Ask Bob!

November 2001

No prizes for finding the invisible question

I have a 1990 Miata that is developing a leak at the to ear of the engine block. I just had the hoses replaced and I am not sure if it is loose hose or something else.

Anthony green, St. Louis, MO

Odds are if it isn't a loose hose, it probably is something else. I think you've figured it out already, so there was no reason to ask the question you didn't ask. Well done.


Buyer beware - and awake

If you would - I am looking to buy a Miata (used) - know very little about them other than I have wanted once since they appeared on the market. Do you have any wisdom you can give me? I can probably handle about $15K at this point. Thanx,

Kevin Hasenzahl, Levittown, PA

Regardless of the vintage Miata you buy, go for the newest car you can afford - and that's to your liking - which has a full and verified (or verifiable) service history. If I were in the market for a used one, I'd avoid a car with many (if any) modifications, as I'd much rather make my own mistakes than buy somebody else's.

If you want more - and better - hints on buying a used Miata, there's a link in the Miata FAQ at to a page written by a bloke named Skip Cannon which offers tons of information on the subject. You can track it down via the FAQ there, but be ready with some strong coffee Kevin, as it can be pretty eye-glazing at times.


Here's one which makes a 1.6 Miata look like a powerhouse

Are you the person who designed the Opel GT back in the early 70's? I went to high school with his daughter Karen and I thought his name was Bob. Hall.

bill denton, San Jose/CA/USA

I'm afraid not Bill, although I was quite a fan of the Opel GT when it was launched. However as a ninth grader I had little opportunity to buy one so I remained an admirer from afar.

Back when Steinmetz was still doing Opel bits and the GT was relatively new, I gave thought to buying one and getting a set of Steinmetz fenders, the suspension kit and some of their Connero engine bits for it. I was enthusiastic till I learned that as an under-25 (at the time way back in 1976) insurance would have been about $2000 a year for a dead stock Opel GT. My ardor for the car chilled considerably after that. The fact the fenders, suspension, wheels and tires cost about 50 percent more than a tidy used 1.9 Opel GT was another contributing factor as well.

You know, my wife's name is Karen. Though her parents had nothing to do with anything Opel or GM other than owning a real hangar queen of a 1977 Nova.


I don't know if I would be bothering you about this but I just bought a 92 Miata and I was wondering how much of a difference there is between the 92 and the 94 models? Also I was wondering what Mods I could do to increase horse power. I don't know that much about cars other then I love em, and by far miatas. Oh also by making an air vent from the headlight,or turnsignal make a large difference in intake?

Well bob thanks a lot for your time,

Steven , orrville/ohio/USA

Main differences would be replacement of the 1.6 litre B6 engine fitted to 1990-1993 NA6A Miatas with the 1.8 litre BP used in NA8Bs and all subsequent models, replacement of the (optional) viscous limited-slip differential with an (optional) Torsen limited-slip, addition of a passenger-side airbag and revised instrument panel on 1994 and later cars, addition of a rear cross brace at the leading edge of the top bay (to aid in compliance with US dynamic side impact safety standard) and (optional) alloy wheels half-an-inch wider than those used on 1990 to 1993 cars.

Power increases are limited by the depth of your pockets, your degree of creativity and how much of the Miata's character you want to eliminate. Considering the depth of the aftermarket serving the Miata, there are far more possible methods of increasing engine output than I can possibly list. You might want to take a slow troll around the vendor area (the 'Marketplace') just to get an idea as to what's out there and how much money you want to spend. Please bear in mind what my Dad once told me; "Speed costs money. How fast do you want to go?"

Without reducing exhaust backpressure and intake airflow restriction, fresh air intake for the OE induction and exhaust systems are unlikely to provide anything beyond incremental increases in power and torque.


I own a silver '90 B-package and I was always under the impression that it was the second year that the Miata was in production but now I am realizing that perhaps it was the first year of production. Also, I have black pin-striping on mine which is not mentioned in that site as an option. I always kind of assumed it was stopped in '90 as I rarely see it. Any thoughts on these questions ?

Elaine Greco, Atlanta, GA

Miata production started in the second quarter of 1989, with the official on sale date of the car 4 July, 1989. For purposes of safety and emissions compliance, all Miatas from the start of production through roughly late July 1990 production were 1990 models. So while a 1990 is the first model year of Miata, it can also be the second (calendar) year of production.

Mazda has never offered pinstriping as a factory option, as neither Mazda's Ujina or Hofu assembly plants - the only places the Miata has been built - have the capability to do it. However, as independent businessmen some dealers have had cars pinstriped. Of course if your car was purchased used, a previous owner might have had it done after he or she took delivery of the car. But pinstriping has never been a factory applied or factory approved option.


How old is old? How used is used? How much is too much?

I have a 1990 Miata, runs good, good paint, but the air conditioning needs replaced. The car has 164,000 miles on it, but it doesn't smoke and seems to be in good shape. I don't know if the engine has ever been rebuilt etc...but it is clean looking. I have been told that to replace the entire air conditioning system it will cost 1700 to 2000. This is more than the car is worth on the market. But, I like the car, and would like to fix it up some. Would this be a mistake considering the mileage? I thought of having the compression checked and the car having a basic look over by a mechanic, I have zero knowledge of mechanics. Or, should I try to trade it in?


Dwain, Bradenton FL USA

Inasmuch as you know the depth of your pockets as well as the degree of attachment you've got to the car, the only person who can answer your question is the guy who looks back at you in the mirror when you're shaving. I've had cars I liked so much I spent far more on them than they were worth, but I never assumed that I'd get any of it back when the car was eventually sold. I did it solely because I wanted to, an irrational but personally satisfying reason. The only thing that's kept me from parting with my money in this foolish manner with a car I really like has been structural rust. And the dreaded tinworm has been a stupendous heart-breaker a couple of times with cars I almost had my heart set on.

Given you car's age and mileage, if I were doing all that work on a car with an unknown service history I'd probably replace the engine and gearbox as a matter of course, along with the differential (opting for a Torsen in the process). While the car was apart I'd also replace every bushing in the suspension. But that's just me. But it'd have to be something I was really, really attached to or a pretty rare bird.

In the meantime, you and the guy in the mirror need to sort out a few priorities as to what the two of you want to do with the car that fits in with your bank balance.


My 90's windshield wipers seem to have only one speed. Kind of slow! Otherwise they seem to be ok. Thanks

Kurt Kightly, Virginia

Sounds like it might be a problem with the wiper motor, or with the wiper relay, or perhaps the wiper delay system. Maybe, though it's less likely, some sort of malady of the wiper linkage itself. Of course it could be something altogether different, but those are my guesses. Since I'm not a mechanic you can rely on any or all of them being right or wrong. But nothing in-between, I can guarantee that.


'M' Marks the Spot

I would like to know if you could provide me with some more information about the special Mazda design team called the M2 .... i know they were able to put out some special edition Miatas ( Roadsters I mean )

I can not seem to find anything much about them on the Internet. It sounds like they are extict, but how did they come into play with Mazda, what is the story behind them and i am really interested in the weird projects that they were involved with.

Their nomenclature suggests that they have created close to 30 concept/prototype cars. From Carols to Cosmos ..... i would love to learn more about them, can you share some info or point me to the right direction to find it ?


Eugen Sofronov, Camabridge, Ontario, Canada

M2 was what the Japanese used to call an "antenna studio". The place was headed up by a bloke named Masakatsu Kato, who was the V701 project leader at Gijitsu Kenkyu-sho, Mazda's Technical Research Division in English. Giken, as the group was more conveniently called, had been given the lightweight sports project after the MRA-developed front-engine, rear-drive convertible concept beat the Tokyo-penned mid-engined, rear-drive and front-engine, rear-drive coupe proposals in the 'Off-line 55' competition.

A few years later when Kato's idea to set up M2 as an advanced product research facility was given a go-ahead and Kato became the first manager of M2.

Nissan started the idea of "Antenna showrooms" in the late 1980s, with the Pike Factory cars (Be-1, Figaro, Pao and S-Cargo) the result of this sort of freeform market research. Mazda decided to get in on the bandwagon with the M2 project, a scaled-down version of the company's product planning department with minimal in-house engineering and design capability as well as a workshop where a limited degree of prototyping could take place. The place was an architectural mess, with a faux roman column poking up out of the roof. There was a cafe and auditorium on the second floor, along with a really good but compact automotive bookshop. There was a Mazda dealer on the first (ground) floor. Planning and development offices were on the third and fourth floors. The coolest thing about the building was the glass and stainless elevator in a large stainless steel atrium. We all nicknamed it "the missile silo".

M2 did about eight MX-5 variants (including a coupe and a 3.0 liter V6), but only three were commercialized. In chronological order they were the M2 1001 (on sale December, 1991 with an official run of 300 cars), the M2 1002 (on sale November 1992 with an official run of 100 cars) was the leather-lined 'prestige' model of the lot and the M2 1028 (on sale February, 1994 with an official run of 300 cars) which was positioned and marketed as the 'Street Competition' M2 car. The 1028s weight some 20kg less than a standard NB8B, and this included a front strut tower brace, hardtop and aluminum roll cage, none of which was fitted to the standard 980kg NA8B. M2 also built and sold a version of the AZ-1 mid-engined two seater (see the October, 2001 "Ask Bob!" for details on the AZ-1 'donor' car) known as the M2 1015 and also did a 2.5 litre MX-3 which ran like a scalded dog but didn't proceed beyond the prototype stage.

As mentioned above, the official number of M2 1001s produced is 300, though as many as 16 additional 1001s - I've heard of eight to 16 cars, depending upon the source - were built, some as pre-production prototypes, some distributed (un-numbered) to 'friends' of M2. The cars' weren't stripped and repainted, but were painted on the Mazda line, using non-MX-5 colors already in the production system for other Mazda vehicles. The M2 1001s, M2 1002s and 115 of the M2 1028s were shot a dark blue reserved for home market Mazda Sentias. The remaining 185 M2 1028s were painted a shade of white used for Mazda Titan commercial vehicles.

Engines in 1001s had the heads pulled, ported and polished and the all the moving components in the valvetrain tidied up. Pistons were replaced (the revised item is apparently no longer in the Mazda parts system, so supplies are scarce) with the total benefit of the engine mods amounting to a rated 130hp at 6500rpm and 15.1kg/m at 5500rpm, though actual figures were 124hp and 14.8kg/m. In Japan, M2 1001s were on a diet of premium unleaded. M2 1002s used the B6 in standard tune and M2 1028s got a lightly massaged (wilder cam and 10.61 compression ratio) 140hp version of the BP 1.8 then fitted to all MX-5s.

The front fascia extension with built-in fog/driving lamps was unique to the M2 1001, but the rear spoiler was available on M2 1028s. The roll bar was deleted from some of the later 1001s built and did not appear on any of the 1002s or 1028s, with 1028s getting the previously mentioned aluminum roll cage in place of the roll bar. The lowered suspension and strut brace was common to all three M2 MX-5-based cars, and the 1001's wheel design was shared with the 1002, which also used the M2 1001's Talbot-style aluminum door mirrors. All three M2 cars had a new center panel for the HVAC and audio, with no center console. The gear lever was in a leather gaiter, with a bright ring securing it right on the carpet-covered center. Power steering was not fitted to early M2 1001s or any of the M2 1028s, but was made a no charge option on the 1001s from about car 60 due to a large number of of owner complaints about the slow steering ratio of the unassisted tiller.

None of these cars were cheap. The M1 1001 retailed for 3,400,000 yen, the M2 1002 was a snip at 3,000,000 yen and the M2 1028 was 2,800,000 yen. As a point of comparison, when the 1001 was introduced, a fully loaded J-Special (the 1992 Sunburst Yellow car but with a 'B' package) was 1,900,000. The M2 cars sold really well at start - especially the 1001 - but demand trickled off quite rapidly. With little else commercialized by M2, the outfit developed the reputation of being a one-trick pony.

In the days before Ford stepped in and Mazda was a financial basket case, some of the planning functions of M2 were brought into the Yokohama Product Planning office and the commercial functions wound down.

To the best of my knowledge, other than a handful of contemporary reports in Japanese publications when the 1001 and 1002 were new, nobody in Japan has chronicled M2's cars or the organization itself. And it's virtually unknown outside of Japan, so I suspect 'foreign' material on the outfit and it's work is even thinner on the ground.


Back to Ask Bob!

04 December, 2001

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