Side effects of drop spindles in an SLA suspension. What am I missing?

So, I've got a vehicle with an SLA front suspension that I'm considering lowering a bit more. It's currently got lowering springs and tubular control arms that also added some drop. Going any lower with springs will cause more negative camber than I want, so I'm considering having a drop spindle made. On the surface, it seems like a drop spindle would have minimal effect on the overall geometry as the only thing that really moves would be the hub/brake/wheel/tire. So tell me suspension experts, what unforeseen side effects am I not considering here?

You're right, the beauty of a drop spindle is that you preserve your suspension geometry. Most off-the-shelf drop spindles that I've been around actually increase your track width by about a half inch, which has the negative effect of increasing your scrub radius. I've also seen some off the shelf drop spindles that relocate the steer arm somewhat to clear the wheel or brakes, and those tend to cause a lot of bump steer problems, so make sure the geometry is either stock or properly engineered.

A drop spindle, in itself, has no effect on suspension geometry on any kind of suspension I can think of.

People use drop spindles to alter geometry by changing the suspension's resting position with a different spring or shock length, and then using a drop (or lift) spindle to compensate for the ride height change, basically allowing you to shift the camber curve up or down.

Are eccentric bolts an option to get the camber back where you want it?

In reply to z31maniac:

Already maxxed out

What car/truck?

I did belltech spindles in my Dakota and it had massive bumpsteer issues. The steering arm and tie rods did not travel the same arc and it sucked to drive at times, namely a turn with bumps as you couldn't predict which way the vehicle would move.

On a good drop spindle, the distances between the upper & lower mount points and the steering arm will all be the same as stock - basically like a stock spindle with the hub location moved. If the steering arm's relative position is different from stock, you'll get different bump steer from stock, which virtually always means "much worse."

Relocating the steering rack/arms to match the change in the outer pickup points for the tie rods should keep the bumpsteer within the stock range.

You can check bumpsteer yourself and try slight changes to reduce it further by removing the shock/spring and carefully moving the suspension up/down and measuring the change in toe. There are special bumpsteer gauges as well, but a string between a pair of jackstands along the side of the vehicle and a good tape measure will generally get you close enough.

Ranger50 wrote: What car/truck?

2000 Ford Ranger 2WD.

No aftermarket drop spindles that I'm aware of, but I've found a company that will build custom spindles to spec. Since it would be custom, my plan would be to change from Ranger hub to Mustang hub and use Mustang brake caliper mounting points to give me a multitude of brake options. The preliminary plan would keep the stock tie rod mounting locations, and do as Gameboy said just moving the hub/spindle location vertically up the knuckle.

I need to do more planning before I commit to anything, and spend some time under the truck. I just wanted to make sure I was thinking along the correct lines.

Thanks for all of the info!

STM317 wrote: In reply to z31maniac: Already maxxed out

Offset bushings?

In reply to codrus: I didn't realize those were a thing. Interesting. If I just wanted to get lower I might consider those. But...

I don't just want to get lower, although I realize that's how I made it sound in my original post. I autocross the truck, and want to run wider tires up front. Something in the 295+ range. This will require fender mods, and I've been considering using prerunner fenders to clear the increased width. I basically want the Ford version of the Black Widow S-10. Nothing is easy though, and Prerunner fenders also raise the wheel opening and having 4 inches of wheel gap in a lowered truck would bother me to no end. So, I've been considering the spindles to raise the wheel/tire into the prerunner fenders, and give me better access to a huge aftermarket of brakes, etc at the same time. Two birds with one stone as they say. And I suppose a lower CoG wouldn't be the worst either.

The scope creep/cost is pretty large here. I know this. I'm just in the preliminary planning stages of this concept. I may decide to skip the cost/hassle of the spindles and wider meats and just keep it as is, I just wanted to consult some wiser minds on the subject before I took my first step down that slippery slope.

Suggestion...

Long shank ball joints on the lower arm. This will increase the spindle height (distance between ball joints), but will keep your current geometry very close. You'll get a quicker camber delta during compression, but that could be a not-bad thing. Cheaper than custom spindles.

There's no question that drop spindles are the best way to lower the car, but I hate to think what a one-off custom set runs. Are you DIYing the design and just farming out the fabrication?

I haven't reached out to the company yet, but based on what some similar projects have cost, I'm guessing it would be in the $1k-1500 ballpark. I should be able to offset a good bit of that cost by selling parts that would no longer be needed if using the drop spindles. Then I just have to pay for all of the other stuff that goes with it like wheel hubs, fenders/ body mods and wheels/tires.

Ranger50 wrote: What car/truck? I did belltech spindles in my Dakota and it had massive bumpsteer issues. The steering arm and tie rods did not travel the same arc and it sucked to drive at times, namely a turn with bumps as you couldn't predict which way the vehicle would move.

Had the exact issue with my brother Dakota. Just fiddled with the alignment untill it got to "ok". Did you find a 'correct' fix?

A drop spindle, in itself, has no effect on suspension geometry on any kind of suspension I can think of.

Technically a drop spindle will change your scrub radius even with the exact same wheel/tire, but i dont think many people care because we all change scrub radius all the time with non-stock wheel/tire combos and hardly anyone ever experiences something so drastic that they bother diagnosing it down to a change in scrub radius.

In reply to Vigo:

Good point.

Plus, depending on the suspension setup, adding negative camber can reduce positive scrub, so shoving the wheels out further or using drop spindles and increasing positive scrub may actually end up putting it back close to where it started from the factory.

curtis73 wrote: Suggestion... Long shank ball joints on the lower arm. This will increase the spindle height (distance between ball joints), but will keep your current geometry very close. You'll get a quicker camber delta during compression, but that could be a not-bad thing. Cheaper than custom spindles.

You'll also need long-shank or flipped rod ends to prevent the bump steer problem.

Ranger50 wrote: What car/truck? I did belltech spindles in my Dakota and it had massive bumpsteer issues. The steering arm and tie rods did not travel the same arc and it sucked to drive at times, namely a turn with bumps as you couldn't predict which way the vehicle would move.

Well now that's interesting...my drop spindles are also from Belltech, with the same issue. I haven't found a fix yet, but if I don't use the drop spindles, I kill ball joints like crazy and have like a half inch of travel.