Touchy subject.

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11-02-2004, 02:45 PM
OUTRACE

Touchy subject.

Ok guys, I just wanna get some honest feedback about my '93. Don't take any offense or think that I hate my Miata..... but I wanna find out if mine is pretty normal for 104k miles.

I bought my 93 from some friends. They're pretty stereotypical gay guys who thought the Miata was "cute" and "fun". They're not car abusers, hard drivers or car freaks of any sort. The car has been very well maintained and seems to run just fine (I think). I'm only mentioning this because I don't want you to think my Miata has been victimized by a crazed 16 year old on a binge.

Here's where I'm going with this......

The 93 seems to be a pretty elemental car. So elemental that it could easily be called crude. The words "shopping cart" come to mind.

It vibrates. It shakes. It rattles. If you roll over a dime on the highway, you can tell whether it's heads or tails. It's downright painful to drive on Dallas city streets. The spring rates seem insanely LOW for something that feels like this, because it bottoms out on a regular basis. It reminds me of my brother's MG Midget from high school, except that it's reliable.

The car is relatively smooth at 70 mph, but at every other speed there's a vibration that seems to come from the wheels.......as if a single bump sets up a resonance in the car that I can force to go away by changing the loads on the car (turning, braking, accelerating, or just waiting for another jolt from the road). I've checked wheel bearings for looseness, and the new tires and rims haven't changed the vibes' amplitude or frequency. These vibrations occur between 20 and 60 mph with their max amplitude at ~35-40 mph.

So my questions are..... Is mine pretty typical? Are the later versions improved? Is there anything I can do about the vibrations? Any tips?
Any surprises?
11-02-2004, 02:51 PM
POS Racing

Is it still rolling around on the original shocks??
11-02-2004, 02:55 PM
sammm

Re: Touchy subject.

Quote:

Originally Posted by OUTRACE

Is mine pretty typical?
Are the later versions improved?
Is there anything I can do about the vibrations?
Any tips?
Any surprises?

Yes.
Don't know.
New shocks or sell it and buy a Lexus.
Don't expect a smooth, quiet ride from a roadster.
I'm surprised you're surprised! :P
11-02-2004, 02:56 PM
OUTRACE

Yeah, it is, but they still seem to be damping street bumps adequately..... They only rebound once from a bump. No pogo effect, no leakage, and no noise.
11-02-2004, 02:59 PM
POS Racing

Quote:

Originally Posted by OUTRACE

Yeah, it is, but they still seem to be damping street bumps adequately..... They only rebound once from a bump. No pogo effect, no leakage, and no noise.

Mazda didn't put lifetime shock in these things, new shocks may help. I put the AGX on the POS, she is no 'lac but It did improve the ride!

BTW. The new ones do seem to drive a bit better. But my reference is a 155K '92 vs. a 22K '02.
11-02-2004, 03:01 PM
sammm

Quote:

Originally Posted by POS Racing

I put the AGX on the POS, she is no 'lac but It did improve the ride!

If you're going to replace the shocks, I suggest you spring for new OEM bumpstops as well.
11-02-2004, 03:01 PM
OUTRACE

Re: Touchy subject.

Quote:

Originally Posted by sammm

New shocks or sell it and buy a Lexus.
Don't expect a smooth, quiet ride from a roadster.
I'm surprised you're surprised! :P

The odd thing is that my racebike is smoother and better suspended than the Miata. The sport-touring bike is on par with my "smooth and quiet" car ('04 F150, so you can tell my standards aren't that high).

I see that's two "votes" for new shocks........ So I guess that's gonna be the next expense......
11-02-2004, 03:03 PM
POS Racing

Quote:

Originally Posted by sammm

Quote:

Originally Posted by POS Racing

I put the AGX on the POS, she is no 'lac but It did improve the ride!

If you're going to replace the shocks, I suggest you spring for new OEM bumpstops as well.

Yep I replace the boots/bumpstops at the same time the originals were crunchy! :shock:
11-02-2004, 03:05 PM
fwMiata

man mine does all that too, and i have agx's and teins... need to get some better tires and a strut brace...
11-02-2004, 03:06 PM
altiain

Well... the Miata is a pretty crude car. It's chassis stiffness is laughable in comparion to typical new cars, even roadsters. Hard to fault for a chassis that was designed almost twenty years ago, however.

The later Miatas have all sorts of additional band-aid bracing, but it's only minimally effective, imho ('01+ models are better, but my '99 still shakes, rattles, and rolls it's way down the road).

Here are a few things to consider. First, short of welding in a good 6 or 8 point cage, you aren't going to really be able to do much about chassis stiffness. However, you can adjust the ride quality through tire and damper tuning.

FWIW, that's one of the reasons I don't own a set of Azenis. I think they're amazing street/autox compromise tires, but they are kind of rough for daily use (imho). I use ES100s on the street instead - they don't offer quite the same level of performance as the Azenis, but they offer a more comfortable ride. I've got R compounds on a spare set of wheels for autocrossing, so ride comfort is more important to me on the street.

If you're stuck with the Azenis, try lowering your air pressure. Typical passenger car air pressures (like 32 psi) are great for responsiveness on a Miata, but did you know that the factory recommended tire pressure is actually 26 psi? Miatas don't need high tire pressures, and lower pressures will generally give a smoother ride quality.

Second, have your wheels rebalanced, preferably using a Hunter GPS 9700 road-force balancing machine. It's a little bit more expensive, but the Miata is incredibly sensitive to wheel imbalance, and even the smallest weight offset can cause slight road imperfections to set up resonances in the suspension, in my experience. Another tip - ask the tech to turn off the "averaging" function when he balances your wheels - it'll mean more work for him to get it right, but it will improve the accuracy of your balancing.

In addition, at 104k miles and 12 years old, your OEM shocks are shot, and likely have been for a long time. Invest in a set of inexpensive adjustable replacement shocks (KYB AGXs and Konis seem to be the most popular choices), and use the adjustability to tune the ride quality to your liking.

Another thing to consider given your car's age would be worn suspension components - bushings, ball joints, and tie rod ends, for starters (all things I plan to replace on my car - a '99 with 91k miles, but three years of hard autocrossing - during this coming off season). But replacing all of these will not be cheap - I'd start with the above recommendations and see if that has a positive effect.
11-02-2004, 03:15 PM
altiain

Re: Touchy subject.

Quote:

Originally Posted by OUTRACE

Quote:

Originally Posted by sammm

New shocks or sell it and buy a Lexus.
Don't expect a smooth, quiet ride from a roadster.
I'm surprised you're surprised! :P

The odd thing is that my racebike is smoother and better suspended than the Miata.

Your racebike also has an incredibly stiff frame in comparison to a Miata (probably something like an one or two orders of magnitude stiffer in bending and torsion). It also has a lot less anicillary stuff attached to it to squeak, rattle, creak, and vibrate. :wink:

It's also suspended by two wheels instead of four, which eliminates any effects of side-to-side mismatches in tire pressure, wheel roundness, damper functionality, ball joint/tie rod health, etc., etc.
11-02-2004, 05:12 PM
fwMiata

i have 0 frame bracing, somehting about 96 base modeals.... suck.
11-02-2004, 05:30 PM
EvilSpeeder

I haven't tried it yet, but I've heard that some of the well designed bolt-in cages can increase chassis stiffness enough to be noticible. I agree with the others on the shock comments. If you're really serious, replace the following (no particular order):

shocks
ball joints
suspension bushings
bumpstops
swaybar bushings
swaybar endlinks

Add the following:

the 94+ under chassis braces (not sure what year your car is, might already have them)
harddog double diagonal bar
GOOD front strut tower bar (not ebay crap)

After all this is done, get a set of good springs (nothing too aggressive) and some shocks to match. Having well tuned spring and damping wheel rates makes all the difference in the world once you have a solid platform.
11-02-2004, 05:34 PM
fwMiata

i did notice a ton of improvement when i put in the roll bar.
i am thinking that my crap tires are out of round or somehting... i have wicked shudder past 65mph, sopts at 70 and gets worse 75 up and doesnt stop. i balanced them out a month ago though.
as far as matched springs, the teins are the only ones that i found that were not custom spring rates on coilovers that retained the same percentage of stiffness over stock.
237 front, 176 rear iirc... they are nice and stiff but not jarring.
i love em.
11-02-2004, 05:41 PM
channelmaniac

Also check to make sure you are using a torque wrench when putting the wheels on... and are you using all of the same kind of lug nuts?

If you have one oddball one then you could have some shimmy...

When I put the rollbar, new KYB AGX shocks, and rearranged the lugnuts
on my 92 B&T the shimmy and handling problems disappeared.

I had a shot shock and 2 different sized of lugnuts. The rollbar helped tremendously in stiffening up the chassis.

Raymond
11-02-2004, 06:00 PM
OUTRACE

Re: Touchy subject.

Quote:

Originally Posted by altiain

It also has a lot less anicillary stuff attached to it to squeak, rattle, creak, and vibrate. :wink:

Yeah, but the old guy attached to it tends to squeak, rattle, creak, and vibrate a lot.
11-02-2004, 06:17 PM
OUTRACE

The rollbar is already installed. Yes, I did it on level ground with BOTH doors open (so as not to induce any twist).

AGX's look like the next good thing. Having my street tires rebalanced is probably in order, as is a lowering of pressures therein. Then I'll remove the Azenis and remount the WalMarts.

Thanks for the feedback guys. I appreciate your candor on the frailties of our common affliction.

Oh, and Sammm. I wouldn't buy a Lexus. It'd have to be the Mercedes E320 CDI. 369 pound-feet of torque from 1800 to 2600 rpm. Zero to 60 in 7.1 seconds. 37 mpg highway. ~$50k. Not bad numbers for a midsized sedan.
11-02-2004, 06:20 PM
fwMiata

a lexus will be infinifty more relaible than a MB
11-02-2004, 06:50 PM
altiain

Quote:

Originally Posted by fwMiata

a lexus will be infinifty more relaible than a MB

Yes, but will it be "infinifty" [sic] more reliable than an Infiniti? :P

Sorry, couldn't resist.
11-02-2004, 07:20 PM
fwMiata

that i dont know... and i cant spell, i reread it too....
11-02-2004, 09:02 PM
OUTRACE

Then I guess I need to find a Lexus that gets 37 mpg, does 0-60 in 6.8-7.1 seconds, has 4 doors, and doesn't say "In the spirit of Chevy and Oldsmobile, I am a re-badged Toyota". :roll: :roll: :roll:
11-02-2004, 09:45 PM
fwMiata

ok i dont get it... i like the is300 myself. or the g35's
11-02-2004, 10:14 PM
OUTRACE

Nothing to get. Do any of the 4 door Lexi get 37mpg AND do 0-60 in 7 seconds?
11-02-2004, 10:15 PM
altiain

OK OUTRACE, we get it - the diesel Benz is da bomb. Back on topic, perhaps? :wink:
11-03-2004, 12:30 AM
fwMiata

ok, ill be blunt. i worked with them and bmw's and they suck when it comes to maintanance. i saw tickets go through that were more than 3 times what i paid for my car.