Gearboxes

MX5s and Eunos Roadsters were available with a number of gearboxes, including automatics.

 

In the UK the Mk1 (1989-1998), Mk2 (1998-2001) and Mk2.5 (2001-2005) were only available as manuals. Any automatic from this period would have been imported.

Which Gearbox?

Mk1s (1989-1998) were only available with a five speed gearbox or an automatic. The 1.6 and 1.8 automatics having different gearboxes and control units.

Mk2 (1998-2001) were usually available with five speed gearboxes, although the import Roadster RS had a six speed gearbox as standard.

 

Mk2.5 (2001-2005) 1.8s could be fitted with either a five or six speed gearbox. The 1.6 model only came with a five speed gearbox.

 

Some of the UK tenth aniversary cars were fitted with six speed gearboxes too.

 

The only automatics available were cars that were imported from Japan. There are a few of these in the UK.

What are the differences between the Five and Six Speed Gearboxes?

The differences you will notice when you drive your Mk1 MX5 with a six speed gearbox are:

  • First gear is much lower - more engine revs.
  • There isn't such a gap between second and third.
  • The ratios are closer.
  • The gearbox isn't as refined as the five speed - it was made by Toyota.
  • The final drive, sixth gear is a similar ratio of fifth in a five speed gearbox. It'll rev a smidge more at motorway speeds.

It'll be much more FUN to drive!

Five Speed vs Six Speed - The Facts

Here are the details of the gearbox ratios. All models with the five speed box have the same ratio. The final drive ratios (differential ratios) are different.

Gear Five Speed Six Speed
First 3.136 3.760
Second 1.888 2.269
Third 1.330 1.646
Four 1.000 1.257
Fifth 0.814 1.000
Sixth   0.843

Can I fit a Six Speed to My MK1?

Yes you can. If you have a Mk1 1.6 - you really should, it's an amazing change.

 

The gearboxes are very similar and no special changes are required to fit a six speed to an early car. Two parts also need changing, although these changes are not essential. The plate between the engine and gearbox should be changed as well as the starter motor.

 

Infact, you can fit a six speed gearbox to ANY MX5 Mk1, Mk2 or Mk2.5!

 

If you are competing in a Speed Hillclimbing Road Going class in the UK, a six speed gearbox can't be used in most cases. Check the MSA Blue Book for full details. If you can't, you'll need a 4.7 ratio differential which gives an advantage.

Pictures to follow

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