My crazy diff ratio change idea

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RRMaximus said:
I looked at your PDFs.

While the gearbox has those two sensors it also has information about which gear it is in, the road speed of the car (from the ABS), the throttle position and the RPM of the engine.

I'm not surprised that the eight speed does not lock up easily given that it was probably intended to be used by people driving in Germany on the autobahn at higher speed.

The gearboxes are from ZF which is a German company so they would be made for the German roads.

Also Range Rover's are sold worldwide and there are many countries where the speed limit is higher than England.

I'm not overly concerned about the torque converter not locking up because I can get the answer using my OBD reader very quickly.

If someone has actual knowledge of ZF gearboxes and can tell me that my change will definitely stop the torque converter locking up than that is a different thing.

I'm not going to spend hours reading through technical manuals that don't answer the question when my OBD reader will do that.
Click to expand...
The auto box is controlled electronically and the firmware can be adapted for many different situations just as it will be different for the petrol engine compared to the diesel.
 
If your diffs new diffs fit physically.
Your torque converter will spend more time out off lockup. That will result in more heat in your atf fluid so a slight decrease in atf fluid lifetime.

Then higher cylinder pressures. It will take x amount of energy to move the car down the road at a certain speed. In order for your engine to produce x amount of energy but at lower rpm it will have to output more torque. Torque is directly related to cylinder pressure. So if your rpm drops by 20% your torque will go up by 20% for the same amount of energy output. If your torque is up by 20% that means cylinder pressure is up by 20%.
Thats not taking into account that engine efficiency changes with rpm so at low rpm you usually have bad efficiency then where the engine makes peak torque you have peak efficiency and then efficiency gets worse again as rpm increase.
So if you drop your engine rpm too far below your peak torque rpm your cylinder pressure will have to be even higher than 20%.
 
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