If you look back on some of the past entries you will find a few on work that was done on a 1996 Mazda Miata. That car came to us with some modifications that, while performance oriented, left it with a ride that was harsh and unfulfilling. After performing some maintenance we worked with the owner to choose a better suspension package as well as some much needed frame stiffening. We also added a roll bar for additional safety. The owner was very satisfied with the results.
This year the owner decided to transfer ownership of that Miata to one of his sons. The logistics of delivery meant that he drove it about half way to Texas. On the way he found the car so enjoyable that he let us know that he was going to find another Miata to replace it and wanted us to think about how it could be modified to duplicate the fun of the 1996 one.
In a week or two he located a 1999 Tenth Anniversary Edition that had barely seven thousand miles on it. So we set to work evaluating the new purchase and getting a list of parts and pieces that would make it the kind of Miata he yearned for.
The car came with original tires that were aged to say the least. While the car had been stored with great care the tires really were shot. We set about to shod it with rubber that would give us the best possible starting point, a set of Bridgestone Potenza RE11 tires. Since this would definitely be a “fair weather” vehicle there was no worry that these tires were “extreme performance summer” rated tires.
We installed the tires and had them “Road Force” balanced using the latest equipment from Hunter. This ensured that the tires were not only balanced, but were a round assembly that would roll true.
After a test drive it was clear that the car needed some help beyond the tires in order to achieve a proper level of handling performance. We dug into Flyin’ Miata’s catalog and chose items that would stiffen up the chassis as well as give us a bit more power.
They have what they call a Cannon rear subframe brace that provides stability for the rear suspension as well as a “butterfly brace” that provide fantastic rigidity to the under chassis. We had installed this brace on the ’96 and found it to be a huge benefit.
The owner wanted to replace the factory Bilstein shocks with Koni adjustable shocks. I must admit that I was more in favor to keeping the Bilsteins since I have always been impressed with their performance on other cars, but we discovered later that his decision was a fortuitous one.
We wanted to get the ride height to look better than it did. The rear appeared to be a little too high for the car when you viewed the fender gap. So I went online and checked what was available from the folks at Swift Springs. My experience with their product has been very favorable. They have a spring technology that is currently the best around with a small diameter wire, they are lighter and use less coils, all of which contribute to less unsprung weight, without the coil sag we have seen in other springs. They had a set that would work perfectly with this Miata. The Swift fronts are rated at 202 pounds/inch and the rears at 157 pounds/inch. They would drop the front 1.0 inches and the rear 1.2 inches. Our experience with the Swift Sport springs was that they did not compromise the ride in any way or fashion which was particularly important for this owner.
Flyin’ Miata has a sway bar (a.k.a. roll bar) set that removes a certain amount of body roll without compromising the ride. This was another excellent choice that would really improve the fun factor of this car.
The owner wanted a little more power out of exhaust system modifications without irritating his neighbors. He picked out Racing Beat four-into-one headers and Racing Beat muffler. He also chose a Randall cowl induction kit from Flyin’ Miata.
He also had some maintenance items he wanted attended to such as a fresh set of spark plugs, wires, and coil pack. While the coil pack might seem like overkill, it had been a problem area mentioned in several forum entries so it could pre-empt some ignition troubles. The brake and clutch fluid needed to be flushed and that meant it was a prudent time to replace the flexible brake hoses with braided stainless steel versions. The brake pads and rotors were, of course, in fine shape.
Since seven thousand miles were on the odometer it was also a good time to change the oil and filter. We use Mobil 1 5W-30 for this car.
In the interests of safety a Hard Dog padded roll bar was added to the list of parts. In my opinion, this should be mandatory in any convertible.
With all this stuff on order the project was just started. Now we had to plan out our process for making all those upgrades and changes. I went over and over in my head just what each area would take in terms of tools and effort and what the best order might be to do all these changes in. The weekend was approaching and parts were piling up.
Saturday morning I drove out to pick up the car, still thinking over just what would be done when. A local shop, Performance Chassis, would provide lift time so I could get the most possible accomplished over the weekend.
The Miata and I arrived and I brought it up on the lift so I could get a good look at things. The shocks and springs were a good starting place and the rear was where I would begin. That gave the exhaust system time to cool before I started on that.
First thing to be removed was the wheels in order to have complete access to the suspension parts.
To start on the rears the anti-roll bar needed to be disconnected as well as the upper control arm and lower shock bolt. The trunk was cleared out of all the grey trim pieces and the gold colored plate covering the fuel lines was unbolted and removed as well. That provided access to the two nuts that held the top of each shock assembly in place. Once they were removed the car went back up in the air and the lower control arm was pried down so the shock assemblies could be removed.
When the assemblies were taken apart on the wall-mounted spring compressor there was a shocking surprise (no pun intended). The bump stops on the rear shocks had become just oily pink powder. Apparently the shaft seals on the rear shocks had dried out and pumped shock oil onto the bump stops which dissolved them. A quick call was put into the local Mazda dealership’s parts department and new bump stops were ordered. They would be in early in the week so it meant that the new shocks and springs would go in, but would have to be pulled out again to have those essential pieces installed.
Bump stops are critical because they keep the shocks from bottoming out and breaking the internal valving or bending the shock rod. The owner was cautioned to be especially careful with railroad crossings and pot holes until the bump stops were installed on the rear shocks. With the new springs a single hump would be cut from each bump stop as required by Swift, but to go without any would be a bad thing long term.
Each shock and spring assembly was put together using the factory rubber spring mounts, but the metal washers between the rubber insulators were drilled out for the larger Koni shock rods.
The rear shocks and spring went in beautifully.
Before tackling the front shocks the exhaust had cooled down enough for some preparation work to go on. First the O2 sensor had to be loosened and removed from the old exhaust. It was important to keep the twist in the wire so that when it was crew in to the new header it would finish up with the wire being straight so I wedged it in a convenient place that would hold the twist. Then I removed the nuts from each of the exhaust flanges including the rear muffler.
I find that to remove exhaust prongs from the black rubber hangers it is best to pry the rubber holes with a narrow screw driver and spray in some silicon lubricant. This allows the rubber to slide off easily releasing the exhaust component. The rear muffler came off easily and the new Racing Beat version took its place just as easily. A new gasket was provided and everything bolted up just like it was a factory piece, only it looked and would sound far nicer.
Now was a good time to add the Cannon rear subframe brace. It meant removing four nuts, two of which were the lock-down nuts for the rear alignment eccentrics. To make certain that I didn’t move things too far out of whack I marked the eccentric washers and the scale on the subframe before I removed the nuts.
The brace slipped over the exhaust pipe easily and a cross piece was bolted on to complete the brace assembly. Then the unit was slipped over the four bolts and the nuts were torqued back in place. That would really stiffen things up in the rear.
I lowered the car again so I could undo the nuts holding the top of the shock mounts and the strut tower brace that came with the car.
With those out of the way I unbolted and removed the air filter housing from the fender so I would have access to the exhaust manifold. Since this Miata had so few miles accumulated it was easy to unbolt the heat shields and loosen the EGR connection. Then it was just about as easy to loosen and remove all the nuts holding the exhaust manifold in place. There is certainly plenty of room to work on that engine.
The EGR fitting was completely loosened and gently pried out of the way while the manifold was pulled off the head. The lower pipe just prior to the catalytic converter was also removed by undoing two bolts that held the transmission to the engine. These two bolts also held a bracket connected to the exhaust. The bracket would be discarded but the bolts would be re-installed to hold the transmission to the block.
It was very easy to slip the new Racing Beat header into place. There was plenty of room and it fit like a glove. The EGR fitting also slipped on and was easy to tighten. This was important because it is usually a place where it would be easy to cross-thread the fitting.
The original exhaust gasket was re-used. This it typical as it is a robust piece anyway. Then the nuts were fit on each of the head studs lightly before the car went up in the air again so the exhaust flange could be bolted together at the cat.
It was a little tricky to get the new gasket in place and lined up properly before tightening down the flange nuts. I found that a flashlight, screw driver and patience was needed to ensure a proper seal. With that accomplished I reinstalled the O2 sensor making certain that the wires were straight when it was tight.
Then back down went the car so the header nuts could be tightened to the specified torque.
We connected up the air filter box so we could test start the engine and make sure there were no exhaust leaks. None were found and everything sounded as good as it looked.
It was time to get back to the front shocks. The lower control arms would have to be unbolted at the alignment bolts so, like the rear, the eccentrics were marked to the subframe and then they were unbolted. These are two bolts used to adjust the front camber and the caster.
This time it was a matter of pulling down on the upper control arm so the shock assembly could be removed.
The spring compressor allowed the disassembly of the unit and this time the bump stops were intact. The gold metal washers had to be drilled out large enough to fit the Koni’s larger shock rods, but everything went together well and it was barely challenging to get it put back into place.
The lower control arms were bolted up and the eccentric marks allowed us to get the settings very close to their original places.
In order to get the top shock nuts back on the car would be lowered once again, but since the strut bar was out of the way it was a good time to change out the ignition parts. New wires were inserted in the new coil pack and then the old plug wires were removed from the spark plug wells. The old spark plugs were wrenched out and proved to be in good shape, but with gaps that had been closed up quite a bit. New plugs went in and the old coil pack was replaced with the new unit and wires. Then the strut tower brace was put into place and the shock mount nuts were tightened down to specs.
Up to that point it had been a ten hour day and we took a break so that we would not be making any foolish mistakes. There would be plenty of time available on Sunday.
The next day it was time to get the Hard Dog roll bar in place. Since the butterfly brace would be installed as well, it was a good time to unbolt and remove the seats as well as clear away the items required for removal prior to the Hard Dog install.
There are excellent instructions available on their web site so I won’t go in to all the details here. The biggest challenge is to take your time trimming the plastic trim pieces to fit around the bar. It is a great safety item and the fit and quality cannot be beat. It is made in North Carolina so the shipping time was a day.
After the bar was the challenge of the butterfly brace. This is made up of five pieces of specially fabricated stainless steel. Their installation requires the carpet be pulled up because there are many holes to be drilled and bolts to be fastened through the floor.
It is mandatory to have some help with this one. So I enlisted the aid of Rodney, perfectionist extraordinaire, to handle the duties on the ladder while I drilled and bolted from below.
First to be installed are the frame rail reinforcement pieces. This brought some frame damage to our attention. The reinforcement pieces would not fit over the rail because the rails had suffered damage from the misuse of floor jacks. The factory rails had to be hammered back into shape before the new pieces could fit over them. Measurements were taken to make certain that things were still square and then the rails were set in place and the first holes were drilled. After the first set of bolts were nutted up the second brace pieces were bolted to the new rails. They were kept loose so that the center section could be bolted in between.
This requires a lot of tedious and careful work so I was fortunate to have Rodney’s help, but the results are always incredible. This bracing provides much needed rigidity, especially with the damage that the factory rails had suffered.
While there was still energy left I changed the oil and filter and then got the car off the rack. I was anxious to see and feel the improvements as well as get it back to the owner so he could experience the transformation.
The car will be back for the installation of the rear bump stops as well as the FM anti-sway bar kit, braided stainless steel brake lines, cowl induction, and fresh brake fluid. We also want to try for an alignment where we can put in more caster.
So enjoy this phase of the transformation and look forward to next weekend’s completion.
Here are some photos to hold you.