Wednesday, March 16, 2011

Winthrop Harbor TCS

It was kind of a mixed bag at the Track @ Harbor Hobby TCS.  Friday and Saturday went great, TQ'd all three qualifying rounds and worked on some guys' cars as well.  It seemed like most guys who tried the front end setup have been pretty happy with it. 

Sunday did not go as well for me.  I just made way too many driving errors, as well as having a bit of trouble with the track conditions.  I think the track built the traction super fast Sunday with all the rubber down from the previous two days, and I was either doping too much of the front tire (1/2) or I had too much throw dialed into the radio.  The first race the car was very good, much like Saturday, but Jimmy Stegen, another Track local and eventual F1 class winner, said he pushed wide on the first corner.  He said he thought he did not let the tires soak long enough, which made me worried I might not have enough traction if I under did things.  I tend to think the track may have come to Jimmy and Mark Rodney a bit on Sunday.  Jimmy remarked his car was "a dream" on Sunday.  My car went toward twitchy or oversteer, but I would say the mistake was probably not reducing the front tire dope to 1/3 or 1/4.  In the end though, I dotted out too many times.  Hats off to Jimmy Stegen and Mark Rodney for coming in first and second, respectively.

One other note if you are using the Mini Revo sized 1800 batteries: Don't charge over 2.5 amps.  I have been charging at 5 amps since I am impatient, and I think this may have also hurt my car.  It felt flat in the second half of the main races, where Jimmy had no problems with his brand new purchased Friday of the weekend 1800 pack.  Just be patient, unlike me.

Anyway, Harbor Hobby has a ton of traction, even more so than the Omaha track.  I wound up setting the ball stud on the camber mount at 4.5mm. I also wound up switching over to the aluminum camber plate, as the plastic one began to wallow out the holes as the ball studs got taller.  I used it in the 1.0 position, and this yielded .5* camber with the settings I used.  For the spacers at the kingpin, nothing changed - the largest spacer on top of the arm, and the 2 smaller spacers under the arm.  I will probably replace these spacers with 1 or .5 mm shims soon so I can test more fine tuning at this position. 

The rear ball stud on the upper arm (the one on the top deck) actually is fairly sensitive as well.  In a practice run, I added .5mm there just to see what would happen, and the car became much more sensitive mid corner.  I think this would be very helpful for lower traction conditions or rubber tire.  It was too much on a track with as much bite as Harbor has.

Over the nose, in the slot of the F60 wing, I added 1/2 oz. (14g) to the car.  I glued in two 7g squares.  This is something to try in high bite conditions, as the car will try to rock back under power and  push.  It keeps weight over the nose so you have more on power steering.  Note you can over do this and wind up with a car that does not center up well.  1 oz (28g) has been the limit for me.  You can also add weight behind the servo which will help add to the front bias, but this is nowhere near as sensitive as adding weight to the wing.  To be honest, I probably could have reduced some of the nose weight for the mains and been fine on steering.  I also added two 7g squares of lead at the very rear of the main chassis, one on each side.

The electronics were also centered in the car since the battery's size allowed for it.  This was not a huge change, but it did let me remove some weight from the car, as I had to add lead to the receiver side because the esc and wires outweigh the RX by quite a bit.  When the traction is as high as it got for a foam tire class, I feel that a lighter car is better.  It will even be less unsettled by tapping the boards when it is light.  You just need to add lead strategically to get the handling you want.  On rubber tire, or for outdoor racing, I feel just the opposite is true.  You want to weigh the car down to make it stable-big battery, heavy parts, plenty of lead.

Throughout the weekend, I retained the high traction t bar with the cutout.  I am pretty sure this should be the default part for 99% of  scenarios.  The stiffer t bars reduce rotation of the car and make it less willing to wrap the corners.  There are situations where this is not desirable, and that is where you need the stiffer bars.  You also want a stiffer bar if you are on a big outdoor track where the car wanders on the straight and is very hard to correct, very sensitive right off center.

I used A tires on all four corners, 58mm rear and 54.5 to 54mm fronts.  All tires had the sidewalls glued to the tread.  The front tire diameter was pretty important, as much over 54.5mm made the car traction roll.
The Detroit gang all seemed to be using the B rubber, which is more like the purple/magenta type of rubber. They did say diameter was important, but they seemed to run bigger tires than I did. The B's always made my car traction roll, and they say the same about the A's...Go figure....

I was able to TQ with a motor that came off the dyno at about 15,600 RPM @ 7.2 volts.  Geared 27/100 on a 58mm tire around 49mm rollout.  Jimmy Stegen had a motor that only cleared 16,000 rpm once.  We were having an informal "crappiest motor" contest, I won 2 rounds to one, LOL.  Really, you don't need to be right at the limit with these cars if you find the gear and the car is good.

I will add pictures and complete setup info a bit later.


  1. Hey Rob Peter again.

    Was wondering if you have a starting setup for pavement. We are going to start running outdoors soon and the next tcs is in a parking lot here in ottawa.

    F1 is running really well now. I haven't changed the front steering to your setup yet. We still can't keep up to the 103,s on carpet though. they are .3 to .4 secs faster a lap.

  2. Hi,
    Yeah, if you are .3 off, you're actually doing pretty well, LOL.

    You will have some different things to do depending on how they prep the track. If there is little prep/no sugar water you will have to work on getting traction. If they get the track fairly sticky, you can run closer to carpet, run the 1800 lipos, use cut down TC inserts in the tires, tire warmers/sxt/tire tweak, etc. For lower traction, just clean the tires with simple green/water straight up.

    Either way, run the option soft rears and the kit fronts to start. Start with stock inserts.
    Raise the front as high as it will go, and lower the rear as low as it will go without bottoming. Gold front spring, but you may need to go to black. I would start with 60K on the king pins. Softest shock spring you can get (red mini, red from black-short set), 20-25 wt oil/3 hole. Probably no lube on damper plate, or possibly even no damper plate at all if you run the new split upper deck. The Split deck should make the car less reactive, and kill some steering. I would also try the heavy pivot plate. I have both, and I will be trying them outside. Also run a big/heavy battery, and stack lead on the car for more traction. I always like the hi traction t bar with the cutout, but I guess the guys at the Tamiya track say the soft t bar is better. It looks the same (green) with no cut out. I'm thinking they are trying to reduce mid corner rotation this way and get a more stable feel.

    The other thing is I would run the upper arms as I have shown for carpet. As an addition, i would get a bunch of .5mm shims and use those instead of the ride height spacers on the kingpins. That way you can play with the arm height at the kingpin/steering knuckle in fine increments. Between that and the camber plate, I think you should be able to get a much better, controllable steering feel without having to make the car totally push like a dump truck. Speaking of the camber plate, you may be able to run a bit more camber with rubber tire if you run the upper arm "foam style". Again, this will add up to more steering that doesn't make the car bananas. I'm going to do a video on my ideas, as I'm going to be getting my "outdoor" car ready soon.