I lift the rear, one side lifts up first, but I think that is just because of the weight. The shocks don't shrink from the static weight at all. My mm2 actually never gets warm at all. I need to gear up a lot.
Running 49s45p gearing
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Old 03-28-2017, 02:26 PM   #144
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sounds like a droop issue, the screws in the A-arms can throw off the car bigtime. get a droop gauge and check it.
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Old 03-28-2017, 09:32 PM   #145
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Both tires leave the ground at the same time. I used a glass table so I could make sure they were exact. Should my suspension be even stiffer? Running the red springs with a lot of reload. If I had a wide road I don't think this would even be an issue, but in my case I am one of those "stick to one side and avoid the middle" person because of reflectors on every street. I can't post links but if anyone has seen "Xray T2 009 5s" from the aussie rossa guys on youtube, I would say this is what it looks like. It really likes to dart around, but nonetheless, I hope to get some clean runs in and uploaded soon, this little tc4 can really move!
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Old 03-29-2017, 02:54 PM   #146
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Well I think you are running the car with the springs pushing the A arms against the droop screws, which is not the way the suspension was meant to run... The car is so heavy that the red springs need too much preload to take the chassis off the ground. You need yellow springs or white springs all around with the suspension set with no preload at all: you need to be able to easily turn all four springs with your fingers when you pick the car off the ground....
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Old 03-29-2017, 10:14 PM   #147
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The car fully loaded w/ the body weighs about 5lbs. I think you're right about that part. I can't really freely spin the shocks, but I thought for strict speed that didn't really matter. My droop setting seems perfect, the tires are nice and even. Upon just hitting full throttle, it always wants to turn left, but other than that, I would say the car is generally pretty controllable. (I am running 2 spools) Maybe it is a weight issue, so would that mean there's too much weight on the right, cause then more grip to the right means leftward turning. Maybe I am overthinking it. I need a good place to start running, how many ft. do most people like to run with? I can work with about 1200ft, about 1/4 of a mile.
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Old 03-30-2017, 08:59 AM   #148
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Wow, five pounds is 2267 grams... That is over 500 grams more than the suspension was designed for, so you will definitely need some white springs(40lbs)... I run my 1721gram tc4 with purple(30lbs) springs all around...
1200 feet is good enough, but I doubt you will be able to get your car to go straight with this suspension issue... I had the same problem when I first started with my tc4's, and I crashed all the time until a fellow racer pointed that out to me... Alot less crashes since then, and no more darting left or right all of a sudden...
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Old 03-30-2017, 07:06 PM   #149
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Wow, five pounds is 2267 grams... That is over 500 grams more than the suspension was designed for, so you will definitely need some white springs(40lbs)... I run my 1721gram tc4 with purple(30lbs) springs all around...
1200 feet is good enough, but I doubt you will be able to get your car to go straight with this suspension issue... I had the same problem when I first started with my tc4's, and I crashed all the time until a fellow racer pointed that out to me... Alot less crashes since then, and no more darting left or right all of a sudden...
Maybe...I will think about the white springs. Upon ANY serious throttle change, whether that be positive or negative, causes a sudden left deviation. This is why I think it is unbalanced or something. Everything else about the handling is flawless, it is just that accelerating or braking causes a very noticeable sudden jolt to the left regardless of trim, toe, caster, droop, etc. I have some body reinforcing to do before I start uploading some vids.
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Old 03-30-2017, 09:21 PM   #150
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Ok... In that case I would check the tire sizes, coning , wheel bearings binding, cvd blown on all sides... If none of them work, then you probably need a rear ball diff instead of a spool to reduce that torque steer...
I have a front aluminum spool, and rear steel ball diff in my hv tc4 with no tracking issues at all even at 1721grams, but I do make sure I true all my tires the same size..
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