Copen Final Drive

anyone have a final drive of copen (5.5:1) that is interested in selling with shipment to the end of the world?


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Alternatively there are usually a 4.933 final drive available on Yahoo auction. Not as low as the 5.545 but lower than our factory one.

Another option is Compact Motorsport in New Zealand can provide new items; which include the bearing required (as per Mick’s latest post).

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@TPG and what would be better 5.5 or 4.9? finally 5.5 can be very short and 4.9 is better?

Ignorant question … what service is reliable to buy things in Japan? zenmarket?


I’m no expert in the matter, but the obvious benefit is the increased acceleration of the lower final drive. So if outright acceleration is your aim, then the lower the better - ie for gymkhana/motorkhana.

There is a potential that a particular track might suit a particular final drive due to where you need to shift. IE maybe with the 5.545 at the end of the straight, do you change up, ease off, or bounce on the rev limiter a bit whereas the 4.933 you can just hold the gear. In this possible scenario is that negative of the lowest final drive offset by increased acceleration at all other corners.

The marketing stuff in the 4.933 is for Copen’s who want to be able to travel more comfortably on the highways. I presume their factory gearing and 5.545 FD means quite high revs even in top gear at 100-110km/h.

Here is a table of relative speeds each gear will obtain. As you can see the Factory gearing’s theoretical top speed is not achievable. I’ve picked 7500rpm as redline and total diameter of the 195/50/15’s I have. Total tyre diameter will impact this - which is why potentially going to smaller rims/tyre combo’s will have an acceleration benefit too.


I’m going to go to the 5.545 it seems to be the most popular.

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Don’t forget a copen has a reline of 8500 but when you use a dsport ecu this is increased to 9000 rpm to match the jbjl.

The jb series of engine is a very fun unit, enough torque to get the turbo spooling and once it does that 15 psi to redline is a hoot.

The jb-det is my favourite daihatsu engine (followed by the k3 4 cylinder engine)


Looking at the change points it seems that 4.9 is better option than 5.5 for me.

great explanation!! very very much thanks, I’ll go for the 4.9


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Did you end up installing a new Final Drive?
I have the copen 5.5 installed, it seems to be perfect for me, but I could imagine it being too short for longer, higher speed type races. What top speeds are you seeing during a race?

I went for the 5.545 final drive and had it installed along with a D-Sport LSD.
Massive improvement in traction out of corners.
The Tailem Bend Track has a ~1km straight and at the end of that I was doing ~160km/h.
Which was the very upper end of 4th - which is accurate in the above table, as it said the theoretical max in 4th was 169km/h.
So I was happy that I didn’t need the 4th - 5th shift as my knee usually gets in the way lol