Looking for a 3.90 to 4.10 diff.

[grannyknot]

The stock M differential ratio is 3.64:1 and I'm thinking about changing to a 3.90 or 4.10 but I really have no idea where to start.
Is there a vendor that sells different ring and pinion gears for these diffs or would I be looking for the entire diff from another car?
Thanks,
Chris

[AK72]

Take a look here -
https://www.ecstuning.com/BMW-Z4-M_C...nd_Pinion_Set/

[86Zed]

The ring and pinion set in both ratios are still manufactured by BMW, available at a number of retailers.

https://www.bimmerworld.com/Drivelin...kaAtHAEALw_wcB

The direction you go depends on your driving preferences and any potential for forced induction in the future.

[tomjonesBT33]

Why are you thinking of making the change? Higher trap speeds? Lower cruising RPMs? Plans to track the car? Just curious.

[maupineda]

My 4.10 gear set have been collecting dust for more than a year, need to make time for the install.

I got mine from diffsonline.

But as said above, ECS, Bimmerworld and a few others sell them.

[grannyknot]

Originally Posted by AK72

Take a look here -
https://www.ecstuning.com/BMW-Z4-M_C...nd_Pinion_Set/

Thanks but all 3 of the ones offered by ECS say they won't fit a Z4M, I'm pretty sure the Z4M diff is different from the E46 M3 diff.

Originally Posted by 86Zed

The ring and pinion set in both ratios are still manufactured by BMW, available at a number of retailers.


https://www.bimmerworld.com/Drivelin...kaAtHAEALw_wcB

The direction you go depends on your driving preferences and any potential for forced induction in the future.

That works, I can't see myself ever going down the turbo or supercharger route.

Originally Posted by tomjonesBT33

Why are you thinking of making the change? Higher trap speeds? Lower cruising RPMs? Plans to track the car? Just curious.

In my previous car, a 1972 Datsun 240Z I had an S54 engine with a 3.91 diff and I'm missing that extra kick in the Z4. Going up in gear ratio takes the rpms with it, cruising speed in 5th gear will be 250-300 rpms higher with a 3.91 than with a 3.62.

Originally Posted by maupineda

My 4.10 gear set have been collecting dust for more than a year, need to make time for the install.

I got mine from diffsonline.

But as said above, ECS, Bimmerworld and a few others sell them.

Thanks, diffsonline looks like a one stop shop.

[maupineda]

Ring and pinion gears are shared across e46, e85/6, e60 and e92 ///M cars.

[grannyknot]

Originally Posted by maupineda

Ring and pinion gears are shared across e46, e85/6, e60 and e92 ///M cars.

Thank you, that's the kind of clear & concise info I need.
So many vendors that sell e46 M3 parts don't have much experience with Z4's,
hard to get a clear answer out of them.

[AK72]

grannyknot
BTW you have great opportunity to try locally 4.10 with supercharger , It feels great

[grannyknot]

Originally Posted by AK72

grannyknot
BTW you have great opportunity to try locally 4.10 with supercharger , It feels great

Is that you Andrey? I accept of course! Looking forward to it, but I know there's a long line up of your friends in front of me.
Are you documenting your supercharger install in a thread somewhere?

I have had that "Chasing more power" sickness before, actually all of my driving life. It's like a gambling addiction, but this time around with this car I'm trying to keep things a bit more basic than the cars I've built in the past.

Bimmerworld seems to have the best deal around for the 3.91 set I want and Diffsonline has a ready to go overhaul kits with everything needed,
https://diffsonline.com/differential.../rebuild-kits/

[AK72]

Originally Posted by grannyknot

Is that you Andre? I accept of course! Looking forward to it, but I know there's a long line up of your friends in front of me.
Are you documenting your supercharger install in a thread somewhere?

I have had that "Chasing more power" sickness before, actually all of my driving life. It's like a gambling addiction, but this time around with this car I'm trying to keep things a bit more basic than the cars I've built in the past.

Bimmerworld seems to have the best deal around for the 3.91 set I want and Diffsonline has a ready to go overhaul kits with everything needed,
https://diffsonline.com/differential.../rebuild-kits/

Yes it is me I may go up north tonight if no rain, we can meet somewhere in Vlad's area

[Vanne]

Bear in mind, as maupineda said, the crown and pin are shared across models, the diff however is different from the E46 M3,if your looking to refresh while your in there...

[grannyknot]

Originally Posted by Vanne

Bear in mind, as maupineda said, the crown and pin are shared across models, the diff however is different from the E46 M3,if your looking to refresh while your in there...

Speaking of refreshing, I placed an order for the 3.91 ring&pinion from Bimmerworld and then found these guys https://racingdiffs.com/collections/types?q=BMW
They having a summer sale on right now so I ordered the whole bearing set with seals , the free play shim, all new clutch pack for 481.00 Euros and that includes shipping, I couldn't pass that up.
I wasn't intending on doing an entire rebuild but hell, I'm in there anyway, might as well do it right.

[Vanne]

thats great, the race pumpkin in the diff in my car is from them, what did you go for?

edit: ***shit!!!!***

i just saw that pic, you didnt buy the whole pumpkin? but friction plates and and bearings? just a heads up, the number of friction plates in the z4m diff differs from the e46m3.. (there are more), MORE IMPORTANTLY!!!, its nearly impossible to open the pumkin.

youll need to make a key.. (gets expensive) and then get about 5 huge blokes on a massive end and see if you can turn it off. Youll also need to drill out the locking ball.

ive got some pics somewhere, but i think they are also shared on here somewhere if you do a search..

Have they shipped it yet? if not, you might be better/cheaper off just buying a new pumkin from them, and you can specify what ramps youll like. this is what i ended up doing after finally getting the fucking thing to open.. yeah i said fucking, its a absolute nightmare...

[grannyknot]

Hmmmm, They have already shipped the parts, well I enjoy a challenge
If I get in trouble I have a local transmission/diff shop near me that checks over my work for me, but if you come across those photos I would really appreciate it, I'll also start searching here on the fourm.
Thanks Vane

[grannyknot]

maupineda , Vanne , I found that thread with all the info and pics of the M3 and Z4M diffs, https://www.zpost.com/forums/showthread.php?t=393888
Good info, I wish I had seen that tool that RacingDiffs sells before they shipped, funny he didn't mention it. Although looking at the image of the tool he offers it doesn't look like it would handle a 4 metre extension needed to remove the top of the LSD unit.
I'll have a go at making one first before I try anything else.

Also, here is RacingDiffs video on the Z4M diff,

[maupineda]

I bought that kit too, as well as the tool, but I have chosen not to bother, I have read that all replacement clutches just don't last as long as the OE, and I have no issue with my diff. so when I do the gear swap, I would leave the diff alone and save the kit for later. My car is 80k km so I don't see the need to bother with the diff at this point.

[grannyknot]

Originally Posted by maupineda

I bought that kit too, as well as the tool, but I have chosen not to bother, I have read that all replacement clutches just don't last as long as the OE, and I have no issue with my diff. so when I do the gear swap, I would leave the diff alone and save the kit for later. My car is 80k km so I don't see the need to bother with the diff at this point.

Makes sense. my odo is at 152,000kms and working fine as well but I thought "while I'm in there"

[Vanne]

No worries, let us know how you get on, at 180km, my clutch plates looked fine too.. anyways have fun..

[grannyknot]

It all arrived yesterday so that's 7 days from Serbia to my door, pretty good.
Everything looks to be top quality, he even has his own seals made up, they feel a little more substantial than the BMW or Victor-Reins seals.

[maupineda]

Is the large pinion bearing there a ball bearing? If so, you receive the E92 kit, which is identical to the E46 v2 and Z4M except for that item, ours is a taper roller bearing. That is not compatible with our pumpkin

[ZStig]

what's the labor estimate to install those gears?