HPI Cup Racer 1M

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  • OK I have found another issue. Due to the motor placement It seems myself and another guy who is running the CR that we are having massive amounts of torque steer. Is there anyway to combat this without screwing around with the balance of the car?
  • Quote: OK I have found another issue. Due to the motor placement It seems myself and another guy who is running the CR that we are having massive amounts of torque steer. Is there anyway to combat this without screwing around with the balance of the car?
    Define "torque steer". The behavior of the car in detail. Some confuse this with ackerman affect, push and other steering behaviors.
  • Quote: Define "torque steer". The behavior of the car in detail. Some confuse this with ackerman affect, push and other steering behaviors.
    When you get hard on the throttle the car pulls (goes) to the left. Moderate to light throttle inputs do not effect this. I really don't know how to explain this more. Me and another guy who race together both have the same issue and run completely different setups.

    I have the same issue in my crawler but run a thicker weight oil in the one side to combat it. Obviously you can't do that in an on-road car since it will cause it to handle differently depending on which way you are turning.

    Just as a reminder I do run on an extremely slick track (rubberized perfectly smooth gym floor) and have to run a really soft setup to even attempt to get traction.

    Will try any suggestions and thanks for responding!
    Adrian
  • Interesting. I've never experienced torque steer with an RC car, since left and right drive shafts are equal.

    It's common on front wheel drive cars where motor is installed horizontally. My ex-Audi A4 with cvt transmission suffered severly from toque steer.

    In short, Id have to guess that you have may have:
    1. Un-even suspension set up / car is not square. Disconnect dampers, sway bars and set droop making sure it's even, then connect sway bars again to see it's even, followed by dampers

    2. You may have a weight issue, causing car to pull in one direction

    3. Perhaps even a bearing that is binding?

    If what I wrote is pedantic, my apologies.. Just adding my $0.02 and thinking out load.
  • Quote: Interesting. I've never experienced torque steer with an RC car, since left and right drive shafts are equal.

    It's common on front wheel drive cars where motor is installed horizontally. My ex-Audi A4 with cvt transmission suffered severly from toque steer.

    In short, Id have to guess that you have may have:
    1. Un-even suspension set up / car is not square. Disconnect dampers, sway bars and set droop making sure it's even, then connect sway bars again to see it's even, followed by dampers

    2. You may have a weight issue, causing car to pull in one direction

    3. Perhaps even a bearing that is binding?

    If what I wrote is pedantic, my apologies.. Just adding my $0.02 and thinking out load.
    Not at all thanks! However I have checked and triple checked those things. The weight thing was also looked at. The only thing I could think of was to add more weight to the right side of the car but that would unbalance the car. What is more baffling is the fact that two of us are experiencing this and run two different setups.

    Maybe the car just has way to much power.
  • Quote:
    When you get hard on the throttle the car pulls (goes) to the left.
    ..My CR'r would spin out when I got on the throttle, ...don't recall if it was left or right. In my case it was the wheels ballooning up on full throttle and getting the car into a spin. (thanks Mike for solving my issue).

    Not sure if that's what it could be in your case, -but since you've tried everything else? What I did was got some some stiffer/harder tires (new wheel/tire combo). ...look back a page or two on this thread and you'll see the messages and which tires were recommened.
  • Quote: ..My CR'r would spin out when I got on the throttle, ...don't recall if it was left or right. In my case it was the wheels ballooning up on full throttle and getting the car into a spin. (thanks Mike for solving my issue).

    Not sure if that's what it could be in your case, -but since you've tried everything else? What I did was got some some stiffer/harder tires (new wheel/tire combo). ...look back a page or two on this thread and you'll see the messages and which tires were recommened.
    I would say the ballooning of the tires is a common issue but between me and the other guy who runs the CR at our club races we probably have 10+ different tire and rim and foam combination's. Both cars pull to the left no matter what the tire/rim choice is.

    I'm going to stick with my original diagnosis of it's the way the motor is mounted and just compensate on the driving side. I'm really nit picking since I really love the car!
  • Guys, torque steer is the reason why all top level touring cars are belt drive. The TC3 and TB evo series are the last of the serious shaft drive cars. .....
  • my new 204Z body

    *ttp://img718.imageshack.us/i/img0329c.jpg
  • I got a handful of these with the cup racer i got the other day from fleabay.
    guess i dont have enough posts to link so theres a space before .com

    rcmart. com/catalog/rc-mchassis-rims-cross-m0302b-5spoke-mini-wheel-8pcs-p-28740.html

    They seem cool, but I cant find the right diameter tires for them. I need tires that will fit the 42mm diameter. Most on rcmart dont list the inner diameter and if they do its something like 38mm...which I find weird for M-chassis tires. or is that including the bead which we glue to the wheel?

    Was thinking the ones by Yeah racing would work but then they have that weird inner diameter...

    rcmart. com/catalog/rc-mini-rubber-tires-yeah-racing-wl2007-tire-4pcs-p-29679.html?cPath=35_1386

    What are people using on their cup racers?
  • I just finished building my CR - and it is my first RC car in about 15 years.

    I really like it.

    She is squirrely when I break the tires loose and squirms both left and right until I ease off the throttle and/or counter steer. I haven't experienced any real torque steer yet.

    What I have done is make sure that she is balanced left to right. Obviously NiMhs are not an option here. My 2S 5,000 mAh LiPos were also too heavy. I ended up with Venom 2S 3,800 mAh 35C LiPos. They balance out the chassis well and their 4mm sockets line up with the chassis - so I only run 4mm male bullet connectors on my ESC. But the middle balance lead is obscured by the chassis and I'm torn about drilling the chassis out to fit it. For now I'm swapping the battery out to charge it.

    The stock "S" tires work very well and I'm not looking for something better or different to run on her. They have a very precise fit on the rims and I doubt that you will find any aftermarket tires that fit (or look) properly or run as well as the stock tires.

    I got carried away when choosing my steering servo. Per the instructions, using a full size servo in the lay down position is not ideal. But finding decent "shorty" or retract servos was not easy either. That's why I chose the Savox SC1251MG. It isn't cheap but it works really, really well. I had to remove some of the material from the stock servo mount to make it fit - which surprised me because it was one of the few servos that had the right dimensions. Besides it being an amazing servo with specs to make other servos blush, it has a gold sticker and a gold anodized aluminum center case which matches the color scheme.

    I also got carried away when choosing my motor and ESC combo. I didn't want to spend $45 for the stock motor or use a cheap sensorless brushless combo that stammers off the line and can't run the stock gear ratios. So I ended up with the Novak Havoc Pro SC Ballistic system with a 17.5 turn motor. It has a silky smooth low speed - I mean seriously smooth low speed. I can barely breathe on the throttle trigger and her tires will silently spin at 30 rpm. Initially this system lacked top speed and had solid and smooth acceleration and brakes but crazy run times - almost 40 minutes. Then I activated the dynamic timing and OMG it now has incredible top speed without losing the smooth low end and still has long run times - over 30 minutes. Plus it has the proper gold (orange) color scheme that matches the rest of the car.

    I have already ordered the Lancia Stratos body and 3/6mm offset wheels and tires for it. The Lancia Stratos is a very rare car that I have always wanted to model but has not been offered before. I'm assuming the Stratos has not been modeled before because of its unique dimensions and FIAT wouldn't allow "melted" RC reproductions of such an iconic car. I can't wait to build the Stratos body.
  • Quote: I just finished building my CR - and it is my first RC car in about 15 years.

    I really like it.

    She is squirrely when I break the tires loose and squirms both left and right until I ease off the throttle and/or counter steer. I haven't experienced any real torque steer yet.

    What I have done is make sure that she is balanced left to right. Obviously NiMhs are not an option here. My 2S 5,000 mAh LiPos were also too heavy. I ended up with Venom 2S 3,800 mAh 35C LiPos. They balance out the chassis well and their 4mm sockets line up with the chassis - so I only run 4mm male bullet connectors on my ESC. But the middle balance lead is obscured by the chassis and I'm torn about drilling the chassis out to fit it. For now I'm swapping the battery out to charge it.

    The stock "S" tires work very well and I'm not looking for something better or different to run on her. They have a very precise fit on the rims and I doubt that you will find any aftermarket tires that fit (or look) properly or run as well as the stock tires.

    I got carried away when choosing my steering servo. Per the instructions, using a full size servo in the lay down position is not ideal. But finding decent "shorty" or retract servos was not easy either. That's why I chose the Savox SC1251MG. It isn't cheap but it works really, really well. I had to remove some of the material from the stock servo mount to make it fit - which surprised me because it was one of the few servos that had the right dimensions. Besides it being an amazing servo with specs to make other servos blush, it has a gold sticker and a gold anodized aluminum center case which matches the color scheme.

    I also got carried away when choosing my motor and ESC combo. I didn't want to spend $45 for the stock motor or use a cheap sensorless brushless combo that stammers off the line and can't run the stock gear ratios. So I ended up with the Novak Havoc Pro SC Ballistic system with a 17.5 turn motor. It has a silky smooth low speed - I mean seriously smooth low speed. I can barely breathe on the throttle trigger and her tires will silently spin at 30 rpm. Initially this system lacked top speed and had solid and smooth acceleration and brakes but crazy run times - almost 40 minutes. Then I activated the dynamic timing and OMG it now has incredible top speed without losing the smooth low end and still has long run times - over 30 minutes. Plus it has the proper gold (orange) color scheme that matches the rest of the car.

    I have already ordered the Lancia Stratos body and 3/6mm offset wheels and tires for it. The Lancia Stratos is a very rare car that I have always wanted to model but has not been offered before. I'm assuming the Stratos has not been modeled before because of its unique dimensions and FIAT wouldn't allow "melted" RC reproductions of such an iconic car. I can't wait to build the Stratos body.
    I used to run my cup racer with a ballistic 13.5 and stock gearing and the car handled the power just fine. FYI A 17.5 with 20 of timing and boost is equivalent to a ballistic 6.5. Its too much for this chassis and tyres. My advice is to turn the timing down and turn boost off.
  • I'm running the stock mechanical timing and "3" timing level and set point in the ESC with a 17.5 motor.

    It seems pretty right and not anything like a 6.5 turn motor - especially considering my run times.

    But I hear you about running too much motor.

    I'm already pushing past its good natured handling with this setup and don't want to fry the plastic drive cups.

    FYI for anyone who is interested in on-road cars like the Cup Racer - yeah don't wreck these things. They aren't Traxxas trucks. Basically, if you stuff the Cup Racer at top speed you will have a very bad and expensive day and you can't bring it back to your LHS and cry foul.
  • Quote:
    if you stuff the Cup Racer at top speed you will have a very bad and expensive day and you can't bring it back to your LHS and cry foul.
    +1 to that! (No I don't speak from experience, ..i've only side swiped curbs w/ my cr ...but only a few times. I try to run in large parking lots w/ lot's of space ..particulary at a near by business park that is always vacant on Sat and SUN's).
  • Hi everyone,

    been checking this thread out since it started. I must say you guys have some awesome rides with mods.

    Its been a while since i started, and glad that its finally finished.

    This is my cup racer: its all stock with Kawada wheels. This is meant to be a replica of Wataru's supercharged Levin from Initial D.

    HPI Cup Racer 1M-sale-014-%5B640x480%5D.jpg   HPI Cup Racer 1M-sale-017-%5B640x480%5D.jpg   HPI Cup Racer 1M-sale-018-%5B640x480%5D.jpg   HPI Cup Racer 1M-sale-021-%5B640x480%5D.jpg   HPI Cup Racer 1M-sale-022-%5B640x480%5D.jpg  


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