yea, I see the post on "knuckles", but I have spent alot of time on a hybrid steering/knuckle setup this week. :rolleyes:
My question is whether or not I should cut/mill in a + Ackerman angle or not. Its a trail only (crawlin') rig.
If so, how many degrees?

Dont worry about it. The ackermann will not be noticable on a trail only rig.

I don't think you understand the ackerman theory if your asking for a angle....? I may be wrong but a angle won't get you where you need to be. Its based on lots of variables. Wheelbase, track width, location of knuckles steering arm geometery. Its not a angle per say as much as a location in relationship to your whole steering system. If you do understand it just lay it out in CAD or in pencil and position it for your setup.....

Here is a very good web page explaining it.
http://www.rctek.com/handling/ackerman_steering_principle.html

Not to the details. I've layed this out in CAD for the Toyotas and I have simulated the whole steering system from lock to lock. I believe its impossilbe to make it perfect so there is no tire scrub through the steering range but you can get it close.

I've had boths types of arms on my 4runner. ones taht have had no ackermann adjustment and ones that do have it. I can tell the difference. the arms that have the proper designed arckerman locations has less tire scrubb and it feels like you can turn the vehicle sharper.

Hope that helps you out.

Thanks rick. That helps. :) No, I just understand the very basics, but that helps--good info.
The arm design is pretty crazy, but the actual bore of the holes for the TREs are going to be the same as *a popular aftermarket arm* as far as length and "offset". I wasnt going to change that.
Thanks for the food-for-thought. :D

Rick, you drive yours on the street. Born Loser will not. This is a trail only rig. If you want to spend the time to incorporate some sort of ackermann the go right ahead. But if this is something that will prove to be rather time consuming....then save your time.

The height of my arms differ in height from the popular histeer arms. I would assume this would affect things...
It looks like it would be trial and error, and I am not building a billion dollar spaceship, so all bets are off. My wheeling is basically "point-and-shoot" anyways, actually STEERING the rig breaks the axles. :D jk
Im at least a 'hair' smarter from ricks link, so thats good.. :)

[QUOTE=4RnrRick] Its based on lots of variables. Wheelbase, track width, location of knuckles steering arm geometery. Its not a angle per say as much as a location in relationship to your whole steering system.

I've had boths types of arms on my 4runner. ones taht have had no ackermann adjustment and ones that do have it. I can tell the difference. the arms that have the proper designed arckerman locations has less tire scrubb and it feels like you can turn the vehicle sharper.

QUOTE]

Please explain 4RnrRick. What arms have the "correct ackermann" for your setup?

"the arms that have the proper designed arckerman locations"


What does ones specs need to be for ackermann to be "correct" on their truck? (with the arms you say have properly designed ackermann)

Well since I do design and CAD for for Sky, I'm running his latest arms.........

As like I said before, I feel its impossible to design PERFECT ackermann for a Toyota. you can get it close but its only that.

As for the on road vs offroad performance comments. I feel a "good" steering arm with ackerman is important in both locations, on AND off road. you will never notice the difference in ackerman design driving down a moderately twisty road or the highway. You just CAN'T feel the tire scrub in those conditions with these types of rigs. Basically at those speeds your not turning the wheel far enough to need the front tires to be mis-aligned from each other...... what you CAN feel is say turning around on a street or in a parking lot. Its just easier and smoother. Thats where the benefit is. see the ackerman 'idea' is to turn have the wheels turn at different rates based on the turning radius. so the tighter you turn, the more important it is. Offroad wise (well in trail running and rock crawling) you are constantly turning the steering wheel from lock to lock and you will notice a difference. especially in how tight you can turn in 4wd.

I had ALL these same questions when I was running steering arms that had no ackerman angle designed into them. Then through careful anaysis and experimentation. I now understand it better....... by no means do I consider my self an expert but I can tell the difference between the two steering arms onroad and offroad. I actually feel its more important offroad since that is where these toyota axles really lack is in turning radius!

One last comment is offroad means different things to different people, but driving on slick rock (offorad) is just like driving on pavement (onroad) in 4wd, or driving in sloppy mud (offroad) is similiar to driving on ice (on-road), so it really doesn't matter...... The two driving styles should be catagoriezed as slow speed and high speed performance of the steering system based on ackerman design..... if your slow speed driving, then I feel proper ackerman design is more inportant then high speed driving.

I really hope that makes sense....

rick,
a question based on your observations of the two different style arms.

how much, if any difference is there in actual turning radius.

i mean i realize the TR is poor with a spooled front, but that last circle must have been 70+ feet across :(

and WHO did the design and CAD for the SKY pitman arms that apparently have the wrong taper on the splines? That was a big letdown for me as far as buying parts from vendors is concerned. I got a big billet piece that ruined my steering box. bummer.

and WHO did the design and CAD for the SKY pitman arms that apparently have the wrong taper on the splines? That was a big letdown for me as far as buying parts from vendors is concerned. I got a big billet piece that ruined my steering box. bummer.

If a part is not right and damaged your box contact the vendor. I am sure Sky will make it right and replace the box for you.

and WHO did the design and CAD for the SKY pitman arms that apparently have the wrong taper on the splines? That was a big letdown for me as far as buying parts from vendors is concerned. I got a big billet piece that ruined my steering box. bummer.

take it up with the vendor, don't go off & ruin this post. Sky has been very good to me, I'm sure you will get this matter resolved, but not by bashing him in public. :(

it worked OK, but cut/grooved/ruined the bottom 'neck' on the box. The splines were obviously VERY different from the stock IFS arm (taper).
I am past all this now, but hope the design of the part has been fixed so it does not happen to people that do not have the ability to fabricate their own parts.

not bashing at all, I believe this has happened before. I thought it had been fixed.

rick,
a question based on your observations of the two different style arms. how much, if any difference is there in actual turning radius.

I haven't actually ever measured it but it also has a lot to do with the tire size, BS and steering stops.....

and WHO did the design and CAD for the SKY pitman arms .............

Ah.... Me and Sky! But they are manufactured by an outside vendor. As for the bad part, take it up with Sky. I know that if the nut gets loose, that can take out the splines. My prototype arm still fits the splines..........

its the taper of the splines that was off. No big deal, I bored the splines on a stocker and made my own. The arm tightened up to the neck of the box and eventually cut thru the cast housing on the box. I could tighten the nut till it pressed the arm into the cast.

I know I'm a newbie but ackerman angle is something that dose not apply to anything that is not a road racing car with a bell crank. If you go to that web site that was listed you will find out that you are not biulding a R.C. car! If you are building a 4x4 you sould just build your steering the way you want .ACKERMAN IS B.S. :flipoff2:

SKIDROW - You obviously don't know your a$$ from a hole in the ground. :shaking:

I put custom steering arms on my rig which were engineered ackerman correct and my turning radius improved drastically. So much so that others with lesser engineered steering arms were asking me why mine turns better. In a parking lot with the steering turned all the way it makes a three foot smaller circle than before without adjusting the stops and with less tire scrub. That could make the difference between making the turn or needing to back up and try again. Don't tell me that "ACKERMAN IS B.S."

If you are using steering radius for ackerman angle that's not
ackerman angle! ackerman angle is found by combining a lot of different angle's!
I'm not trying to start a problem but every time someone start's a post on the net I have to teach alot of people that there chasing the wrong dog!!
Ackerman in short form is camber caster&toe in a turn it take's to long to spellout with my typing because I type about 5 words a min. :D

i have 4x4 labs on my rig & i'm game for any steering comtest took 4" out of my raduis

just for the sake of education ackermann is also known as toe out on turns.

like rick explained it is used to differntiate the arcs required for the front wheels to make the same turn.

obviously if you turn left, the left wheel needs to make a smaller circle that the right and vice versa.

mind you, if you get away from a factory wheel/tire combo, there are a lot of other factors involved.
scrub radius, wheel track and wheel base all play a big part.

the "... you dont need it on a trail rig..." is BS. proper steering geometry is important for safety, parts wear, and drivability of a rig.

...every time someone start's a post on the net I have to teach alot of people that there chasing the wrong dog...
It's a good thing we have you around to straighten things out for us. :rolleyes: Hold on a second while I go PUKE :barf:

Yes, proper Ackerman does improve the driveability of a vehicle.

Yes, proper Ackerman does decrease turning radius.

Yes, proper Ackerman will reduce tire wear. (Non-issue on trail rig)

No, you don't have to design it into your steering arms if you don't want to.

At least you have try'ed to look it up and yes it is toe in on turn's. But steering arm lenght won't change it.thank you!! :D

I drove the rig in the alley for the first time today, since the revamp.
The steering is OK on pavement..its an inverted 'T' setup for now (DL>TR). I am definately getting more tire-scrub than w/ the Marlin setup. Its not bad though. Its a trail/alley rig only so wtf. Goes well w/ the 1-link rear. :P

Skidrow shut up, no one said anything about it beening about the lenght of the arm, the very first question is what angle! And as for the R.C. car thing, you must not know much about R.C. Cars because there are alot of RC monster trucks in the professional racing world that actually have just as or even more complicated suspension and steering than your toyota. You could stand to learn A LOT from them.

Born loser, if you think it is good now then go with it. It seems to me that it is a good thing to have.
Adam