Robbins Glass Window Top Installation

by Ken Stoorza

It's been a couple of interesting days installing a Robbins glass window top on my '90 B. It's done; it looks great. I washed it today and the rain rail, etc. seems to work OK. I guess I can claim victory. This was the original top; the plastic rear window went opaque about three years ago. I've been putting this off, obviously, for a while. The top has been visibly wearing out also. A couple of the seams opened up and the fabric from the front top bow pretty much disconnected from the top years ago. For 11 years of service, I can't complain. 

As far as expectations: to be honest, I really didn't expect it to be this difficult. It seemed like almost every aspect of it was filled with interesting challenges. I am an engineer by profession and know my way around mechanical things fairly well. I have a good sized garage to work in and a pretty decent complement of tools. Did my own timing belt change, brakes, clutch slave cylinder and not much else because not much has failed on this car! Early in the game, I purchased the workshop manual and had that for reference. I also read Brian Dore's account of changing tops as well as the accounts of others who commented on Robbins tops and installation. So I guess I was as prepared as could be. So there is no way I can spend a couple of days and not use this forum to decompress and, possibly, provide some information which could help others.

I initially liked Brian's approach of not removing the top. Also, the Robbins instructions (which are barely comprehensible) didn't indicate that the top should be removed either. I started out with the intention of not removing the top, but once I got into the nitty gritty of the "B" pillar attachments, I thought again. After spending about an hour a) screwing around with the various fasteners and that devil screw and b) trying to visualize how I could re-install something properly which I was having a tough time uninstalling, I opted to remove the top. It's really no big deal; matter of fact, I immediately realized that this was easier and, as I progressed through the procedure, kept thinking that this was, indeed, a smart thing to do.

Before I started, I bought one of those pronged deals that one uses to remove door (and other) upholstery. It cost about $10 at Pep Boys and worked great. I used my Makita with various bits which made parts of the job go easier. One of the reasons it took longer than expected was that I took my time, cleaned and vacuumed things during various stages of disassembly.

When drilling out the tension cables, one of the plastic pieces cracked. Not wanting to wait till Monday when the Mazda parts department would be open, I fastened a metal bracket around it and epoxyed the whole mess together. I fully expect that it will work fine. Matter of fact, it's probably "over engineered". That's the good news; bad news is chalk up another hour or two.

I believe that having the frame on the garage floor (with a blanket underneath, of course) made re-assembly easier. Even so, there was quite a bit of grunting on my part to pull the sides of the top over the "B" pillars, especially the second side. Fortunately, there is a lot of free sunshine here in California, so I put the top out in the driveway (on a blanket) and waited about 10 minutes. The black plastic heated up and the top expanded a little so I was able to muscle the second side into place. I honestly don't think I could have done as good a job in this area if the top was still on the car. I had drilled out the bracket which sandwiches the fabric (and is held together, primarily, with those aforementioned little screws that are a *lot* easier to deal with with the top off) and, before riveting the bracket back on, tweaked it a bit with needle nose pliers to make certain it fit really well.

Following the directions in the shop manual, I went for double sided tape on the header. When it came time to doctor up the ends (at the header where the weatherstrip screws in), I used double sided tape where the top tabs fold under and contact cement to hold the corner bits under the weatherstrip together. I glued these up, applied clamps and took a break. When I came back about an hour later, they were ready to assemble.

I enlisted the aid of my 18 year old daughter (who will soon get this car) to help me put the top back on. I removed the antenna before we started. I underestimated the weight with regard to my daughter. I work out regularly and was content to stand there and ponder for a while. Meanwhile, I noticed her side sinking lower, and lower so I had her land her side first (keeping an eye on the rain rail, body, etc...she did a good job). Once the top is landed in the general area, you can go back and forth and individually position each side. There is a tab that engages the shaft of a screw which makes positioning of the mechanism very easy.

Now the fun really begins.

That glass window that we love so much weighs more than you would expect. So much, as a matter of fact, that it tends to a) fall into your face when you are attempting to attach the rain rail to the 13 bolts and b) tends to pull free from these very short bolts the sandwich of fabric and rain rail which you have been pushing, grunting and sweating to align. What you need to do is stuff something in there to hold the glass window up. I found that a 12 pack of toilet paper (any brand will probably do) did the trick. About this time, my neighbor came by to return my section ladder which he borrowed the day before (this was day two for each of our respective projects....his was painting a big room). I took a well deserved break from the rain rail installation to store the ladder away and chat with him ("you're really installing this top yourself?".....the man knows a challenge when he sees it. Noticing the toilet paper he commented, "Is it really all that bad?").

I have this problem of absent mindedly putting something down and forgetting where I put it. You might think it's something really bad, probably brought about by age and stress, but I've been doing this since I was about 5 or 6. When the neighbor arrived, I was pondering the "IMPORTANT" note in the Robbins instructions (there are about three of them) regarding the sequencing of the rain rail nuts. Also in the forefront of my consciousness was Brian Dore's opinion that it didn't really matter how you tightened them. When you consider that some of these are tightened in sequence after the rain rail frame has been already tightened on either side by neighboring fasteners, it doesn't make a lot of logical sense which of these intermediate fasteners gets tightened first. So like Robbins and Brian Dore, I have my own opinions: 1) the purpose of Robbins introducing a sequence is to make certain that the rain rail gets evenly spread out. Considering this, I first secured the rain rail with the nuts without the three frames. At this point, I want to thank whoever it was who suggested the tool to align the top, rain rail and studs. I went to the local hardware store and bought some thin wall copper tubing that had an ID (inner diameter) which fit over the 6mm or so of the stud. I cut about four lengths around 3 or 4 inches long. By poking these through the top and rain rail, you could feel around until you hit the stud (the threads make it easy), then force the tool over the stud; viola...all is aligned!. Once you do several of these in different locations, the ones in between pretty much align themselves. Remember, this is still opinion #1. 2) I also theorized that once I got all 13 nuts installed in this manner, not only would the rain rail be properly aligned, but the job of installing the frames would be a lot easier once I removed the nuts, one frame at a time and then reattached them with the frame. The success of this, of course, was dependent on the 12 pack of toilet paper keeping the heavy glass window in place. To be honest, I really don't know how I would have installed the fames otherwise. I am not strong enough to brute force them on....especially the long one.

So as I mentioned: the neighbor arrived with the ladder, we chatted and I crawled back into the Miata for the umpteenth time and could not find my 10mm socket in the short extender that I was using to tighten the rain rail nuts. That bad old habit of blanking out where I put things struck again. Kill another half an hour looking, re-looking and admitting defeat. Kill another hour going to the hardware store to pick up new ones. During this time, I figured it probably fell into that hole in the shelf below the rain rail and wondered if it would rattle around in there until I had to disassemble the car to retrieve it. (towards the end of the job, I theorized that this opening may actually lead to the trunk...found the socket and extender behind the spare. You learn something every day!)

Aside from one (more) dopey mistake I don't care to admit: everything went back together predictably well. I installed the extensions to the frame stops, which Robbins supplies with the top, in the shelf area . I added the rubber things to the stops on the B pillar, although for the life of me, I can't figure out what they do (I believe this may have been one of the IMPORTANT notes). I followed the IMPORTANT note about holding each side of the top down while tightening the respective three bolts which hold that side of the top assembly. I then socked them down to something like 15 lb/ft. This IMPORTANT note was not in the workshop manual....maybe it was a glass window thing.

So now it was done. Next step...latching of the top. This is yet another area where previous do it yourselfers have felt the pain. With my daughter working the latches and me grunting and pushing once again (be prepared to do a lot of this), they wouldn't go. Later that evening, as I was putting stuff away, I reasoned that if I could close the latches with the window down, perhaps it would stretch things out to where a mere mortal could close it properly the next day. Also, predictably, the sun would be back tomorrow to help with that "thermal coefficient of expansion" thing. Believe it or not: this actually worked. Unlike the contributor who messed around with the latch adjustment; I really didn't want to do this. Why screw up a perfectly good adjustment? Besides, my hands were numb from all that grasping, pulling and pushing; the last thing I wanted to do was grasp, pull and/or push something else.

Once done, I noticed what the guys who wrote the workshop manual may have referred to as a "small sag", which one could remedy with steam. This was not the Brian Dore sag, which he fixed by doing some more pulling and grunting of his own; these appeared to be legitimate "small sags" and I was tempted to get the steam iron to see if this actually worked. Better judgment prevailed and I did nothing. I noticed that after a day of driving around in the Warm California Sun, the small sags have become either highly inconsequential sags or no sags at all. Probably has to do with what Robbins called either "conditioning" or "seasoning" of the top which is brought about by leaving it up for 24 hours after installation.

Alls well that ends well. I washed the car today and checked for anything wet inside, especially in the area behind the seats where the rain rail, the 13 nuts and three frames live. So far, so good. Got out the wax and now it's looking great once more.

Would I do it again? I'll let you know in about 10 years. Probably not; mainly because I will have lost any skill that I gained over the last two days. Also, I'll be in my early 60's and will likely not want to deal with crap like this anymore. I can see now why people entrust this sort of thing to the professionals. I am amazed that they can do something like this in four hours!. I suspect that their procedures include cutting the old top off, removing the frame and using tools that would impress the hell out of us amateurs. Plus, I suspect that doing several of these a day can either make you better or, as Nietzsche would suggest, kill you.

Thanks for all of you who were brave or ignorant enough to do this previously and post your experiences. This helped a lot. I hope that this tome will, likewise, help a well intentioned Miata owner or, better yet, sufficiently put the fear of God in him or her. In either event, it will have served a good purpose. Wow. this got long, I guess my fingers are back to normal.

Back to the Garage

28 December, 2000