I'll try to be brief on this even though it's a weird thing that may be difficult to describe. Also I'm on my phone so please forgive errors.

Very quick summary: did some suspension work, got an alignment, and now my steering feels twitchy and unpredictable at times. Want to know why and how to fix it.

Now all the bloody details I can think of...

Background:

Couple weeks ago put in a 22mm rear sway bar and new rear end links on my r53. No real change to handling but slight upgrade under normal driving conditions (this isn't a race car).

Last week put in new inner ball joints (meant to outers as well but ran out of time and had to push that for another time), changed inner/outer axel boots, front end links, and (most importantly) added the Alta PSRS (positive steering response system). I took it for a test drive and things felt mostly normal but I still went and got it aligned at a reputable independent shop the next day. Got everything back in the green to stock specifications. (Don't have my printout anymore because I compulsively throw away papers but it was all basically neutral afterwards.)

Side note:

The PSRS has two installation options. My buddy, who has more experience than I do on car work, did the install of that while I changed axel boots and whatnot. He said that he pressed in the new bushings to be 45 degrees rotated, which (according to Alta's install instructions) should give some slight castor to the alignment to reduce lift and enhance turn-in. Not really sure what that is supposed to feel like, but I assumed a tighter, more responsive or even aggressive feeling steering experience.

Here is the key link to the Alta PSRS install instructions:

http://altaperformance.com/attachment/74757-.pdf

Result:

True to the advertisement, my steering is tight and responsive. Feels great. Most of the time. No play in the wheel and any input to the steering wheel translates to movement of the wheels. However...

Weird symptoms:
​​​​​​​
Since a few days ago, I started noticing some weird, faint, and quite inconsistent clunking sort of sounds when turning from a stop (like from a stop sign or in my driveway or a parking lot). We put the car on a lift, checked it out, and saw that we hadn't tightened the lock nuts on the front end links properly. Did that and also checked for other obvious signs. Nothing really seemed out of the ordinary. Outer ball joints could use replacement (120k miles) but they aren't alarmingly bad and I have their replacements lying around for a rainy day.

Put the car back down and drove it a bit to test. Didn't hear any noises and things feel normal. And then...

Really weird symptoms:

Noticed this the other day and today while driving. The closest I can describe it is like "tramlining," where the car wants to get dragged along with every bump/groove in the road. Except this is more of a slight, abrupt jerk or twitch of the steering direction when under slight load.

For example, taking a gentle curve on the highway at 70mph (normal driving, normal occurrence) will cause the car to twitch one way or another unpredictably during the curve. Definitely not confidence inspiring at all. At first I was wondering if this was just a feature of the PSRS but the more I experience it the more I feel like it's something wrong.

Best link I found that addresses similar issues is below, which blames steering bushings:

https://www.yourmechanic.com/article...nting-bushings

But it feels a LOT like that second issue they raise. Jerky and inconsistent and kinda scary when it happens in a subtle way.

So here are my questions (finally):

Does anyone have experience with the PSRS?
Does this sound like a bug or a feature?
What do you think we did wrong that we may have overlooked?
Is it possible that my steering bushings were going bad and I didn't notice until I made some changes to the suspension?
What recommended fixes or diagnostics would you perform?
Does this sound like a problem that will continue to get worse until it is addressed?
Should I just take this back to the shop that did my alignment?
Should I have an actual, factual mini mechanic look at it ASAP?

Thanks for reading and thanks in advance for any advice!

 

For someone on the phone, you sure can type well and recount the events better than any eyewitness.

I just have some thoughts. The control arm bushings you installed added caster. I know caster quite well from bicycles and motorcycles. Contrary what some performance vendors like to tout. On racing road bikes caster angle is reduced to give the bike livelier steering response, while the run of the mill bikes have more caster to add straight line stability. The latter feel dull but is easier to ride and more stable. For someone who does not ride well a road racing bike can be intimidating and unstable. For an experience rider it is more responsive and more efficient.

On a 4 wheel car most people increase caster to increase steering wheel weight (in your hands) in a turn. The more caster the more the steering wheel wants to return to the center straight ahead position. It is like on a bike, when you build in a lot of caster. It increases the tendency to track straight, and I fail to see how one can claim the steering will be more responsive. In your case, the responsiveness is likely from the harder bushing material tighten up the sloppiness of the worn stock bushings, not the increase in caster angle.

As the increase in caster angle increase the steering wheel weight (in your hand) obviously while in a turn, the steering rack is under more lateral force. This force is imparted onto the steering rack bushings, the rack and pinion gears, and the steering column linkages. These are the clues that may aid in finding the problem. Your outer ball joints might also play a part in this snap steering symptom.

 

Going to move you to the Mod Suspension section.

Twitchy in corners is not good.

 

Thanks for the feedback. What you say makes sense to me, which is why I am having so much trouble figuring out if this is a bug or a feature.

I have emailed Alta about it. Maybe their techs will have some good input.

I also think that I will call the shop that did the alignment and see if I could bring it to them Monday morning to look things over. Maybe something isn't torqued that wasn't obvious to me and my buddy. Or maybe they will identify a different cause. Who knows?

If everything seems right after that, I'll have to do some driving and see if this is something I'll have to live with or something I'll have to correct somehow.

In the meantime, more opinions will always be appreciated.

 

Can you give us the final alignment recordings? Have you checked that you don't have any pre-load on any of the drop-links? (done with the vehicle level and fully loaded on all four wheels).

 

Successful resolution today!! Very happy to have my car back on the road.

I heard back from Alta yesterday, although they weren't very helpful. They were more leaning towards the "You just gotta get used to it" thing but I knew something felt off.

So after work yesterday morning I propped up one wheel at a time and took a gander. Didn't see/feel any obviously loose bolts (though I am no expert) HOWEVER I did notice something weird. When I tried to rotate the wheels outward away from the center of the car, I was getting some play in them that seemed to travel all the way through part 8 in the install diagram in the directions below:

http://altaperformance.com/attachment/74757-.pdf

I couldn't figure out how to solve this, but I made an appointment to have the shop that did the alignment on it look at it again today. And I borrowed a car till then to avoid making things worse.

After a test drive and a discussion with the mechanic about what I had observed, he threw it on a lift and saw exactly what I meant. Definitely a bug and not a feature. But he also saw the problem.

Basically we had failed to properly torque the bolts that secure that part to the chassis of the car (they're hard to get at with the axels installed, since you have to sneak a wrench in from below around the top).

​​​​​​​He did the best he could to tighten it and advised me that, if they start to feel like they are loosening again, to back them out all the way (which would mean removing the axels) and putting them in with lock tite. Good advice I think, but hopefully not required.

For now, my car feels great again. Nice, tight, responsive handling. Definite upgrade though not too dramatic as these cars come pretty good from the factory.

So, a word of advice, for anyone's who may put in the Alta PSRS: make sure to tighten those bolts down when reinstalling and don't be afraid to use some lock tite!

Thanks to those who responded to help!

 

Thanks for the follow up. Improperly tightened control arms!?

Glad you got it figured out and back on the road.