Ackerman on a front steer

[Anonymous]

Looking for some info or a chart how to setup the ackerman on a front steer either rack & pinion or conventional steering.

 

[stangg]

I didn't think the type of steering would matter since I always thought Ackerman was only determined within the spindle (balljoint and tie rod mounting points) This article says rack and pinion doesn't have as much ackerman... I'm assuming it's because of the angled tierods which would also have some effect on it.
http://www.circletrack.com/chassistech/ctrp_0407_ackermann_steering_system/index.html

I have '01 spindles on my '68 with an '89 rack and although I never measured its ackerman, I don't get any noticible scrub when at full lock. The front steer spindle's arms are splayed outward... with the tie rod mount on the outside of the lower ball joint. The lower ball joint should land on the imaginary line going between the tierod and the center of the rear axle. In my case, the king pin angle is pretty steep, so I'm not sure how much of an impact that has on ackerman. It does strike the center of the tire's contact patch, so that helps to reduce scrub radius... on 4WD, I'd assume a centered king pin angle would also help on torque steer.

 

[Anonymous]

From what I have read the 4 wheel drives don't care too much about it. Even my 250 you can notice it in a tight turn. I am guessing the angle of the nuckle steering arm is where most of the problem is coming from. Since I flipped the nuckles everything is now working aginst me. I keep tossing the rack back on and off the car as well as a drag link setup. There may be some hope in using a drag link with the gear and idler creating their little circles. I may be able to use their small radius to alter the ackerman enough to at least get things moving the right direction. If this doesn't cure work, I may have to go in search of a different set of nuckles. Any ideas, I'm all ears.

 

[stangg]

Any chance you could retrofit a steering arm/knuckle off of another spindle to bolt on to your current knuckles. Fatman fab makes their own steering arms that converts the Mustang front steer spindle to rear steer. The GM 60s'70s GM A bodies also use a a bolt on steering arm.... I'm sure there are others.
http://www.fatmanfab.com/projects.php

Are you also looking at the bump steer as you go through your testing? I think that would have a much bigger impact on handling than ackerman.

 

[Anonymous]

Bump steer is number one on the list that I'm looking at. I have almost no change on the ackerman until about 20* either right or left. I gonna try to lengthen the pitmam and move the gear from side to side this morning and see what result that has. I am wondering if in production vehicles "if" some racks have different length tie rods? Not a lot of info on the web that I've been able to find so far on this.

 

[Anonymous]

Here's a couple photos of my bassackwards steering using the rack. I agree, relocating the arm would more than likely solve the problem.

 

[Anonymous]

I'm finally have it going the right way using a see-saw type arm with the rack. Now to adjust the ackerman you move it forward and aft. The angle of the pivot arms was the key. I'm probably not going to use it but it was a great learning experience. Now if I can use the gear and get things going the right way I'll be in business. I also added a photo of my homemade angle indicator. Worked like a charm and I think it was fairly accurate.

 

[Anonymous]

Here's a couple photos showing the tie rod ends moved in. It solved the ackerman problem but created another one. They now hit the rotor. I have another solution in mind and will try it tomorrow.

 

[Anonymous]

To bring things up to date.... I have decided to use an extension bolted to the steering arm. This corrects the tie rod/ king pin axis angle to where is supposed to be. It appears that it is within 1/4" through the turn. Also I was making a mistake using the protractors like in the previous photos. I did angle the protractor back 3* to comp for the caster but didn't raise the outside up to match the 8* formed by the upper (strut nut) and lower pivot point (ball joint). I was actually trying to measure an oval, like if you cut a piece of pipe at an angle then place it on a flat surface. The best way that I found to measure the ackerman was to use a straight edge to mark a piece of paper. Course you need to start with 0* and with the rotors in alignment then measure every 10* and record each set of lines (first two lines "a", second set "b" and so on). After such you can clearly see the ackerman changing through the turn once you measure each angle. Here's a couple of photos of adaptors/relocators I made. Also I will be using a differently designed tie rod end to clear the adaptor.

 

[RyanG85]

Interesting but you're making me feel stupid...... I was lost in the first post. Keep up the good work!

 

[Anonymous]

Here's some info. I can tell you this has been a good learning experience. My big problem came when I change the knuckles from left to right and right to left moving the steering arms in front which made my ackerman work backwards (the link below shows them in the rear). It's always the little things and I made a mistake or two when measuring and wanted to pass this info along so that others wouldn't repeat those I made.


http://en.wikipedia.org/wiki/Ackermann_ ... g_geometry

 

[Horseplay]

Here's some info. I can tell you this has been a good learning experience. My big problem came when I change the knuckles from left to right and right to left moving the steering arms in front which made my ackerman work backwards (the link below shows them in the rear). It's always the little things and I made a mistake or two when measuring and wanted to pass this info along so that others wouldn't repeat those I made.

Yeah, because the rest of us doing home-built, four wheel drive classic mustangs could use the assist. :roll LOL

My head hurts from reading this and I'm not even trying to understand it!