Diff. swap question?
 

Hi guys, rencently a buy and ionstall a supercharger kit(you know the history), so i decide to swap my auto tranny by a manual. But y have a dude, i know my car have a 4.44 diff. and 95 manual ti have 3.45 that is perfect to may swap, first question:

i have a 4.10 from a 1989 325i, it fit on my car and work fine???

what others diff are recomendes to swap in my ti??

I need answer and opinion of others diff, quickly because my tranny swap is planning to be finish tomorrow and the next is the diff.

Thanks guys for the help/....:biggrin:

Please people, some words to give me light, also i have a 2.93 from 528e is a e28 from 1986

go with a 3.45 Ti Small case diff or e30 3.73 LS or 3.64 LS which are the larger case diffs, but bolt up the same with the Ti.

The E28 528E diff is the same one I just put in. It fit with no problems. As far as ratios, I would imagine with your supercharger, you would want to stay with a ratio of 3.45 or lower I.E. 2.93.

So I think the E28 528e 2.93 would be a winner.

you do NOT want a 4.10 diff! you'll be revving like crazy :)

how much high speed cruising do you do? the higher the ratio, the higher the revs at a given speed. the 2.93 will likely be too low (you'll accelerate slower) and the 4.10 too high (at highway cruising speeds, you'll be at very high revs). the 3.45 should be good since that's stock for the ti. if you don't mind revving a little higher (10% higher), you could do the e30 3.73, but it may require some mods to the underbody with a heavy hammer :)

are these diffs limited slip or open? with more power, you're really going to want to find a limited slip diff (aka LSD). the ease with which you can find one of those may decide your ratio for you.

If bolting on is the issue, it turns out many diffs fit without modification. I personally think you should not go higher than the stock manual tranny ratio (3.45), if you are planning on adding a supercharger/turbo. Staying with a stock 3.45 Ti diff seems questionable with a supercharger; get a widebody (6 cylinder) diff.

it really depends on what he wants to do with the car. there are a number of guys that track their DASC'd ti's and went with the 3.73 LSD for better performance. if all he does is drive around town, the 3.73 will also be fine. if he does a lot of highway cruising, the 3.73 could annoy him. the 2.93 is quite a bit lower (at least 15%). DustenT has the stock 3.45 LSD on his and it's holding up fine. could also have an e28 5er LSD rebuilt with the ratio you want and higher lockup if you wanted (stock is 25% and most places offer at least 40%).

Speaking of lockup, I haven't even tested my new diff's performance. It definitely is limited slip, but what can I do on the road, or from a starting position to see the true advantages of the diff?

take corners fast :)

turn off traction control and give it gas on a damp road from a stop.

ok guys is i understand , the correct and best number to me if between stock 3.45 and above 4.10, i not like the idea of 2.93 because i like much the big wheels, actually i run 19" in my ti and two 15" JL audio in the trunk, so i think to put one little higer than stock, in what car i find it, e30 or e28?also what is "plug and play"? my mechanic have a lot of diff in him house, but i need to go there and look the vin # to find the ratios because he dont have any info , he have about 15!!! diff and all are fron e30 and e28, so i think one of them is for my swap, so please give me ore opinions and numbers, i really leally apreciate your help people...thanks

Fernando

make sure whatever you put on is limited-slip. It'd suck to have all that power and just one wheel spinning...

Ok man, good point thanks for that

Hi poeple, i look in realoem for about two hour i'm looking for a 3.6xx diff. that exist?? if yes in what car??? i have recognized all diff in my mechanic yard. The list above. tell me the better to me...


4.10 from 1989 auto 325i(like new)
2.93 from 1986 manual/auto 528e(good look)
3.25 from 1984!!! 533i auto/manual(look very old)
4.44 from my 1997 318ti auto

4.10 ... too high
2.93 ... imho, too low
3.25 ... might be ok
4.44 ... way too high

3.73 LSD from e30 325 (many have this, even with DASC), but you will be revving 10% higher than you would with the stock 3.45

3.64 LSD (we believe from an e28 5 series)

3.45 LSD from manual trans 318ti or 1.8/1.9 4-cyl z3

thanks cali, i go with the 3.25, i a stupid question(i think) about this... all e 30 are lsd? Also .. i only install the 318ti flanges into the 6cyl diff, put the diff on the car and use my stock axles right?? Also i know i need to change the cover of the srie 5 diff by a e30 cover(i have about 5 covers)