e46 M3 5 speed swap question

**wrcdave** · 05-01-2012, 06:45 AM

I am about to replace my 6 speed e46 M3 transmission and I wanted to do the 5 speed swap. I am gathering info right now but just curious to those that have done this already. Do I have to change the differential input shaft for the new driveshaft to mount up properly? I am on a time limit between events so I'm not sure if I can get everything done in time. Thanks.

**Ianik** · 05-01-2012, 06:50 AM

Just curious, why do you want to swap a 6spd for a 5spd ?

**PerkM3** · 05-01-2012, 09:11 AM

Contact James at BimmerWorld, I spoke with him about this a while ago and he mentioned being able to source everything I would need in a more or less bolt on package.

**Jmabarone** · 05-01-2012, 09:19 AM

Originally Posted by Ianik

Just curious, why do you want to swap a 6spd for a 5spd ?

5 speeds are lighter, have the same overall final gear ratio, more common, and stronger.

**jonmacs22** · 05-01-2012, 09:46 AM

Not sure about "stronger," comment, but I think cheaper when being replaced is another very key component to the reasoning.

**will v** · 05-01-2012, 11:37 AM

If i remember correctly the clutch is also a consideration - you want to match the clutch to the trans so I'm pretty sure you'd have to pick up a new clutch to match the zf 5 speed

Those in the know correct me if i'm wrong

**ninekrpm** · 05-01-2012, 11:43 AM

http://forums.bimmerforums.com/forum....php?t=1668622

From the thread:

Recently went through a 6speed to 5speed conversion as well and found the net weight savings to be limited. Here is my experience…and some thoughts.

The FW/PP/Clutch upgrade to a lightweight option cancels each other out as you can go this route and save 25-30 #'s with either tranny...so the net gain is limited to the tranny swap itself. That said, the tranny (only) swap gets you about 15-17 #'s. However, you also have to factor in the longer drive-shaft that is needed for this, which is about 3#’s heavier than the oem 6speed tranny.

Here is exactly what is needed for a 5speed conversion…

- 5speed ZF tranny from an e36 M3 ($500)
- Drive-shaft ($600-700 with core exchange)
- For the shifter (keep your existing shifter and swap out the selector rod with a non-M e46 model) or (replace the oem shifter with the BW race shifter $300 plus the non-M e46) selector rod.

So at the end of the day, the net gain is minimal @ 20#’s especially when you factor in that the weight savings are the center + “bottom” of the car.

One should do this; but prioritize this accordingly into your build plan…

**trahsub** · 05-01-2012, 11:54 AM

Originally Posted by jonmacs22

Not sure about "stronger," comment, but I think cheaper when being replaced is another very key component to the reasoning.

I believe the syncros are considered stronger in the 5 spd...or it may be that the 5 and 6 speeds have the same real estate to deal with, so 5 speed has a little more breathing room (less heat)?

**wanganstyle** · 05-01-2012, 12:19 PM

Originally Posted by trahsub

I believe the syncros are considered stronger in the 5 spd...or it may be that the 5 and 6 speeds have the same real estate to deal with, so 5 speed has a little more breathing room (less heat)?

The 6 boxes are paired with higher power engines than the USA zf5 boxes. More stress on the box.
The zf5 is mainly cheaper. Driveshaft to fit is easily gotten Oem, 330i non zhp.

Clutch can full interchange between e46m and e36m 5 speed, the friction disc just needs to match the input shaft. 6mt has a big input shaft, otherwise both use 240mm setups.

**will v** · 05-01-2012, 12:56 PM

Originally Posted by wanganstyle

Clutch can full interchange between e46m and e36m 5 speed, the friction disc just needs to match the input shaft. 6mt has a big input shaft, otherwise both use 240mm setups.

Thanks for clarifying - This is what I was alluding too.

OP - what is your goal of the swap? Did something fail in your current set up? If you don't have to/want to replace the clutch I wouldn't bother

**wanganstyle** · 05-01-2012, 01:23 PM

Originally Posted by will v

Thanks for clarifying - This is what I was alluding too.

OP - what is your goal of the swap? Did something fail in your current set up? If you don't have to/want to replace the clutch I wouldn't bother

S52 clutch works great for s54 engine, I ran one complete w zf5 speed before in a former e36m. The only specific thing to each transmission is the friction disc itself, one can plug and play a e36m friction disc into stock e46m clutch setup and just bolt on the zf 5 speed.

S52 Oem dual mass (22#) is a little lighter than the s54 dual mass (30) so some weight savings can be found while retaining dual mass fly and stock pressure plate.

**Greg S** · 05-01-2012, 01:29 PM

You'll also need an E46 non-M 5 speed trans crossbrace. The 5 speed is 23.5lbs lighter than the 6 speed.

**wrcdave** · 05-01-2012, 03:18 PM

My fourth gear syncro went in my 6 speed and the e46 M3 tranny's are still very expensive even second hand. Since my M3 is a track only car and the 5 speed trann's are so cheap that in the long run it will save me money. I've also heard that the 5 speed syncro's are tougher and last longer than the 6 speed but I have no data to back that up. Thanks so far for the input. Does anyone know if the replacement driveshaft will bolt up to my oem diff or do I have to pull out my diff. In the future I will do the 4.10 gears but I am doing the JRZ suspension first and I am on a budget.

**Greg S** · 05-01-2012, 03:32 PM

Driveshaft will bolt up.

**wrcdave** · 05-01-2012, 05:43 PM

Great. I also have the JB lightened aluminum flywheel installed, can I keep this and just get an e36 M3 clutch?

**CP Louie** · 05-01-2012, 07:15 PM

Originally Posted by Jmabarone

5 speeds are lighter, have the same overall final gear ratio, more common, and stronger.

He meant "same fifth gear ratio" not "final". These young people, what would they do without us older guys? Final in a 6 speed is sixth gear Jake...

**Ianik** · 05-01-2012, 07:34 PM

Ok, perhaps a good option in USA... A 6 speed trans is cheap here...

**Jmabarone** · 05-01-2012, 08:44 PM

Originally Posted by CP Louie

He meant "same fifth gear ratio" not "final". These young people, what would they do without us older guys? Final in a 6 speed is sixth gear Jake...

I thought 6th was 1:1, so I was wrong in a different way.

**PCarroll** · 05-02-2012, 08:24 AM

The first 5 ratios are the same. 6th is overdrive. So you have to match the diff correctly.

1st 4.23:1
2nd 2.51:1
3rd 1.67:1
4th 1.23:1
5th 1.00:1
6th 0.83:1

The 6s do wear out faster IMHO. Best explanation I have heard is the synchros are the same but there is more rotational mass. So they are working a lot harder. You need a different cross brace as well as a different shifter. The only difference with the clutch is the friction disk splines and the size of the throw out bearing. They have to match the transmission.

I personally like the 6 closer gears. I have a 4.75 diff. But the diff was a big investment. I used to run a 4.10 and almost never used 6th. Why did I even have a 6 speed in my E36? It was left over from being a street car. I had built an E36 Evo replica...