Since everyone else has a V8 build thread...
10-31-2012, 11:22 PM
#211
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Hmmm. How about half way up that spacer, have some type of channel that comes off of the crossmember that helps support the center of the spacer? It could be as simple as having a third hole (first two attach the spacer to the rack and inner tie rod respectively) and have a mounted rod that the spacer slides side to side on, at least keeping that spacer in line with the axis on which the rack is angled at. That might help with side loads and from the twisting that would probably occur with just the spacer attached. The length of the rod would need to be able to handle the full length of travel though and there would need to be some way of keeping that area sealed, greased and clean while in use.
Also, if there was a way of measuring the forces that the steering exerts there, I could possibly figure out the spacer thickness and material through FEA if needed.
Also, if there was a way of measuring the forces that the steering exerts there, I could possibly figure out the spacer thickness and material through FEA if needed.
Keeping in mind the new theoretical pivot point is now located to the top of the red line. I think I know what you are explaining. Like a support bolt that stabilizes the upward extension that has a stationary slider plate welded to the crossmember. I can see that working, but that's a bit complicated with many pieces needed. If you only need an inch or so, the bump steer kit is probably the way to go. I will figure this out and get back to this thread with what I come up with.
10-31-2012, 11:30 PM
#212
Three Wheelin'
A) You don't have a clue about my education.
B) You don't have to be an engineer to clearly see that your proposed solution wouldn't fix the geometry problem (specifically the bump steer issue).
All it would do would be to provide a means to connect the tie rod end to the steering knuckle.
THE SAME BUMP STEER ISSUE WOULD EXIST.
Yes the top of tie rod would be flat (or parallel to the control arm).
However... that's not what matters. What matters is that the arc of the tie rod as it moves through its travel matches the arc of the control arm as it moves through its travel.
And... that won't happen with your solution because you haven't moved the base of the arc. IT WILL HAVE THE SAME ARC AS IT DOES NOW. And thus the same bump steer issue it has now.
In this particular case, the only way to fix it is to either raise the rack, modify the steering knuckle (not smart) to lower the tie rod connection point, or use some sort of spacers to get the tie rod connection point to the steering knuckle lower.
What engineering school did you graduate from again?
TonyG
B) You don't have to be an engineer to clearly see that your proposed solution wouldn't fix the geometry problem (specifically the bump steer issue).
All it would do would be to provide a means to connect the tie rod end to the steering knuckle.
THE SAME BUMP STEER ISSUE WOULD EXIST.
Yes the top of tie rod would be flat (or parallel to the control arm).
However... that's not what matters. What matters is that the arc of the tie rod as it moves through its travel matches the arc of the control arm as it moves through its travel.
And... that won't happen with your solution because you haven't moved the base of the arc. IT WILL HAVE THE SAME ARC AS IT DOES NOW. And thus the same bump steer issue it has now.
In this particular case, the only way to fix it is to either raise the rack, modify the steering knuckle (not smart) to lower the tie rod connection point, or use some sort of spacers to get the tie rod connection point to the steering knuckle lower.
What engineering school did you graduate from again?
TonyG
Still working on my new spindles, hope to have an update soon
Last edited by mikey_audiogeek; 11-01-2012 at 02:20 AM.
10-31-2012, 11:39 PM
#213
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You might be able to compromise with both parts. Have the rack spacer go up an inch or two and also run bumpsteer tie rods to the point where you start to get close to the wheel. Technically the rack spacer mentioned is doing actually like what the tie rod bumpsteer bits do, just at the other end. I can see a combo of the two as a possibility for such an extreme example, which should cut back a lot of the stresses at the rack spacer.
11-01-2012, 12:02 AM
#214
I'm pretty sure that Tony thinks that the upper 90-degree 'elbow' in that PC paint drawing would be solid, while I believe Rob is suggesting that the top one would have a joint on it, so that it becomes the point about which the tie rod pivots while the suspension moves.
Or maybe I'm wrong. I was always pretty bad at MS Paint.
11-01-2012, 02:22 AM
#215
Three Wheelin'
...which is why I gave up on the 996/997 parts. Got a better solution in the works that doesn't require either of these mods.
11-01-2012, 09:31 AM
#217
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You might be able to compromise with both parts. Have the rack spacer go up an inch or two and also run bumpsteer tie rods to the point where you start to get close to the wheel. Technically the rack spacer mentioned is doing exactly like what the tie rod bumpsteer bits do, just at the other end. I can see a combo of the two as a possibility for such an extreme example, which should cut back a lot of the stresses at the rack spacer.
11-01-2012, 12:19 PM
#218
Rainman
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Is there any rack exposed at full lock, enough to put some sort of triangulation brace on the upright?
11-01-2012, 12:48 PM
#219
Nordschleife Master
There is a side welded on each side of the round stock that goes upwards and then the rod end from the steering arm is in the middle of those 2 sides with a bolt straight through. If that makes sense
11-01-2012, 01:50 PM
#220
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Your description is basically right. It is a heavy round piece of chrome moly is about 100 mm long that is bored out and attached to the rack with a M14 12.9 allen head bolt.
There is a side welded on each side of the round stock that goes upwards and then the rod end from the steering arm is in the middle of those 2 sides with a bolt straight through. If that makes sense
There is a side welded on each side of the round stock that goes upwards and then the rod end from the steering arm is in the middle of those 2 sides with a bolt straight through. If that makes sense
Wow, that is exactly..... no kidding, what my friend and I were discussing on how to do it. The two uprights would look like a triangle though, back to the original length of the rod.
11-01-2012, 01:51 PM
#221
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11-01-2012, 02:49 PM
#222
Three Wheelin'
11-01-2012, 07:00 PM
#223
Nordschleife Master
Side note: my engine bay is a bit messy... SINCE I SPUN A BEARING AND DESTROYED MY 3.0L 16V TURBO YESTERDAY!!!
Sorry for that I just had to scream a bit
Such irony as this was the last test before winter and I have a dry sump setup incoming
Nevermind, here's the pic! It might look crude but was designed by DTM race car fabricators and have survided harsh endurance racing (although a wheel to wheel incident resulted in a broken bolt in the past)
11-01-2012, 10:40 PM
#225
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