Thinking of switching to 3.45 diff

Stainless 45 · 05-29-2012, 08:20 PM

I've done some research on here but most of the info is a little older. I'd like to get some current opinions from those who have switched to the 3.45, or have had one for a while. What I'm after is street driveabilty, and for the car to be a little quicker off the line.

I would probably go with Dinan considering the warranty. Has anyone installed the diff themselves? Any problems?

DCT by the way.

GIdriver · 05-29-2012, 08:51 PM

Intrested as well.

klammer · 05-30-2012, 12:25 AM

I have it and love it. Can't be bothered to look for it, but many posts on the subject.

eeeboy · 05-30-2012, 12:31 AM

I went with the Dinan 3.62. I lost about 500 rpm's at 80mph...it launches off the line like the car should. If I didn't have it, I would get rid of the car.

JesusMChrist · 05-30-2012, 03:15 AM

Quote:

Originally Posted by Stainless 45

DCT by the way.

6MT only have the option of a 4.10 differential as the (stock) final drive ratio is already 3.85

I am interested in hearing opinions myself, the concept of gaining that much torque is definitely intriguing!

Stainless 45 · 05-30-2012, 06:03 AM

Quote:

Originally Posted by klammer

I have it and love it.

Klammer- I've read your posts and found them very informative. I'm hoping to hear from some others who have done the swap also.

3.45 is as far as I'll go since I don't want to compromise highway driveability, but would love that extra torque.

pbonsalb · 05-30-2012, 06:29 AM

The diff ratio is a great mod as long as the higher highway rpm do not bother you. To calculate them, go to www.diffsonline and open the mph/rpm spreadsheet under the Technical tab. You can save it to your desktop. Plug in your tire sizes and gear ratios-- it is set up for an E36/46. You will see your speeds in each gear each 250 rpm.

I have run 3.15, 3.23, 3.38 and 3.64 on my E36 M3. I could feel the difference between the 3.23 and 3.38 and between the 3.38 and the 3.64. You can calculate the difference -- the % is your increase in torque multiplication at all speeds. Very roughly, anything from about 5% on up you can probably feel if you know your car well.

MPG usually drops slightly. The RPM increase on the highway won't be bothersome except maybe with a really loud exhaust. These engines are so smooth and designed for high rpm use.

I have a 6MT and would consider a 4.10 if I ever came across one cheap while I had the cash burning a hole in my pocket. I'd probably buy a Vishnu meth tune first.

Stainless 45 · 05-30-2012, 08:56 PM

Have any of you done the work of swapping out the differential yourself? Doesn't seem that complicated, being that it comes already set up from Dinan. Might be a good time to address those mounting bushings/bolts that are giving some problems in another thread.

SouthShoreM3 · 06-01-2012, 10:05 PM

I know you are in terms of a diff for the DCT, but I have the 4.10. It is one of the best additions you can do to the given the value and core exchange from Dinan. In the 6mt it revs quite quickly off the line so if you aren't a quick shifter it can take some practice. Daily driving it is fine and the higher tpms I actually like as the exhaust meant always sounds great and practically keeps you out of the drone scenario on aftmrkt set ups.

There is a difference in the speedometer and of course you lose a good amount of top speed. I have to be concerned or disappointed if I can't go more than 180 (and when do we ever really drive that fast legally).

I did notice though on a larger diameter tire the mph adjusts back to normal with the 4.10. So if you ride on 20s you will not notice the speedometer difference.

I would highly recommend this mod more than anything cosmetic that's the same cost. Just make sure you treat the new diff like a new car for the initial 1200 mile break in and get the right diff fluid installed. On occasion you can hear some clicking when making figure eights, but after having it for over 2 years it does not do that anymore or I just don't notice it.

05-29-2012, 08:20 PM	#1
Stainless 45 Captain 87 Rep 602 Posts Drives: Last of the V-8 Interceptors Join Date: Oct 2010 Location: Long Island, NY iTrader: (1)	Thinking of switching to 3.45 diff I've done some research on here but most of the info is a little older. I'd like to get some current opinions from those who have switched to the 3.45, or have had one for a while. What I'm after is street driveabilty, and for the car to be a little quicker off the line. I would probably go with Dinan considering the warranty. Has anyone installed the diff themselves? Any problems? DCT by the way. __________________ Blue Thunder -2011 LeMans Blue e92 DCT, ZCP, European Delivery. BPM Stage II. Dinan 3.45 Rear. Borla/Encore Innovation Exhaust, LUX Angel Eyes, Forgestar F14's, Turner road armor. "Last of the V-8 Interceptors, a real piece of history..."
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05-29-2012, 08:51 PM	#2
GIdriver Major 68 Rep 1,359 Posts Drives: 2014 E63 AMG-S Join Date: Dec 2010 Location: Somewhere in Time iTrader: (0)	Intrested as well.
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05-30-2012, 12:25 AM	#3
klammer Brigadier General 97 Rep 3,246 Posts Drives: 11 spc gry m3 e90, 19 X5 Join Date: Jan 2010 Location: chicago iTrader: (0)	I have it and love it. Can't be bothered to look for it, but many posts on the subject. __________________ mods: track ready stuff
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05-30-2012, 12:31 AM	#4
eeeboy Second Lieutenant 25 Rep 283 Posts Drives: 08M3 Space Gray DCT Join Date: Apr 2006 Location: Irvine iTrader: (0)	I went with the Dinan 3.62. I lost about 500 rpm's at 80mph...it launches off the line like the car should. If I didn't have it, I would get rid of the car.
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05-30-2012, 06:29 AM	#7
pbonsalb Lieutenant General 5228 Rep 10,613 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	The diff ratio is a great mod as long as the higher highway rpm do not bother you. To calculate them, go to www.diffsonline and open the mph/rpm spreadsheet under the Technical tab. You can save it to your desktop. Plug in your tire sizes and gear ratios-- it is set up for an E36/46. You will see your speeds in each gear each 250 rpm. I have run 3.15, 3.23, 3.38 and 3.64 on my E36 M3. I could feel the difference between the 3.23 and 3.38 and between the 3.38 and the 3.64. You can calculate the difference -- the % is your increase in torque multiplication at all speeds. Very roughly, anything from about 5% on up you can probably feel if you know your car well. MPG usually drops slightly. The RPM increase on the highway won't be bothersome except maybe with a really loud exhaust. These engines are so smooth and designed for high rpm use. I have a 6MT and would consider a 4.10 if I ever came across one cheap while I had the cash burning a hole in my pocket. I'd probably buy a Vishnu meth tune first.
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05-30-2012, 08:56 PM	#8
Stainless 45 Captain 87 Rep 602 Posts Drives: Last of the V-8 Interceptors Join Date: Oct 2010 Location: Long Island, NY iTrader: (1)	Have any of you done the work of swapping out the differential yourself? Doesn't seem that complicated, being that it comes already set up from Dinan. Might be a good time to address those mounting bushings/bolts that are giving some problems in another thread. __________________ Blue Thunder -2011 LeMans Blue e92 DCT, ZCP, European Delivery. BPM Stage II. Dinan 3.45 Rear. Borla/Encore Innovation Exhaust, LUX Angel Eyes, Forgestar F14's, Turner road armor. "Last of the V-8 Interceptors, a real piece of history..."
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06-01-2012, 10:05 PM	#9
SouthShoreM3 Passes everything but the gas station 49 Rep 795 Posts Drives: 2010 E90 M3 Join Date: Jul 2010 Location: Boston, MA iTrader: (2)	I know you are in terms of a diff for the DCT, but I have the 4.10. It is one of the best additions you can do to the given the value and core exchange from Dinan. In the 6mt it revs quite quickly off the line so if you aren't a quick shifter it can take some practice. Daily driving it is fine and the higher tpms I actually like as the exhaust meant always sounds great and practically keeps you out of the drone scenario on aftmrkt set ups. There is a difference in the speedometer and of course you lose a good amount of top speed. I have to be concerned or disappointed if I can't go more than 180 (and when do we ever really drive that fast legally). I did notice though on a larger diameter tire the mph adjusts back to normal with the 4.10. So if you ride on 20s you will not notice the speedometer difference. I would highly recommend this mod more than anything cosmetic that's the same cost. Just make sure you treat the new diff like a new car for the initial 1200 mile break in and get the right diff fluid installed. On occasion you can hear some clicking when making figure eights, but after having it for over 2 years it does not do that anymore or I just don't notice it.
	Appreciate 0 Quote