Diff swap back - BMW Forum

Stoopha · 10-21-2005, 08:19 AM

Hi,

Can anyone tell me what diff a '95 318i should have?

I bought a 318 in december '04. It does 101mph flat out (down hill with a hind wind) and does 0-60 in a shade under 8s. The book says it should take 10.8s for 0-60mph, and have a top speed of 125 mph. I want to change the diff back so I can can get a better mpg. I am british and so we pay £1 a litre over here, thats about $5.90 a gallon (sorry don't know what imperial units you use over the pond, quarts?)

It used to do 29 to the gallon on the original engine, but I got a new engine for £650 and now it does about 31. According the reference information it should do 34. (old diff wrong-did lots of motorway driving-operated at 5200 rpm for hours-consumed oil too quick-ran on no oil-went 'pop') Still runs at 5000 ish for long haul motorway runs. This is too high. Yes I know this will make it 'slower', yes I know it is a 'slow' 318. But put it this way, I'm not bimmer modder. I want to go from a to b. I ended up with a bimmer by accident, I really wanted a cheap-to-run, cheap-to-insure nissan micra/toyota starlet.

I have TOTALLY loved throwing that 318 round corners, and of all the cars I've driven (a lot - hired everything through work) it is definitely the best handling. I love slewing that tail end round corners. My girlfriend screams when we go from 30 to 40 in it. Wahey!

What diff should I have?

thekid · 10-21-2005, 10:57 AM

hmmm, I may have an idea for you if you could wait a couple months for this. Check out how much it would cost to ship the diff to the states. I am inclined to simply trade diffs with you (stock 1995 318i diff). I am not sure how much shipping would be, but it may be cheaper than you buying another diff (usually several hundered dollars in the states used). I have a mechanic here that could take it out and ship. The only problem is I can't be without my car for longer than a few days until decemeber. In which case we could take out the diffs and ship them to each other (also give you time to find alternative form of trasnportation for a week). Lemme know what you think about this and we can start talking if you're interested. It would shipped to zip code 72207 in the US.

Stoopha · 10-21-2005, 11:23 AM

Yeah sounds good. Shipping to accross the pond may be £$£$£.

I have crawled under the beast and checked it out. It looks ok. I just think it is not a standard 318 diff. If we swapped you'ld be shipping to DN41 8DZ in the United Kingdom. Let me do some research and I'll get back to you.

mmclaren · 10-21-2005, 02:19 PM

ur running a 4.1 dif which is the auto dif on ur manual. Its the current setup i have, cept we pay like 1/3 for petrol as you do.
Ive only recently had my changed and the fuel economy is not much different, little less wear on ur engine as its not always at high revs.
I think a stock 318 should be a 3.8 dif..
But i suppose it does add up fuel.. Especially at the prices you pay for fuel

thekid · 10-21-2005, 03:19 PM

Quote:

Originally Posted by mmclaren

ur running a 4.1 dif which is the auto dif on ur manual. Its the current setup i have, cept we pay like 1/3 for petrol as you do.
Ive only recently had my changed and the fuel economy is not much different, little less wear on ur engine as its not always at high revs.
I think a stock 318 should be a 3.8 dif..
But i suppose it does add up fuel.. Especially at the prices you pay for fuel

I had heard that the auto diff made a much larger reduction to top speed than he claimed. Tell me about yours though... I've been wanting to do it but thought it lowered top speed to below 100mph... what's your engine RPMs at 75/80 mph?

mmclaren · 10-22-2005, 01:21 PM

at 120km or about 73mph im doing around 4k revs in fifth and thats with a 4.1 dif setup

thekid · 10-22-2005, 01:36 PM

That's not that bad, I had always thought it was much worse. I am going to do this as soon as I can now... perhaps in december...

buuhh99 · 10-22-2005, 06:19 PM

check out this site go to driveline u can get a differential in almost any ratio

bimmerworld

buuhh99 · 10-22-2005, 06:20 PM

any thing from a 3.45 -4.44

thekid · 10-22-2005, 07:12 PM

Those are expensive, I could get a used 318i diff for a lot less than that and get the 4.10 gearing.

buuhh99 · 10-23-2005, 12:54 AM

its lsd one, and u can get differetn percentages of locking and it is new, and i could increase my top end to over 200 mph with the 2.29(notice it is for the 6 not the 4, so no 318 doin 200)

thekid · 10-23-2005, 03:25 PM

errr... we were wrong some where. it is 4.40 gear'd diff not 4.10 on the 318i auto...`typo perhaps?

thekid · 10-26-2005, 03:47 AM

I sourced a 4.40 diff, the stock from an auto 318i, here in the states for $225 + shipping. So if we could work out the shipping for less than that, I would be up for the trade.

Furious · 10-26-2005, 03:57 AM

those gearings are extremely too high for anyone with a 6cly, i would never bother, with gas prices as they are and if the car is a primary daily vehicle your gonna be sitting on high revs alot. a 318 is sufficient but still a manual 318 really should work with the 3.91 it was given, i really dont think theres need to change them around

*edit- just realized you DO have a 318 kid, but even still a 4.44 is a bit much

///M Power · 10-26-2005, 05:11 AM

Yeah 4.44 seems to be overkill. Look in a low 4 range. This seems to work best for the i4's from what ive seen.