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Old 08-13-2007, 04:22 PM   #61
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Hey John (yeah, I'm stalking your threads! LOL) I was thinking about what you said re: chassis tweak and oblonging the deck screw holes.

What about opening up the holes just a bit and adding a top-hat or bushing? That should give a good interface between the CF and the screw and allow you to really tighten down on it, still getting that good tight joint.

Just a thought - I don't know what you'd use - but I'd assume the bushing would be slightly less deep than the thickness of the CF to allow for some compression. . .
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Old 08-13-2007, 04:48 PM   #62
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Note to all. There is a discussion of side to side balancing and corner weights on the previous page.

Boomer-Good to hear from you on this thread. I found a satisfactory solution to the double plate chassis is the blue locktite under the heads of all the screws that mount the two plates. The Locktite fills the space between the screw and the carbon fiber making it a pin, and it adheres the beveled part of the flat head screw head which actually has enough surface area if glued. I would imagine the proper way to have a tweak free double plate chassis would be to actually bond it into one expensive piece. Thats why I like the molded chassis better. It is already bonded into one tweak free piece. One has to be careful with the plastic chassis that the motor is not melting the chassis like in the old TC3. This caused tweak problems even with the molded one piece chassis. The motor would melt a piece of plastic under its mount. When it cooled, it would shrink a bit. This would pull up the right rear corner of the chassis. After Barry Baker saw my mod to cure this, they came out with an Aluminum motor mount for the TC4. Photos on the FTTC3 thread. Your idea on the plates would work but would need the locktite glue up as well as friction is not enough in the small crashes even.

Bump Steer
Some undesirable traits in a car are darting left and right when it encouters bumps and also changing steering throw with chassis roll in a corner. Both of these problems can be caused by bump steer. You check bump steer easily with the car in your hands. Straighten the front wheels. Push the tire up through its entire travel. Does it stay pointed in the same direction. If not you have bump steer. A little bump toe out is OK, Bump toe in is usually avoided. Bump toe out means as the tire goes up into bump it toes out slightly. What this does in a corner is gives you an easy to drive forgiving car. If you steer a little bit too harshly the car will roll more the tire will bump toe out just a little, this will cause the car to ease up on its steering in stead of increasing steering and spinning out.

With the roll center at the ground I had to add a little over 1/8 inch of spacers to the outside of my steering link under a long ballstud to reduce a large amount of bump toe in. This big of a stack is not desirable. If it is possible to lower the inside with a short ball stud I will do so later. I may end up changing roll centers after I drive the car. I will use this stack for now.
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Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-bump-steer-002-resized.jpg  

Last edited by John Stranahan; 08-15-2007 at 08:58 PM.
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Old 08-13-2007, 08:45 PM   #63
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Belt Tension: AE FT team driver Rick Howart reported on the TC5 thread that initially belt tension on the Tc5 wil feel a bit tight, but that I does loosen up. its the new belt design and its properties...not worry too much here...

Diff height: its interesting that team Losi drivers suggest that the best set up is to have the rear diff low, and the front diff set high. They claim that after much testing they have received the best results with that combo, and indeed, it seems that fromt all their set-ups that's what they run most of the time.

On the other hand, Schumacher Mi3 drivers have reported that on the Mi3, running the rear diff high, and the front high, is the way to go for outdoor asphalt, and if a bit more front steering is needed, to set the front diff to the low position for added front steering.

Apprarently diff height affects axle angles, and some favor carpet racing, were tires are very low in diameter and car sits much lower than asphalt TCs...lowering the diff helps the drivetrain efficiency and smoothness in carpet situations, and the opposite is true on asphalt....however, it also effects roll center, which also affects handling characteristics. THese are not my findings, but rather what I have read from Schumacher drivers and Losi...I dont know what AE reports in that reguard and it'll be intersting to find out what they have learnt about this on their car.
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Old 08-13-2007, 09:03 PM   #64
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YYhayyim-Thanks for the front diff height report. I imagine that the major change from moving the diff is just from moving the center of gravity slightly up or down on that end of the car. The axle angle does change, but it just gives a slight forward or rearward thrust to the hub that is just dissipated by the suspension as the hub cannot move in these directions. The roll center does not change. My front diff is down slight and rear is up slight.
I can tell you that Losi and Associated manuals don't even agree on the big stuff like changing front spring tension. RC Knowlege of weight transfer seems to be completely backwards most of the time. People that write little RC books seem to do so without reading any full size racing car books first. And they are proud of this fact. How can I believe what they say about diff height when the effect is sure to be very minimal. I await your or my experiment on the subject. Mine is not likely to come very soon.
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Old 08-13-2007, 09:24 PM   #65
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cvds of all brands offer some unusual properties that not many people understand.. as cvds spin, they have a natural tendency to want to straighten out.. this straightening out pulls the chassis with it.. if the cvds are angled down, they will tend to pull that end of the chassis down, or up yields up.. if there is a lot of plunge at the diff end, some of this effect is mitigated because of friction.. when i used to run offroad, on loose tracks sometimes we actually ran the rtr dog bones rather than cvds in associated buggies to free up the rear suspension..
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Old 08-13-2007, 10:18 PM   #66
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Tally thanks for the post. Looks like we have almost the whole crew over here now. I bet on the off-road car the bones were swept forward. I forget.

Here is an experiment I did with the Losi XXXS. I was looking for little effects like you are talking about and mostly looking for reasons why the XXXS was a half lap slower in stock than the TC3's and Yokomo's. One striking difference was the front dogbones are swept way back as they go out on the XXXS. I unhooked the spring and shock with the wheel off rested the stock front suspension on my finger and gunned the car. The arm lifted some. This takes away traction. I put the dogbone running straight out by changing (making custom) inner A-arm supports. With the dog bones straight out I noticed no lift. This did not change as I moved the suspension up and down. On the Yokomo these bones are swept forward. This drives the tires down on acceleration. The change in thrust at the wheel seems to be at right angles to the angle of the dogbone. On the TC3 the dogbones are mostly straight out, but it just has a superior drive train for stock motors. I believe that this effect is caused by the sliding action of the bones on the outdrives rather than out at the CVD. The effect would be eliminated, I believe with an inner cardan joint (what they call CVD) and telescoping center to the drive axle. Losi actually made a plastic rear drive axle just like this. It really did not slide well enough to work well. I noticed the team members making similar mods to their front suspension soon after or near the same time to straighten out the swept back bones.
The other part of the 1/2 lap is in the Losi single belt. Interestingly the Losi XXXS has an advantage on an oudoor very loose track with stock motors. It has better top speed. It has more friction than a two belt car when highly loaded but less friction than a two belt car when lightly loaded.

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Old 08-13-2007, 10:40 PM   #67
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Well I repeated my experiment with the TC5. I took the wheels off so I could spin the crap out of it. I took the right front shock off. I went to maximum droop. Supported the arm with my finger like before. I could feel absolutely no extra or diminished weight on the hub from the up or down angle of the dogbone as I moved the suspension up at full throttle or when goosing the throttle. The force here is forward or backward like I mentioned before. It should have no effect on traction. The center of gravity certainly affects traction. Moving the diff 1/8 inch is sure to be a slight change though. I would compensate for the move with maybe a slight change in droop.

Rear Roll center
I set my rear roll center at the ground to start with. I used the medium lower A-arm mount on the lower hole. My inner camber link pivot is in the inner middle hole. Outer hub hole.

Negative Camber gain
When the car rolls it is helpful for the camber to change in a negative direction to keep the tread flat (The top of the wheel moves inward with roll). This really helped the steering on my pan car custom front end.
The way I set the front camber links was to try to mimic this front end. Upper link is short and aimed down as it goes in. The result was: as I push down on one side of the car to make it roll, the tire stays vertical. There has to be some negative camber gain for this to happen.

At the rear, by experience I set the camber link differently. The tire actually goes more positive with roll. This seems to help the touring car transition faster in a chicane or S turn. I can change both after a track test.

John

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Old 08-13-2007, 11:25 PM   #68
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No I do not know who manufactures the Flightpower batteries, but I do believe they also make the TrakPower batteries. You can buy the batteries from Tower.

I love your "research" and thoughts in this thread. I am thinking about joining the electric crowd only because I love onroad, and electric onroad is the closest I can get around Santa Barbara CA without driving too far. The TC5 was recommended to me by Korey (Xray driver) if I am looking to save a few $$ in the long run with parts support. I love the JRXS Type R but many people have told me to stay away from it, especially since I will be running asphalt.
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Old 08-14-2007, 01:11 AM   #69
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Quote:
Originally Posted by yyhayyim View Post
A few new Lipo packs to consider and test:

1) Flightpower EVO packs(I belive these are the ones suggested a few posts before) http://www2.towerhobbies.com/cgi-bin...?&I=LXRVT8&P=7

2) Trackpower: http://www2.towerhobbies.com/cgi-bin...&I=LXRWF7&P=ML

John check this out:
http://www.flightpower.co.uk/

They are made by Enerland in Korea

And the packs I was referring to were the EVO30 Premium packs.
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Old 08-14-2007, 07:19 AM   #70
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From FlightPower website : "FlightPower manufacturing is located in a 9500sq ft air conditioned factory unit in business district of Bayan Lapas on the tropical island of Penang Malaysia. The raw material for production is the highest quality Lithium Polymer cells produced exclusively by Enerland of Korea. FlightPower is therefore an applications technology company whose added value is quality controlled assembly for optimised performance, reliabiliy and merchantability"

...Seems OK on paper, but we'll wait for John to get to the bottom of it...
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Old 08-14-2007, 07:29 AM   #71
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Quote:
Originally Posted by John Stranahan View Post
At the rear, by experience I set the camber link differently. The tire actually goes more positive with roll. This seems to help the touring car transition faster in a chicane or S turn. I can change both after a track test.
...

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Old 08-14-2007, 07:53 AM   #72
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yyh, that won't work because cornering force is generating a torque in the hub. You have a lateral force at the road surface / tire intersection, and it's being solidly resisted by the lower hub pin. That's a torque, and it has to be resisted by the upper turnbuckle. Putting a shock there ensures it won't be solidly resisted, ensuring the hub will flop around.
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Old 08-14-2007, 09:34 AM   #73
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YY - wouldn't the cornering force be pushing the wheel to do the opposite of what we want it to do? (tendency to pos camber while we want neg camber)

So, using a dynamic camber link (a shock) would allow pos camber, even though it would slow it down.

Somehow you would need something that would react to force somewhat the way a viscous coupled LSD does - counter to tendency - fluid becomes MORE viscous as plates spin, as opposed to, say, syrup which gets less viscous.

You would need a shock that fights the pull by contracting in a predictable fashion.

At least those are my pre-coffee thoughts! It's a cool idea, though!
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Old 08-14-2007, 10:29 AM   #74
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Rezenclowd3-Thanks for the post. Welcome aboard. The TC5 is a good choice. I believe the thunderpower cell I am using is from Enerland in Korea. It is a good cell so far. I have over 25 cycles on it. It is prepared for harsh duty in the TC.

So is pinballed from corner to corner good or bad?. On the TC probably more benefits would be gained from active rear toe, Like the 5 link German full size TC's have on their rear ends. This would be easy to do on an old Shumacher with rear toe links. You would add some rear bump steer in the proper direction. The RC TC car is somewhat resistant to benefits from camber due to the round shape of the rubber tires. I agree that the upper shock is causing the wheel to move in the wrong direction for the reasons that Adamge and Boomer noted, but maybe this is the effect you are looking for to transition better.

Thanks for the posts. I put an old Losi Skoda II body on the car; it is ready for duty. The track is almost finished with repairs.

John

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Old 08-14-2007, 10:39 AM   #75
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just wondering why do you have the esc mounted on top of the battery? Isnt going to affect the way the car handles having that much weight that high?
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