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Gearbox grommet

I could see the road from my gearbox.

A tale of the importance of checking everything when buying a second hand car. Especially the things you wouldn’t even think of at first glance…like the rubber grommets on the gearbox..

It was a fun game of car trash and treasure many moons ago when I bought my RX7. After the factory blow off valve was put back in (for compliance reasons they took it out, even though it came with the car from factory, go figure…) and an alarm was installed, I finally took the time to go over it from top to bottom to see what I could find. While there wasn’t any hidden Japanese Pirate booty, a hidden samurai sword or even some feudal artwork from the land of the rising sun stuck in the upholstery, I did unearth the following:

300 Yen

A plain screwdriver

A ticket to something. Not sure what, I can’t read Japanese.

Lots of dodgy wiring

And a hole in the side of the gear stick grommet covers that you could see through to the road below.

Gearbox grommet
Unrecognizable when I sold it, but the ripped cover and stuffed grommets meant you could both hear and see the road..

Yeah,  I can’t call myself much of a car design specialist, but even I knew that you shouldn’t be able to see the road you’re driving on, simply by looking at the gearstick.

So one weekend when I decided to swap over the gear knob (from the Cue Ball they originally mounted to a much cooler looking and easier to use carbon fiber OBX shifter) and found out what the problem was – the three rubber boot seals that sit under the vinyl cover? The seals/grommets that protect against noise and heat and help muffle the engine roar in the cabin?

Those rubber parts which serve a lot of useful purposes?


In fact it looked like nuclear Armageddon under the cover with melted rubber slag, grime and 20 year old spilled gearbox oil all meeting in unholy matrimony to create a mess of biblical proportions. All three thick rubber seals had died in a complete blaze of glory and obviously decided to sacrifice themselves never to be used again in an obvious gear boot suicide pact. I didn’t pull them out, they fell to bits just looking at them – leaving a trail of rotting rubber carcass and black sludge in their wake. Unmolested, they’re supposed to look like black rubber donuts with a small hole in the middle. Mine however look like they were massaged with a hi octane flame thrower.

Gearbox grommet
My Rx7 had three of these and they were all falling to bits.

So in new RX7 owner tradition, I followed the time honored code of ‘She’ll be right mate’ and promptly ignored it. It wasn’t affecting the handling or making too much of a noticeable difference to anything so I let it be.


Fast forward 4 years and I was patching up project Seven with the intention of eventually selling it, so I ordered a couple of bits from an Rx7 half cut sitting pretty in Tasmania. A week later and a lovely big box full of goodies rocked up to my door with the first thing to be replaced being the remaining ten percent of the gear boots and sludge and assorted crap that has kept my gearbox company for so long. So on a day that was just too hot to even breathe properly, let alone work on a car, I set to work with operation gear boot.

The bits of what was left coated everything around it with black death on it’s way out – including the drivers seat, the inside of the vinyl cover, some of the centre console, my t-shirt, hands and a couple of bricks in the driveway.

The metal plate that held the bottom scraps of the gearbox grommet to the car sliced open three of my fingers so that what wasn’t covered in rotting black slime was now getting covered in my lifeforce.

And after covering anything else unmarked with sweat (it was over 40 degrees in there) I finally managed to clean up the fallout, degrease the whole area and put 3 fairly new gearbox grommets back into the hole where death once called home. And happily I could see the road no more.


I’d heard that replacing the gearbox grommets with ones that you know, actually do what they’re supposed to, would eliminate some noise from driving. That was a massive understatement as going from next to nothing noise elimination to 3 layers of thick noise absorbing rubber was like fitting a silencer to the 13B rifle. It sounds like someone’s holding a big thick pillow over the block every time I fire it up and amazingly you can now have a conversation mid drive without having to raise your voice every time you put your foot down. I love it – you can still hear that amazing rotor sound, it just won’t give you industrial deafness so much.

The only question renaming of course is: Why oh why did it take me so long to buy a newer gearbox grommet set?

If yours is stuffed too, find someone selling a set cheap. And try not to bleed on everything when you swap them over…

Alternatively you can order one for the FC3S through Amazon: MAZDA RX-7 1986-1991 NEW OEM SHIFTER DUST BOOT

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