I Need more caster, (lowered spindles) Options

[Optimusglen]

Hey all, I know that almost none of you would have any experience here, but I wanted to pick your brains.

As a refresher, the caster of the front end is the angle of the steering axis front-to-back. 0 degrees is straight up and down, +5 degrees has the top pointed back toward the windshield. Lower caster makes the car turn quicker, higher gives you straight line stability and makes steering inputs a little harder.

The factory slots in the strut towers give enough adjustment when the car suspension is all in-spec. But what if it's... purposefully out of spec?

Case in point, I have a 914 that I've gone the ORV route with. The spindles are dropped, effectively giving me more ground clearance and room for the larger tires. (215/75R15)

(IMG:http://www.914world.com/bbs2/uploads_offsite/live.staticflickr.com-19709-1779110937.1.jpg)

Now, of course, when one part of the geometry changes, that means everything changes. I did get an alignment when I finished putting it all together, and it's technically "in-spec" but it does feel a little squirrely at higher speeds, like on the highway or long backroads sweepers.

My thought is to give it more high-speed stability and give it more positive caster, but the struts are already at the full extent of the adjustment window up top. Not only that, but the portion that protrudes through the sheetmetal also is a limiting factor.

I'm hesitant to trim the sheetmetal. The slots would be simple enough, but the center hole for the strut has a lip bent up. If a portion of that is cut away, I imagine it could/would compromise strength?

This might be a similar issue many of you track racers have when trying to maximize camber, does anyone have any insight?

[sixnotfour]

https://tarett.com/products/monoball-strut-...dBoCc0wQAvD_BwE

[mlindner]

I did open my slots up to have more negative camber....Make sure you have 1/8 inch toe in. If your 0 or toe out the car will be twitchy at speed. Mark

[Superhawk996]

Your handling problems are not likely to be solved simply by adding more caster but obviously it won’t hurt.

Because of the lift you’ve got a lot of things going on that have changed roll centers and have probably given you a pretty ugly set of toe curves both front and rear. In addition to geometry, you’re going to get a lot more aero lift due to the raised ride height that won’t help at high speed either.

I’m going to drop a link

https://www.youtube.com/watch?v=7QZ5z66PhdU?si=nrVv6Q0spN53Hxfd


To a series of vehicle dynamics videos that are good because the professor uses examples that include the 914 and his overall discussion is aimed at helping the mini-Baja team develop a suspension that is aimed more at off road use. I.e high Cg and high roll centers.

There is no one place in this series of videos to point you to for a quick solution to settle down your car but you will need to understand the implications of what has been done by lifting

Note: There are more videos than this intro video that can be accessed by his channel on YouTube

[East coaster]

I did similar mods to mine, but the alignment is in spec and doesn’t seem to have any ill habits. I’m running the same size tires too.

[Optimusglen]

Because of the lift you’ve got a lot of things going on that have changed roll centers and have probably given you a pretty ugly set of toe curves both front and rear.

Thanks for that video link!

Agreed, I have some other revisions cooking, but I didn't want to muddy the waters of this post. I think my next area of attack is the bump steer, but all the bump steer kits are designed around raised spindles, not lowered ones.

And to calrify a bit more... I don't expect this to handle like a race car, that's not the purpose. "Squirrely" is maybe an exaggeration; I never felt it was unsafe on the highway. "High speed" in my case means standard speed limits on a highway, 65-70mph.

[Superhawk996]

Nice car BTW - someday I may do a similar build now that I’m way out in the woods. (IMG:style_emoticons/default/popcorn[1].gif)