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Old 11-18-2002, 09:13 AM   #3001
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Lonestar: It's not a theory, it is fact. I've worked on real race cars on scales, read the books, RC cars on scales. The left/ right % (and the front rear %) does not change with preload/ ride height. It only changes the corner weight and then all the other corners change too. You have to move weight or add/ subtract weight for the left/ right % (or the front/ rear) to change. Period.
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Old 11-18-2002, 10:12 AM   #3002
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Lonestar- you are correct that shock length wont matter with the droop screws in.I guess maybe I am lost on what you are trying to do? If you can get the car on scales and get the L\R balance within a 10 numbers of each other it should be fine.The front to rear difference is set on the track.If you are oversteering then increase the weight on the rear.I wish I had written down my number to give as a reference.How old is your car? I had one of the first ones out and it had a problem with the shock tower not sitting square on diff case.So I always had to have a little lean to the car to get it to balance.I believe they fixed that on all the newer cars.The other thing to do is to check your scales.Get some lead weights and check your scales difference.They are always a little off.
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Old 11-18-2002, 12:57 PM   #3003
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slop is built into the rack. It has to have SOME slop or else it would bind on the bushing/bearings. If you stop to think about it, as the rack slides left on the bearings, one surface of the bearing is moving left and the other is moving right. If there were absolutely no slop, it would bind on the wrong side. . .

Minimizing that slop is what is the challenge. That's the only part of the TC3 that I really don't like.
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Old 11-18-2002, 09:43 PM   #3004
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What slop are you talking about. The tc3 has no side to side slop. If the rack has a front to back movement than it would not effect the turning ability of the car. Boomer is absolutely correct in saying the slack is needed beacuse there is only one bearing on each side of the rack and would not work if the bearing touched both sides. This rack is a simple design and works well.

Lonestar-There is no slop free system to fix your problem
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Old 11-18-2002, 10:56 PM   #3005
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Lonestar:

Hi,

as for the slop in the steering rack..... you need some play for it to work right. you can adjust the up and down movement by shimming bearings/bushings in the rack . for a slop free ( well almost you could install a nitro TC3 steering setup in your TC3. I have done this on one of my cars with good results. the steering rack ball studs are same as the rack only inboard more. you will lose some of the ackerman (sp??) you had with the rack. and the TC3 will turn in tighter than one with the rack........ and you have to do some milling on the chassis to get it to fit.
I have holes to mount it like the NTC3 and 180 degrees from the NTC3.

thanks
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Old 11-19-2002, 12:41 AM   #3006
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Default Re: What would it matter

Quote:
Originally posted by rangulo
What slop are you talking about. The tc3 has no side to side slop. If the rack has a front to back movement than it would not effect the turning ability of the car. Boomer is absolutely correct in saying the slack is needed beacuse there is only one bearing on each side of the rack and would not work if the bearing touched both sides. This rack is a simple design and works well.

Lonestar-There is no slop free system to fix your problem
Brand new FTC-3, built according to the directions and according to the experience from building two Team TC-3's, had some degree of, shall we call it, play from side to side as an effect of the rack having a very small amount of up and down and longitudinal allowances. Not much, but I call 1/16th inch at the wheels play.

Satisfactory play, yes. I don't think it matters much.

It does get a bit worse as time goes on. I still dont' think it makes a big difference. Keep the rack clean, blow it out, keep crap out of it, keep good ball ends (RPM) and you're gonna stay in good shape.

Most of the play in my front end comes from the hub carriers. . .not the rack.
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Old 11-19-2002, 08:29 AM   #3007
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Howdy folks

Jack: to use PK style plugs, if you don't feel like dremeling the chassis, use an extra battery bar to solder your female plug on, out of the way... like this:




craig: I'm just trying to get that car to turn the same left and right and track straight... So far it turns spontaneously to the left under brakes and goes to the right on the throttle.

jsp: interesting... I guess there's only one way to be sure... the 4-scale board!!! I'll take may car such at it is to do, add 10 turns to one of the shock collars, write down the results, and let yall know.

Steering rack solp: same here, around 1/16inch or 2mm of slop at the steering block end... The steering rack floats all over the place on the bearings. Might be time to get a new one. I do understand that in order to move freely on its post, it can't touch both sides of the bearings at the same time (duh)... but if you want to relate this to a "design" factor, that's what I'd call a "design flaw" rather than a "feature"! I unfortunately don't have the time to do the NTC3 mod. But I'll find a way to reduce it... one of the solutions would be to force the rack to always stay against one side of the bearings, for instance, maybe using rubber band or something. Just brainstorming...

ttyl
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Old 11-19-2002, 08:43 AM   #3008
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I use a 4 scale board plus it just makes common sense.
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Old 11-19-2002, 10:03 AM   #3009
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Just curious, what is the advantage of having threaded tie rods instead of the standard chassis braces?

Is it possible that is the cause of your chasis tweak???
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Old 11-19-2002, 10:37 AM   #3010
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Lonestar have you checked to see whether the chassis itself is straight.
From the pictures it looks like someone may has attacked the car with a dremel round the motor mount (not a good place to remove material) but it's difficult to tell. The non standard brace arrangement ( tie rods) will allow the chassis to twist more as well, possibly contributing to your problems. Make sure the length of the rods is correct too. The standard front and rear braces are different. You may have mounted a tie rod on the wrong end of the car.

Have you tried changing the tyres?
Sometimes if you don't glue one quite right or if you accidentally use one with a wrong insert / different compound it will have the effects you describe.
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Old 11-19-2002, 10:52 AM   #3011
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First thing I would recommend is putting the stock chassis braces back on.Then set you toein back to 0 or maybe -1,you have to much toe-out.If you are needing more initial steering change your C-hubs to 4 degrees.If you still have problems with it steering more one way then the other check this.Put the car on a flat board and use the knife test to check tweak.The car should touch both tires and the same time.The front is the only one that matters,but check the rear also.
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Old 11-19-2002, 05:02 PM   #3012
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Lonestar........I agree with Craig.....put the other braces back on...and less toe-in........
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Old 11-19-2002, 05:05 PM   #3013
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Just wondering how much uptravel you guys have when running foams. With 62mm wheels and my droop is 6 in the front and 4 in the rear, this gives me 7mm uptravel in the rear and 5mm in the front. As the wheels get smaller the droop stays the same but the uptravel gets less and less due to adjusting the ride height up. I am just wondering where is a good place to start and why even bother measuring droop.
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Old 11-19-2002, 07:43 PM   #3014
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Lonestar: have to agree with the others. put back the stock braces and try starting with 0 toe up front. those tie rods look trick but i assume it will be a bit more of an effort to get chassis tweak right. plus tie rods do come loose or adjust after a few bumps or hits. i mean the same thing happens with camber links, if you check every so often, camber link angles do change and you find yourself having to re-set them once in a while.
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Old 11-20-2002, 01:27 AM   #3015
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Folks,

it's not my car. Mine still has the stock braces. I just posted that pic to show how to use extra baterry bars to mount PK-style plugs... but it's not my car.

In Europe it's getting more and more common to actually use rods and ballcups to replace the stock braces, in order to finely adjust chassis tweak. very trendy indeed, but I don't feel like doing it. As you guys say, it's to much work to get the tweak right and I don't want ot get into this game.

As far as dremeling the chassis, what you see on this pic is a small fan mounted to blow on the motor. With the current generation of batteries, and because most controlled TC racing here is limited to 12-turns motors, you can afford to pull a few more mA in order to cool down the motor better. It's getting incredibly common here, mine has this mod too. Basically once the battery's plugged in, the fan blows. The effects are terrific, not only does the motor stay cooler during the run (hence more consitent from a power standpoint), but for practice, you only have to wait like a quarter of the cool-down time if you want to go back on the track. You do have to shave some vertical plastic off the chassis to fit the fan, but tweak shouldn't be affected unless the chassis already has a LOT of fatigue.

Will go back to the track tonight... and let you know.

Cheers,

Paul
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