Rostra Precision Cruise Control 250-1206 supplied by Moss

[7/16/2002] Reviewed by: Andrew MacLeod -

Applicable to: '90 - '97 1.6 liter 1.8 liter

This is an aftermarket Cruise Control Unit purchased through Moss.

A couple of problems that have been raise4d by other users: Firstly on Canadian and Australian delivered MX5/Miatas there is no speed sensor at the rear of the speedo to send a speed pulse. Moss is yet to get back to me on this point and their after sales service seems poor. A SOLUTION: I purchsed a 0.1 amp, 24 volt reed switch (cost about $3) from an electrical suppplier. This can be stuck to the rear of the speedo (which needs to be removed from the console unit)above the rotor (there is an obvious place). Earth one end andd conect the other to the grey wire from the cruise unit and you have a speed sensor. The second issue for right Hand Drive Countries, the cables sent by Moss are about 2 feet too short and need to be extended.

Once the unit is installed make sure that the cable attached to the accelerated is as tight as can be without opening the throttle. This prevents surging.

Under 30 minutes to remove completely

Roestra Cruise Control

[7/8/2002] Reviewed by: Ken Johnson -

Applicable to: '90 - '97 1.6 liter

Roestra Cruise Control specialized for the Mazda Miata.

My experience with this product has been good. It was installed last Friday, July 5, 2002. The project took a total of about 5 hours because we had trouble with the first mounting bracket. The bracket needed to be adapted to mount high enough to clear the washer tank and the intake manifold. Other than that, the instructions were comprehensive and simple to follow. I purchased this product from Performance Buyers Club to guarantee that I was buying the right product. I learned this from those who posted their reviews before me.

I have been very satisfied with this product since I have installed it. Going up hills, the cruise control accelerates appropriately. I definitely recommend adding this if your Miata has become a highway cruiser as much as a backroad driver. Having cruise control has certainly helped to make more car more comfortable. I look forward to my first long drive in this wonderful car. I would definitely do this again if I ever bought another Miata without cruise control.

Over 30 minutes to remove completely

Rostra Miata Cruise Control (a.k.a. MAX-5 Cruise Control)

Reviewed by: Allan I. Aizenman -

After-market Miata Cruise Controls

Those whose Miata for one reason or another did not come equipped with a factory installed cruise control may find my experiences with two varieties of one particular brand of after-market cruise control of interest.

Please note that I am handicapped in that I have no personal experience at all with the factory-installed Miata cruise control. Any reference that I make to the factory model is based on the description of that unit as it appears in the 1990 shop manual.

There are two after market cruise controls that I know of that are supposedly designed specifically for the Miata. Both are made by Rostra Precision Controls Inc of Laurinburg, North Carolina. Like the factory unit, both use a servo assembly to control the throttle cable, with the servo activated by engine vacuum tapped from a fitting on the top of the intake manifold designed for this purpose.

Both units come with an identical stalk-mounted control switch which fits very nicely on the lower steering column shroud. The control falls readily to hand, as the saying goes.

Neither unit comes with a speed sensor. All Miatae, whether cruise control equipped or not, supposedly come with one, and there is supposed to be a terminal (‘RSW') on the back of instrument cluster bezel which provides the output of the speed sensor. Possibly this is the case on US models, but my early 1990 Canadian had no such sensor, and I had to purchase a third-party one, the Mazda unit not being available as a separate unit, in Canada anyhow. This set me back $Cdn 75.

Both units require connections to be made for electrical power and brake switch de-activation.

Rostra Model 250-1206 (for 1990-94 Miatae) :

Someone referred to this unit in an earlier posting as the ‘single piece' control. It costs $US 140 from Moss Motors, shipping charges and the accursed Canadian GST not included.

The ‘single piece' refers to the huge (7"x6") servo module which mounts on the driver's side fenderwell to the immediate right of the air flow meter, taking up almost all available space and just barely fitting in with my Flying Miata strut brace. Electrical controls (the ‘regulator') are on a small box attached to the servo. In addition to the brake de-activation, this unit requires a connection to the Miata's clutch switch.


This cruise control never did work properly. It surged violently at speeds under 50 mph and over 75-80 mph. In the speed range where it did work, you always got the uneasy sensation of slight surging, with the feeling that the unit was being constantly activated/deactivated to maintain speed. Aside from that, it had a annoying tendency to stop working completely after a few minutes, meaning that the car would start losing speed. The resume/accel function never worked worth a damn.

Faulty unit? Incorrect installation? I don't know. I could not find the problem.

Someone on had posted a supposed solution to the surging problem on another Rostra unit, which involved ensuring that there was no slack in the throttle activation cable, but this did not help me at all. From what I have heard and read, I am not the only person to have had difficulties with this model. My verdict : NOT RECOMMENDED. DO NOT BUY.

I had written the control off as a useless piece of junk. I was seriously considering removing it entirely, when I heard about - and promptly ordered - the ‘two piece' Rostra model.

Rostra/MAX-5 16-R Cruise Control

This one set me back $US 180 from Performance Buyers Club, again not counting shipping costs and those forever accursed Canadian taxes. The servo module on this (possibly newer) model is much smaller (4"x 3") and seems to be very similar in size to the factory unit. The owner's guide states that it is a Rostra cruise control modified by Performance Buyers Club specifically for the Miata.

The servo module is supposed to be mounted on the engine firewall immediately under and to the left of the windshield washer fluid reservoir. However, the very much larger reservoir on Canadian models such as mine made this impossible, and the servo ended up immediately behind the air flow meter. It fits in quite nicely there, though it may make a planned future installation of a Jackson Racing cold-air induction unit difficult if not impossible.

This model comes with the electronics (called the regulator) in the form of a small flat 2x3x1/2" module which attaches to the inside of the lower steering column shroud. This seems exactly equivalent in size and function to the factory module (which is located on the driver side firewall under the dash). The regulator is hooked up to the control switch, the brake de-activator switch, the servo, etc, and there are more wires going through the firewall than with the single piece unit. Once installed, there are some minor but important adjustments to be made via a road test.


This model has worked well from the very beginning, and does what a cruise control is supposed to do. I never had any of the surging problems described with this unit in the posting. The device is stable, and maintains speed in all speed ranges quite accurately. The resume/accel functions and set/coast work exactly as they are supposed to. I don't know how this cruise control compares to the factory unit, but it must come pretty close. My verdict : RECOMMENDED.


Since installation of the cruise control, my speedometer needle vibrates slightly. This is no big deal, and is probably a result of the third party speed sensor being a very tight fit on the speedometer cable as it passes through the instrument cluster. The speed sensor is just barely touching the edge of the instrument cluster panel. The factory sensor is supposed to be smaller in diameter and supposedly does not have this problem. Unfortunately, my understanding is that you have to buy the speedometer to get the factory sensor - it is not available separately.

Conclusions :

1. If at all possible, buy a Miata with the factory installed cruise control.

2. If you do have to get an after-market cruise control, make sure that you are getting the two-piece Rostra/MAX-5 unit. I don't know if it is available from anyone except Performance Buyers Club.

Reviewed by: Todd Barker -

Created for those of us with a "Base" or an "A" package, but want the luxury of cruise control :)

I purchased the kit from PCB because it was a "MAX-5" product. I thought this was somthing special designed just for the Miata. Now, looking at other ads, I beleive it's might be the same kit sold by Moss Motor and M&M Marketing. (but I don't know this for certain)

The unit installs in the factory loaction, you have to remove and stock throttle bracket and use a new one (supplied). Attaching the wiring inside the car is very straight forward and easy (unless your alarm installer placed the alarm brain right where your hand needs to be) :) A custom mount is provided for the controler (on/off switch, ect.), choosing the mounting angle and location was the hardest part. My freinds have looked at the install and thought it was the factory unit, under the hood AND inside the car. **Very important** The instructions do not tell you that IF (and when) you need to adjust the length of the cable by the throttle body, you just need to disconnect the cable from the bracket, THEN spin it arround the cable. It doesn't look like it, but it does move forward and backwards this way. Total install time took me about 4 hours, this was because I didn't know how to adjust the cable lenght (at least 40 minutes) and time I wasted trying to work arround the brain for my alarm (almost an hour till I just disconnected the brain)

Once installed, my first drive was very disappointing. The cruise would just keep surging on and off the throttle (over and over and over). NOT FUN. BUT.... I though about why it was doing this, and after inspecting the way I connected it to the throttle, I left a little slack in the cruise cable. (the instructions warn you not to leave it too tight, but it doesn't tell you what will happen if it's too loose.). Once I tightened it as much as possible without opening the throttle, the cruise has worked wonderfully.

Would I install it again? YES!! I drive to Oregon a couple of time a year (900+ miles each way) and the thought of this drive without the cruise is just painful. I realized the key to the kit was to fine tune it AFTER you drove it a couple of time. I have had it installed for 2 months now and I only had to fine tune it that first day.

Back to Product Reviews 19 August, 2002