1. Does anyone know why BMW changed the final drive ratio from 4.10 to 3.46 from 9/99?
2. If I change mine (7/2000) from 3.46 to 4.10, what is the downside?
3. I use Dinan s/w and so the RPM limit is raised, please keep this in mind, in case it has a bearing on your answers. Thank you very much.
Thanks very much for that Vince.
Additional questions.
(1) Is it safe for the car to make this modification?
(2) I assume its a straight swop – how long would it take?
(3) The process is reversible, correct?
1. The pre 09/1999 models have a A4S 310R transmissions. The "4" in A4S refers to 4 forward gears. Post 09/1999 models have A5S 360R transmissions, ie 5 forward gears. This is also the same transmission installed on several other BMW models. The transmission gear ratios have changed hence the drop from 4.10 to 3.46.
2. Downside is subjective. 1st gear will be shorter nad most likely rendered useless. Top speed will be reduced as well. And in some of the gears, while cruising, you may rev a little higher.
3. Dinan transmission or engine s/w or both? The car will still shift as needed.
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1. The pre 09/1999 models have a A4S 310R transmissions. The "4" in A4S refers to 4 forward gears. Post 09/1999 models have A5S 360R transmissions, ie 5 forward gears. This is also the same transmission installed on several other BMW models. The transmission gear ratios have changed hence the drop from 4.10 to 3.46.
2. Downside is subjective. 1st gear will be shorter nad most likely rendered useless. Top speed will be reduced as well. And in some of the gears, while cruising, you may rev a little higher.
3. Dinan transmission or engine s/w or both? The car will still shift as needed.
References :
Own 3 BMWs. Race one of them (legally sanctioned org).
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