Differential parts compatibility - DISCUSSION

[cooljess76]

It should be fine for a little while as long as you take it easy and don't romp on it too hard.

[tiFreak]

Originally Posted by 318ti808

The PP seller is willing to help out by swapping in a M3 coup rear setup or the appropriate diff from a 325i.

unless those are parts out of an E30 they won't work in the ti

[maverick]

Okay, lt me get this straight as I have heard all sorts from all sorts of places. I have a 3.73LSD medium case out of an e30 325 that I want to put in my 96 318ti. It seems reading it all here that my best bet is the 3.73, using e30flanges, e30 halfshafts and e30 stub axles, shimming the ABS and thats about it, am I right??? Do I have to change bearings or anything for the stub axles, or just remove the nut and swap with new retainer?

Sorry if I sound ignorant but i am on this one as if a fool listens to too many fools he is follish, and it seems this is a very good source for the staright story.

Dave

[cooljess76]

Originally Posted by maverick

Okay, lt me get this straight as I have heard all sorts from all sorts of places. I have a 3.73LSD medium case out of an e30 325 that I want to put in my 96 318ti. It seems reading it all here that my best bet is the 3.73, using e30flanges, e30 halfshafts and e30 stub axles, shimming the ABS and thats about it, am I right??? Do I have to change bearings or anything for the stub axles, or just remove the nut and swap with new retainer?

Sorry if I sound ignorant but i am on this one as if a fool listens to too many fools he is follish, and it seems this is a very good source for the staright story.

Dave

You're good Dave, that's everything you need to do and the diff should work fine. I'm pretty sure you'll need the e30 speed sensor and you should also change the gear oil and rear cover gasket. Since your car is a '96, you may or may not need to hammer the cross beam under the floor pan.

[kuleinc]

I have a 95ti with some random open diff in the back, I'm pretty sure its rubbing on the floor (ie no hammering done) because you can "hear" the engine rev from the trunk, its quite amusing... does anyone have a chart of which diff ratios give you what engine speed at 65 mph?

[cooljess76]

Originally Posted by kuleinc

I have a 95ti with some random open diff in the back, I'm pretty sure its rubbing on the floor (ie no hammering done) because you can "hear" the engine rev from the trunk, its quite amusing... does anyone have a chart of which diff ratios give you what engine speed at 65 mph?

random open diff? did someone swap out the original? You say it's rubbing on the floor, so i'm assuming it's a medium case. There's usually a tag attached to the rear cover which will have the ratio stamped on it, but you can also jack both wheels up, put it in nuetral, spin the driveshaft and count how many rotations it takes to make the wheels spin one complete rotation. Obviously, make sure the car doesn't fall on you since it will be in neutral and the parking brake will be disengaged. As for finding out ratios vs speed vs rpm, just do a google search for a "BMW final drive calculator".

[kuleinc]

I was hoping to find a chart to look at

[spidertri]

The speed depends on the transmission ratios, diff ratio, and tire size. I don't think you'll find a chart. I have a spreadsheet that calculates everything if you search google like Jess said you'll find it.

[kuleinc]

Im thinking 3.45 or taller, just worried the car will be too slow, or too droany on freeway. It's hard to choose when u haven't tried each ratio....

[cooljess76]

Originally Posted by kuleinc

I was hoping to find a chart to look at

Did you even search? I just googled "BMW final drive calculator" and this was the second on the list of hits:
http://www.bokchoys.com/differential/GearRatios.htm

Find 318ti auto or manual(whichever one you have), plug the numbers into this calculator(4th on the list of hits)
http://www.google.com/url?sa=t&sourc...hImdmmznsLXGRQ

click "recalculate" and you should see a chart with speeds listed according to RPM and transmission gear.

Here's what it looks like, however your results may vary depending on YOUR tire size and final drive ratio:

[kuleinc]

I'm at work with my phone, I'll search or check it out when I get home tonight

[RCV7]

Hey, guys. I just read this whole thread. Very informative. I'm a noob so please bare with me. I have a stock '96 Ti active. I"m about to purchase a Z3 2.8 engine and a ZF trans from an M3 complete with clutch and drive shaft. I gather I can't use either difs from my ti or the donor M3. I'm Looking to get an LSD dif.
1. Can I use a Z3 6 cylinder dif and if so which ratio would be best and easiest to bolt up? I'll be using both 16 and 17 inch rims with low profile tires.
2. What kind of gearing would a 3.15 from a Z3 give me with this setup?
3. Should my hybrid drive shaft be from my existing ti and an M3, 328 or Z3? I really don't want high rpms at speed or the opposite. This will be my dd as well as autox and some track. Your thoughts are appreciated. Thanks in advance

[maverick]

Originally Posted by RCV7

Hey, guys. I just read this whole thread. Very informative. I'm a noob so please bare with me. I have a stock '96 Ti active. I"m about to purchase a Z3 2.8 engine and a ZF trans from an M3 complete with clutch and drive shaft. I gather I can't use either difs from my ti or the donor M3. Can I use a Z3 dif and if so, auto or manual and which ratio would be best and easy bolt up. I'll be using both 16 and 17 inch rims with low profile tires. I really don't want high rpms at speed or the opposite. This will be my dd as well as autox and some track. Your thoughts are appreciated. Thanks in advance

You can use the one from the Z3 if it was a 6-cyl car as if a 4-cyl likely the same diff in the ti and it will fail more than likely with a 6-cyl feeding it. The ZF I am not sure about as may change the drive shaft length, maybe someone knows more on that than me. If you don't want revs and the ZF is a 5 speed you want a manual diff and likely no more than a 3.23 or somethin in that area. If you want more power then you have to deal with higher revs.

Some body else can refine this maybe.

Dave

[bmorekirby]

ok. so how big of a hammer do i need to beat in the subframe? i have a 4 pound maul i tried, and it didn't cut it.

thanks,
john

[cooljess76]

Originally Posted by bmorekirby

ok. so how big of a hammer do i need to beat in the subframe? i have a 4 pound maul i tried, and it didn't cut it.

thanks,
john

Hey John, don't beat on the subframe, it's the floorboard above the subframe that hits on older models.