Diff. Number

[aaron_silva]

I was under my car looking around and checking stuff out and I looked at my tag on my diff. It has the number 4.27 XXXX. I was wondering if someone could explain what the different ratios mean in terms of performance. Is this a good diff for the m42?

I really do not know the concepts behinde the different ratios/number. What do they really mean?

TIA
Aaron

[Rob]

http://auto.howstuffworks.com/differential2.htm

EDIT- For every 4.27 turns of the driveshaft, the rear axles turn once [thanks franz]


by the way, is your diff an LSD? If so, can I have it? :P

[franz]

http://auto.howstuffworks.com/differential2.htm


for every 4.27 turns of the rear axles, the driveshaft turns once. I think......


by the way, is your diff an LSD? If so, can I have it? :P

The other way around. 4.27 will give more torque and more revs for any given gear/speed combo.

[aaron_silva]

Rob, sorry it is open. If I remeber correctly the diff number would say LSD also.

[Rob]

corrected* myself franz.

aaron, no worried. I think the tag would have said 'S 427"

[Super Eta]

correct myself franz.

aaron, no worried. I think the tag would have said 'S 427"

You are correct if it was an LS it would say either S 373 or in your case S 427.

[aaron_silva]

So, final consensus, a 4.27 is good...bad...for my application (m42 motor)?

[franz]

So, final consensus, a 4.27 is good...bad...for my application (m42 motor)?

good for acceleration, a little bad for mileage and high end speed

do you have a cabriolet?

If so, that was stock. If not, it's an upgrade.

[Rob]

1991 318iC


stock equipped.


I'd imagine finding a 4.27LSD is not easy....

[808BMW]

1991 318iC


stock equipped.


I'd imagine finding a 4.27LSD is not easy....

I'd rather have a large case 4.10 LSD :P
Unless this is large case (I'm assuming not)