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Old 06-03-2008, 10:41 AM   #2161
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Default Ackerman

For another ackerman adjustment, what about putting another hole just forward of the stock one in the chassis stiffner, this should move the unit ahead and make for a longer link which should change the ackerman? At least thats what I'm thinking it would do, please let me know if I'm wrong.
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Old 06-03-2008, 01:09 PM   #2162
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For another ackerman adjustment, what about putting another hole just forward of the stock one in the chassis stiffner, this should move the unit ahead and make for a longer link which should change the ackerman? At least thats what I'm thinking it would do, please let me know if I'm wrong.
This would move the steering rack into the diff pully.
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Old 06-03-2008, 01:18 PM   #2163
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For another ackerman adjustment, what about putting another hole just forward of the stock one in the chassis stiffner, this should move the unit ahead and make for a longer link which should change the ackerman? At least thats what I'm thinking it would do, please let me know if I'm wrong.
If you mean another hole in the upperdeck I have already tried that. I thought that the car would steer more but it turned out to be quite the opposite; it was understeering. The team drivers in Europe have added a piece to the steering lever instead. It seems that lengthen the arm have a more positive effect than moving the whole assembly forward.
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Old 06-04-2008, 12:51 AM   #2164
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So, still running the rdx with dual bell crank steering. What is the advantege to running centerpoint, and is this more of a personal preferance/tuning option or does one have a clear advantage over the other.

thanks in advance.
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Old 06-07-2008, 06:14 PM   #2165
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put a spool in the rear it will steer then!!
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Old 06-09-2008, 09:05 PM   #2166
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Kinda slow around here.


Whats a safe starting gear for a 10.5 on a large track?
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Old 06-09-2008, 10:22 PM   #2167
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maybe around a... 4.8-5.3 depending how bif the track is?? I run a 5.8 at my home track which is about 90x40

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Old 06-10-2008, 11:22 AM   #2168
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Kinda slow around here.


Whats a safe starting gear for a 10.5 on a large track?
Depending on what motor, your ESC profile, etc. but for Novak around 5.0- 5.2 ish, Orion and Speedpassion around 5.4. Not sure on LRP.
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Old 06-10-2008, 11:26 AM   #2169
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has anybody had success running 5-cell, carpet-rubber? (brushless!)
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Old 06-10-2008, 02:27 PM   #2170
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Like around 155x60, big
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Old 06-11-2008, 10:50 PM   #2171
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Whats a safe starting gear for a 10.5 on a large track?[/QUOTE]

I suspect you're running rubber tires?... Quite honestly, it can vary quite a bit on your ESC - motor combination.
Let's say we're using Novak 10.5 motor:
LRP ESC 5.0 - 5.75 FDR
Novak ESC 4.75 - 5.50 FDR
This all depends on timing in the motor and track layout.
LRP unlike the Novak has adjustable timing built in.
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Old 06-12-2008, 08:09 AM   #2172
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Quote:
Originally Posted by DavidAlford View Post
Kinda slow around here.


Whats a safe starting gear for a 10.5 on a large track?
4.8 will be a good starting point for a 160X60 track w/ rubber tires using Novak motor and LRP TC ESC. With the 13mm rotor you can gear around 4.6 and end off after a 6 minute run around 165F w/ 85F outside temps. So starting around a 4.8 and then gear from there and check temps
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Old 06-12-2008, 08:52 AM   #2173
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So, still running the rdx with dual bell crank steering. What is the advantege to running centerpoint, and is this more of a personal preferance/tuning option or does one have a clear advantage over the other.

thanks in advance.
ok, gonna try this again. I see that there is more akerman adjustment available by running center point steering and that the phi utilizes the geometry of the car to complement this. As I'm running the old rdx with dual bell crank steering am I simply at a loss or is there a benefit to dual bell crank style?

i have read that sometimes center point can yield a sporatic corner exit and that dual bell crank can sometimes yield sporatic corner entry......? I have no clue if this is correct as I had to translate it from various sources and apply here.

I bought the center point top deck for the rdx, the phi center bell crank and still need the post to complete the setup,,,, but I'd really like to know what the 'pros' think....

I really appreciate any time you have to respond to this,
many thanks,
Casey
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Old 06-12-2008, 09:28 AM   #2174
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The only thing related to the steering system itself that determines a car's behavior is Ackerman. The center point steering, when set as most people do (inside hole on the steering block), delivers a difference of 9 degrees between the inside and outside wheels at full-lock (steering blocks hit stops on caster blocks), with the inside wheel having a higher angle with respect to the centerline than the outside. The RDX dual-bellcrank steering, when set with the shortest toe links, as most people do, delivers a 6 degree difference between inside and outside. The optimum angle is dependent on the tire. Certain tires require higher degree of slip angle to produce maximum lateral force than others. The right Ackerman setting is largely dependent on the type of track you run on. A very tight track with lots of 180's favors a car with more Ackerman because of the high degree of difference in wheel speeds and corner radii. A more flowing course, with larger radius corners where cornering speed is the absolute priority, requires less Ackerman (more equal steer), but only to a point. See below...

The other thing to consider is scrub. Most RC car tires will produce more lateral force when the slip angle is increased. However, it comes at a cost as too much slip angle will also create excess scrub. In a physical sense, this means that there will be enough of a component of the lateral force in the longitudinal direction to slow the car down. Theoretically, if one could turn the wheels 90 degrees, all the lateral force generated (with respect to the tire) would go into scrub, and that would slow the car immensely. The optimum Ackerman setting is a fine balance between creating lateral force and inducing scrub.
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Last edited by Brian McGreevy; 06-12-2008 at 09:53 AM.
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Old 06-12-2008, 04:48 PM   #2175
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Brian, can you tell me what the difference in degree is when using the outside holes full locked?

Thanks
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