What is the vertical height of the center of gravity for a '90 Miata? I want to do some weight transfer and roll stiffness calcs and need this dimension. I know how to calculate it but I do not have access to a set of scales to take the measurements.

Bob Ramberg, Naperville, IL USA

Damned if I know. I don't even know what the valve overlap on the intake cam was for 1991 EC-spec Miatas either. Or the alloy formulation for the aluminum head. But then at Mazda I had as much need for that sort of information as a stockbroker has for knowing the germination time for seed corn planted in equatorial areas. The corporate environment of vehicle concept development allows you little time or opportunity to specialize once the car's in the hands of the production development guys. All they had us do was drive prototypes to give a 'thumbs up' or 'thumbs down'. The car felt - and feels - real good, so I'd guess the eight of the CG is just about right. Does that help?

bwob

My fuse for my radio and interior lights has blown. I have now bought 3 new ones and they keep blowing when I put them in. they are the red 10 fuses. Is this normal or do I have to take it to a shop? Thanks for your time

Dave Simpson, Abbotsford British Columbia

No, it's no more normal than, say, having a small cerebral hemorrhage every couple of days or so. As for having to take it to a shop, well, you don't have to if you don't mind changing fuses till something major goes wrong. I know the next time I get a small cerebral hemorrhage, I'm not going to bother with a doctor visit either. Yeah, right...

bwob

Dear Father Bob,

I am a proud owner of 99 Miata roadster I call him my little boy. See him and I are always in trouble with those wonderful people in blue. I have a number of aftermarket goodies to make that big smile on the front a little wider. But the problem is that those wonderful people in blue always want to stop me. I have slowed down, (really) but they still stop me! All my friends say to get rid of him. Hell no!!!!! What can I do to make the like my little boy?

Paul Frizado, Assonet Mass. U.S.

Paul, he needs to learn self-control. I suspect as his father, you'd be just the person to help him with the lesson. Leading by example, as it were. Being a parent is never easy. Are you up to the task?

bwob

I have a '91 limited edition Miata in British racing green and I need to replace the top. To maximize resale value is it best to replace it with the original black top, or will it hold it's value if the color of the top is changed to tan?

Danny, Pacific Palasaides, CA, USA

When are you going to sell it? If you're going to be living with the car for a while, put on what YOU want. Who knows, if you hold onto it long enough,. it may need another top before it's sold off. If you're really worried about resale, don't forget the clear plastic seat covers. the next guy will appreciate that.

bwob

I am a happy owner of a 1990 Mariner Blue Miata with 91,000 miles. When this car was built, the national speed limit on the highway was 55mph. Now in many places the limit has been raised to 70 mph. So to travel along at the speed of traffic the RPM's are nearing 4,000. Is this a concern for extended highway driving? I do choose more scenic side roads as often as possible. I believe the designers got this car right and I intend to keep it stock. Had the designers known the speed limit was going to 70, would they have made 5th gear a different ratio? Thanks, Ty

Ty, WA, USA

Is there anything I can do to my car to decrease the RPM's? I take long trips and when my car travels at 80mph the RPM is at 4. Something is going to go wrong if I keep it that high. I know a supercharger makes the car faster but does it lower the RPM so my car doesn't overheat?

Nate Evans, PA

Ty, the 55mph limit wasn't a point of concern as regards the gearing of the Miata, even in earliest M1 form. the transmission and final drive ratios were selected to balance highway driving with in-gear acceleration. Despite the fact the US was going to absorb a large percentage of Miata production, it was a 'world car' to the degree we wanted to have a little mechanical variation between global markets. This kept the costs in line so it would be affordable.

Nate, a supercharger will do absolutely nothing to change the number of revs the car's turning at a given road speed.

That can be altered one of two ways. First (as simplest of the two) would be to to use a taller final drive ratio. This entails replacing the differential or differential internals IF suitable replacements are available. I believe Mazda uses a different final drive in the automatic Miata which might address the problem, though I suspect it might just as easily make it worse. If the final drive of the automatic is numerically lower than what you have (say yours is 4.081 and the automatic is 3.731), it would be an improvement. I'm not sure what's in the system nowadays as regards alternative final drive ratios for the Miata at a factory or aftermarket tuning level.

The alternative is even more expensive, and that's to replace the transmission or again the transmission internals, with something offering taller ratios. Changing a differential would be small beer alongside the costs you'd encounter in the world of transmissions.

bwob

I've read on Miata.net that rumors say there will be a new MX-5 on 2003, featuring rotative engine. Can you confirm? Will it substitute the actual model or be a different car than the MX-5?

Personally I would prefer Mazda fully understands what a big part of the MX-5 success has been simplicity, affordability and reliability.

Alberto, Roma, Italy

Why did Mazda select such a weak engine for the Miata? Why not a nice rotary engine like the rx7 or a V6. That would make the Miata just that much better. Since the 99/00 model is so EXPENSIVE, why does that still come with a sorry excuse for a factory roadster engine. Sure you can add aftermarket parts, but if the Miata came with 200hp out of the factory a car enthusiast like me wouldn't have to shell out an extra 3000$ just to get a few more horses.

sam kosari, calabasas/ca/usa

Word from two opposing camps here.

Sam, it's not a weak engine for the car. Rather I'd say it's a weak engine for you. If the car were noticeably underpowered, Mazda would have built a lot fewer than half a million of 'em, and I'd bet Credits to navy beans that there wouldn't have been a second-generation of the car. Mazda offered up an excellent rotary-engine sports car for enthusiasts, who didn't vote with their pocketbooks in sufficient numbers to keep the RX-7 alive. A rotary Miata wouldn't have fared much better than the RX-7 did. More out-of-the-box performance would have upped insurance costs (as was the case with the RX-7) as well as increasing the initial price. If you think a $20,000 Miata is expensive now, It's be prohibitive in 1990-92. Which is what you'd like would have cost. The Miata would have had popularity - and success - on a par with the Capri XR2 Turbo or delSol.

As for the Miata having a "sorry excuse for a roadster engine", I can see you've never driven a BMW Z3. Like the car for what it is, and be thankful it's still affordable. As for the overall statement that's repeated now and again that the car's underpowered, I'll reiterate if you can't go fast with 90hp, 900 won't help you. But if you are helpless and need 900hp, there are plenty of people in the aftermarket who will be more than willing able to supply you with a surfeit of horsepower.

Alberto, Mazda recognize the fact that the unique blend of dynamic balance (entertaining performance with a good chassis) and affordability is what's made the Miata the best selling sports car in history. Balancing that with increasing costs and stronger competition is tough, but as the M2 shows isn't impossible. Don't worry.

bwob

What do you hear about a new Miata? Not the 2001, but maybe a roadster version of the RX-Evolv,... Will Mazda put a rotary engine in a ragtop? If they do, will it be the same car (an engine option) as a piston ragtop, or will it be something else?

Aaron Pailthorp, Seattle, WA USA

The production version of the Evolv show car and the Miata will share a common floorpan, probably including toeboard. The Miata will continue as a four-cylinder with horsepower in the 107-121kW/145-165hp range, while the production RX-Evolv will get a 184-210kW/250-290hp rotary. The Evolv will be on a longer wheelbase than the Miata with a tight, but functional, rear seat.. there will be no piston Evolv, nor will there be a rotary Miata.

bwob

This isn't strictly a Miata question, but since most Miatas have manual transmissions, I figured it'd be of interest to Miata owners. Ok, the question when coming to a stop is it better to downshift to lower speed, or to just brake the car? It seems to me that a transmission/clutch is a more expensive repair, and that brakes are for stopping (right?), but most of my friends downshift to stop the car. Your advice is appreciated!

Doug Mandell, Portland, OR USA

Doug, your question is kinda like the long-ranging controversy as to whether you're supposed to eat cinnamon toast with the buttered, sugared and cinnamoned side facing 'up' or 'down'. The 'ups' will tell you that it ensures none of the extra flavorings will fall off, as they will if you consume the toast face 'down' The 'downs' will tell you that it'll ensure you get the full effect of the flavor hitting your tongue directly, without the insulating qualities of the bread first striking your palette.

Yes, if you're ham-fisted with your gearbox and down shift at too high a road speed for the gear ratio you're dropping the car into, the resultant transmission and gearbox repairs are likely to cost you more than normal brake maintenance will. By the same token, it's easy to go through a set of brakes by showing them the same disregard. It's a matter of taste and/or personal preference. The choice is as clear as the one between blondes and brunettes.

I've got a thing for blonde Asian girls (which is why I married one), so you'll have to figure where I sit on the downshift vs. brakes debate. After you decide for yourself, that is.

bwob

I thoroughly enjoy your quick wit and sense of humor! It's very refreshing to read the "Ask Bob" column each month on Miata.net. Thanks so much for taking the time to write for the Miata.net web site. I'm sure you have many other pursuits you enjoy and could easily not find the time.

Afterthought-Why do you think the Miata is not viewed as a true sports car by the general populace. I usually have to go into a dissertation on the design process and handling characteristics that make the car incomparable after someone comments about what I see in driving a "girl's car." I can only shrug and think to myself, "Some people's kids..."

Michael Hark, Enterprise, FL

Michael, I'm not altogether sure I'd go along with your observation that the Common Horde don't consider the Miata a genuine sports car. I think there's a tendency in the general public to consider anything open car with two seats a sports car. Then again, I remember that there were ads for one of the US pony cars in the early 1990s (I can't recall as to whether is was Mustang, Camaro or Firebird) which pointed out that the United States Auto Club (one-time Indy organizers) 'certified' this hefty hunk of Detroit Iron a 'Sports Car'. The stuff Infomercials are made of.

But I can't really boast. Here in Australia, Celicas and Hyundai Tiburons are considered sports cars by locals. If that's the case, it might be a good thing the Miata's not thought of as a sports car...

All (well, some), joking aside, if somebody doesn't accept a Miata as a genuine sports car, then they haven't got a clue as to what a sports car is in the first place. They've probably been driving sports utilities too long and are confused by the word 'sport'. I'd keep such individuals away from my daughter.

bwob

Hello I read a article u posted a month ago. I wanted to know what kind of engine will fit a Miata 12a,13b rotary??? or the Nissan SR20DE ?? what year engine can fit the Miata 91 ????

jessie lee, san fransico/ ca /usa

Anything can be made to fit. It just depends upon your level of creativity (or insanity), depth of your pockets and skills with a gas axe/Oklahoma hot wrench. So you have to ask yourself, "do I feel creative/insane/wealthy/torch-proficient". Well do you...Jessie?

bwob

Is it possible to install a POWER convertible top? And also, is it possible to re-install a new (2001) Miata engine? (I have a 2000 automatic). I was just curious because if it is possible, I would like to take it into Diablo Mazda and have that done. PLEASE REPLY

Brian, San Ramon/CA/USA

Yes on both counts, though neither would be cheap. You'd have to buy the engine new, and that would be no bargain. In fact on a horsepower-per-dollar basis, it'd be an impressive waste of money.

The power top would be even more of a currency consumer, as you'd have to develop the entire system on your own or pay someone else to do it. And I wouldn't count on selling the design to Mazda afterwards, as a power top is about as sympathetic to the car's concept as, say, stretching the Miata to limousine proportions and replacing the Mazda four with a Pratt & Whitney R-2800.

If you want more go and a power top so much, it would be much cheaper to buy a Porsche Boxster S. Or two. However, I don't think Diablo Mazda would offer the best price on the Boxster(s).

bwob

How do you spell Miata?

Larry, WEST COVINA, CA

I use the Roman alphabet myself. It's jam-packed with 26 of the most useful letters you'll find this side of Cyrillic. And the price its right.

bwob

What changes took place that make the later M1s sit up so much higher in the rear compared to M1s of earlier years. I have a '97 and even after installing Racing Beat springs the thing sits up too high in the back for my taste.

Jason Reinhart, Ft. Lauderdale/FL/US

When my Mariner Blue 1990 was replaced with a BRG 1991, I noticed something on my first drive into the office. Leaving Dana Point and travelling along Pacific Coast Highway through Laguna Beach, I was sometimes 'caught' at the signal where Laguna Canyon Road "T"ed with PCH. Sitting at the intersection in my '91, I noticed I couldn't see the overhead traffic signal at the intersection. I was at the limit line of the intersection as I always was, but the signal was just obscured by the windshield header. "What gives" I thought.

This bothered me so much, when I got into work I mentioned it to Iida-san, my boss. He thought there might have been a change with the seat that wasn't listed in the early documentation from Mazda in Hiroshima, but there was apparently no change.

On a trip to Japan some months later, I mentioned it to a friend of my in the Engineering division. He also noticed it when he got his 1991. Checking with the specs, nothing had been changed as regards the seat design or configuration. What had changed, however, was the supplier of the seat mounts. Though within design limits,. the seat mounts from the new supplier were marginally taller, so they raised the seat a few millimeters, just enough to notice.

There are tens of thousands of parts in a car. Nowadays, manufacturers often have multiple suppliers of some components. In some cases existing suppliers might close or get bought out so others must be brought in. With this kind of potential volatility in the business, some detail differences between cars from a manufacturer are awfully hard to avoid. A change of supplier might have caused the spring problem you mentioned.

Remember also that Mazda was in a fight for survival in that period, with cost-cutting galore (which is why later M1s and the M2 don't have an oil pressure gauge). There might have been an internal decision to standardize on a single rear spring (if there were different ones to begin with) to reduce plant complexity as well.

By the same token, if you say the car sits high even with the Racing Beat springs, there are a couple of other possibilities first is build variance. The fact that Mazda cranks the Miata out by the thousands means that not all will be put together identically (remember, while there's a ton of robot assembly, much is still done by people). Every car company is in the same boat in this regard and to varying degrees. All it might take is a couple of millimeters here or there and your car could sit high.

Number two only counts if you bought your car used - it might have been Liberaced at a traffic light and put back together poorly. Pick the one you like best. If the problem continues to bother you, I'd recommend you buy an earlier M1. You get an oil pressure gauge that way as well.

bwob

Bob, I love my 1996 limited edition, but if the Miata was (at least) 24" longer from the front wheel base it would truly be perfect. The extra length would make the front end not look so stubby from the side-view, also add more leg space, luggage space behind seats, and possible more goodies to increase the engine's horsepower. Again, I love my Miata but if those changes were made all my automotive wishes would have come true. Honda's new two seater is longer,but Mazda's over all design is way-better. Please suggest this to the powers that be.

Keith White, Las Vegas, Nev

Let's not and say we did. Mazda has sold more than 500,000 Miata (more than any other sports car in history)because of what the car is. Start adding more horsepower, pumping the dimensions out and it will cease to be a Miata. Mazda used to build a larger, more powerful sports car, but people stayed away in droves. Ditto, BMW's larger, more powerful Z3 is sinking to oblivion, with the badge all that's keeping the thing afloat. Why mess with success? The Miata isn't perfect, but the flaws don't diminish the strength of the basic concept. And if you just can't live without something bigger and more powerful, I'm certain any BMW dealer can arrange immediate delivery of a Z3 - or two - in your choice of color. And at a special price.

bwob