[porsche959]

Planning to swap out my stock n52 6sp dif to a auto 3.73 dif, but is it worth it?

My recent negative experience with the BMS pedal tuner has be 2nd guessing.

I have read that the 3.73 applies more torque across the rpm range but is that true?

In the real world, what does it feel like? Does it feel like the car is putting down more power/tq? Or does it feel like you just have to shift sooner? Ie- 2nd gear feels like 1st, 3rd feels like 2nd, etc.

Thanks

[Efthreeoh]

The N/A subforum has several posts on the subject. Of the posts I've read, everyone who made the swap felt it was worth it. Pulling the diff is not that difficult. You do need some air under the car because the 3 mounting bolts take an s-load to break loose if using hand tools.

[porsche959]

Originally Posted by Efthreeoh

The N/A subforum has several posts on the subject. Of the posts I've read, everyone who made the swap felt it was worth it. Pulling the diff is not that difficult. You do need some air under the car because the 3 mounting bolts take an s-load to break loose if using hand tools.

Thanks.

Yeah I’ve only seen positive reviews.

But can’t understand the concept of how it would apply more torque at different rpms? I guess it’s the same torque but just at different gears? So the old dif would get a certain amount of torque at 50mph but now you feel its at 40mph? If that’s the case, might as well keep it in a lower gear. Maybe the fun of it is rowing through more gears? I derno.

[Efthreeoh]

Originally Posted by porsche959

Thanks.

Yeah I’ve only seen positive reviews.

But can’t understand the concept of how it would apply more torque at different rpms? I guess it’s the same torque but just at different gears? So the old dif would get a certain amount of torque at 50mph but now you feel its at 40mph? If that’s the case, might as well keep it in a lower gear. Maybe the fun of it is rowing through more gears? I derno.

The differential is a torque multiplier, which changes the final drive ratio of the drivetrain. Numerically increasing the diff number lowers the ratio, increases the amount of torque to the rear tires. The diff in the manual 325i is 3.23. The percent change between 3.23 and 3.73 is the percent increase in torque you'll get with the swap. Rough math says 27 pound-foot increase. The trade off is the engine RPM increases for the same road speed of the old diff because the lower ratio, thus increasing fuel consumption. The higher torque value provides faster acceleration time. Makes the car quicker off the start line.

So if you get a good diff for $200 or so, it's a cheap and easy bolt-on torque increase.

[TunafishE93]

You will be losing about 9 mph of speed at 3000 rpms. For example 3.23 at 3000 would be 69mph and 3.73 at 3000 would be 60mph. In fifth gear.

[Rmtt]

Hands down the biggest SOTP difference you can do on these cars. Much more so than the other mods I have.

Makes the car feel completely different, and a blast to drive. I found mine out of a car that was totaled from a front impact. Roughly 22K miles on it. Drained and replaced the fluid with Redline, and still had less than $300 in it altogether.

Changed it out by myself with car on jack-stands.