530i ManualRear Differential change from 2.93 to 3.46 or 4.1!

Hi,
I have had a 530i 5-Speed for some months ago. Its in good condition except for eating LOTS of oil, but nevertheless, I want to swap the rear differential.

From my research, the 530i manual version has a 2.93 final drive ratio and its 5th gear is 1:1 so direct drive with no overdrive. I am finding that E46 and E39's models generally use 2.93, 3.15, 3.46, 3.62, and 4.1 between all the models and wagons.

I searched a bunch of forums on this and people say they have had great results, however they do different ratios. Has there yet been an established optimal ratio to go to? Personally, I could care less about the gas mileage and I do barely any interstate high speed travel so cruising at 5k rpm is not a worry. Most of my commuting is city up to about 55mph.

I realize that 4.1 will give me the best acceleration and I even calculated entirely at what rpm's what gear will be at what rpm and redline as such, however all of that simulated. Can somebody attest here if 4.1 is *reasonable*? Is 1st gear too short to be useful? Do you lose traction easily and burn out (which I don't want)? Is the difference in acceleration day and night (you are putting about 40% more torque to the wheels)?

I also see 3.46 which I personally think is more reasonable, because it should provide a lot of extra torque, but at the same balance it out somewhat with rpm's and not having to shift extremely quickly (although I am new to manual and enjoy shifting a lot very much, haven't gotten tired of it).

If anybody has personal experience driving this and can say what they feel, please do!

Also, I'm trying to find out if 528i diffs fit 530i and if not, can you just take the head connectors off the old one and use them on the new.

Thank you for any help!

A 4.10 would be insanely tall for a manual transmission 530. I'm using a 3.91 rear in a 325 non-vanos and it's on the brink of being too much shifting. 1st is almost useless.

I would personally be tempted to swap in a 3.15 in my 530 as I believe a 3.46 would detract too much from the car's personality of a highway long-distance transportation vehicle, but that's just my personal opinion.

4.10s would turn your trans into a 4-speed, it would completely eliminate the need for first gear. You *would* zip right up to 80 mph, although you wouldn`t want to remain there for long. A 3.46 will give you plenty of new oomph out on the road, and is by far the best, most cost-effective performance-enhancing mod you can do.

Originally Posted by BMWEFOlogist

Hi,
I have had a 530i 5-Speed for some months ago.
Its in good condition except for eating LOTS of oil...

Have you replaced the CCV yet?
Oil filter housing gasket leaking?

Originally Posted by granlund

A 4.10 would be insanely tall for a manual transmission 530. I'm using a 3.91 rear in a 325 non-vanos and it's on the brink of being too much shifting. 1st is almost useless.

I would personally be tempted to swap in a 3.15 in my 530 as I believe a 3.46 would detract too much from the car's personality of a highway long-distance transportation vehicle, but that's just my personal opinion.

Well, I generally travel short distances, trips are well under 20 miles in back roads and city roads of which 99% of the time the speed limit is 30mph-50mph. Sometimes I get onto the beltway which is 55-60mph, but rarely and usually not for long. I'm looking for something that gives me a big punch when I hit the gas, just for fun and because the roads I drive sometimes require really quick passes for safety and convenience reasons, so passing power is a big plus.

Originally Posted by Fast Bob

4.10s would turn your trans into a 4-speed, it would completely eliminate the need for first gear. You *would* zip right up to 80 mph, although you wouldn`t want to remain there for long. A 3.46 will give you plenty of new oomph out on the road, and is by far the best, most cost-effective performance-enhancing mod you can do.

Yeah, that was my initial thought, I would really like to use all 5 gears. Although, if second gear is THAT powerful, then it would seem rather convenient in that I can just 2nd gear to get moving and not worry about 3rd for a while. However I agree, I am leaning towards 3.46, just to not disrupt the fine balance of *driving a car* and *shifting gears every 2 seconds like a maniac*.

Originally Posted by Jason5driver

Have you replaced the CCV yet?
Oil filter housing gasket leaking?

Yes and Yes!

The engine has zero leaks whatsoever and I check often, its dry as a whistle. I even poured special chemical into the oil and used a special flashlight in the dark to check for leaks, kind of like CSI. It literally consumes oil, there is no other explanation I can come up with. I changed sparkplugs and it looks like oil is not being cleaned off the cylinder walls (due to residue on the spark plugs)as well as it should so its burning up during combustion. I also changed the oil yesterday from a cheap off brand temporarily to test if my oil pan gasket replacement was not leaking...to official BMW oil rated for my engine. I am thinking the oil may be thicker or thinner which may affect the engines ability to clean it up off the walls during the strokes.

I was thinking for a while that I just have bad piston rings, but if they let through THAT much oil, wouldn't I have massive pressure losses during combustion resulting in power loss? The engine seems very punchy and accelerates very well to suspect that. Maybe valve seals.

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Either way, thank you very much for the help so far! Any word if 3.46 diffs from other models require different fittings or are they drop in replacements? Bolts and all connectors?