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-   -   Better Steering - Fixes, Diagrams, Ackerman Angle Explained (http://www.diygokarts.com/vb/showthread.php?t=23785)

Half-breeder 10-19-2013 10:18 PM

Better Steering - Fixes, Diagrams, Ackerman Angle Explained
 
4 Attachment(s)
Ok I have fiddled w/ atleast 50-70 different scenarios/setups/positionings, studied numerous sites on the Ackerman 'reasoning', and have come up w/ an explanation/fix for the problems vs solution...

Problem w/ (most) go carts steering, that points forward(leading arms), is the lack of Ackerman(outside wheel turns more sharply than the inside... causing 1 wheel to be drug as the other grips). When taking a turn it is a 'given' that the inside wheel is not only traveling at a slower rotation... but also a 'tighter' path... so therefore, the more, tighter of a turn being made... the more the 'inside' wheel 'should' angle vs the outer.
http://i3.photobucket.com/albums/y57.../Ackerman1.jpg

To correct this... a 'farther' throw of the tierod, must be performed to the inside wheel, while a shorter throw, to the outside. 'This' can be performed 3 different ways...

"If" there is room the typical way to improve Ackerman is reverse the spindles to a rearward facing position, and the 'geometry' is corrected('if' mounting holes line up w/ Ackerman angle 'line' on the spindles)... Example of Ackerman w/ 'trailing' arms.

Another way to correct Ackerman(for forward facing spindles) is 'extending' the tierod connection point, on the spindle arm, 'past' the kingpin and 'outward', towards the wheels to lineup w/ the 'line' to create Ackerman...This procedure is not widely used/done, due to clearance issues...
(the one on the 'right')...
http://i4.photobucket.com/albums/y14...I/ackermn1.jpg

A 3rd way, which I did, because of clearance issues w/ wheels vs spindles, was take the distance that you would use for the above(2nd) example tie-rods, but move them inward instead of out, crossing them over/past the pitman arm... by using a pitman arm 'plate' to separate the 2 arm connections from each other, and create the necessary movement needed for proper Ackerman...
http://www.diygokarts.com/vb/attachm...3&d=1381194504

...a resemblance of the pattern I followed...
http://i24.photobucket.com/albums/c1...tmanArm1-2.jpg

From my 'trial n errors' I found that there is a difficulty in trying to find the happy medium in creating the plate, hole placement points. Most end results are uncorrected Ackerman and/or unaligned neutral positioning, or even worse.... binding. The truth is... unless the length/width are identical... there 'is' no "set" measurements. Little bit like a wedding dress... someone could mass produce them to fit a 'set' sized bride... but EVERY bride is shaped/sized/fit different... so measurements and calculations HAVE to be done, inorder to be 'custom' and actually 'perform' properly... and even 'then' it's all about 'guesstamations' of experience, and individual preferences.... but the procedure in 'finding' said guesstamations are 'set'... Ill try to simplify my procedure...

The angled difference, from the center of the rear axle to the center of the steering spindle pivot('kingpin') of both sides, is the angle that the plate needs to imitate. To attain the angle, lay a line from said points(thread/wire/yarn/etc... has to be straight). place a paper, under the center of the rear axle, as close to the frame, where the lines meet. W/ a single light directly above, trace the shadow of the lines, creating the "V" shaped angle, to the paper. Measure up from the focal point of the "V" 3-4 inches, and cut out the "V" shape. Place template of the angle on plate, and trace the patterned angle to the plate(centered). After attaining the angle at which the holes will be aligned on the plate... the 'length' of the plate needs to be equated... too long will result in a shorter turn of the wheel to attain FULL turn(too responsive... can be dangerous)... too short and a FULL turn will not be attained(shortening of turning radius).
***Trial and error part...best to use a practice plate (I used bumper plastic)*** First, take tierod ends(ones that will be in the pitman plate) and afix a small, short nail(smaller the better...w/ a 'head' nail only needs to stick out 1/2") ONto the end of the threaded stub(the one that goes through the plate), centered, as if an 'extension' of the rod(this will help w/ the trial n errors... plus smaller holes are easier to drill than big ones). I found tape to be a suitable implement in temporarily holding said nail to the 'stub'.
...Photoshop example...
http://i3.photobucket.com/albums/y57/Tihmbo/nail.jpg

Place the plate onto position(the pivot of the angle centered to steering rod end)... clamp and drill a hole 'below' the 'single' hole that 'was' the tierod end mounting point on the factory pitman arm...(NO WELD!!!...This will create a strong enough mounting even for driving!)
http://www.diygokarts.com/vb/attachm...4&d=1381893197

Drill 2 small holes(diameter of the nail) next to each other, on the angled lines(1 each line). Place nails into the holes(opposing sides) and set steering wheel at neutral position(straight ahead). Set the alignment. Then, remove nails, turn the steering, replace nails, and view from above, to check the Ackerman. If Ackerman is not suitable... remove nails from holes and redrill either above or below the current hole, keeping the new hole beside the new hole on the opposite side... staying on the 'line'... repeat till satisfied. Once position is attained... drill 'appropriate' holes larger to accommodate tierod ends. Shims/washers 'may' be needed dependent on the nuts used and the plate thickness(Lock tight 'red' after all is situated... no need for lock washers).

Also, the spindle arms themselves play a vital role in turning radius w/ proper Ackerman. Most karts will have spindles that have arms that are not 90degrees off the steering knuckle, they will be angled 'inwards'(factory false hypothesis of a 'fix' of Ackerman). The actual arms themselves will hinder turning radius(the angle amount, that the wheel turns) by making contact w/ the pivot bracket, hindering it from traveling any further.
http://i3.photobucket.com/albums/y57.../clearance.jpg


Another 'issue' is clearance of the opposing arms that cross each other on the pitman plate. Alotta times it is found that the nuts/extending bolts, will hinder free travel of the tierod ends and cause binding... there for a 'low-profile' nut and a shortened bolt 'should' be implemented to clear each other in a turn...
...protruding bolt hindering arm travel/swing...
http://www.diygokarts.com/vb/attachm...3&d=1382139857

...proper nut/bolt clearance...
http://www.diygokarts.com/vb/attachm...7&d=1382160380


After all is said and done(if done correctly), turns should be MUCH more effective and should appear somewhat like the attachments of this thread...Ackermann corrected.

Attachments are before and after(daylight=before/darker=after)

itsid 10-19-2013 10:32 PM

Nice!
just one minor thing: the guys name is Ackermann <-2 'n' ;)

'sid

Half-breeder 10-19-2013 10:46 PM

lol.... ill have to remember that... thats ok, most ppl forget the 'h' in 'my' name...lol

itsid 10-19-2013 10:52 PM

Quote:

Originally Posted by Half-breeder (Post 292442)
lol.... ill have to remember that... thats ok, most ppl forget the 'h' in 'my' name...lol

LOL
So you end up being Gordon Shumways Mom?

Well then Ms. Shumway, some cat for your tea?

'sid

danssoslow 10-19-2013 11:56 PM

Quote:

Originally Posted by itsid (Post 292443)
LOL
So you end up being Gordon Shumways Mom?

Well then Ms. Shumway, some cat for your tea?

'sid

I see what you done there.

J_Walker 10-20-2013 12:35 AM

not to hijack the thread or anything, but I've been wondering. how does ackermann work with suspension?? Of course it's going to be more complicated. but anyone know? I just spent the last hour or so trying to figure it out on my own.. and I can't seem to see it in my head...

Half-breeder 10-20-2013 12:41 AM

I would guess the same, just adding in the variables for camber/caster... but youd get a better response by starting ur own thread asking and plastering w/ pics... I made 'this' post for the moderators to make sticky ...NOT to fill up w/ 'other' stuff.

J_Walker 10-20-2013 12:55 AM

Quote:

Originally Posted by Half-breeder (Post 292466)
I would guess the same, just adding in the variables for camber/caster... but youd get a better response by starting ur own thread asking and plastering w/ pics... I made 'this' post for the moderators to make sticky ...NOT to fill up w/ 'other' stuff.

Ah okay, just found the answer to my question anyway!:2guns:

OzFab 10-20-2013 10:11 AM

Quote:

Originally Posted by Half-breeder (Post 292466)
I made 'this' post for the moderators to make sticky ...

Done; great job :thumbsup::thumbsup:

firemanjim 10-20-2013 11:45 AM

To be fair n honest.... the second to last pic is of my kart. I know why you used the pic (its cool) ,but there is nothing wrong with the way the bolts/nuts are. Its only an illusion. That pic is at neutra. When turned left or right,the rods actually rotate and clear everything for full turn ,lock to lock. My pitman arm has 2 angles to it, so the angles of the rods shift. I have about .100" clearance between the rod end and nut/bolt pictured, at minimum....the bottom one ends up with more than .250" of clearance.....

Half-breeder 10-20-2013 02:56 PM

Quote:

Originally Posted by firemanjim (Post 292521)
To be fair n honest.... the second to last pic is of my kart. I know why you used the pic (its cool) ,but there is nothing wrong with the way the bolts/nuts are. Its only an illusion. That pic is at neutra. When turned left or right,the rods actually rotate and clear everything for full turn ,lock to lock. My pitman arm has 2 angles to it, so the angles of the rods shift. I have about .100" clearance between the rod end and nut/bolt pictured, at minimum....the bottom one ends up with more than .250" of clearance.....

If that be the case... just from lookin at your plate setup... looks like youll turn better to the left than the right... But it is an optical illusion... Its probably the other way round... Hehe:cornut:

firemanjim 10-20-2013 03:18 PM

:lolgoku: yep, got more grip turning hard right than hard left....:cornut:
Gonna go out n see what I can do about flipping the spindles, flipping and swapping left to right,and just swap left to right. I'm gonna redo the pitman arm if need be. If necessary, I will just flip them, cut the arm a little shorter,and add a cheap rack-n-pinion. I like to have complete control for high speed high-jinx.... :lolgoku:
I will post some pics, as long as I still have daylight to take good one's. This is a great idea for a sticky. I knew NOTHING about steering geometry when I built my first kart so this can be SUPER helpful for the next "all this is new to me" guy.....

Half-breeder 10-20-2013 05:02 PM

Quote:

Originally Posted by itsid (Post 292443)
LOL
So you end up being Gordon Shumways Mom?

Well then Ms. Shumway, some cat for your tea?

'sid

Ha ha... My real name... Not my nickname!

Funny guy!

Doc Sprocket 10-20-2013 05:09 PM

Well done, sir! Thank you for putting forth the effort for everyone's behalf!

firemanjim 10-21-2013 09:13 PM

10 Attachment(s)
After flipping,turning and flipping, and flip flopping, it can only go the way it is...... :censored::mad2::mad2:
So, I cut off the original spindle arms and made some new ones. A little shorter,and at a 90 to the spindle. Now they fit inside the wheels..... In order to get correct Ackermann geometry, I need like another inch per side on the rods, so crossing the pivots helped out with that.... Have MUCH MUCH tighter steering now. AND NOW THE DOWN SIDE......
Because I shortened the spindle arms, my steering is SUPER responsive.... TOO responsive. Dont think I can let my son drive it like that, too dangerous. :mad2::censored:
Bact to the drawing board... enjoy the pics, maybe use for "do's & dont's" of steering.....

Half-breeder 10-21-2013 11:23 PM

Nice trial n error... I knew shortening the arms would cause the steering to be 'too' responsive(atleast for my kinda taste) but that is what I was thinking you wanted... the 90degree angle 'is' handy(after done w/ Ackermann) it'll shorten your turning radius considerably. I 'could' have less turning radius, myself... but the bars on the passenger side are in the way, so to be 'equal', I balanced out the difference... so I wouldnt turn 1 way further than another. Your error isnt 'that' bad of a deal though... all that needs to be done to correct(what youve done) is shorten the pitman arm also. By doing so... you will equate the 'swing' radius and the steering will become 'proper' again. Not sure the dimensions/lengths of your cuts... but from the 'looks' and my guesstimation, to me, you probably only turn the steering right at around 90-100degrees from full left to full right steer, where as mine has bout 160degree steer(whatever the 'factory' steering limiter allows).

Having put your arms at a 90degree... you will have to get longer tierods... if you had kept the factory arms on your spindles, you probably coulda got away w/ stock length.

The flipping of the spindles does 'nothing' as far as fixing Ackermann, unless your flipping them to 'trailing'. If kept at 'leading', all flipping the spindles does is raise/lower the frames ride height(if your spindles arms are higher/lower than the spindle race... like mine).

Yea, this is one for the *Dont do* pile IMHO...

firemanjim 10-21-2013 11:45 PM

Well, its not THAT bad.... the turning radius is down to less than one lane ,right turn... one lane on a left turn..... And yes,I had to make the rods longer by 2&1/2"...

I knew shortening the arm would do that,but I didnt figure ONE INCH was gonna make that big of deal. If my steering wheel was a clock face, with a pointer pointing at 12 @neutral, full turn to right only points at like 10:30-10:45 and left would be like 1:15-1:30.... I prefer more like 9:30 to 2:30.....
I have an idea though.... what about a triangular plate like the yellow one posted earlier. Making the arms longer, wouldn't that give me more swing at the wheel?

Half-breeder 10-22-2013 12:13 AM

Quote:

Originally Posted by firemanjim (Post 292857)
Well, its not THAT bad.... the turning radius is down to less than one lane ,right turn... one lane on a left turn..... And yes,I had to make the rods longer by 2&1/2"...

I knew shortening the arm would do that,but I didnt figure ONE INCH was gonna make that big of deal. If my steering wheel was a clock face, with a pointer pointing at 12 @neutral, full turn to right only points at like 10:30-10:45 and left would be like 1:15-1:30.... I prefer more like 9:30 to 2:30.....
I have an idea though.... what about a triangular plate like the yellow one posted earlier. Making the arms longer, wouldn't that give me more swing at the wheel?

...making the arms longer 'would' fix the steering wheel shortness turn(your 9:30-2:30)... and shouldnt mess w/ what Ackermann you have now(id still equal out your localization of the tierod ends on the pitman arm plate... or youll continue to turn different radius' left from right).

As far as making the yellow triangular plate... I thought that is what you did already(just not triangular).... your "optical illusion".

OzFab 10-22-2013 12:41 AM

Man, those tie rod ends are aweful close to the rim; is there any binding on the outside wheel in turns?

Rule of thumb is the tie rods should form a straight line from one wheel to the other...


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