E90 E91 E92 E93 xDrive 328xi 335xi Final Gear Ratio Change to 3.63 Possible?

Soravia · 12-18-2019, 06:59 PM

Will the front differential ratio being unchanged be an issue? I assume they are only connected by clutches instead of a gear diff, so there won't be any affect to xDrive operation?

I want to trade top speed for a little more responsive throttle on first gear when the wagon is fully loaded

blown07 · 12-19-2019, 11:08 AM

Quote:

Originally Posted by Soravia

Will the front differential ratio being unchanged be an issue? I assume they are only connected by clutches instead of a gear diff, so there won't be any affect to xDrive operation?

I want to trade top speed for a little more responsive throttle on first gear when the wagon is fully loaded

You would kill the transfer case in no time. I would guess that the triple light fault on the dash would appear and the transfer case would open. This would be the equivalent of putting much smaller diameter tires on the rear of the car.

MightyMouseTech · 12-19-2019, 11:40 AM

Quote:

Originally Posted by blown07

Quote:

Originally Posted by Soravia

Will the front differential ratio being unchanged be an issue? I assume they are only connected by clutches instead of a gear diff, so there won't be any affect to xDrive operation?

I want to trade top speed for a little more responsive throttle on first gear when the wagon is fully loaded

You would kill the transfer case in no time. I would guess that the triple light fault on the dash would appear and the transfer case would open. This would be the equivalent of putting much smaller diameter tires on the rear of the car.

Exactly. Will kill the transfer case in no time.

floydarogers · 12-19-2019, 06:27 PM

Quote:

Originally Posted by Soravia

Will the front differential ratio being unchanged be an issue? I assume they are only connected by clutches instead of a gear diff, so there won't be any affect to xDrive operation?

I want to trade top speed for a little more responsive throttle on first gear when the wagon is fully loaded

You can't change just the rear. As noted by the other responders.

Soravia · 12-19-2019, 06:47 PM

So I'll need both the front and the rear. Probably a good time to do with the engine oil pan gasket?

It will be different from front and rear tire diameter difference because the rolling speed (not driven speed) of the ABS sensors will be the same, at least until power is applied?

I figured it applies torque to the front wheels instead of direct gear driven like the rear.

tlow98 · 12-21-2019, 12:56 AM

I thought stock was 3.91? Maybe I read that wrong tho?

rothwem · 12-21-2019, 08:33 AM

Quote:

Originally Posted by tlow98

I thought stock was 3.91? Maybe I read that wrong tho?

The automatic cars are 3.91, but I think the manuals are 3.64.

Op could conceivably go with a 3.91, but I honestly thought that the gearing was plenty short on my 6mt xdrive wagon

Soravia · 12-21-2019, 06:51 PM

I think manual is 3.38 final drive.

12-18-2019, 06:59 PM	#1
Soravia Captain 116 Rep 598 Posts Drives: 2011 E91 Silver xDrive 6MT Join Date: Apr 2013 Location: Kentucky iTrader: (0)	E90 E91 E92 E93 xDrive 328xi 335xi Final Gear Ratio Change to 3.63 Possible? Will the front differential ratio being unchanged be an issue? I assume they are only connected by clutches instead of a gear diff, so there won't be any affect to xDrive operation? I want to trade top speed for a little more responsive throttle on first gear when the wagon is fully loaded Last edited by Soravia; 12-18-2019 at 07:04 PM..
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12-19-2019, 06:47 PM	#5
Soravia Captain 116 Rep 598 Posts Drives: 2011 E91 Silver xDrive 6MT Join Date: Apr 2013 Location: Kentucky iTrader: (0)	So I'll need both the front and the rear. Probably a good time to do with the engine oil pan gasket? It will be different from front and rear tire diameter difference because the rolling speed (not driven speed) of the ABS sensors will be the same, at least until power is applied? I figured it applies torque to the front wheels instead of direct gear driven like the rear.
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12-21-2019, 12:56 AM	#6
tlow98 Major General 2280 Rep 5,183 Posts Drives: 2009 E91, 2014 F15 x35i Join Date: Aug 2011 Location: Bay Area iTrader: (2)	I thought stock was 3.91? Maybe I read that wrong tho?
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12-21-2019, 06:51 PM	#8
Soravia Captain 116 Rep 598 Posts Drives: 2011 E91 Silver xDrive 6MT Join Date: Apr 2013 Location: Kentucky iTrader: (0)	I think manual is 3.38 final drive.
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