A short blog on these as many people don’t seem to know the facts, as the supplier of these to MX5parts I do 🙂
The problem we are fixing arose because the original 6 speed plastic bush doesn’t fit very well. It never did, right from new. It doesn’t wear out, it just never fitted properly. The NC1 ‘box has a different size bush to the NC2/3 type, if you look carefully at the picture you can see the difference.
Originally I got a fellow enthusiast (thanks Archie) to check out the 5 speed bush to see if the same applied, I sent some precise measuring equipment and he advised it fits perfectly. Since then I checked a few more and can confirm it doesn’t wear and does fit fine.
So to sum up; buy a bush for a 6 speed to make those changes more precise, don’t waste your money on a 5 speed one. Buy from MX5parts or me to be assured absolute precision and quality, buy elsewhere for questionable quality – you won’t know the difference as you can’t measure it. I only know it can be made worse, not better, as the ones we sell are a perfect fit.
Where does it go? It goes here:
Tips for fitting: There are plenty of online guides, Youtube etc. One thing I would add is put the new bush on your finger and drop or push it into the hole in the turret. As it’s a very precise fit you may need to rock it around a bit before it slides in. Then put the lever ball into it. Don’t drop it into the turret elsewhere! You’ll spend ages with a piece of bent wire trying to find it. Don’t ask me how I know this.
There is also mucho confusion about turret oil. It is separate from the main gearbox. It needs nothing more than the same oil you put into the gearbox. I would just put enough in to cover the moving parts you can see, no more. There is no reason to put special magic fairy tears £50/litre oil in there. All that lives in there is a few levers and joints, nothing high tech or rotating.
Is your 6spd gearbox notchy and difficult when cold, but ok when warm? This bush will not cure this problem, it’s something else.
We have our own blended oil for this problem you can read about it here: http://www.duratecnc.co.uk/?page_id=348
The 5spd is less prone to this problem, but this oil will work in that too if you want to make it even smoother when cold.