numog, because of the different opinions that I've seen i decided to look myself.. This is at least the label which is on the axle of my roadster 3.7, manufactured in Summer '14. Since you have the same car, can you check on yours? The first gear is close to useless, I start in 2nd, from there it fitts.
You can check the ratio by marking the wheel or brake drum, and the propshaft UJ. With the gearbox in neutral, and the car jacked up safely, note where the propshaft UJ starts - easier from the 6 o'clock position. Then slowly rotate the wheels. Make sure that both wheels turn at exactly the same rate - you may need a helper. 3.07 is only a shade over 3 revs. 3.70 is closer to 4 revs, so 1 revolution of the roadwheel will produce either 3 revs of the prop, or nearly 4.
Not all Roadsters have had the same axle ratio. It depends on the gearbox, and whether top gear is direct drive 1:1 or overdrive (0.85ish). From memory......the S1 had a direct drive top gear with a 3.07 diff. The S2 and S3 had an overdrive top gear with a 3.7 diff. I don't know what the ratio is of 6th gear on the current box, but 3.7 could well be the right ratio.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4
Dave, thanks for the advice. That is the logical next step. But I will let the dealer do that in my presence. Things start to make sense now: The speedo is showing numbers 20% to high, that's about the difference between 3.07:1 and 3.73:1. Morgan said, the can't correct the speedo, there is no mistake. Someone fitted the wrong axle. 3.73 is the ratio of the 4/4, without limited slip differential (to avoid the misleading term LSD). I thought the 4/4-axle is a lighter version, the one installed looks exactly like the Roadster axle. We will see.
2015 Roadster 3.7
