65 mph HARD shake

Yes, I know that everyone and their dog has reported this problem, but
I'm starting to think that mine might be a little worse. I've got a
'99 Miata I purchased back in July, and it has always had the 65 mph
shake. I had new tires put on and asked them to take extra care when
balancing the wheels. This seemed to make the shake all but completely
go away. Over the past 6 months the shake has returned and gotten
worse. I examined my tires and they were shot, looked as though the
alignment was out. So I had the car aligned (which was severely out of
adjustment as it turns out), then purchased new tires again last week.
The shake has not gone away, in fact it feels like it is still getting
worse...

It starts at around 58-59 mph and can go up as high as 75+ mph
depending on what mood it is in. It is a hard shake, I feel it all
over the car, seat, steering wheel, dash, mirrors shake, I can see the
hood shaking relative to the road, and the entire inside of the car is
rattling (the top hinges, stuff in glove box, basically anything that
isn't welded). Not sure where to go from here, the guy I had align it
said that none of the suspension/steering parts appeared to be broken
or too worn, they were just badly misaligned. All tires are sitting at
29psi.

Any ideas?

-Tim

Forgot to mention, this car has about 123,000 miles on it. So even
though the alignment guy said everything appeared fine, I supposed it
is possible that some parts could be worn, just not sure where to
start.

Thanks,

-Tim

My car had this problem, too. I installed a shock tower brace and it
helped immensely. I even put a cheap one that I got off Ebay on. I am
sure you will get a lot of people saying that shock tower braces on a
Miata don't help but I feel that this mod made my car a lot less loosey
goosey in the front.

DBLZOOM wrote:
> My car had this problem, too. I installed a shock tower brace and it
> helped immensely. I even put a cheap one that I got off Ebay on. I am
> sure you will get a lot of people saying that shock tower braces on a
> Miata don't help but I feel that this mod made my car a lot less loosey
> goosey in the front.
>

I think that the strut tower braces help, even the cheap ones, at least
to some degree.

This problem being described, however, is more than simple cowl shake.
It sounds like he has a bent and/or badly balanced wheel, but they have
been balanced more than once and they have not told him anything is wrong.
Unless the shop is incompetent, I would start looking at other parts of
the front suspension like the hubs, a-arm bushings, shock mountings, etc.

It might help to take it to a new tire shop or mechanic anyway.

Pat

I would agree that a bent wheel or some such problem is very likely, do you
have access to a spare set of wheels and tires or a friend with a miata
who'll allow you to investigate this? It'd be easy to do at home, swapping
out all 4, if the problem goes away you might even be able to figure out
which one / ones have the problem by doing a quick test drive in between
swapping each tire back onto the car.

Chris
99BBB

"pws" > wrote in message
news
> DBLZOOM wrote:
>> My car had this problem, too. I installed a shock tower brace and it
>> helped immensely. I even put a cheap one that I got off Ebay on. I am
>> sure you will get a lot of people saying that shock tower braces on a
>> Miata don't help but I feel that this mod made my car a lot less loosey
>> goosey in the front.
>>
>
> I think that the strut tower braces help, even the cheap ones, at least to
> some degree.
>
> This problem being described, however, is more than simple cowl shake. It
> sounds like he has a bent and/or badly balanced wheel, but they have been
> balanced more than once and they have not told him anything is wrong.
> Unless the shop is incompetent, I would start looking at other parts of
> the front suspension like the hubs, a-arm bushings, shock mountings, etc.
>
> It might help to take it to a new tire shop or mechanic anyway.
>
> Pat

wrote:
> Yes, I know that everyone and their dog has reported this problem, but
> I'm starting to think that mine might be a little worse. I've got a
> '99 Miata I purchased back in July.
>
> Any ideas?
>
> -Tim


My '91 had the worst shimmy I've ever seen when I bought it last year.
It had 90k on it and original shocks. I put Bilsteins and Yoko tires
on it and the shimmy was gone. I didn't do anything else at the time
(I didn't even have the chasis braces in yet). when I put my Blizzaks
and steelies on the winter there was a light shimmy at 65 +/- 3 mph,
but nothing as bad as the shot shocks. Makes me thinnk this is why
Mazda started putting Bilsteins on at the factory.

That is good idea. I actually do have a friend across the street with
a '93 Miata and I bet he'd be willing to let me try his wheels.
Hopefully they will fit. I don't mind spending the money to fix it,
but I'm a tightwad by nature and hate the idea of throwing 100's of $'s
in a direction without knowing if it is going to fix the problem. It'd
be nice if there were a way to try and diagnose w/o dumping a bunch of
money into new rims or suspension parts that I may not need.

This is a good step in the right direction, thanks.

-tim

wrote:
> That is good idea. I actually do have a friend across the street with
> a '93 Miata and I bet he'd be willing to let me try his wheels.
> Hopefully they will fit. I don't mind spending the money to fix it,
> but I'm a tightwad by nature and hate the idea of throwing 100's of $'s
> in a direction without knowing if it is going to fix the problem. It'd
> be nice if there were a way to try and diagnose w/o dumping a bunch of
> money into new rims or suspension parts that I may not need.
>
> This is a good step in the right direction, thanks.
>
> -tim
>

That is a good idea by Chris.

Unless you've got extra-large rotors, the wheels from your neighbor's
'93 miata will fit.

You can actually do two wheels at a time, because the miata is so easy
to lift one entire side up rather than one corner at a time, but if it
cures the problem, then as Chris suggested, you will want to switch them
back one at a time to find the problem wheel.

Be careful doing hard starts if you have 2 different types of tires on
the back while you are investigating the problem. That rear end can get
very *squirmy* depending on the difference in tires.

Good luck,

Pat

On Thu, 13 Apr 2006 12:46:48 GMT, wrote in
oups.com:

> Yes, I know that everyone and their dog has reported this problem, but
> I'm starting to think that mine might be a little worse. I've got a
> '99 Miata I purchased back in July, and it has always had the 65 mph
> shake. I had new tires put on and asked them to take extra care when
> balancing the wheels. This seemed to make the shake all but
> completely go away. Over the past 6 months the shake has returned and
> gotten worse. I examined my tires and they were shot, looked as
> though the alignment was out. So I had the car aligned (which was
> severely out of adjustment as it turns out), then purchased new tires
> again last week. The shake has not gone away, in fact it feels like it
> is still getting worse...
>
> It starts at around 58-59 mph and can go up as high as 75+ mph
> depending on what mood it is in. It is a hard shake, I feel it all
> over the car, seat, steering wheel, dash, mirrors shake, I can see the
> hood shaking relative to the road, and the entire inside of the car is
> rattling (the top hinges, stuff in glove box, basically anything that
> isn't welded). Not sure where to go from here, the guy I had align it
> said that none of the suspension/steering parts appeared to be broken
> or too worn, they were just badly misaligned. All tires are sitting
> at 29psi.
>
> Any ideas?
>
> -Tim
>

Last time I bought new tires the installer did what was supposed to be
a high precision balancing. But he was using weights that weren't very
close in value to what was indicated. I tried to impress on him that
it needed to be done to a much higher tolerance. But he insisted this
was fine. It wasn't, and the shimmy was quite severe.

I went to a shop with a better reputation to have them
rebalanced. Even they tried to laugh at me when I told them that they
needed to use the smallest weights they had, trying to tell me that it
wasn't such a big deal. I insisted, and the shimmy went away.

I would try to find another set of Miata wheels as suggested elsewhere
and verify that a good balanced set makes your problems disappear. If
the other wheels are just as bad, then you know you have other
problems.

If it was the wheel, find a shop that takes you seriously.

"Chris D'Agnolo" > wrote:

>Jeff might have a good point on the shocks if they're high mileage but I'm
>with Tim, no / low cost repairs are the best. The miata can be so picky
>about wheel balancing some people say that you have to go to the place that
>has the really state of the art machine. You can find lots of info on
>miata.net .

The problem can hardly be shocks or other non rotating parts. It has to rotate
with the wheels to appear in the shimmy range. A bent wheel and an incompetent
shop* sounds the most likely to me, but it could be tires or brake disks, or
smaller parts too. Though shocks and braces might well be able to mask the
problem a bit.

Leon

* Or a shop that thinks nothing of a wheel that is "just a bit" out of round,
unaware of the sensitivity of the Miata. Which is not very competent anyway
in my book.

>Keep us posted,
>Chris
>99BBB
>
> wrote in message
roups.com...
>>
>> wrote:
>>> Yes, I know that everyone and their dog has reported this problem, but
>>> I'm starting to think that mine might be a little worse. I've got a
>>> '99 Miata I purchased back in July.
>>>
>>> Any ideas?
>>>
>>> -Tim
>>
>>
>> My '91 had the worst shimmy I've ever seen when I bought it last year.
>> It had 90k on it and original shocks. I put Bilsteins and Yoko tires
>> on it and the shimmy was gone. I didn't do anything else at the time
>> (I didn't even have the chasis braces in yet). when I put my Blizzaks
>> and steelies on the winter there was a light shimmy at 65 +/- 3 mph,
>> but nothing as bad as the shot shocks. Makes me thinnk this is why
>> Mazda started putting Bilsteins on at the factory.
>>
>
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas