Z4 6 Speed Gearbox in a Z3. - Help

Please can someone can help me.....

I want to fit a 6 speed trany in my 2.8 M52TU Z3.

I have been offered a GS6-17BG box from a Z4. The Z4 had the new N52 engine. Does anyone know if the GS6-17BG will bolt up to my engine? Are the gearbox bolt locations onto the engine on the N52 engine and the M52TU the same?

It looks like it will from the line drawings I can find, but the drawings are poor and I don't want to end up with a box I can't use.

Several members have installed 6 speeds, (Mpire comes to mind) use the search to find out particulars.

I have spent a good few hours searching but I cannot see where anyone has taken a box from an N52 machine and shoe horned it into a Z3. The bolting patterns look similar, but its a big risk incase they don't totally match.

Looking at the flywheel in the N52 it only uses 6 bolts where as the M52 has 8. I will therefore have to use my existing flywheel, but that means I will need to do some kind of mod for the bearing housing for splined input shaft end bearing. The clutch has a different spline profile so I will need the Z4 clutch, The Z4 clutch is only 228mm where as mine is 240mm. These problems I feel I can overcome, but I just need to be sure the bell housing will bolt up. Someone must know.

Ask the seller to put a piece of tracing paper over the end of the bell housing and pencil rub the holes. Then you can use that to match up the bolt holes on your car.

Tracing paper is a good idea, but I'm not sure the junk yard man will be that helpful.

I am still hoping it is possible and appreciate any information related to this. I have a 98 Z3.
Also, do the 5spd manual transmissions installed in the z3's come with different gear ratios depending on the motor installed?
Thanks!

Originally Posted by oliver.mogan

I am still hoping it is possible and appreciate any information related to this. I have a 98 Z3.
Also, do the 5spd manual transmissions installed in the z3's come with different gear ratios depending on the motor installed?
Thanks!

All the 6 cylinder Z3's came with the same transmission. The rear diff ratios were different depending on the motor. I swapped a euro E36 6 speed into my Z last fall. Here is the link.

http://forums.bimmerforums.com/forum...and-Diff-build

The other option for you is that you can use a US E46 6 speed but it requires a different clutch set up. Those are cheaper to come by but also a bit of piecing together of different parts to make it work properly. I have heard of people using a Z4 box but have not come across a DIY for it so I don't know what parts are necessary to make it work. My guess there is a whole lot more fabrication involved so it is more cost prohibitive.

Here is another link to UUC's website concerning the 6 speed swap.

http://www.uucmotorwerks.com/98M3/up...6SPD/index.htm

The swap is not really cost effective in any sort of way. I figure I'll have to go 130,000 miles in 6th gear to break even in gas savings but I love having the 6th gear and would do it again in a heartbeat.

Originally Posted by oliver.mogan

I am still hoping it is possible and appreciate any information related to this. I have a 98 Z3.
Also, do the 5spd manual transmissions installed in the z3's come with different gear ratios depending on the motor installed?
Thanks!

Depending on the engine and year, there are different transmissions and diffs:

all 1.9s S5D 250G Getrag trans 3.45 diff
2.3 99-00 " " Getrag trans 3.15 diff
2.5 01-02 " " Getrag trans 3.46 diff
2.8 97-00 S5D 320Z ZF trans 3.15 diff
3.0 01-02 " " ZF trans 3.07 diff
///M S52 " " ZF trans 3.23 diff
///M S54 " " ZF trans 3.15 diff

the automatics are differently entirely

the Getrag and ZF trans are essentially the same ratios wise:
Getrag 1st->5th 4.23 2.52 1.66 1.22 1.00
ZF 4.21 2.49 1.66 1.24 1.00