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      03-23-2010, 10:24 PM   #1
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dinan 4.10 diff

any opinions on this product, i was offered a great price and im going to be pulling the trigger on it this week, id like to get some feedback if anyone has it and how much of a difference it really makes
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      03-23-2010, 10:55 PM   #2
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also interested??
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      03-23-2010, 11:04 PM   #3
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im sure someone has done it
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      03-23-2010, 11:27 PM   #4
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should have it on in a week or so, i will post back
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      03-24-2010, 12:00 AM   #5
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Check out this post - http://www.m3post.com/forums/showpos...0&postcount=60 - car test simulation software suggests the stock FD ratio is optimal in terms of the quarter mile anyway...
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      03-24-2010, 12:19 AM   #6
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thanks for the link, i only read through the first page as i didnt see anything to do with the 4.10 gear for the 6mt, thats what im looking for. ive heard great things from people who did a diff upgrade in the e46 i would really like to know if anything negative has come from this
if nobody can chime in i guess ill be the test dummy
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      03-24-2010, 12:26 AM   #7
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Quote:
Originally Posted by Studntloan View Post
thanks for the link, i only read through the first page as i didnt see anything to do with the 4.10 gear for the 6mt, thats what im looking for. ive heard great things from people who did a diff upgrade in the e46 i would really like to know if anything negative has come from this
if nobody can chime in i guess ill be the test dummy
The 4.10 will definitely feel faster because in gear acceleration is improving (~6.5%) and if you do the maths the actual time spent in gear decreases by around 12% (basically the ratio between the two final drives squared - i.e. 3.85/4.10 ^ 2). So you are getting pulled harder and the engine is revving even quicker - all equates to an atmosphere that suggests the car is an animal...

So it will "feel" faster in terms of butt dyno but the reality is it very much depends on the scenario as to whether you will get better performance or in some cases worse performance.
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      03-24-2010, 12:40 AM   #8
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i understand what your getting at, i have read that its basically a "feel good" butt dyno and that it wont give it any numbers on the dyno, but if it realistically does make the car faster, say stock m3 vs m3 with 4.10s and the 4.10s pull on the stock m3 then it actually did make the car faster and not just feel faster, along with this mod i do plan on doing the stroker so im sure it will all contribute to making this car more of a monster
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      03-24-2010, 12:42 AM   #9
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Don't do it.
But pm me the "great deal" detail and contact info asap.
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      03-24-2010, 12:45 AM   #10
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      03-24-2010, 12:46 AM   #11
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Quote:
Originally Posted by Studntloan View Post
thanks for the link, i only read through the first page as i didnt see anything to do with the 4.10 gear for the 6mt, thats what im looking for. ive heard great things from people who did a diff upgrade in the e46 i would really like to know if anything negative has come from this
if nobody can chime in i guess ill be the test dummy
I think the thread mixja was looking to link to was this one.

http://www.m3post.com/forums/showthread.php?t=287873

I read it the other day - starts out on a DCT diff question then broadens out in to a conversation on diffs in general for both transmissions. There are some strong opinions involved and a bit of drama for good measure, but an informative and entertaining read!

If you're considering the mod - you shoud read it.

I found the debate interesting because everyone seems to want a little something different from their cars depending on how they drive and where they drive (city, hwy, track, autocross, drag etc) In my opinion, the diff you choose can and should match your driving style.

So there is no "right" solution, but one that fits your requirements and maybe not someone else's
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      03-24-2010, 02:54 AM   #12
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Quote:
Originally Posted by Studntloan View Post
i understand what your getting at, i have read that its basically a "feel good" butt dyno and that it wont give it any numbers on the dyno, but if it realistically does make the car faster, say stock m3 vs m3 with 4.10s and the 4.10s pull on the stock m3 then it actually did make the car faster and not just feel faster, along with this mod i do plan on doing the stroker so im sure it will all contribute to making this car more of a monster
Well based upon the graph I linked to (see below), the software predicts basically identical times for 3.85 vs 4.10 (around 12.85s) down the quarter mile. Changing the FD ratio higher also means more gear changes depending on the scenario you are looking at, and with a MT that brings a performance penalty if you have an extra gear change (DCT is a non-issue since it changes so fast).

What would you consider your yardstick for performance? Say a rolling start from 30mph in 2nd gear?

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      03-24-2010, 08:11 AM   #13
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i never thought about it as my yardstick for performance, i was just really looking for the car to be a little bit more lively
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      03-24-2010, 09:27 AM   #14
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what im really looking for is someone who actually has this mod, not a graph
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      03-24-2010, 04:46 PM   #15
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Quote:
Originally Posted by Studntloan View Post
what im really looking for is someone who actually has this mod, not a graph
-So that you can get some results from a random bad driver?
-So that you can get results and compare them with
-2 different cars?
-2 different drivers?
-2 different environmental conditions - temp, humidity, altitude, etc.?
-So that you can have someone tell you his very expensive mod really "feels" faster?
-So that you can make some other non apples to apples comparison?

Sorry, a bit harsh, but simulation works; it is how your entire car, no matter what you drive was engineered and developed! It takes the guess work out of a many types of mods. You should trust it more. Have you seen Pencilgeeks simulation results vs. test? Have you seen all of the other test vs. simulation results here in the forum? I'd be happy to help you understand it more (no sarcasm there - a genuine offer).
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      03-24-2010, 05:56 PM   #16
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Swamp I browsed threw this thread last night but way to tired to post.

Let me get this right in lamens terms you are saying in a mt a 4.10 is going to end up hurting performance? I know it will hurt top speed and whatnot but how will it hurt performance.

I only ask because I plan a 3.62 on my dct and i don't see how performance is going to be hurt other then my top speed. Please enlighten me as I am somewhat green on the topic.
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      03-24-2010, 09:16 PM   #17
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+1 every diff i have had helped, never hurt the performance. i lost a little top end mph and the rpm was a tad higher but thats it. unless you were reffering to that as losing power. for what i gained in acceleration it was worth what i lost up top

i will write a review after i get mine and do the 1,200 mile break in on it and can go past 5500 rpm, no sense writing one bf that
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      03-24-2010, 10:12 PM   #18
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oh no i forgot about the break in guess im going to have to break it in really fast, swamp, ive seen lots of people spend tons of money on bumpers and cosmetic mods that look worse then stock, id rather have it in performance, as far as i can see everyone chiming in saying its not worth it doesnt have it, ive talked to one person who does a while ago and they said it was the best money theyve spend on there e92, also alot of e46 owners have done this mod and all of them have nothing but great things to say about it
im not trying to start a fight at all, but what i was really looking for is for someone who has done this mod and has had a negative experience with it
thanks for anyone chiming in and giving your input
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      03-25-2010, 12:19 AM   #19
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Quote:
Originally Posted by Studntloan View Post
oh no i forgot about the break in guess im going to have to break it in really fast, swamp, ive seen lots of people spend tons of money on bumpers and cosmetic mods that look worse then stock, id rather have it in performance, as far as i can see everyone chiming in saying its not worth it doesnt have it, ive talked to one person who does a while ago and they said it was the best money theyve spend on there e92, also alot of e46 owners have done this mod and all of them have nothing but great things to say about it
im not trying to start a fight at all, but what i was really looking for is for someone who has done this mod and has had a negative experience with it
thanks for anyone chiming in and giving your input
Whether you have a negative experience really depends on what you are looking for. If you are looking for a better quarter mile time and are expecting 0.2 or 0.3 second improvement, then you will be disappointed.

I was heart set on a 3.62 diff for my DCT, even armed with the knowledge I have around negligible raw performance gains. What put me off was the fact that some DCT users have reported the engine shifting to RPMs close or exceeding redline in automatic mode.

Of course you won't get that with the MT differential, so as long as you are happy that in a point-to-point hard out race the 4.10 diff probably won't make you any faster, then go for it. I certainly believe the driving experience will be better with the 4.10 diff - whether that is worth thousands of dollars, well that comes down to the individual person. Certainly many people won't pay thousands of dollars for something that doesn't give a measurable performance improvement.

Finally just so you are aware of this, you can achieve exactly the same outcome of a higher ratio FD by making your wheels smaller in diameter (reducing diameter of wheels increases torque applied at the wheels, but because circumference is reduced, a proportional decrease in vehicle speed at given engine RPM also occurs).
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      03-25-2010, 12:24 AM   #20
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^^ thanks, your on point tho, im really doing this for more driving pleasure as silly as it sounds, im not a 1/4 kinda guy so i guess i know what im in for, i ordered the diff today so i should have it within the next few weeks, ill have a full right up, im sure i will be happy
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      03-25-2010, 01:43 AM   #21
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Quote:
Originally Posted by BaLLzZz View Post
Swamp I browsed threw this thread last night but way to tired to post.

Let me get this right in lamens terms you are saying in a mt a 4.10 is going to end up hurting performance? I know it will hurt top speed and whatnot but how will it hurt performance.

I only ask because I plan a 3.62 on my dct and i don't see how performance is going to be hurt other then my top speed. Please enlighten me as I am somewhat green on the topic.
Have a look at the tread linked to in post #11 just above. A pretty thorough debate. The essense of a diff mod is that there is no such thing as a free lunch. Well, that is of course unless the OEM really chose a really bad ratio, perhaps optimal for some metric and you want a different metric optimized. Like was said here and over there, you get more in gear acceleration with a higher FD diff but you spend less time in each gear. In other words you race you buddy in identical cars with equal skills just one has a higher FD diff. Let's also say you have a rolling start with minimal traction issues. He'll take the lead because he gets more torque to the ground. But he reached redline sooner and has to shift. Then while he is in the higher gear you are still accelerating MUCH harder in the prior gear. In any race in a single gear he'll probably win, but over multiple gears the advantage will likely be equalized or go back to you. This also is in line with the prior explanations about the feel factor - mods can be REALLY deceiving in this manner. More acceleration in any given gear and quicker to get through the gears. One (the first) helps raw performance and feels like it does the other actually hurts raw performance but will also feel like it helps.

Again no such thing as a free lunch.

Quote:
Originally Posted by H Bomb View Post
+1 every diff i have had helped, never hurt the performance. i lost a little top end mph and the rpm was a tad higher but thats it. unless you were reffering to that as losing power. for what i gained in acceleration it was worth what i lost up top
I absolutely challenge that position. They have always helped? Tell us which cars, which FD before and after and which exact metrics you measured with enough repetitions to positively identify the difference.

Quote:
Originally Posted by Studntloan View Post
^^ thanks, your on point tho, im really doing this for more driving pleasure as silly as it sounds, im not a 1/4 kinda guy so i guess i know what im in for, i ordered the diff today so i should have it within the next few weeks, ill have a full right up, im sure i will be happy
Nothing like have a preconceived notion and then meeting that notion subjectively... Ugh. Look I am not saying everyone needs to worship at the 1/4 mi. altar, I certainly don't. Just think very carefully about this before you do it. As well get some hard data before and after, personally I don't trust a butt dyno further than I can kick it.
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      03-25-2010, 02:35 AM   #22
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^ Each to his own - at least the OP is better informed now and is comfortable in his decision...

Personally I wouldn't do it on a MT car just because extra gear changes do penalize you. I would do it on a DCT car if the software was smart enough to adjust the shifting behaviour (based on engine RPM rather than speed - which is does for the most part with the DCT but clearly not in all situations based upon some user reports)...
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