3.91 Diff Install.

[Z4Murder]

So I am FINALLY getting around to having my gears installed... I ordered them from Turner a while ago, just looked at the site, guess they don't sell them anymore?

Anyways, an experienced local race shop is going to install the ring and pinion for $600, awesome price it seems, they said it's an all day job. My issue is this: They said i need a new install kit including the shims and possibly bearrings and all, and I have no idea where to find this.

I searched the forums, Tischer BMW, and real OEM. Could someone please advise on where I can purchase what I need as far as an "install kit"?

In other news, I finally paid off my car!!!!!, going to buy a grand cherokee or an x3 xdrive35i now so i can store this beauty every winter.

Thanks in advance

[beta]

This thread lists all the parts you need.

At some point I should write it up in my mod thread so it's cleaned up a bit. You need the bearings from summit racing plus a few other parts. The shims should be something that the diff installer has, as he'll need the correct shims to adjust the gears.

[Z4Murder]

Cool, thanks alot.

could anyone verify these are the correct parts... copied from the above mentioned thread

I ordered the 6 items below for my install:

33121205138 securing plate for pinion
33121204657 crush sleeve
33107510289 output seals X2
BMW Pinion seal- 33121213949

TMK-HM803110 bearing race - ( From summit racing )
TMK-HM803149 inner pinion bearing - (From summit racing )

[Z4Murder]

Instead of the BMW diff fluid, I've got 4 quarts of redline. I also have the
M diff drain: Screw plug with O-ring (33117525064)
M diff fill: Hex bolt + washer (07119905641 + 07119932112)


so that should complete everything right?

[Z4Murder]

thanks to intgr8r in above mentioned thread and beta for good info

[beta]

Yep that should be everything. I'm going to go get my post break-in diff fluid change tomorrow.

[v8z4]

Anyone know where to get 4.45 or 4.56 gears for the 210mm M3/Z4M diff?

[Z4Murder]

Parts are on the way. looks like total for the ring and pinion, parts and labor is going to be about $1500

[Z4Murder]

Car is under the knife. Hopefully getting back by the end of the day today... but we all know how that goes.

[inTgr8r]

In for updates.

[dubsesd]

Anxious to hear your review

[dubsesd]

And? How is it?

[Z4Murder]

The car feels absolutely awesome. This break-in period can't come soon enough. Zero leaks, no added noise, driveability hasn't changed much at all. I'm obviously cruising around at slightly higher RPMs now, but nothing too extreme. The few pulls that i have done so far, I can definetely feel the added torque. I have to say, for the z4m, gear swap-out is the best bang for your buck mod IMO.

$600 total covers the 1200 mile fluid change. Great service from the guys at Competition Transmission. Took a look around their huge shop, It's clean and they've got some mean all out drag cars.

[dubsesd]

If you were doing it again, would you do 4.10?

[inTgr8r]

Originally Posted by dubsesd

If you were doing it again, would you do 4.10?

Lol.... The age old question


It would be a tough decision

[dubsesd]

i know....im leaning towards 3.91, just dont want to get it and say to myself, "maybe i should have gotten 4.10?"

[Gt4]

Originally Posted by dubsesd

i know....im leaning towards 3.91, just dont want to get it and say to myself, "maybe i should have gotten 4.10?"

I had a 3.91 last summer and I have a 4.10 now, go 4.10!! And I have a ESS vt445!!!

The difference between 3.62 and 3.91 is almost the same as 3.91 and 4.10.

[dubsesd]

thats what ive been thinkning lol. how is your 1st gear with the 4.10's?

[mgwatson48]

Where is the cheapest place to buy the gears alone?

[seank]

Originally Posted by Gtfour

I had a 3.91 last summer and I have a 4.10 now, go 4.10!! And I have a ESS vt445!!!

What a great combo: fun and reliable. You must have a huge smile every time you drive.

[Gt4]

Originally Posted by seank

What a great combo: fun and reliable. You must have a huge smile every time you drive.

Need to admit that the 4.10 is one of the best mod I did to the car! It's so fun when a car is rev happy.

Even with the SC, the 4.10 is very streetable. All the gears are shorter. First gear is still useable on the street. 2nd gear is border line on the track when you floor it. There is wheel spin up to red line but if you go a bit smoother on the gas pedal and try to get maximum grip, you can still use 2nd gear even on the track. Let just say the gas pedal isn't an on/off switch like before

[philjw]

Originally Posted by dubsesd

i know....im leaning towards 3.91, just dont want to get it and say to myself, "maybe i should have gotten 4.10?"

Just do the 4.10! I'm still in my break-in period, but this mod was absolutely worth it. Obviously haven't been to the track yet, but first gear is very useable. Granted, I don't have a supercharger like some other folks here... In any case, just do it!