Convertible Confusion

Well here’s a vehicle that I’ve ignored for too long. My 1999 Miata Sport. It’s been off the road for at least 3 years. At least there are 4 registration stickers that I had never put on the license plate.

Why had I stopped driving it? Three reasons: alternator over-charging, convertible top was torn, and sometimes the clutch pedal would go to the floor.

For the alternator, the problem was that it was charging at almost 16v constantly. This makes the little gel cell battery very unhappy and it kills the battery is short order. I went through several dead batteries before I decided to check the voltage while charging.

Looking at the internet for answers was very underwhelming. Several other people ran into the issue, but no definitive issue was defined. The issue is further complicated because some engineer decided to be cute and put the voltage regulator in the ECU instead of the alternator. So, it could be a bad alternator, a bad ECU, a bad connection, …or another random bad electrical connection somewhere in the system that is small enough not to pop a fuse, but enough to suck down some volts such that the voltage at the ECU reads low. Which, of course, the ECU tells the alternator to crank it up.

Such a shitty design.

I replace the alternator. Not with a cheap aftermarket or a junkyard special. No, I spend the big bucks and buy the best OEM alternator there is. I also find a used ECU out of a wreck. Oh, and I ditch the weenie gel cell battery for an Odyssey deep cell.

With all the new parts assembled and the wallet lighter, I tackle the project. Alternator isn’t hard, just annoying and a reminder that my back is old and doesn’t appreciate bending over that far, that long. ECU is under the dash between the clutch and brake pedals, mounted vertically. Ok, another weird design choice, but it isn’t hard to remove and replace. The battery is nowhere near the stock size. It does fit in the battery hole in the right corner in the trunk, but it is much shorter and wider. Being an former engineer, I know that my solution of using the cardboard packaging that the battery came in to hold the battery up high enough to sit level isn’t the best, but it is what was handy. Good enough. The battery hold down clamp fits and holds it well. I’m sure it’ll be fine longterm. I also make sure every connection I took apart goes back together with dielectric grease.

Fire it up and it reads 15.1v. Well….shit. I’m going to call that good enough for now. That is less than 3% over spec. Perfect.

Onto the top. It started with a little tear just behind the driver’s head. No biggie. Then I noticed the top of the rear glass window was flexing more when the door was shut. About 8 inches of fabric had separated from the glass. Oops. Order a top. Which sounds simple. But there are multiple options, multiple materials, multiple colors, multiple manufacturers. Someone just take my money!

Preparing for the replacement, I watch several videos. They are all different, but eventually you can make out some best practice themes. A tip to future Youtubers making repair videos: if you make a mistake, mention it at the start of the mistake, not 15mins later. But otherwise the process seems a fun mix of knives, rivet guns and weatherstripping glue (no included).

I start removing the old top. Like most videos, I decide to remove the top frame from the body. In general, it comes apart without drama, just snapping a couple old plastic christmas tree clips. Once off the vehicle, the old plastic top comes off the frame in undramatic fashion.

Reading the instructions, I realize that the printed paperwork from the manufacturer is utter shit. Imagine an old black and white photocopy of a photocopy. But worse is that they seem to skip a step in the reassembly. I realize that between the half-assed videos and the poor instructions, not one was 100% correct. Oh well, al least it mostly goes back the way it came apart.

There is an order to reassembly, but it is all straightforward. Tuck this corner before screwing the flap down. Glue this before that. It goes together but I did have to run out for replacement christmas tree clips as the old ones died. Finally all back together, I threw it back onto the car.

The next part is the only tough part of the job. How bad was it? One father and son team on YouTube broke the project into 3 videos: removal from vehicle, removing top from frame, mounting new top to frame. Yup, they didn’t even show the final installation.

What’s so bad about it? Around the back of the cockpit, there are 13 studs that the top mounts to. The top is very thick in this area. And there is a plastic rain rail on both sides of the doubled up canvas. So it is thick and the whole parameter seems about 2 inches too long, since you are approaching it from the inside of the curve. Basically, it is a pain in the ass to get the top lined up and over the studs. Did I mention that the holes for the studs don’t exactly line up through the 5 layers? Or that there are two sealing washers on either side of the top per stud? Or that you have to make sure the back edge of the rain rail needs to tuck under a rubber lip of the body seal? All whole crouching between the seats and below the mostly raised top?

After much pushing and swearing, I get the two side rail nuts started. I get the rear portion of the top over the studs, but the metal rail doesnt want to line up well. So I throw nuts over the studs to keep the top from falling off the studs. Then take a long lunch break, because my arms are tired and I’m hungry.

After lunch, I tackle the center rail and immediately regret it. My full stomach does not appreciate being bent in half and pushing hard. There is a lot of burping. At least this time I find the issue. There are 3 metal rails with a U-shaped cross-section that curve around the back over the studs. I had put the two sides on, but the center wouldn’t fit between the ends of the sides since they all have curved ends. So, I take off 2 of 3 of the nuts on one side and rotate the side bracket out of the way. Now the back will fit on the studs. Catching a thread on each nut takes an incredible amount of force to compress all that material onto the studs. But eventually, I get them all on. And the side brackets lines up again too. It took a little persuasion, but it ended up fitting.

Now, with all the nuts started, but before torquing them, you are supposed to latch the top. Sounds easy, right? Pull forward and close the latches. But new tops are notorious tight, so I expect some effort. I had already turned up the garage heater to help.

It wasn’t enough. On the first attempt, there was a 4″ gap. Uh, what? After much studying, I notice the rear top frame hoop isn’t far enough back. It was caught on a fabric seam. While pushing the top as far forward as I could, I pulled the frame hoop back and it made a satisfying move into its new home.

Now it’s only 2″ away. Well, 1.5″ if I give it all I’ve got. Time for more heat. I try a heat gun, but it is cooling as fast as I heat up another area. I pull out my Little Buddy propane heater and put it between the seats. In order to keep the heat in, I put some coats across the gap at the front.

After 30 minutes, it warm enough so that I can get the top header to touch the windshield header, but still need about 3/4″. So I start cleaning up the shop and putting away unneeded tools. Finally, the top is hot to the touch. I sit backwards in the passenger seat, pull the header forward and grab the top frame for additional force. Oh fuck! That metal is hot! I had to grab some gloves just to grab the top frame. Yes, it was hot. After 10 minutes of swearing lubricated pulling, I got it close enough to catch the latch. I should mention that I had adjusted the top latches as far out as they would go. And it barely caught.

The driver side was much easier, but still required swear-laced effort to make contact. Stepping back and looking, the top definitely isn’t where it needs to be, with an inch gap at the top back corner of the windows. But it is latched. I’ll let it stretch overnight.

The next day, I tackle the clutch. I had gone to the part store to order rebuild kits for both the master and slave cylinders, but they no longer sell those. You can only buy pre-assembled units. Well, for $24 each, I’m not really complaining. Less work for me.

The clutch system is a very basic hydraulic system. The biggest pain is accessing the slave cylinder, but it is relatively easy through the passenger front wheel well. One flare nut and two nuts/bolts and they are off and the new ones on. Bleeding the system isn’t hard…with two people. By myself, it is a lot of up and down and around the car. I loose track of the number of bleeding cycles, but it is a lot. I am now sweating.

At first I was worried about the pedal feeling really weak, until I realizes that u was comparing it to Jeep clutches. And yes, compared to those, they are very lightweight. I tighten it all up and drop the jack and fire up the engine. At this point, I realize that it’s been well over 3 years since the last oil change. I check and it’s black.

As I back the car out of the garage, I am reminded about the clutch squeak that I had totally forgot about. With the engine running, when letting the clutch out, just when it starts to grab the disk, there is a loud squeaking with the rotation of the clutch. I assume the worst, throwout bearing. Not a bad swap…once you pull the transmission back. Fuck.

The next day, I surf the interwebs. All the throwout bearing failures are what you expect; a bad bearing rattle. Not a squeak. Huh. Search squeaky clutch. It’s dumb nuts simple. The metal end of the slave cylinder presses against the end of the metal throwout bearing fork. No lube,, metal to metal contact and clutch vibrations on the fork create a squeak. Throw some lithium grease at the junction, cycle it a few times and magically the squeaking disappears!

Do a quick oil and filter change and throw on the new registration sticker. Get the insurance reinstated and drive it to work.

First pull to 6k, is met with a slight hesitation around 5k. After that, no issues. There is some slight shimmy from 3 year stationary tires. I am completely caught off guard by the steering. It is tight and very precise. Totally on rails. I guess when you are used to drive Jeep made boats around, especially old CJ5, modern steering seems like magic. And with the big Jeep converted to hydraulic steering and its vague steering at the center, the instant turning just off center is phenomenal.

The only negative is that corners are a lot less exciting to drive with the Miata. Too easy. Turn, go, magic. None of these steer-by-ouija board, turn and pray, turn some more or less, of the jeeps. But all in all, I call this repair a success!

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