M3 4.1 diff swap: it's good!
Discussion
Just in case anybody is wondering, as I was before I had it fitted but feedback was a bit non existent to be honest, yes 
, the modification is well worth it.
I did have a re-map by West Tuning at the same time but never the less, it is like a different car now. It feels a lot more urgent and even in 6th gear it accelerates quite hard from cruise. Revs are up by 500 @ 80 mph but it is no big deal really.
I intend to fit a lightened flywheel next, some better breathing and a CSL steering rack.
I have spent loads on engine tuning in the past and with BMW's in particular have experienced diminishing returns due to the fact that they are very well optimised power wise in the first place.
I am therefore trying an alternative method of tuning and even if there are no actual power gains as such, a quicker 'feeling' car will hopefully be the end result.
By the way, the car is an E46 if it helps?
, the modification is well worth it.I did have a re-map by West Tuning at the same time but never the less, it is like a different car now. It feels a lot more urgent and even in 6th gear it accelerates quite hard from cruise. Revs are up by 500 @ 80 mph but it is no big deal really.
I intend to fit a lightened flywheel next, some better breathing and a CSL steering rack.
I have spent loads on engine tuning in the past and with BMW's in particular have experienced diminishing returns due to the fact that they are very well optimised power wise in the first place.
I am therefore trying an alternative method of tuning and even if there are no actual power gains as such, a quicker 'feeling' car will hopefully be the end result.
By the way, the car is an E46 if it helps?
Edited by GTWayne on Friday 22 April 09:34
Yeap, I went from 3.23 to 3.64 on my E36 M3. Makes a huge difference, make the car a lot more responsive, just flies through the rev range, great pickup. It's exactly how it should of been from the factory. Much more performance than you'll ever get from trying to tune a naturally aspirated engine whilst saving a fortune. With the ratio swap I did, I got 14% more torque at the wheels.
If I ever get a Z4M it'll be the first performance mod I make.
You should be able to sell your old 3.64 easily to the E36 guys.
If I ever get a Z4M it'll be the first performance mod I make.
You should be able to sell your old 3.64 easily to the E36 guys.
Edited by scz4 on Friday 22 April 18:05
As far as I am aware it is not a ratio that is fitted as standard to any BMW. I have heard that such CWP sets may have been available to purchase through BMW motorsport but the one I have had fitted originated from the states. Simpson Motorsport can sort it for you for roughly 1500 GBP. There must be other outlets but I bought mine as a built up S/H unit so did not need to look further.
I changed the diff ratio in my E30 (to quite a rare ratio) which was also an LSD and the difference was fantastic. Don't understand why more people don't do a diff swap, seems like a quick and easy way to improve acceleration. The loss of a bit of top speed is largely irrelevant to most people IMO.
RLK500 said:
What diff. do you drop into your E30 ? I have allways felt the gap between 3rd and 4th in the e30 M3 was too big and apparantly a diff swap sorts that. Has that been your experience ?
Mine was just a 325. I put in a LSD from a 320 touring that was 4.46 ratio 
Think the original was somewhere around 3.6 (can't remember exactly). Big difference!shim said:
Glad you are enjoying it Wayne
Yes indeed. The interior is all back in now and I am really pleased with the way things are going. HSD's on next weekend then back to West for AP's, all be it a collection of used ex BTC calipers and some WRC discs that I just happened to have kicking about, as you do 
and a geo then maybe a trip to Oulton I fancy to 'sample the wares' 
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