An obvious advantage of tie rod end spacers is to decrease ball joint wear on lowered cars, but i am confused about theory on how these spacers actually increase steering angle and reduce bump steer. After studying multiple suspension diagrams I am somewhat convinced that tie rod end spacers actually have a negative impact on steering geometry; increasing bump steer and doing nothing what so ever for steering angle. Someone please enlighten me.
How do tie rod end spacers increase steering angle?? suspension gurus needed!
Re: How do tie rod end spacers increase steering angle?? suspen ... (redsx13)
It has to do with the kinematics of the tie rod.
with a lowered car, the stock tie rod angles up. when you hit a bump like this, the difference between projection of the tie rod to the ground before the bump and at the bump's peak will be higher than the difference if the car was at stock ride height. (the higher the difference, the more bumpsteer - if you can make the tie rod parallel to the ground again, you can reduce bumpsteer)
i'm not too sure about increasing the steering angle.. i'll think a little bit more.
with a lowered car, the stock tie rod angles up. when you hit a bump like this, the difference between projection of the tie rod to the ground before the bump and at the bump's peak will be higher than the difference if the car was at stock ride height. (the higher the difference, the more bumpsteer - if you can make the tie rod parallel to the ground again, you can reduce bumpsteer)
i'm not too sure about increasing the steering angle.. i'll think a little bit more.
Re: How do tie rod end spacers increase steering angle?? suspen ... (crzycav86)
ya thats what the aftermarket parts companys say, but really think about it. here is a diagram that will help...crzycav86 wrote:It has to do with the kinematics of the tie rod.
with a lowered car, the stock tie rod angles up. when you hit a bump like this, the difference between projection of the tie rod to the ground before the bump and at the bump's peak will be higher than the difference if the car was at stock ride height. (the higher the difference, the more bumpsteer - if you can make the tie rod parallel to the ground again, you can reduce bumpsteer)
i'm not too sure about increasing the steering angle.. i'll think a little bit more.
Re: How do tie rod end spacers increase steering angle?? suspen ... (redsx13)
That picture is drawn incorrectly.
When you put the spacer on, you have to increase the length of the tie rod, otherwise you'll have a ton of toe out. The tie rod will still intersect "line 1". what i said before still applies.
When you put the spacer on, you have to increase the length of the tie rod, otherwise you'll have a ton of toe out. The tie rod will still intersect "line 1". what i said before still applies.
Re: How do tie rod end spacers increase steering angle?? suspen ... (crzycav86)
Actually, you have it backwards. When installing tie-rod spacers you must decrease the length of your tie-rods to avoid toe in.crzycav86 wrote:That picture is drawn incorrectly.
When you put the spacer on, you have to increase the length of the tie rod, otherwise you'll have a ton of toe out. The tie rod will still intersect "line 1". what i said before still applies.
Re: How do tie rod end spacers increase steering angle?? suspen ... (redsx13)
where are all the engineers
Re: How do tie rod end spacers increase steering angle?? suspen ... (redsx13)
Hold the car still and move the wheel.
All your suspension links are going in circles around their chassis mounting point, which means arcs, which means as you go up or down your going in and out as well.
Since all your links are of different lengths, rotating around different points, with different starting and finishing angles all outboard ends of those links are going to want to move at different rates, in different directions, ect...
this means that no only is your wheel moving in and out, the top ball joint is moving in and out at different rates then the bottom, and at different rates then the tie rod.
This means your wheel will start to tip and twist. This is not a bad thing, smart people can use it to change the wheels alignment to meet the different needs of different situations BUT this can only be resolved instantaneously and as you move further away from that the geometry as it existed at that instant.
To keep the wheel from steering as it moves through its travel the steering linkage needs rotate along with the upright, and this is accomplished by pointing it at the wheels instant center.
However as you move the suspension through its range the instant center not only moves up and down, but in and out. The result is that what was pointing at stock ride height isn't once you make a significant change from that.
As a thought example imagine dual A- arm suspension with a VERY short upper link, and a VERY long lower link both starting more or less horizontal. It will take nearly no suspension deflection to move the upper link to a near vertical position, while this small deflection will result in little to no change in angle of the lower arm.
With both arms starting parallel their lines never intersect and initially we have an IC that is infinitely far away. At this instant both ends are moving purely vertically, and the steering linkage would need need to do so also. This means it too would need to be horizontal and it would be pointing off towards our IC, infinitely far away.
Now our suspension continues to move, lets say all the way to its limit where our TINY upper link assumes a vertical position. Lets also assume that our upright is shaped in such a way that our steering linkage, like our lower control arm, is very very long. In this new position both the steering and lower control arm linkages are significantly long enough that our small deflection to reach maximum travel produces only a negligible change in angle.
We now have our lower control arm more or less horizontal, our upper control arm vertical and the instant center becomes the intersection between the lines of the two. However due to its length our steering linkage is still more or less horizontal, and is now pointing far away from our new instant center and the two begin to rotate independently.
Please don't be modest, if you do no fully understand the concept of instant centers in four bar linkages let me know and I will be more then willing to do my best to explain.
As far as overall steering angle: there is usually two parts to it, the shims at the steering knuckle adjust the geometry of the tie rod pointing it towards the instant center of the suspension, while a different spacer is added to the tie rod where it mounts to the rack to add steering angle. Not sure how that one works, never spent much time thinking on it.
All your suspension links are going in circles around their chassis mounting point, which means arcs, which means as you go up or down your going in and out as well.
Since all your links are of different lengths, rotating around different points, with different starting and finishing angles all outboard ends of those links are going to want to move at different rates, in different directions, ect...
this means that no only is your wheel moving in and out, the top ball joint is moving in and out at different rates then the bottom, and at different rates then the tie rod.
This means your wheel will start to tip and twist. This is not a bad thing, smart people can use it to change the wheels alignment to meet the different needs of different situations BUT this can only be resolved instantaneously and as you move further away from that the geometry as it existed at that instant.
To keep the wheel from steering as it moves through its travel the steering linkage needs rotate along with the upright, and this is accomplished by pointing it at the wheels instant center.
However as you move the suspension through its range the instant center not only moves up and down, but in and out. The result is that what was pointing at stock ride height isn't once you make a significant change from that.
As a thought example imagine dual A- arm suspension with a VERY short upper link, and a VERY long lower link both starting more or less horizontal. It will take nearly no suspension deflection to move the upper link to a near vertical position, while this small deflection will result in little to no change in angle of the lower arm.
With both arms starting parallel their lines never intersect and initially we have an IC that is infinitely far away. At this instant both ends are moving purely vertically, and the steering linkage would need need to do so also. This means it too would need to be horizontal and it would be pointing off towards our IC, infinitely far away.
Now our suspension continues to move, lets say all the way to its limit where our TINY upper link assumes a vertical position. Lets also assume that our upright is shaped in such a way that our steering linkage, like our lower control arm, is very very long. In this new position both the steering and lower control arm linkages are significantly long enough that our small deflection to reach maximum travel produces only a negligible change in angle.
We now have our lower control arm more or less horizontal, our upper control arm vertical and the instant center becomes the intersection between the lines of the two. However due to its length our steering linkage is still more or less horizontal, and is now pointing far away from our new instant center and the two begin to rotate independently.
Please don't be modest, if you do no fully understand the concept of instant centers in four bar linkages let me know and I will be more then willing to do my best to explain.
As far as overall steering angle: there is usually two parts to it, the shims at the steering knuckle adjust the geometry of the tie rod pointing it towards the instant center of the suspension, while a different spacer is added to the tie rod where it mounts to the rack to add steering angle. Not sure how that one works, never spent much time thinking on it.
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Re: How do tie rod end spacers increase steering angle?? suspen ... (Red coupe)
Pretty sure the rack travels a little farther than the inner tie rods allow before making contact with the rack. The spacer adds a little rack travel by moving the inner tie rod out so basically you can actually turn the steering wheel a little bit more.