Yup, thanks! These motors are rated at 7.2v
Stalling motors causes them to become like not-so-big resistors too. 
Hi again,
Have you made any other modifications to the track system? They look awfully tight. On our in-house bot you can lift the tracks off the front of the assembly enough to easily stick a pencil between the tracks and the lexan components. Did you do anything that would affect this? Something is not adding up here…
Hi Jim,
That’s good info, thanks!
No, no other modification (other than sanding down the Lexan with a fine sanding block on a Dremel yesterday, which got it rolling). The motor shafts ride in the original holes, and the tracks read (on the fish scale again) nearly identical tension - below a tenth of an ounce - to the original motors/tracks. I first built everything exactly to the instructions so I could take exact measurements.
The sprockets were a couple tenths of a mm out of alignment with the idlers, not enough to matter, but I lined them up to the best of my measurement equipment yesterday. They’re within a hundredth of true, but the Lexan flexes more than that.
The only change I made originally was to add new motor mount holes keeping the shaft in the identical position to the original. And I selected my motors to have the same 6mm shafts.
The Lexan platform itself has only been modified with four new mounting holes for the arm support.
That’s the entirety of the modifications made.
Now that I have sanded down the side panels, I’ll run your pencil test and report back.
Thanks!
Ok - mine was too tight still to get a ball-point (couldn’t find a pencil 
) in there. I pulled the sides off and put them on the mill and machined off exactly .0625" (1/16th) around each radius.
Now it looks like this:
http://www.jlrdesigns.com/4lynx/track-fit2-001.jpg
http://www.jlrdesigns.com/4lynx/track-fit2-002.jpg
http://www.jlrdesigns.com/4lynx/track-fit2-003.jpg
http://www.jlrdesigns.com/4lynx/track-fit2-004.jpg
http://www.jlrdesigns.com/4lynx/track-fit2-005.jpg
You know - I wonder if the laser-cutter just wasn’t having a bad calibration hair-day…
No the laser is pretty much dead on accurate. It’s like a stepper controlled plotter and there is no calibration. I grabbed a side panel from the shelf that was just made yesterday and compared it to the in-house bot which has panels that were cut when I designed the bot. They are exactly the same. I had a set of treads built and tested them to ensure they didn’t change. The sprockets are also injection molded so they didn’t change. I even tested the nylon bushings and standoffs… I’ve compared and tested everything I can. Your motor mod must have increased the tension on the tracks. I can find no other explanation. Bear in mind 20 thousandths off can make a BIG difference. Here is an image of our stock TriTrack Chassis to illustrate the clearance it has on the tracks…
Thank you for the effort and illustration!
Taking the material off the sidewall seems to have resolved the issue.
The max error for the new shaft placement was 1/2,300th, or 10/23,000th rather than 20/1,000th or 2/100th.
Regardless, mine aren’t quite that loose yet (nor were they with the stock motors), so I’m going to loosen 'em up a little more - but I do think it’s resolved, and the motors are behaving pretty happily. I’m encoding a video of it performing if you’d like to peek at it. No general publication until after I disassemble everything, turn it into a “kit”, let the kids build it, modify it a bit, practice, and then compete it in March. 
I agree it’s resolved somewhat, but I’m at a loss. At this point I just wanted to figure it out. Can you measure the distance from the front passive sprocket to the rear passive sprocket, closest edge to closest edge. It should be 6.935" minus the lasers kerf.
That’s sprocket to sprocket outside minus teeth? Let me take the micrometer up there, or I guess I should bring the 'bot down to the lab instead.
Ok - I see what you’re looking for. Who stole my danged imperial hex wrenches?!?
Hmm, I get no where even in that neighborhood for inside edge to inside edge of sprocket. I must be misunderstanding - let me shoot a photo - sorry I don’t understand what measurement you’re looking for!
As you can see from this photo, nothing about the passive idler sprockets is in any way modified or changed from the stock build.
Um, did I write this? lol
What I meant was measure from the holes where the passive sprocket bearings go. Doh!.. I thought that would be easier than trying to measure from the center of the holes. Sorry for the confusing post.
Hi Jim,
No problem! I was wondering how the kerf played into what I thought you wanted measured. Now it makes more sense - that’s why I use photos.
Alas, it will need to wait a few days. Professionally I often work on very very precise components. I can measure to a fraction of a wavelength of light - but only up to 12cm. I can measure to the 10,000th inch with reasonable accuracy, but only up to 6". Anything bigger than that and I’m usin’ a ruler, which doesn’t really help us here. My laser calipers will do 8", but there’s not really anything good to put 'em against in that measurement.
I ordered a 16" micrometer but it won’t be here until next week. Apologies for the delay!
(Hmm. My Hilti laser will do 1/64th inch out to 600+ft. Wonder if I can get a measurement there…)
I’ve got the same problem. I should also mention that my motors are pulsing, they’re not spinning smoothly. I know this my sound stupid…So I just sand off the corners down a bit?.
(I’m using BS2 on BotBoard 2 with 2 Parallax HB-25 motor controllers and standard Tri-Track motors, running on 12V DC)
Please reply! 
Can you please post a picture showing how tight the tracks are? Will need more information in order to help you. No don’t sand anything. The kit should build perfectly. You may have made a mistake.
here’s the video of my robot with no load on it, RUNNING AT FULL THROTTLE (at 12V). as you can see, the tracks aren’t too tight - they look pretty much like the ones on the lynxmotion in-house robot.
The problem you are having is shown in the first 5 seconds in your video. The little black plastic battery holders will not work!!!
One The wires are too small to carry the required current for the motors/motor controllers.
Two The little springs in the battery holder do not make a good connection and can not pass much current.
Look at any of our 4WD Rover or TriTrack tutorials and you will see big heavy duty wires. That’s why!!!
Thank you so much! However, it doesn’t say anywhere that battery holders won’t work and that I need a battery pack! :S Now I’m out of money, not able to buy a pack and charger, so I have to wait for my birthday… :S
Thanks anyways!
No we don’t specifically mention you can’t use those cheap crappy battery holders. However, we do mention under “powering options” what battery packs are recommended for the chassis.
Powering Options
The robot is compatible with the following batteries and chargers.
Chargers & Accessories
> 6.0 - 12vdc Ni-CD & Ni-MH Universal Smart Charger (USC-02)
Batteries
> 12.0 Volt Ni-MH 1600mAh Battery Pack (BAT-01)
> 6.0 Volt Ni-MH 1600mAh Battery Pack (BAT-03)
> 6.0 Volt Ni-MH 2800mAh Battery Pack (BAT-05)
Yeah, good catch Jim. Wow. That’s a fire risk right there.
Just for your future reference roksraka - never use a wire gauge smaller than the gauge of the wire the manufacturer sent you. Ever.
Heavier gauge wire costs more, and the manufacturer is always looking to reduce costs. So they’re going to send you the minimum you need. The gauge of the wire on that switch is far far larger than what you have coming off the battery pack. Stranded wire will carry more current than solid wire.
Top-quality NiMH AA’s can source upwards of 30A and deliver 2800mAh. They might be passable depending on whether you’re using stock motors or not. Each 5A stall motor running from it’s own dedicated AA pack might be workable. Just make certain the batteries don’t heat up too much. You’ll shorten the life of the batteries at the least, and may cause them to explode.
You can never have too heavy a gauge wire. Use the heaviest that is reasonable, put always heavier than any manufacturer-delivered part.
In my case, I was using Tenergy competition sub-c NiMH 4800mAh batteries which have 10G wire coming from them. My delivery system used 10G to each of the motors and 6G to the motor controller. So my wire was overrated many fold. Power delivery wasn’t the concern.
Great job with that video. If only more people that have issues did what you did. 
Anyway, once you beef up the power structure, you’ll be ready to tear up the carpet!
hi all i have also same problem of power i cant rotate it if any one can find the solution please inform me.