Miata rattle/wobble

I have a noise/vibration on my '96 Miata that's driving me crazy, and I haven't had any luck trying to track it down.

What I'm feeling & sometimes hearing is an undampened vibration somewhere in the front end, that seems to be lower & toward the center of the car(as opposed to out at the wheels). It can happen at very slow speeds when I hit a rock in my driveway, or at highway speeds on expansion joints & potholes, and just about anywhere in between. I don't really feel it in the steering wheel as much as I feel it in the whole car. It doesn't make the car change course, but it's not cowl-shake either...I think I have that one figured out.

I've checked the front end multiple times, I've had it on a lift, and I moved everything independently when I had it pulled apart to install new springs. An alignment didn't help either.

The ball joints all feel tight, all the tie-rods are good, but the passenger's inner has about .001" of wiggle in it. It's barely enough to feel by hand & I don't feel any steering deflection. The front swaybar mounts & endlinks all feel solid. All the suspension bushings feel tight & I've checked the shock mounts too.

What else am I missing????

From the reading I've done, it seems the Miata is prone to that type of vibration due to issues with tires and wheels that aren't balanced properly.

Try rotating the wheels and see if that changes the vibration at all.

Could it be the hood? Both my miatas had weird vibrations from the hood not latching tight, or a wore out hood hinge.

Joey

The vibration only happens when I hit a bump, at a wide range of speeds, and has happened with 3-different sets of tires, so I don't think that's what's causing it.

I've never seen the hood vibrate & it feels latched tight. The vibration feels like it's under, or close to the floor.

petegossett wrote: The ball joints all feel tight, all the tie-rods are good, but the passenger's inner has about .001" of wiggle in it. What else am I missing????

I've had a similar issue with a slightly "lose" suspension bush on my last Miata. That was on the rear and that went away after we swapped out the subframe (well, I had one with a 1.8 LSD so it would've been rude not to).

If you've know anybody who's got a Miata that doesn't exhibit this symptom it might be worth checking if that does have the same give in the tie rod and if it doesn't, swap it out...

Actually, another thought just occured to me - have you checked the (camber, I think) adjustment bolts? One of the other problems I had with the aforementioned Miata was that one of the bolts was lose (had separated from the plate IIRC) and that produced all sorts of slightly odd symptoms when going for it...

Are the engine mounts in good shape? They can tear and separate, but still look like they are in good shape. I don't have any experience with this problem, but just another thing to look at.

Do you feel it through the steering, or just through the chassis of the car?

Not really through the steering - other than when the whole chassis vibrates, I feel that vibration also through the steering wheel....does that make sense????

If you can't feel it directly through the steering, I'd be looking at things like motor mounts, as Phil suggested. Tough one to diagnose via a forum unfortunately, and it's certainly not a common problem.

A couple updates:

At last weekend's autox I spun on my last run. The car had felt nice and composed on my previous-5 runs, but the last run at the end of a looong lefthand sweeper the car spun to the left. There was a bump in the corner, but it hadn't affected me previously. Afterward, driving home I noticed the steering wheel was cocked to the left a bit, although the car didn't pull at all. Also while driving it last weekend I noticed the wobble seems to happen when the left wheel hits something.

Today I finally had a chance to pull the front wheels off & take a look. I really expected to find signs that an eccentric bolt or something had slipped, but everything is still in place. Once again, I took a prybar to the control arms, balljoints & endlinks and can't find any deflection anywhere.

At this point, I'm really tempted to install polly bushings & replace the inner/outer tie rods, and all-4 balljoints just to rule everything out(and the car does have 120k on it).

So, my questions: How much of a PITA are the bushings to remove/install? What's the best deal on quality tie rods & balljoints - dealer? Napa? Ebay?

I figure now is the time to do it once right, get it all aligned(again), and hopefully be done with it...and if not, I'll move on to the engine mounts.

Having recently spent far too long wrestling with the ball joints on a 116k Miata suspension, I'd suggest starting with the engine mounts.

I was unable to separate the lower ball joint from the spindle, with big hammers, prying, and a lever-type ball joint separator. Regreased all the others and put on new boots, which were also not fun.

The bushings can vary in difficulty, depending on age, corrosion, and tools used. Apparently there's a HF press that will knock them out easily, but some still have trouble.

Well, at this point I need an alignment & one of my inner tie rods has the most miniscule amount of play in it, so I figure rather than putting off the inevitable & just having it aligned I'll go ahead & rebuild the whole thing first.

I just had my lower balljoints out when I swapped springs over the winter, so I'm OK there, and I have a small press. I'm also lucky to have rust-free Miata.

Where should I source the balljoints & tie rods from though?

CGLockRacer wrote: Are the engine mounts in good shape? They can tear and separate, but still look like they are in good shape. I don't have any experience with this problem, but just another thing to look at.

X2 plus transmission mounts. Also is the exhaust flexing/touching anything?

2002acr wrote:

CGLockRacer wrote: Are the engine mounts in good shape? They can tear and separate, but still look like they are in good shape. I don't have any experience with this problem, but just another thing to look at.

X2 plus transmission mounts. Also is the exhaust flexing/touching anything?

There aren't really any trans mounts in a Miata. The trans is bolted to the engine and the tail is supported by the PPF (Power Plant Frame), which goes between the tail of the trans to the diff. No bushings there.

However, check the diff mount bushings while you're under the car. Those might be torn also, but I'm sure you'd get a big thunk when shifting if they were.

Obviously I don't know Miatas and when I suggested mounts I don't think they are actually torn or separated. Just old and soft, especially if there ever was an oil leak. In my wrenching days (yeah, 15 years ago) I used to get the wierd vibration problems in the shop I worked at and some of them turned out to be the engine or transmission oscillating in the mounts from the driveshaft forces.

If this thread is still alive, I have an opinion. Working on a 97 Miata with low speed front end clunk even running over small rocks. Sounded like badly worn upper BJ or tie rod end, or Control arm bushing. All were good. I took a rubber hammer to everything except my head. Peeled the boots off of the steering rack and tapped the steering rod. I got a heavy metallic noise. Held the rod where it enters the rack and no noise. ... the bushing at the end of the rack is worn. . I haven't yet checked to see if there is an adjustable packing or if I am due for a rebuilt R&P. Stay tuned...

The steering shaft from the steering column? Weird, I wouldn't have thought of THAT!

And FWIW, I still have the noise on my car. I drive it much less now though(went from 50kmi/year down to about 2000), and I keep thinking that someday I'll save up the money for new bushings, ball joints, tie rod ends...oh and while I'm in there, maybe a set of those Afco's. Of course, I'd need a new set of wheels & tires at that point. And geez, if I'm going to have it off the road for that long, maybe I should just go ahead and turbo it....

...and then i start doing the math & realize it's going to be a few more years.

Keep me posted on the outcome though!!!

I realize it's a bit late to chime in, and that I'm not intensely familiar with Miata architecture but...

This sounds like two separate issues to me. Clunk over bumps sounds like a bad sway bar bushings or strut top mounts. Off centered steering after a big lateral load sounds like worn out steering rack bushings.

Best of luck with a solution.

Because it's easy, check that the two steering column bolts are holding it in place properly. They're up behind the metal cover under the column. The column can tend to loosen up, especially if you use the wheel as a handle when you're climbing in or out.

Don't just crank down on the bolts. They have wedge shaped spacers in there. Loosen the bolts, push in the spacers and retighten.