I have a 10th Anniversary edition (my third MX-5, I am obsessed!) and I am looking for help with a problem I have with the gearbox/transmission (6 speed).

I have taken it back to my dealer but they refuse to accept that anything is wrong (quote: "they all do that" and "it's because its got a close-ratio gearbox").

In brief, the problems I have are:
A very poor quality gear-change, very stiff in the first three ratios. 1st to 2nd is the worst. Even when shifting slowly and deliberately and with the clutch fully depressed, I "beat" the syncromesh (i.e. the gears grind). To better illustrate what some might regard as a subjective issue, I drove along a smooth road at about 20MPH, turned the engine off and coasted, all the while shifting up and down all the gears. With the window open, each gear-change was accompanied by a sharp metallic clang and a muffled thud from the gearbox. When coasting in 1st gear with the clutch depressed, there is a loud chattering noise from the gearbox that is not present in any of the other gears. Maybe this is related and maybe normal, I don't know.

When the car is fully warmed up, there is a distinct, high frequency chattery rattle when accelerating in 4/5/6th gears at about 40-60MPH. The noise is road speed related and seems to come from the rear of the car. The car has now done just over 6000 miles and the quality of the gear-change is getting worse and is spoiling my enjoyment of the car. The gearbox is normally such a delight on MX-5s that I just don't want to put up with it like this!

If anyone has advice or suggestions on the possible cause(s) of the problems or how to get Mazda UK to take this seriously I'd very much appreciate hearing from you. (4/00)

I don't think I have all the problems you've listed. All I will say is that downshifting to second for the first few times from cold in the morning can be hard work. Its always at the same junction as well. I come out of my drive first thing in the morning, drive half a mile down the road, and have to turn right at a T-junction. The roads are quiet here, so I can usually just downshift to second and turn straight away, but every morning I have to really give the shifter a tug to get it back into 2nd. The next time I come to use it though its usually ok.

I might try a gearbox oil change to Redline synthetic which is always recommended on this list to remove notchy changes. Can't hurt trying I suppose. (4/00)

With the window open, each gear-change was accompanied by a sharp metallic clang and a muffled thud from the gearbox.

I don't get the above, but I do have a slight crunch on my first couple of 1st-2nd gear changes in a morning when the gearbox is cold. It goes away after about 2mins of driving and never comes back until cold again. It isn't stiff however just crunches a little. I get no problem at all between any other gears. I find your testing technique interesting. Surely with the engine off, you lose the oil pump and servo assistance; if their is any. This may sound stupid, but have you driven many convertibles? It's common to hear some mechanical noises with the roof off any car as you lose a lot of sound shielding.

When coasting in 1st gear with the clutch depressed, there is a loud chattering noise from the gearbox that is not present in any of the other gears.

Sounds bad. I don't get that; although I can't say I ever drive with the cluth down.

The noise is road speed related and seems to come from the rear of the car.

I get that exact noise and without a doubt this is resonance. I assume it is vibration in the LSD, only a guess though. Being a physicist I appreciate that every object on the earth has a resonant frequency and assuming the problem is resonance I fail to see how it could be avoided. Mine has done this since day 1 but only if accelerating from low revs in 4th or above. I rarely hit fourth below 60mph and when I do, when accelerating tend to drop to 3rd.

The gearbox is normally such a delight on MX-5s that I just don't want to put up with it like this!

I've now done nearly 16,000 in mine. The gearbox has never altered for me and been the same since day one. (4/00)

My Icon with 6 speed is giving a "notchy" gearchange from 1st to 2nd and also 2nd to 3rd. I had 2 others say the same but that is a small proportion of 6 speeders around so it's very inconclusive.

I took mine to the midlands to consult my uncle who was a gearbox development engineer before he retired. He road tested it and said that it was nothing serious and would almost certainly free up sooner or later. He said it definitely wasn't the linkage which he thought was very good, and was not consistent with a design fault or mechanical problem. He prescribed exactly what the Mazda dealer did - use standard oil up to say 10k then synthetic but he also said that it would be a good idea to change the oil early, say at 3 - 4k as that would get rid of any swarf etc. Mine is just coming up to 3k so I'm about to give it its 1st change.

Since I posted the message I've noticed a slight improvement so maybe its a new gearbox thing? After all, 3k is still very new. (1/01)