MX5 NC Gearbox Issues
In the last 3 weeks we’ve had a couple of NC’s in the workshop with gearshift issues. Basically they had lost either 1st /2nd gear or 3rd/4th gear. The selectors on a NC have plastic bushes that deteriorate over time. On our race cars we use a replacement alloy bush shown. This works very well without wearing out the actual selector. It does make the gearbox a little notchy and also amplifies the 2nd/3rd gear low down grumble they are known for.
- Pic of the broken bush. The white line on the RH bush shows a crack in it. It is unusual to find one cracked – usually they are in 2 pieces by the time we get them!! As the cars are getting older clutches are being replaced and I’d suggest you replace these bushes when the gearbox is out. It is literally a 15 minute job with the gearbox on the bench.
- The top cover with selector removed from the gearbox
- Selector section removed
- The selector and has the bushes for 1st/2nd and 5th/6th
- The 3rd/4th selector located on the side of the gearbox
- The metal selector bush that transfers the top selector movement to 3rd/4th. Although very hard to see the R/H pic show the "flats" that have developed on the bush
- Finally the turret oil is separate to the rest of the gearbox. If the box is out I’d recommend changing it too.
- These are most of the bits we stock for the NC 6 speeds. Each car takes 3 of the selector bushes and we generally always have them in stock