The MR-S seems to be a great car but the owners group has an average IQ of potato. The responses to Mikey's K20 swapped MR-S in particular were incredible.
What thickness and at what points? I was really surprised how bad the hardtop fits with those things... I've got it closer but still not happy with it.

 

Ya, you're right. The part that I thought was steel is just injection molded plastic. Whatever. It transformed my car.

 

I'm greatly interested by the fact that I've heard numerous people indicate that installing a hard top on their car caused it to become much more rigid.

Beyond the simple fact that the notion of 30 lbs of plastic sheet adding chassis stiffness is preposterous, I go back to my own personal experience of having run a hardtop, very occasionally, on my 90 and 92 cars. While the hardtop obviously cut down on wind noise dramatically, it's presence greatly increased the amount of squeaking present in the cabin, serving as a reminder of just how much chassis flex was actually going on.

 

Rennenmetal brackets with factory plastic panels hashed out ITT: https://www.miataturbo.net/general-m...nfusion-79145/

After fiddling with the solid, one piece brackets, I was able to nearly eliminate all hardtop rattles, squeaks, and leaks. One thing that was paramount was getting the chrome latches tighter on the Frankenstein's Monster's bolts, which was done easily with some flat washers. You also need to put some kind of padding under the latch. Gorilla tape folded over a couple times works for now, but a thin piece of foam or mouse pad would work nicely.

 

Why not? You think that 5# of sheet metal bolted to the floor pan has any affect? Hint: it does, which is why the FM butterfly brace sells. It's also not just "plastic", but SMC, which is fiberglass reinforced and also molded into a shape conducive to bracing the part that flexes the most.

I have had exactly the opposite experience. Since mounting my HT (including side latches, which are extremely important), my dash/console no longer squeaks like before. Add in the fact that wind noise is greatly reduced, and it becomes a much more civilized environment.

While not as much rigidity is added as a decent roll bar, it is noticeably better than the soft top and no other bracing.

 

My OEM hardtop has easily been the best fix for NVH and the slight 65mph shimmy I had going on. My rollbar did very little, the FM frame rails provided protection from scrapes and that's about it, but that hardtop completely transformed at least how it feels driving it on everyday roads.

 

Comparatively speaking, yes.

FM's undercarriage brace is made from a material which is quite stiff (steel), and is rigidly fastened to the chassis in 16 locations, with bolts. (It also weighs 32 lbs according to FM, not 5.)

The factory HT is made from a material which is highly flexible and somewhat elastic, and it is mounted to the body with a handful of latches and studs designed to afford easy adjustability and fast, tool-less removal.



Yes, the overall effect is a more civilized car. Less buffeting, less wind noise, less water entry... But even though I had all six attachment points in both cars (franky bolts, side latches, front latches) and they were all adjusted as well as possible, there was a lot more squeaking in the cabin, in the form of the seal at the lower rear edge of the top rubbing against the trim strip of the body, with the top than without it. That's not conjecture.

 

But geometrically Joe, using a wet noodle turn the car into a coupe is going to add significantly more stiffness than gluing an uncooked noodle to the frame rails.

 

 

I always wondered why that is. The earlier MR-2s have had people do just about everything to them but all I ever see on an MR-S is dress up parts.

 

There's some good MR-S builds out there. Fact is, there weren't a whole lot of them. The slice of the community is about the same as the Miata community. 80% mentally challenged, 18% old men wiping the car down with diapers, and 2% with an IQ greater than eggplant.

There's just a smaller sample size to begin with, so there's not enough of the 2% (MiataTurbo equivalent) to create their own community.

If/when i get one, i'll probably just do the build thread here because i hate sorting through bullshit.

 

My OEM hard top has decreased the stupid miata wobble/shimmie/whatever its called. By a very noticeable/significant amount. I've tested this at least a dozen times to make sure its not placebo effect. Not as effective as roll bar, but anyone that thinks I'm making this up is welcome to stop by for an on/off test. Agan, VERY significant difference with HT on vs off.

 

+1 to this.

Hardtop made ours feel like a car, not some limpdick floppy piece of crap that feels like it's going to fly apart on the highway.

 

Same with mine. The shimmy at 65 isn't bad with the top down, but it's gone with the hardtop.

 

Well, I guess when I get home from this deployment a second Miata will be in my future.

 

Location, location, location. The way I see it (meaning mostly just educated guessing) the major problem with the NA is a lack of torsional rigidity. In my minds eye I see the chassis twisting around an axis somewhere inside the transmission tunnel. The FM frame rail covers are made of steel and fastened to the floor of the car with a whole bunch of fasteners, but they're not really located where their stiffness can do much good. I added a pair and didn't perceive much difference. I have a butterfly from FM that never got installed because it reduces ground clearance and frankly I just don't see how it could add enough rigidity to be worth it. Keith has written that in his opinion the rail covers do more that the butterfly. (If anyone wants my butterfly pm me with an offer. I'm too lazy to list it.)

Getting back to the goal of improving torsional rigidity, the top of the windshield is far from the twist axis and thus provides better leverage for the hardtop to work. It's true that if you grab an unmounted hardtop you can twist it pretty easily, but the frame rail covers and butterfly twist easily too. Fortunately, none of them need to support torsional loads when the whole car twists. The hardtop needs to keep the top of the windshield from moving from side to side and it's actually pretty stiff in that direction even though it's made of fiberglass and tempered glass and a little bit of plastic.

I don't know what to tell you. My top has never squeaked even when the latches were not adjusted well. I didn't even realize that the rear brackets (Frankenstein bolts) could be adjusted and one of them was pretty sloppy for a while. Even when everything was not as tight as it could be I perceived an improvement in the stiffness of the car. When I managed to get everything tightened down really well I perceived an additional improvement.

Could it have been placebo? I don't know; I never took any quantitative measurements, but I believe the improvement to be real. I wanted the frame rail covers to make the car awesome, but they didn't. On the other hand I bought the hardtop for an HPDE and wasn't really expecting it to make the car feel different, but it did.

One thing I can say with absolute certainty: the hardtop killed cowl shake almost completely. There can be no illusion there. That alone makes the hardtop worth the price.

I have the Rennenmetal SM brackets now. They might have provided an improvement over tight latches, maybe not. They definitely are better than loose latches and it was getting hard for me to keep the side latches tight. I'd like to make a bolt-on bracket for the rears, but I can't get the stupid Frankenstein bolts out!

 

Frame rails really help with firming up the seats... I can attest to this, 2x.
As someone who is now at 245lbs... I had them installed when I was up at 265lbs.
The first thing I noticed was how the seats no longer leaned or gave when I sat down.
A lot firmer.

All you skinny guys wouldn't notice this difference either way... but I did.
Same thing happened when we did them a 2nd time on our other NA.

Firm seat. Less give. Strengthened up the seating area.

And... as someone who once tore a hole in the floor pan of my 5.0 from my weight and overaggressive shifting... it was a godsend.

 

Xida 600/300 harddog door bars,fm frame rails. I had the shitty 65mph shimmy. Bought new TRM c1m 15x7 and 205 rivals, still had a shimmy at 65, after Road forcing them to under 10lbs still had the shimmy, i tried road forcing them again 3 more times with no difference.

Just picked up a hardtop and now the shimmy is gone, true story

 

No scientific data, but my car feels much looser hard top off than hard top on. More squeaks and rattles without the hard top, plus it feels like the body flexes more over uneven surfaces like highway joints.

I don't understand people saying they need to add padding underneath the frankenstein bolt latches. From Mazda there should be a rubber pad attached exactly in this location to stop clunks. I also adjusted them to hold the rubber snugly against the body with no gap.

 

Pic? My car came with no such padding.