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Old 10-27-2007, 03:25 PM   #376
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Track Test
Track Clean Moderate traffic 13 cars, Low to medium traction. Temp cool. 75F

Foam Vs Rubber
I gave the Jaco Prism Foams, which I prefered over the GRP, in Magenta compound a good test against the Nitro's. While I could keep up with some, others were able to make gains on each lap. I would describe the traction level as low-medium with this tire. The track really had sufficient traffic to build up a good line although there was still some dust from recent high winds and construction. There were no gains to be felt from having a low body and lighter weight.
I put on my well aged set of CS32 GL. Oh my gawd! The difference in traction was striking. The car was a rocket. Several people commented it was faster that before. The car was actually pulling the front wheels coming out of a medium speed turn which we corner at about 30 mph on the Radar. The Nitros had a hard time with it even on the straight. We will see at the next club race if lap times are actually improved. As was noted earlier in the thread, rubber is able to pull more g's cornering, or forward, the lighter the load on the tire. The car definitely had a lot more forward traction. It was aparent that the rubber tires were gripping better from the lighter car. I was able to gear "1/2 tooth up" from before on rubber. I rate the traction medium-high on rubber.
Bummer-I sure did liked those prism wheels.
The foams do have an advantage on the hairpins. I get more turn in and more cornering grip from them on these two very tight turns. I suspect it is from the effect of caster that I discussed earlier in the thread. The wide tire lets the negative camber gain be more effective.
Now if you race on sugar water treated track or a high grip track, I am almost certain the foams would be faster just from the lighter weight. They need the good forward grip to be fast though, on my track.

Rear Wing
I found a good wing much like the Stratus stock wing, from J Concepts. I had it mounted a bit up but that was too much wing on the sweeper. Here it was just right. It is very similar in size to Ooligans' wing pictured previously.
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Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-jconcepts-wing-003-resized.jpg  

Last edited by John Stranahan; 11-01-2007 at 08:40 AM.
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Old 10-27-2007, 10:15 PM   #377
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Titanium Hinge Pin Set
a Lunsford titanium pin hinge pin kit for the TC5 is now available. If you run ballast these are not really needed. If you run oulaw TC then these will lighten things up a little. I ordered direct from Lunsford.
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Old 10-28-2007, 05:08 PM   #378
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I'm not hopeful shortening those FMA packs to fit in a "normal" sized battery space is possible without some kind of reengineering of how the circuit board attaches to the end. While a bit of the length of made up of a piece of foam on the non-connector side, the majority of it has to do with how the circuit board is attached. While the cells seem to be a reasonable length, the board is attached with the tabs sticking straight out, causing it to be unusually long. When comparing it to the construction of an Orion 4800, you can see that they folded the tabs in a way that brings the board very close to the cells, and reduces the length. In fact, these Saehan cells appear to be the exact same length as the ones used in the Orion 4800. Someone with enough skill could likely attach Orion's circuit board and use them in that same, friendly enclosure. Sadly, I'm not sure that someone is me. :-(

Hopefully we'll see Saehan's cells assembled in a manner that's more friendly to R/C cars in the future, it sounds like they're truly the best option at this point.

I fear I may have damaged my pack trying to carefully bend the tabs inward to shorten its overall length. While I can read a reasonable voltage across it when it's resting, attempts to charge it cause the voltage to spike beyond 8.4 and cause the charger to shut off. Similarly, attempts to discharge the pack cause the voltage to appear below the cutoff, also prompting it to shutdown. I didn't short it that I'm aware of, but the stress of bending the tabs may have done it in. I have the pack quarantined, and will likely have to destroy it. Bummer.
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Old 10-28-2007, 06:40 PM   #379
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syndrome. I'm so very sorry to hear that. Send me a few pictures of the end if you would by e-mail to [email protected]. Maybe another pair of eyes would help. Normally a short occurs with plenty of fanfare. You would have been aware if you shorted it. Was the pack OK to start with? Maybe it came dead.
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Old 10-28-2007, 06:56 PM   #380
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Originally Posted by John Stranahan View Post
syndrome. I'm so very sorry to hear that. Send me a few pictures of the end if you would by e-mail to [email protected]. Maybe another pair of eyes would help. Normally a short occurs with plenty of fanfare. You would have been aware if you shorted it. Was the pack OK to start with? Maybe it came dead.
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John,

I don't think it's shorted, just damaged somehow, presumably from trying to bend the tabs inward a bit to reduce its length. I didn't give it a full charge, but it did at least start taking a charge when it was new, so if it's damaged, it's my own fault. I sort of went into this knowing that was a definite possibility, but it's disappointing that it appears to have ended that way. Looking at the pack, it appears the tabs are pushed through slots in the PCB and then soldered down. I'm wondering if perhaps I can unsolder those tabs, shorten them somehow, and then solder them back to the board. This introduces the risk of damaging the cell's packaging where the tab exits if it gets too hot, but if I can fold the tabs to shorten them, I may be able to reuse the portion that's already soldered.

John, I'll get some pictures here in a bit and send them your way. I installed Leopard on my laptop last night, and haven't completed getting my computer back up to speed, including Photoshop and the like.
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Old 10-28-2007, 09:57 PM   #381
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Pictures sent.
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Old 10-29-2007, 02:31 PM   #382
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Ackerman

Ackerman was added to steering linkage so that the inside tire could corner with a tighter radius than the outside tire. See photo 1.

I took the TC5 and made a simple sketch. The steering links are in the book position which is outside on the steering arms and forward on the bellcrank. I made two lines on the wheel edges with the wheels straight. I drew a line at 20 degrees to the outside front with a protractor and ruler aiding me. I aligned the front outside wheel to this line and drew a line for the inside wheel. The measure there was 23 degrees. The difference is the result of Ackerman. See photo 2.

I went to the track and ran a pack to get a feel for the car. I had changed the rear spring and shock upper position to get a more vertical shock on my custom shock tower (photo 3). Traction was medium from weekend activity. I had good steering everywhere but my two hairpins. I increased the ackerman by moving the steering link outer pivot inward on the steering Arm. Steering on the hairpins and tight corners improved. Steering on the wide turns was still OK. I quit here as the Can fell loose on that X11 motor. The last screw failed. I have a spare motor for the race Saturday. I can increase Ackerman farther still by moving the steering link inner pivots back on the bellcrank.

I measured the Ackerman back at home just for fun. There is no real need to do this. When the outer tire turned 20 degrees the inner tire turned 26 degrees. Thats an increase of 3 degrees. The car was dialed.

Anyway tinker with this somewhere down the line. The book positions are usualy pretty good.
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Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-schematic-ackerman005.jpg   Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-ackerman-resized.jpg   Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-rear-custom-shock-tower-resized-003.jpg  

Last edited by John Stranahan; 10-29-2007 at 03:00 PM.
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Old 10-29-2007, 05:31 PM   #383
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Manic RC- I have two sets of those caps with no problems. There are two types A and B one for the left and a different one for the right. Install them with the milled recess for the cams inwards. The vertical shock tower face will go forward on the front of the car, rearward on the rear of the car. It is hard to tell from your description what the problem is unless they got bent in a crash. I suspect you have them facing the wrong way as the two flats on one side (bulkhead) are different heights.
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John, thanks for the quick reply. I've attached a picture that will hopefully describe the problem a little better. In the picture, you are looking down at the point where the caps mount to the bulkheads (assembly flipped upside down). The caps are mounted to a shock tower (correct A and B side as shown) and a machinist's parallel is placed flat against one cap to show the misalignment between them I am speaking of. If I visually inspect shock tower mating surfaces on the caps, I can see that they are machined at a slight angle instead of flat like they should be. Note that the car has never been driven, so this is not from crash damage.
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Old 10-29-2007, 06:15 PM   #384
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I see the toe. The cap looks straight though. Take them off the shock tower and see if any burs are in the graphite hole. Mount them first to the bulkhead and then snug the shocktower screws last. See if the problem goes away. I supect now with a good pic that the screws are just a little crooked in their holes.
John

Last edited by John Stranahan; 11-14-2007 at 10:38 PM.
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Old 10-30-2007, 01:07 AM   #385
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Originally Posted by heretic View Post
old yokomos too, the tiny red ones.
Ah yes, on the MRsomething something4 and the carbon version of the YF-2. The most fun I've ever had driving a TC was with a YF-2
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Old 10-30-2007, 11:12 AM   #386
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Here is another shot of the cap without the tower. Hopefully this will clarify further.

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I see the toe. The cap looks straight though. Take them off the shock tower and see if any burs are in the graphite hole. Mount them first to the bulkhead and then snug the shocktower screws last. See if the problem goes away. I supect now with a good pic that the screws are just a little crooked in their holes.
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Old 10-30-2007, 02:51 PM   #387
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ManicRC-Ok then. They are busted. Send the part back. I put a straight edge on four caps that I have off the car. They are all straight. I would write and try to get them to send you the part with that last photo as proof. You should still be able to use the part then. Things will be under some tension but the car will work just fine.

Caps are also available from tower hobbies and Stormer hobbies.
John

Last edited by John Stranahan; 10-30-2007 at 03:24 PM.
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Old 10-30-2007, 05:21 PM   #388
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you could file or machine that surface flat and trim the other side down to match.

as a band-aid fix. associated should make that right for you... they're pretty good about it.
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Old 10-30-2007, 07:33 PM   #389
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John,
Have you tried increasing the caster with the foam tires? I went through the posts and your last reference indicated you run 4 degrees? Increasing the caster may give you additional camber gain which would allow you to reduce the static negative camber increasing your forward drive. The caster will incease the outer tire negative camber and reduce the inner neg camber in the turns. The fronts when not turning will be more upright and will generate more forward bite. I think the foams have less compliance than rubber tires and are therefore more sensitive to camber.

My car reacted favorably to increasing caster (changing from 4 to 6). It improved corner exit and cornering force at the same time.

Etienne
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Old 10-30-2007, 08:15 PM   #390
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Etienne-Thanks for the post. I will have to say that the difference between the foams and the rubber tires on that day was so striking that small improvements to the foams had little chance of catching up to the rubber tires. The foams just need more traction from the track or more weight to perform better. They work well on the heavy gas cars and may work better on a 53 ounce electric TC. I found with a light 1/10 pan car that I could get better traction and acceleration from foams by adding a second LiPo battery (7 ounces more).

I see your point on the camber. I did not try 6 degrees with the foam. I may experiemnt with that on my hairpins later. The foams were better on the hairpins from the reason you stated, less compliance, this made the caster more effective in adding wedge and also adding negative camber which you mention. One thing I found out with our surface is that the foam needs a certain loading before they hook up. Making the front tires more flat would decrease the loading per square inch and may be a detriment to forward traction on a light car; possibly a benefit on a heavy car. If I put the 6 degree blocks on (I have these in the box). I'll put the Prism foams on for a quick test. I am pulling the front wheels with rubber tires in one place. The foams are not even close. This is just traction from the back tires.
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