I'm not sure I can tell you anything here. I know what toe in/out is (I am toe out in the front) and I know what bump steer is (never looked to see if it has any) but I'm not sure what "bump toe in/out" is.

I haven't checked it but not a lot. Definitely no preload on the springs but probably not more than 1mm either.

That is likely true in some regard but I'm not sure where else to go to try and increase the front grip other than to do things I know correct that. This does however sort of jive with something I said earlier in regard to the other cars I've driven - maybe my issue is the rear is too locked in and I am pushing beyond what the front is capable of doing and I need to work on freeing the rear.

The one thing I didn't think about (and is likely not the issue but worth mentioning nonetheless) is that on the Roche I have run a Black Art and a Bomber body but nothing else. On all my other cars I have always run AMR12s and TR12s. The SM has a TR12 on it currently. I am sure Christian can chime in regarding the Bomber.

I just glanced quickly at it and ironically last night one of the things I did was put an ASC gold and .020s into the car. One thing that I mentally can't deal with is a spring rate listed as soft/medium/hard. I don't know if it is my OCD or the fact that I work in real racing for a living but I have to have numbers for spring rates and the Associated have that so I switched to a known standard starting point.

In theory the springs I ran Friday night should be close (Roche soft front, med-hard center) but I don't have a spring rater (yet) so Idon't have direct numbers to compare with.

I look at all your settings and they look pretty std to me. I am a bit lost when it comes to roche springs though.

I am still thinking that tire prep might be to blame, as it usually is on a 12th scale. Fwiw, I consider front camber, tires and tire prep 90% of my set up, with everything else adding up that last 10%.

Now here are things I like with Xenon front ends:

-soft springs : I run our new green spring, this is around a 10lb spring or equivalent to around a AE 0.014. It makes the car super easy to drive. Sometimes I run the red which is like a 12lb spring which is similar to an AE 0.016, however most of the time it feels too stiff. Maybe a bit of Kyosjo 30k on the king pins.

Rear: I don't know how thick green lube is, but I never go over 15k in my tubes. In higher bite 7-10k is my choice. My starting point is always 10k though.

For side springs, I only like to use linear ones on a 12th scale, to me, it makes the car easier to drive. You could try an AE black or green and see how it does. I do prefer xray silvers or our new yellow and green on the sides. For ours, you do have to use our spring perches. I know a lotbof people like SM springs too, and that might be something you already have.

Now tire prep I might be able to help. With green rears, you have to watch out sauce curing times. I typically wipe my tires off 10 minutes or so before I hit the track. This gives me better rear bite out of the gate. The fronts are not so temperamental. You could have an imbalance of grip creating your issues.

Now for experimentation purposes also try this: increase your front camber to about 1.75 -2 degrees on each side and turn down Your dual rate way down. What I want you to test this for is to see if you are simply not generating enough front contact patch when at high speed. Maybe like stated above you are running too much d/r trying to get steering and this could be making the car over steer at low speed. If the car generates too much steering at speed now, then what you were lacking was simply front camber.

And sorry, don't have a lot of experience with the bomber body. I always run our body. It simply works best for me, after all I designed it to do what I wanted it to do

Bump-toe is just that, bump steer. When you compress your front suspension, do your front tires toe in, out, or none at all? I set my car up such that it toes the front end out under compression, makes the car smoother.

In slightly.

As am I which is why I am switching to AE.

They call it the light tube lube.

I was up to as high as -2 degrees of front camber. I backed out of it in an effort to try another avenue (in the setup sheet I posted). In previous iterations I was running a lot of camber and more spring. I took camber out when I went to soft fronts.

i am in the same boat...returning to 1/12 after several years! SO excited! there is a small group of 1/12 scale racers here and i'm hoping we can build more this year!

I may have just had a revelation. I was staring at my weights and realized the LF/RR cross was way high. Having done setups on real race cars for years I know that a heavy driver cross will cause a push in right hand corners and an oversteer in left hand corners.

All 3 high speed corners I am struggling with are right hand corners and all the low speed stuff where I am oversteering are lefts. I am going to correct the cross and hit it again.

Attached is a rough sketch of the layout. X's are corners where it pushes and checks are where it oversteers.

Any thoughts related to my question regarding a 64 pitch pinion and spur set up? I will be running a 17.5 Speed Passion motor. The track will be quite large with a big sweeper and straight section. I'm just not certain where to begin related to gearing.

1/12th has always been my favorite class of racing.

Thanks in advance for any help that can be sent my way!

One thing that has changed with 12th scale (and RC in general) is that people no longer focus on a specific gear ratio. Everybody now does it with rollout/FDRs which take into account tire size. For 17.5 you will want to start around a 100mm rollout (which means the car will travel 100mm per rotation of the motor). Things that go into the calculation are:

- Tire diameter
- Pinion size
- Spur size
- Transmission ratio (in a pan car this is 1:1)

The calculation is:

(Tire size * pinion * pi) / (spur * internal ratio)

So if you are running 41mm rear tires, a 72T spur and a 56T pinion it works out as follows:

41 x 56 x 3.1416 = 7213.1136 / 72 = 100.18mm rollout.

As tires wear the diameter will get smaller, for example using the scenario above but with 40mm tires your rollout is 97.74mm so you would want to go up 1-2 teeth to get back to around 100 (1 tooth would be a 99mm and 2 teeth would be a 101mm).

As for what rollout you want to run this can only come from experimenting. Start around 100mm and check temps after 8 minutes. If the motor is hotter than 140-150 then decrease rollout a little at a time until temps are within reason. If it is cooler then increase rollout until you get too hot. I generally do 2mm jumps either way when I am tuning.

http://www.rctech.net/forum/electric...e-rollout.html

EDIT: Attached are the 2 charts I made in Excel. I run a 72T spur in 17.5 and a 76T in 13.5 currently. The green is my target rollout which I specified in my spreadsheet (100mm for 17.5 and 90mm for 13.5). Feel free to use it as a guideline.

Drew, thank you very much for the reply. The explanation of rollout and chart is very helpful. This will be very useful. I now have a plan on how to proceed.

Thanks!

If your cross weights are off then your chassis is off... a few things to check.

Front suspension arms are tweaked.
Chassis is tweaked.
Pod is tweaked.
Side springs aren't set correctly.
Tires on the car aren't perfectly trued upon this cross weight measurement
Front spring is damaged.
Electronic layout is not balanced on the chassis.

Have you done the "coin trick" to check for tweak?

It passes the coin trick fine - but the coin trick is never anything I have put a ton of stock into beyond a quick and dirty basic check. I use scales and levels to check for chassis tweak (as well as straight edges and such).

It is possible it is an arm but not likely springs or any chassis tweak. Electronics layout is pretty much "what it is" since there isn't a ton of room for playing. This could be the issue but the heavy side of the car is the side with the electronics.

Side springs - maybe. When my cross is where I want it and the level says the rear pod is flat the left spring has a good bit more preload on it than the right. Probably in the order of 2 turns.

Tires - possible. On my list was to true up a set of tires I won't race for doing setups. Just haven't done it yet and way cheaper than setup wheels.

I don't even bother with scales on a 1/12th scale. I just balance the chassis using pins, make sure the side springs are set, make sure the lower arms are equal heights L/R, pod is square and tweak free, tires are trued equally, and then once is all said and done I do the coin trick.

Scales. I've tried it. I didn't like it.

The On Point youtube videos are great for checking tweak and getting rid of it.
https://www.youtube.com/watch?v=-ct2L3KEkE0