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EXPLAIN ACKERMAN AND ITS EFFECTS

EXPLAIN ACKERMAN AND ITS EFFECTS

Old 06-22-2015, 12:43 AM
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Default EXPLAIN ACKERMAN AND ITS EFFECTS

Hi all,its not something i play around with much so would be good to hear from others on how and why you shim it ,i think its the next step for me to find those last few tenths,im struggling with coming off a sweeper to then get it turned in at the end of it,kinda mid to exit issues ,tyres grain up quite quickly so was thinking maybe lose some toe out (which is the change i make instead of adjusting ackerman) and add shims to alter the ackerman,i drive an xray t4 15
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Old 06-22-2015, 01:12 AM
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I have very little experience with ackerman. Normally I just run the kit 1mm (T4'14). Today I was running on a track with sweeping 180s. The car was having trouble with mid to exit, feelinv like it was bound up and just wouldn't rotate. Adding 1mm (total 2mm) did help quite a bit. So I think you're probably on the right track.

More shims on most modern TC's with bellcranks and links straight across, will reduce ackerman, giving less inside wheel and and more outside.

One thing I've noticed with only front toe changes is that more toe out gives better turnin but washes out mid corner. Thinking about Ackerman with respect to that, I'd think less Ackerman would counteract that mid corner washout. As for when to use toe and when to use ackerman... *shrug*
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Old 06-22-2015, 01:29 AM
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I find this from RCF1.FR
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Old 06-22-2015, 02:07 AM
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more shims generally means more aggressive turn in
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Old 06-22-2015, 08:51 PM
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I've found for tight technical tracks you want to run the steering links inline with the steering bridge or servo saver. Like this ____ ____.

If you're running on a wide-open and flowing track (less technical) track. You want to run the links swept back creating an upside down v like this "^" shape. This I've found made the steering mild and easy to drive.

Below was based on a tight technical track layout. See picture below.

Track experience with using different ackerman positions on my 1/12th are :

A) Swept back ^ position.

1) The car was very mellow and easy to drive. However, it was a little too mellow on corner entry.
2) I had to turn up the steering EPA to 90% in order to get the car to "cut" or "carve" into the corner.
3) However, the car was very stable throughout the corner EASY TO DRIVE, however, it wasn't super precise in or out of the corners. It took a lot of work to maintain tight lines.

B) Inline position.

1) The car was reactive and turned in hard on corner entry. It "cut" or "carved" the corners precisely.
2) I did have to dial down my steering EPA to 65 to reduce the twitchy steering.
3) The car was relatively stable, but it had a darty feeling. Which was ideal for tight technical tracks.

You'll need to examine the track layout your running on in order to decide on what ackerman position you need to use.

Last weekend I was running my links sweptback like this ^ and the fastest lap time I managed was 9.400. After speaking with the fast guys, the mentioned to run the links inline for a sharp turn in. Boom! I made the change and dropped my lap times down to a 9.184. Makes a big difference.
Attached Thumbnails EXPLAIN ACKERMAN AND ITS EFFECTS-img_3213-3-.jpg  

Last edited by EDWARD2003; 06-25-2015 at 05:14 AM.
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Old 06-23-2015, 12:56 AM
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Edward,
The way I read your post, you state the effect opposite of the other posts.

...
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Old 06-23-2015, 01:38 AM
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I think the ackerman setting is also dependant on the tyres you're using, as each manufactures tyres have different slip angles, whilst different track surfaces make a difference as well.
On carpet I tend to run 0mm, whilst on asphalt it will depend on the tyres, but anything from 0mm to 2mm.

Each corner has an optimum ackerman angle for your car, what you're doing is trying to find the best compromise to give you better lap times. Sadly there is only one way to find out, testing.
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Old 06-23-2015, 01:42 AM
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Originally Posted by Stein Tumert View Post
Edward,
The way I read your post, you state the effect opposite of the other posts.

...
I know! Weird, eh?

You don't have to believe my word. I just wanted to mention my experiences using Ackerman on a 1/12th.
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Old 06-23-2015, 04:45 AM
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The thing to remember about ackerman is that it is not a "one way gives more steering, the other less" type thing. It is a one particular setting gives the most steering and anything different from that in either direction will give less.

So why make it adjustable when one setting is best? Because what the best setting is will be different depending on track, tires, grip level and even set-up.
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Old 06-23-2015, 05:24 AM
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I agree 100% with Edward
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Old 06-23-2015, 06:59 AM
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Do carpet plots actually exist for Rc Car tires?
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Old 06-23-2015, 08:24 AM
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Originally Posted by Skiddins View Post
I think the ackerman setting is also dependant on the tyres you're using, as each manufactures tyres have different slip angles, whilst different track surfaces make a difference as well.
On carpet I tend to run 0mm, whilst on asphalt it will depend on the tyres, but anything from 0mm to 2mm.

Each corner has an optimum ackerman angle for your car, what you're doing is trying to find the best compromise to give you better lap times. Sadly there is only one way to find out, testing.
Completely agree. I suggest one start with tires and inserts, dual rate, etc before messing with ackerman settings.
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Old 06-23-2015, 11:56 AM
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http://www.rctek.com/technical/handl...principle.html
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Old 06-23-2015, 12:18 PM
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One of the questions I have always had about Ackerman, is how does it work on a Touring car with a spool? When a spool equipped TC turns does the inside tire not slip as it can't turn faster then the outside tire? So if the tire is already slipping what effect if any would Ackerman have?
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Old 06-23-2015, 01:37 PM
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Originally Posted by Stein Tumert View Post
Awesome site. Thank you.
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