BMW 6-Speed Manual (E86 Z4 M Coupe, S54) gear ratios
The BMW 6-Speed Manual (E86 Z4 M Coupe, S54) is a six-speed manual gearbox.
First gear is 4.35:1 and 6th is 0.85:1. Divide one by the other and the overall spread is 5.12:1. That is a wide spread: a short first to get the car moving and a tall top to bring cruise revs down.
6th is an overdrive at 0.85:1: the output shaft turns faster than the input shaft. 5th is direct drive at 1.00:1.
The biggest step is 1st to 2nd, where the ratio drops 43%. The smallest is 5th to 6th at 15%. A drop that size lands the engine well down the rev range after the change, so it pays to know where the torque lives.
The final drive lives in a separate diff, so the speed table shows three common ratios: 3.42, 3.73 and 4.10. With a 3.73 final drive and 225/45R17 tyres, 6th at 6,000 rpm works out at 226 km/h (141 mph), and first runs out at 44 km/h (27 mph). At 70 mph in 6th the engine turns about 2,990 rpm.
Ratios
BMW 6-Speed Manual (E86 Z4 M Coupe, S54): ratio per gear, and how far the ratio drops from the gear before.
Gear
Ratio
Step
1st
4.35:1
-
2nd
2.50:1
42.5%
3rd
1.67:1
33.2%
4th
1.23:1
26.3%
5th
1.00:1
18.7%
6th
0.85:1
15.0%
Road speed at 6,000 rpm
Road speed at 6,000 rpm on a 225/45R17 tyre (1.993 m rolling circumference), by final drive. No slip, no drivetrain losses.
Results are theoretical: stock ratio specs, your inputs, no drivetrain losses. Verify with your drivetrain supplier before spending real money.
Swapping the engine as well? StandaloneHQ counts the inputs and outputs the new engine needs and shortlists the wire-in ECUs that fit: ECU Pinout Planner.
BoxSelector crunches gear ratios, tyre sizes, and RPM figures to give you useful speed and cruise data for your build. The results are theoretical, based on stock ratio specs and your inputs, and assume perfect mechanical conditions, zero drivetrain losses, and a world without speed bumps, traction limits, or your right foot getting sweaty. Real-world results will vary. Probably a lot for automatics.
Don't run a build off this tool alone.
Use it to narrow your options, start a conversation with your builder, and stop arguing on forums... then go talk to someone who can actually look at your car.
We're not liable for your decisions.
If you fit a TH400 and wonder why there's no 5th gear, that's on you. BoxSelector and its author accept no responsibility for mechanical failures, unsuitable gearbox choices, blown differentials, bent input shafts, voided warranties, shed fires, or any other consequences arising from using this tool. You're a grown adult building a car. Act like it.
Gear ratios may have changed, and manufacturers love to quietly update things.
We've done our best to source accurate ratio data from factory specs and reputable technical references. Some ratios (particularly on production variants with running changes) may differ from the figures listed here. Always verify critical specs against your actual unit or a current manufacturer source before committing to anything expensive.
The Google search links are... Google searches.
The "Transmission Adapter Search" and "Transfer Case Adapter Search" features open pre-formatted Google searches in a new tab. We're not affiliated with any of the suppliers, parts retailers, or manufacturers that show up in those results. We get nothing if you click them. We're just saving you the effort of typing.
This site shows adverts.
BoxSelector uses Google AdSense to display advertisements. These are served automatically based on your browsing behaviour and site content. we don't choose specific ads or endorse the products shown. If an ad is annoying or makes your wife angry, that's between you and Google.
The tip button is genuinely optional.
The "buy me a drink" button is a voluntary tip, but nothing is paywalled, and nothing changes if you don't use it. If you do, thank you. My 10mm socket fund appreciates it.
External links
Where BoxSelector links to external sites (manufacturers, reference sources, or otherwise) we're not responsible for their content, accuracy, or whether they've gone offline since we linked them.
