Limitless How to setup your car for straight speed run?

[rotauq]

Yes, that supposed 2050kv stocker is always around 1900kv on my motor analyzer. All of the ones I have. A great candidate for 8S running. I am using Hybrid Ceramics on 2 of them now. For high sustained RPM's, the stock motor bearings are the weak link out the box.

1900kv on 8S Before i switched to TP motors i used run goolRc 4082-1900kv on my hobao. Somehow it feels so much better reaching 130mph on 35$ motor, tweaked, bearings upgraded and overvolted, than some out of the box top performing high-end motor

 

[SrC]

Some of the cheaper motors just need some tweaks and TLC to perform exceptionally well.
Even re-shimming them better can help at times.

 

[LibertyMKiii]

I'm just not a believer in the shaft support bearing. Well, I understand that it works, but I feel it's like a band-aid to an inherent problem being a long/too narrow rear shaft and all. Arrma should have revised the rear half shaft/Dog bone instead. But I guess a cheap bearing and plastic support was quick and cheaper to do.?‍ I just find that disappointing. I don't feel anything should touch a spinning driveshaft. You would never see that on a scale car.

I know that Subaru uses a bearing carrier in the middle of their rear driveshaft and they fail too

I hate to say it but Mr. FloPacks product is a good one to solve this problem. In simple terms it is an elongated center spool shaft to reduce the rear dog bone length.

 

[Lukas412]

1. To avoid blow overs
Set the rear high and front low.
Set the rear spring pre-load as tight as possible.
Reduce the rear wing to lower drag and reduce the rear squat that may cause blow overs for your car.

2. Adjustments
Front and rear Camber should be close to zero or slightly negative leaning inwards, but not more than 1.5 deg.
Front toe should be slightly in but also just barely like 1-2 deg. As you get more skilled you can try adjusting to zero but this setting will be safer for getting started.
Rear toe follows the above. After getting some experience and reaching 130+ then look at reducing rear toe in with an aftermarket solution like EMP or others.

3. Balance and vibrations
Balance your GRP or Hoons tires (this is a must when over 100mph)
Put O-rings or nitro fuel tube in the outdrive cups to reduce the play in the dog bones (not too tight)

4. Practice practice practice
Never go out your first time and expect to hit 140
Gear for 80 then 100 then 120 etc.
I also recommend starting with GRP rubber tires until you get to 130mph then make the switch to foams.
Learn to read the data logs from the castle esc and post in the forum if you would like guidance.

This post is fantastic. I'm just building up my Infraction for some speed runs and I have not heard a lot of this. Thank you! Would you mind explaining the effects of camber/toe in? Especially how it relates to being more/less skilled?

EDIT: I guess your vids already do this!

 

[SrC]

I know that Subaru uses a bearing carrier in the middle of their rear driveshaft and they fail too

View attachment 112441

I hate to say it but Mr. FloPacks product is a good one to solve this problem. In simple terms it is an elongated center spool shaft to reduce the rear dog bone length.

Subaru and other Mfrs. have done this, but shaft spins within the bearing carrier. Yes still weak link. Big Straight job Trucks also do this. Easier to acommodate different truck chassis lengths. The Arrma fix just keeps bearing pressure to one position at the shaft. And undue Friction results. Hence bricked bearings also. That bearing goes thru hell.
Like Flopack's design, to reduce overall rear half shaft length keeps oscillation in check. But you still need a shortened driveshaft. Just make a thicker stronger shaft to begin with like upgrades we see available, or relocate the center diff/spool rearward at least 10-15mm during manufacturing. Like the other Arrma rigs. Think Mojave setup. More equidistant front and rear shafts.

 

[LibertyMKiii]

This post is fantastic. I'm just building up my Infraction for some speed runs and I have not heard a lot of this. Thank you! Would you mind explaining the effects of camber/toe in? Especially how it relates to being more/less skilled?

EDIT: I guess your vids already do this!

I don't know if I specifically go into detail about why.
Toe in provides stability, but at the cost of friction. Once you max out the car then you might want to try zero toe as it may help you get some additional speed. The cost is potential unstable behavior, especially if you have concrete roads where groves in the road can make it have odd behavior with zero toe in. Camber is less impactful but you wouldn't want it to go positive... One thing to consider is how the suspension is going to move under load versus how it sits on your table.

 

[SrC]

at 1:23:12 he says that one word

Referring to what he calls Road Bashing??? ?‍

 

[rotauq]

Referring to what he calls Road Bashing??? ?‍

Haha, no just some random time reference. It's a great video, very long and full of many specifics. Obviously there will be some things here and there were someone could disagree or have a better solution (in the meantime). Just for the great effort he made, we should abstain from commentary

 

[SrC]

Haha, no just some random time reference. It's a great video, very long and full of many specifics. Obviously there will be some things here and there were someone could disagree or have a better solution (in the meantime). Just for the great effort he made, we should abstain from commentary

^^^Absolutely . I watched this video countless times. When I first saw it I said wow this guy is different, he wants to share everything. He wants everyone to enjoy speed running as much as he does. He is right many of the speed big guys keep their secrets. Unlike many other genres of surface RC. I probably learned 75% of my Speed running from Raz. The fundamentals I had down pat already.( Electrics , gearing, chassis setup.)

 

[SrC]

I don't know if I specifically go into detail about why.
Toe in provides stability, but at the cost of friction. Once you max out the car then you might want to try zero toe as it may help you get some additional speed. The cost is potential unstable behavior, especially if you have concrete roads where groves in the road can make it have odd behavior with zero toe in. Camber is less impactful but you wouldn't want it to go positive... One thing to consider is how the suspension is going to move under load versus how it sits on your table.

I notice some of the Drag guys set camber way negative at the front. (tire leans inboard) Less drag or friction when riding on the edge of your tires.
Also, setting toe-out a tad bit is compensated under load. The wheels want to naturally toe-in under load.(4WD) If even a degree positive under that load. I usually set about 1 degree toe-out. Under load it zero's out. Depends how well the car is setup. How tight the front end ST is. (slop) If its nice and tight I may go zero. Too much toe-out makes the car wander a bit. Much drag also. Too much toe-in makes it darty, especially with road steer.( bad surfaces) It depends on your car. And I find that 2 identical cars handle different no matter what. Its hard to make one a duplicate of the other sometimes.
All settings have to be done on a level smooth surface with its running weight (including the body if practical)
I use a cross weight scale also. Not truly necessary, but does help a lot using by using Ballast weight with a scale can help handling issues. Knowing cross weight and Fr/Rr weight bias of a rig helps dial in the traction better.

Edit: corrections made.

 

[SrC]

Yep same here, I put those darn expensive Boca ceramics in it.
I have a routine of oiling the bearings after the 4th outing. Sometimes more often if it is going higher speeds. Adding synthetic bearing oil to any bearing makes a big difference.

I have seen a few people loose the rear shaft support bearings on the infraction/felony so I oil those between each outing. It is clear to see those make a lot of contact on the dogbone. (My Limitless started life as a Felony)

Yeah Boca also. I am not a fan of ceramics in general, but for the motor I guess I can justify it. I know they handle temps in a motor somewhat better also. Giving them a try.

 

[IDNTH8T]

Hey guys, coming over from the Nitro scene with the purchase of an infraction. Preparing my rig for speed runs (160+ My goal at least) I’ve been educating myself via this forum and YouTube. Currently the car is completely stock, what chassis upgrades have you guys deemed a must for speed runs?

For electronics I‘m using a Futaba 7PXR transmitter, SkyRC GNSS, just ordered the XLX2 esc and am still researching motor, servos, and receiver. I plan on documenting the entire build and sharing results and lessons learned in this forum.
Thanks in advance!

 

[bkhlouf]

Welcome to the speed addiction! ?
The majority of speed runners are using TP Power motors especially the 4070 with something like 2000-2200kv on 8s and bit higher kv on 6s. Personally I am using the TP POWER TP4260CM-V1 2080KV 8S MAX 8MM SHAFT and will be testing the castle creation combo xlx2 1100kv as well. I noticed some people reaching decent speeds with this combo provided you are geared up properly. In term of transmitter/receiver the radiolink RC6GS coupled with the R6FG receiver. Budget option with remarkable performances!

 

[IDNTH8T]

Welcome to the speed addiction! ?
The majority of speed runners are using TP Power motors especially the 4070 with something like 2000-2200kv on 8s and bit higher kv on 6s. Personally I am using the TP POWER TP4260CM-V1 2080KV 8S MAX 8MM SHAFT and will be testing the castle creation combo xlx2 1100kv as well. I noticed some people reaching decent speeds with this combo provided you are geared up properly. In term of transmitter/receiver the radiolink RC6GS coupled with the R6FG receiver. Budget option with remarkable performances!

Thanks for the info! I saw Raz run the CC combo it looks promising... Wish I would have known about radio link before purchasing the futaba. What’s your PB? Saw Raz pushing his perfect pass product but am pretty sure I can set throttle latency via my radio ?‍

Any chassis mods/upgrades aside from alignment & dogbone sloop?

 

[rotauq]

Welcome!

Definitely don't go for a 4070CM-3200kv hooked up to 8S, your esc won't like it
In general don't overvolt on the motor specs (with some tolerance). Good batteries and capacitors should be on your research sheet as wel.

 

[LibertyMKiii]

Agreed with the above.
The TP4070 in the 1700 to 2200kv range is a solid setup.
You could also run the PPS motor mount and run a TP5650 or TP5660 motor. Something around 1100-1450 KV on those motors works well.

If you run a motor at 1700kv or lower you will want to run the Arrma limitless optional 29t spur gear.

I recommend cutting your Teeth at lower speeds. Try to run 80, then 100, then 120, then 130, then 140.....
There is quite a learning curve on car setup and trigger pull to get used to.

 

[claytonbakerjr]

1. To avoid blow overs
Set the rear high and front low.
Set the rear spring pre-load as tight as possible.
Reduce the rear wing to lower drag and reduce the rear squat that may cause blow overs for your car.

2. Adjustments
Front and rear Camber should be close to zero or slightly negative leaning inwards, but not more than 1.5 deg.
Front toe should be slightly in but also just barely like 1-2 deg. As you get more skilled you can try adjusting to zero but this setting will be safer for getting started.
Rear toe follows the above. After getting some experience and reaching 130+ then look at reducing rear toe in with an aftermarket solution like EMP or others.

3. Balance and vibrations
Balance your GRP or Hoons tires (this is a must when over 100mph)
Put O-rings or nitro fuel tube in the outdrive cups to reduce the play in the dog bones (not too tight)

4. Practice practice practice
Never go out your first time and expect to hit 140
Gear for 80 then 100 then 120 etc.
I also recommend starting with GRP rubber tires until you get to 130mph then make the switch to foams.
Learn to read the data logs from the castle esc and post in the forum if you would like guidance.

I made a few short videos that go over some of these topics. Diff fluid is an open debate I have done locked, 500k, 1mill, 2 mill, and stock fluids.

I see a lot of people use the wording "balance your tires" but what I really do not see is how they are doing it. I mean yes I see guys balancing their tires on the car/truck itself but to me that seems kind of pointless since the other variables of vibration come into play as well, but I'm a newb to street runners so is there a Jig or something simple to design to make balancing more true to the tire/rim itself? I do see things out there that use the stock 17mm wheel hub but do guys buy an "extra" wheel hub for this purpose?

 

[1coopgt]

I see a lot of people use the wording "balance your tires" but what I really do not see is how they are doing it. I mean yes I see guys balancing their tires on the car/truck itself but to me that seems kind of pointless since the other variables of vibration come into play as well, but I'm a newb to street runners so is there a Jig or something simple to design to make balancing more true to the tire/rim itself? I do see things out there that use the stock 17mm wheel hub but do guys buy an "extra" wheel hub for this purpose?

This is what I picked up .

https://smile.amazon.com/gp/product/B076X6S94N/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[LibertyMKiii]

I see a lot of people use the wording "balance your tires" but what I really do not see is how they are doing it. I mean yes I see guys balancing their tires on the car/truck itself but to me that seems kind of pointless since the other variables of vibration come into play as well, but I'm a newb to street runners so is there a Jig or something simple to design to make balancing more true to the tire/rim itself? I do see things out there that use the stock 17mm wheel hub but do guys buy an "extra" wheel hub for this purpose?

It completely blows my mind that 1/8 scale tire balancers are so hard to find with the grown popularity of the Arrma speed runners. Something like what @1coopgt posted would be good. I was able to pick up one of these back before they stopped selling them:

As you mentioned there are ways to make your own with an extra wheel hub, bearing and hex.
I cannot vouge for the quality of this one, but it looks to be very similar to the dynamite one and should work fine. (never bought from that site either)
https://dialedhobbies.com/rs-613-detail

 

[claytonbakerjr]

It completely blows my mind that 1/8 scale tire balancers are so hard to find with the grown popularity of the Arrma speed runners. Something like what @1coopgt posted would be good. I was able to pick up one of these back before they stopped selling them:

View attachment 137332

As you mentioned there are ways to make your own with an extra wheel hub, bearing and hex.
I cannot vouge for the quality of this one, but it looks to be very similar to the dynamite one and should work fine. (never bought from that site either)
https://dialedhobbies.com/rs-613-detail

Yes I also seen that the Dynamite one is no longer made which looked to be a great solution.