Ackerman angle - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 16 Old 06-02-2015, 10:28 AM Thread Starter
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Ackerman angle

Have any of you messed with this?

I am into drifting with my fox, as well as open track and autocross. Currently i'm at the point where i will be cutting my front spindles to change the tie rod mounting location for more steering angle, and quicker response.

In doing this, I can essentially choose my own ackerman angle. 0 degrees is recommended for most aggressive drift driving, but I dont want to make too much of a sacrifice for grip driving.

I know its not as bad as CC here, but please dont hate on drifting. Just looking for some info on what grip drivers like for ackerman angle.

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post #2 of 16 Old 06-02-2015, 10:29 AM Thread Starter
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and a picture of said drifting, because who doesnt like pictures?

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post #3 of 16 Old 06-02-2015, 06:45 PM
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If you move the end of the steering arm rearward to speed up the steering ratio, that is going to reduce the ackermann effect quite a bit. Try to move the end of the steering arm outwards towards the brake rotor. This will restore some of it. You will then have to use a rod end on the end of the tie rod.

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post #4 of 16 Old 06-03-2015, 01:52 PM Thread Starter
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Thanks Jack. I need to take some more measurements from my car to hopefully calculate the ackerman, but by just looking at it, I was going to be moving the steering arm inwards instead of out. Your response will help judging how well my calculations came out.
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post #5 of 16 Old 06-04-2015, 06:14 PM
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post #6 of 16 Old 07-13-2015, 03:24 PM
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You can remove material from the steering rack mounting face to the K-member, and/or add washers to adjust Ackermann as well. In other words, moving the steering rack longitudinally is another Ackermann knob. Email me if you need more details.

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post #7 of 16 Old 07-13-2015, 11:48 PM
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I removed 1/4" from the back mounting face of the rack to increase Ackerman per the Mathis book. Is it possible you can move the rack forward for the opposite effect?
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post #8 of 16 Old 07-14-2015, 12:27 AM
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Yes, just add washers between rack and k-member. When the angle between the spindle arm and tie rod is 90 degrees, you have zero Ackerman on a rack and pinion style steering.
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post #9 of 16 Old 07-15-2015, 12:16 PM Thread Starter
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wow thats good to know.
Im getting my spindles cut next week. moving the mount for the TRE back 1.5" and in .125" I can fine tune ackerman with moving the rack
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post #10 of 16 Old 07-15-2015, 09:22 PM
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What Ackerman angle would be best for a road race type vehicle, and how would you go about doing it?

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post #11 of 16 Old 07-16-2015, 02:41 PM
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What Ackerman angle would be best for a road race type vehicle, and how would you go about doing it?

Like setting an alignment, "ideal" Ackermann will be vehicle-specific and track specific (e.g. more toe out for slow tracks with tight turns and less toe out for fast tracks with high speed straights. Or setting less static camber for a car that has it's ride height in the fat part of the camber gain curve instead of the flat part of the curve.)

Same goes for Ackermann, the tighter the turns, the greater difference between the inside radius and outside radius as a percentage, so more Ackermann is desirable. Check out racing go-kart alignments for some mad Ackermann angles.

Not only does Ackermann increase the slip angle of the inside tire, but it works together with caster to amplify the weight jacking effect on the inside tire when turning. If you are caster limited, adding more Ackermann may help.

On a mustang, generally speaking, more Ackermann is better because you bump into physical limits of the OEM chassis before you can go too far (like with caster).

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post #12 of 16 Old 07-16-2015, 06:21 PM
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Quote:
Originally Posted by fast_frank_d View Post
Like setting an alignment, "ideal" Ackermann will be vehicle-specific and track specific (e.g. more toe out for slow tracks with tight turns and less toe out for fast tracks with high speed straights. Or setting less static camber for a car that has it's ride height in the fat part of the camber gain curve instead of the flat part of the curve.)

Same goes for Ackermann, the tighter the turns, the greater difference between the inside radius and outside radius as a percentage, so more Ackermann is desirable. Check out racing go-kart alignments for some mad Ackermann angles.

Not only does Ackermann increase the slip angle of the inside tire, but it works together with caster to amplify the weight jacking effect on the inside tire when turning. If you are caster limited, adding more Ackermann may help.

On a mustang, generally speaking, more Ackermann is better because you bump into physical limits of the OEM chassis before you can go too far (like with caster).

Frank
Thanks Frank.

I moved the whole front suspension forward about 3-4" so I guess I'm pretty good on caster, and Ackermann [just finished painting the car so I haven't had a chance to check alignment].
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post #13 of 16 Old 07-22-2015, 09:54 AM Thread Starter
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well I cut and re welded my spindles. Steering response improved 10 fold, and I have a lot more steering angle. Well see how it does at the track this weekend.
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post #14 of 16 Old 07-22-2015, 10:25 AM Thread Starter
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this is a rough comparison of a stock spindle vs a cut spindle. I cut mine 1.5 inches.
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File Type: jpg 1 inch cut.JPG (42.9 KB, 12 views)
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post #15 of 16 Old 07-23-2015, 06:41 PM
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Originally Posted by 88lxvert View Post
well I cut and re welded my spindles. Steering response improved 10 fold, and I have a lot more steering angle. Well see how it does at the track this weekend.
I'm not understanding, where did you cut the spindles?

Can you post a picture of the spindles?

I would be more than a little worried having my spindles cut, and re-welded. Not that there is anything wrong with it, just would bother the heck outta me.
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post #16 of 16 Old 07-24-2015, 08:19 AM Thread Starter
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this is a comparison pic.
I was/am pretty nervous about it. I work in engineering and spoke with my chief engineer and with our top welder in the shop. They gave me pointers on what to do, and then checked it out for me after the cut. I should be good. I have tested it so far, and no signs of cracking. The spindles are cast steel, which with some preheating, and slow cooling, welds a lot like regular mild steel.
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