New Miata owner

My wife and I just bought a 1999 Miata. We love it so far. I just sold a
1970 VW Karmann Ghia and am switching from the aircooled VW newsgroup to
here, so I am a newbie. My first question is this. When following the car
home after we bought it, we noticed that the speedometer seems to be off.
When the car is going 65 (according to the car following) the speedometer
reads 70. I thought it might be attributable to the 50 series tires that
are on the car, but we have the Leather Package which includes the Touring
Package which had 50 series tires on it from the factory (I thought maybe
they were added later).
I am not as concerned about the speedometer being off as the RPM range the
car is in when driving 65 MPH. The car revs at 3,700 RPM. This seems
excessive, but being new to Miatas it may be OK. Is this RPM normal for
driving at 65 in a Miata.
Thanks in advance for your help and I hope to be a regular on this
Brian Turner
Reply to
Brian Turner
RPM's seem about right....maybe a fuzz high. Miatas are a high RPM car. The 1st one that I drove, I couldn't believe how high the RPM's were on the highway too! The speedometers are usually a bit optimistic. I would guess a couple of mph high at 65 could be considered normal. The car following might be just the opposite like my truck is.
Reply to
They are none too accurate, and tires make a difference. The answer is to check with a GPS, if you drive within a hair of the "they will probably not ticket me" speed like I do.
Reply to
Leon van Dommelen
In article ,
Regrettably quite normal. You learn to adjust. The odo is accurate, though.
It's fine. The rev limiter at 7300 will keep you out of trouble, and the car will run happily at 6000 all day. It doesn't start making reasonable power until 4000.
Reply to
Lanny Chambers
I love the aircooled newsgroup, they've helped me out a bunch in the past with a 74 Super Beetle that finally wore out both me and my daughter. The good news is that this group is as helpful and as focused as that group (which is rare). It may not be quite as diverse but it's probably not far off.
One thing you'll find out is that the miata is worlds more reliable and just as much fun, the love affair is just beginning!
Chris 92BB&T
Reply to
Chris D'Agnolo
IIRC, my 96 read about 3MPH high at 65. Haven't checked my 03.
IIRC, that is required by law.
It sure feels to me like the M2s have to be revved higher than the 1.8L M1's.
Reply to
Grant Edwards
This is 'normal' for a Miata. My GPS consistantly reads 65mph when the speedometer reads 70.
Seems a bit high -- although they may have changed the gear ratio in the newer Miatas. My '94 reads 3500rpm at 70mph (indicated) and 4k at 80mph in 5th gear. Be aware of the rev limiter around 7200rpm, which in my car I hit at 65mph in 2nd gear and 80mph in 3rd. Haven't hit the rev limiter in 4th or 5th. Theoretical speed limit of my Miata would be 144mph, haven't tried that yet. ;-)
Reply to
G. Burkhart
Yeah. My '02 SE does that too. 70MPH indicated is something like 64.6 MPH according to my GPS.
Sounds about right.
Reply to
Dana Myers
Yep, mine reads about 70 when going 65. I've never had a speedo that read low or accurately. But this one is more optimistic than any other. Note, the odometer is not off by anywhere near as much, perhaps 1% high? Would make an interesting fight for warranty coverage if it was that far off!
My calculations for rpm at 65 (actual) mph: 5-speed: 3360 6-speed: 3100 MS Miata: 3220
Reply to
My 94 was higher rev, if you don't hold to 5k+ regularly you're not enjoying the car enough. If you occasionally get that hydraulic lifter noise after a good run you're in the ballpark, if you get it every time you be runnin her a little hard. My new 04 MSpeed has a better torque curve that and the 6 speed keeps the average rev down a bit. First gear is a shorter run though took abit to get used to shifting her fast enough not hit the limitered. 4k'ish is a good spot for driving S-curves and about where she sits at 80 mph in 6th.
Reply to
With stock tires/wheels, my '99 runs about 20mph/1000rpm in top gear- that is, 3000rpm at 50, and near 3300 at 65. Yours sounds a bit high, so perhaps the current tires are not quite the same diameter as the originals. (Note- 50-series tires are NOT the original fit on 14" wheels; mine are 55's).
On the other hand, if your speedo is off, the numbers could be different. Double-check your speed with a handheld GPS, or just by timing between two mile markers on the freeway while holding an indicated 60mph (which should be obviously one minute).
The Miata engine, based on a never-produced late 1980's turbo motor design for the 323, is extemely durable and doesn't seem to mind the RPM at all; many have achieved far beyond 100,000 miles with no problem. The secondary intake runners in the '99 open at about 3500, so running near that speed actually gives a bit better response for passing manouvers.
Keep changing the oil, and keep driving!
Joe Silver '99
Reply to
I had the same qualms when I first experienced the Miata's high revving ways. It's just geared that way and you'll get used to it and even come to enjoy the sound.
My 93' has a variable tach--sometimes over 4K at 75mph, sometimes under and I'm even used to that.
My speedometer was dead on, then I switched tires--supposedly exactly the same diameter-- and now it's about 3 MPH off. Go figure.
The upside--top down of a sunny day on the Pacific Coast Highway and the smile it puts on my face far outweighs everything else.
Reply to
Tell me more about the MS. I've only had the one test ride. Leather or cloth? Red or Titanium? Any quirks?
Reply to
Thanks for your response. The tires on my '99 are 195/50 R-15. This was the stock wheel and tire combination for the leather option that year. The tires are worn down to the wear bars which might confirm your theory that the tires are smaller in diameter. When I replace the tires I hope to se a little reduction in RPM. Being a first time owner, I need to get used to the little nuances of the vehicle, like the high RPM, the incorrect speedometer, the check engine light and the dipping idle.
Brian Turner
Reply to
Brian Turner
Not sure what "dipping idle" is. Are you using you A/c? yThat will cause the idle to change. Larry Hill
I need to get used to the little nuances of the vehicle, like
Reply to
Larry Hill
The were the same listed dimensions, which is the size the manufacturer sells them as. To get the actual size, you need the manufacturer's tire-specific data.
Don't ask me why the manufacturers do not produce consistent tire dimensions. If I could figure that out, I would be famous explaining why Microsoft cannot follow the established standards of the software they copy from others.
Reply to
Leon van Dommelen
you won't SEE any reduction in RPM at a specific MPH ! you haven't changed any gearing between the engine and the final drive. you may go a few MPH faster at a specific RPM, but that's because your new tires may have a greater circumference, and cover a bit more highway per revolution... but your speedo/tach won't reflect any change.
Reply to
Pete Breemhaar
WRONG! WHAT ARE YOU THINKING? The diameter of the tire is a part of the overal gear ratio equation. Larry Hill
Reply to
Larry Hill
That's quite right, but the speedometer doesn't measure the *actual* speed of the vehicle over the ground it effectively measures how fast the *differential* is rotating. That is, it is really just a "rev counter" for the driven wheels which has the face calibrated in mph/kph and not rpm. The value shown on the speedometer is therefore only correct for one wheel/tyre rolling radius. So, changing the tyre diameter will indeed change the overall gearing and hence the *true* "speed over the ground" value BUT the value shown ON THE SPEEDOMETER will not change since for any give gear/rpm combination the differential is still rotating at the same speed.
Reply to
Stephen Malbon

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