Zf tranny...what diff?

[Wanganstyle]

e36m has 3.15, 3.23, 3.38 oem final drives. ZF 1:1 5th is good with any, although in a e30 with much less weight and less rear traction a 2.93 from late model seems popular; better on fuel as well

my eta went from 2.93 to 3.07, but it dosn't have power like my S52 does.


zfsg320 with a 3.38 will land you human freeway speeds right under 4,000 rpm, top speed with stock 6430rpm redline is just shy of 140.
with a 3.23 final you top out over 145


if your e30 has alot of rear traction and you want to have more accelleration, then perhaps a 3.46 from e28 would be nice to fit. its popular to have 3.46's built up for street/play E36m's

the zfsg320 is setup with s52 in most high (usa) performance application, with 7200 rpm usa engine redline, the track racers usually prefer 3.64 or 3.73 final drives to max acceleration without running out of rpm's.

s50b30 with much more rpm's can do a 3.90, 4.10, 4.27 final for track use; similar to S54.

Currently the S52 (e36) is paired with an overdrive 5th and a 4.10 final and thats pretty good, with a 1:1 5th gear and 4.10 final, it should fly UP HILL :)

perhaps I will fit in a 4.27 final drive for tarmac rally@!!

[328ijunkie]

Did you swap coding plugs?

[kalib0y]

I will check. I dont remeber if I swapped in the plug when changing the cluster. Thanks for the input

[328ijunkie]

Yup.

[kalib0y]

okay, to set everything straight on my end. My car really is doing 80mph at ~3600rpms...the reason why? I am running the E30 M3 cluster and tach with the correct coding chip when I should have swapped in the 325is tach.

The E30 M3 tach stops at 8000rpm so the positions of the RPMs are shifted a bit. 4000 on the e30 m3 tach is positioned where the 3500 is on the325is tach.

The way to fix my problem with my RPMs is swapping in the 325is tach...

[328ijunkie]

okay, to set everything straight on my end. My car really is doing 80mph at ~3600rpms...the reason why? I am running the E30 M3 cluster and tach with the correct coding chip when I should have swapped in the 325is tach.

The E30 M3 tach stops at 8000rpm so the positions of the RPMs are shifted a bit. 4000 on the e30 m3 tach is positioned where the 3500 is on the325is tach.

The way to fix my problem with my RPMs is swapping in the 325is tach...

So you have the M20 coding plug in the S14 tach or no? The tach knows what its displaying. Just like if you put a Eta tach in a I car. It would wrap all the way to where 6500 would be if the display went that far. You can still use the M3 tach just fine as long as the coding plug thats in there is for the M20

[kalib0y]

Yes I have the correct plug in there. The plug ending in "468", so if I swapped in the M20 tach then it should be perfect

[328ijunkie]

Hrm. Well what im saying is that the tach should look at the coding plug for the correct RPM scalar. If you really do have the right coding plug in there then something else weird is up.

[kalib0y]

well the swept area seems correct, because if you look at both clusters where my needle is at 4k, 12 O'clock, on the s14 cluster is exactly 3500 rpms, also 12 O'clock on the m20 tach.

So essentially it works perfectly with the m20 plug, but the background stickers is off now because the M20 tach stops at 7000rpm and the s14 stops at 8000rpm

[mohamadr89]

just for verification....i have a s50 with a zf tranny. i just ordered a 328i driveshaft and a 6cyl z3 diff with a 3.15 gear ratio. will this diff work with my set up? to my understanding all i have to do is change the out flange. please clarify if your familiar with this set up. thanks guys

[mohamadr89]

I need to get her on the road!!! Lol

[e30rapidic]

will work fine provided that;

1 - the drive shaft is from a manual
2 - the flange on the back of the drive shaft is the same bolt pattern as the input flange on the diff. e36 drive shafts came in both 4 and 6 bolt patterns.

also need to use the e30 centre support bearing

[Jszy25]

Stock diff in a 91' 318is is a 4.10?

I guess with my ZF trans I'll be pulling some revs on the highway when I bring it home haha