Dinan 3.62 Diff question

[ecksreturns]

Hey guys . Now this may sound stupid , but I have been looking around this forum and could not find a proper answer .

I am on the lookout for the Dinan 3.62 LSD , and wanted to know that do I have to send my diff to Dinan , or can Dinan build a new diff for me and then can refund me the value of my diff when I send it back ? Since I reside in India , it is difficult for me to take the diff out and ship it to the US , as that renders my car useless for a good month or so . And since Dinan has no email address , I can't communicate with them on this (time difference does not allow me to call them) . So , can any one chime on this with their experience with Dinan LSD's ?

[Lemans_Blue_M]

Originally Posted by ecksreturns

Hey guys . Now this may sound stupid , but I have been looking around this forum and could not find a proper answer .

I am on the lookout for the Dinan 3.62 LSD , and wanted to know that do I have to send my diff to Dinan , or can Dinan build a new diff for me and then can refund me the value of my diff when I send it back ? Since I reside in India , it is difficult for me to take the diff out and ship it to the US , as that renders my car useless for a good month or so . And since Dinan has no email address , I can't communicate with them on this (time difference does not allow me to call them) . So , can any one chime on this with their experience with Dinan LSD's ?

I know this is not what you are asking but...DON'T BUY A 3.62:1 RATIO DIFFERENTIAL for your M-DCT equipped car.

It's not a good fit performance wise. That gear ratio doesn't work well at all with a 7-speed DCT transmission.

So basically, all of the effort needed to ship your OEM 3.15:1 diff half way around the world, and pay for the new diff (plus all the labor labor charges) will be a waste of money in my opinion.

My advice, is to use that money on more effective aftermarket performance mods like a high-performance exhaust system, pulley, high performance air filter, custom ECU tuning, wheels, or exterior body panels.

Just my .02 cents.

[ecksreturns]

Originally Posted by Lemans_Blue_M

I know this is not what you are asking but...DON'T BUY A 3.62:1 RATIO DIFFERENTIAL for your M-DCT equipped car.

It's not a good fit performance wise. That gear ratio doesn't work well at all with a 7-speed DCT transmission.

So basically, all of the effort needed to ship your OEM 3.15:1 diff half way around the world, and pay for the new diff (plus all the labor labor charges) will be a waste of money in my opinion.

My advice, is to use that money on more effective aftermarket performance mods like a high-performance exhaust system, pulley, high performance air filter, custom ECU tuning, wheels, or exterior body panels.

Just my .02 cents.

Okay , I am ready to discuss this . I would not want to go through all the effort to be disappointed in the end . So , what supports your view about this ?

[Lemans_Blue_M]

Originally Posted by ecksreturns

Okay , I am ready to discuss this . I would not want to go through all the effort to be disappointed in the end . So , what supports your view about this ?

Start by reading this thread...

http://www.m3post.com/forums/showthr...ht=3.62&page=2

You will find several reasons (evidence) to why this is a bad idea.

This will explain why this particular ratio is not ideal for this car. (and the DCT transmission)

Bottom Line: You won't get your 'bang for the buck' out of this proposed modification.

Just trying to save you from making a very costly mistake, that won't really make any difference in your overall performance.

If your heart is truly set on doing this modification anyway...you would be much better off in the long run with a 3.45:1 ratio.

A differential simply gives you a slight advantage off the line in 1st and 2nd gear, after that...the advantage is gone. The disadvantage is that you will burn more fuel with a 3.62 ratio, as your cruising rpms will increase to maintain your normal highway speeds.

In all honesty, you'll get more performance out of exhaust mods + pulley swap + custom tune at the end of the day.

[mixja]

Yeah the 3.62 is probably "bang for your butt" as opposed to "bang for your buck" as it will feel faster due to the increased in-gear torque, but in reality is not and sometimes is worse depending on the situation...

I agree 3.45 is the better option if you were going to do this modification. 1st gear with 3.62 is too short...

[ecksreturns]

That was a very good read! Definitely helped me save 3000 $ . But the question still stands , if I wish to get a 3.45 diff from Dinan . Is there no way that they can build a new one ? Is there another way to get the same FDR 's from a different manufacturer ? I checked diffsonline and could not find it there .

[Lemans_Blue_M]

Originally Posted by ecksreturns

That was a very good read! Definitely helped me save 3000 $ . But the question still stands , if I wish to get a 3.45 diff from Dinan . Is there no way that they can build a new one ? Is there another way to get the same FDR 's from a different manufacturer ? I checked diffsonline and could not find it there .

You will simply have to make the sacrifice of staying up late and calling diffsonline or Dinan when they are open. Diffsonline may not have the 3.45:1 ring and pinion option listed, but I'm sure they can get it as well.

I would advise you to call first (to explain exactly what you want), and then follow up with them via e-mail. They need to know how you want to coordinate things since you live in India.

I can get you an e-mail address for a Dinan rep, that's not a problem. Diffsonline's e-mail address is on their website.

To answer your basic question:

YES, you can buy a new performance differential with the ratio you want without removing your differential first.

Now, you should know that taking this path will cost you a lot more money initially, because there is a CORE CHARGE associated with this kind of mechanical upgrade.

So if you don't send then your stock 3.15:1 diff first, they will charge you the core charge upfront. (at the time of purchase)

Now once you receive the new 3.45:1 modified diff (and install it in your car), you can then ship the OE 3.15:1 unit back to diffsonline or Dinan for a core charge credit reimbursement to recoup the upfront core charge fee you had to pay.

[ecksreturns]

Originally Posted by Lemans_Blue_M

You will simply have to make the sacrifice of staying up late and calling diffsonline or Dinan when they are open. Diffsonline may not have the 3.45:1 ring and pinion option listed, but I'm sure they can get it as well.

I would advise you to call first (to explain exactly what you want), and then follow up with them via e-mail. They need to know how you want to coordinate things since you live in India.

I can get you an e-mail address for a Dinan rep, that's not a problem. Diffsonline's e-mail address is on their website.

To answer your basic question:

YES, you can buy a new performance differential with the ratio you want without removing your differential first.

Now, you should know that taking this path will cost you a lot more money initially, because there is a CORE CHARGE associated with this kind of mechanical upgrade.

So if you don't send then your stock 3.15:1 diff first, they will charge you the core charge upfront. (at the time of purchase)

Now once you receive the new 3.45:1 modified diff (and install it in your car), you can then ship the OE 3.15:1 unit back to diffsonline or Dinan for a core charge credit reimbursement to recoup the upfront core charge fee you had to pay.

So if I understand you right , it is possible for Dinan to send me a 3.45 diff first and then refund me the Core charge after I have installed this new diff and sent them my own diff? If that is the case , I would be really thankful to you if you can provide me with an email address for a Sales Rep , who can understand my situation and provide me with what I need .

[Lemans_Blue_M]

Originally Posted by ecksreturns

So if I understand you right , it is possible for Dinan to send me a 3.45 diff first and then refund me the Core charge after I have installed this new diff and sent them my own diff? If that is the case , I would be really thankful to you if you can provide me with an email address for a Sales Rep , who can understand my situation and provide me with what I need .

Correct.

That's the way it works if you don't want to remove your stock differential first.

The upfront core charge will be credited back to you when they receive your stock differential.

PM sent with the e-mail address of a Dinan performance representative.

[turbo8765]

3.62 is an awesome upgrade and is the exact FD ratio the car should've come with from the factory. You will be very pleased with it. Throttle response is unbelievable, and useful acceleration can now be produced below 3000 rpm in second and third gears. If you read any complaints about the S65, of which there are very few, it's likely related to a relative deficit of "low end" torque during daily non-spirited driving. The 3.62 cures this.

My friend ordered his 3.62 from diffsonline and had the diff installed at local shop. A couple thousand miles later his average MPG is unchanged. This is due to the fact the he now used 7th gear in town in situations in which it was previously too tall. IF you do most of your miles cruising on the hwy, then you will likely see a decrease in fuel economy. If, however, you do most of your miles cruising on the hwy, I'm not sure why your driving a V8 M3.

How many of those who attempt to discount the benefit of the 3.62 have actually driven a car equiped with this FD ratio? I have and it's awesome.

[mixja]

Originally Posted by turbo8765

3.62 is an awesome upgrade and is the exact FD ratio the car should've come with from the factory. You will be very pleased with it. Throttle response is unbelievable, and useful acceleration can now be produced below 3000 rpm in second and third gears. If you read any complaints about the S65, of which there are very few, it's likely related to a relative deficit of "low end" torque during daily non-spirited driving. The 3.62 cures this.

My friend ordered his 3.62 from diffsonline and had the diff installed at local shop. A couple thousand miles later his average MPG is unchanged. This is due to the fact the he now used 7th gear in town in situations in which it was previously too tall. IF you do most of your miles cruising on the hwy, then you will likely see a decrease in fuel economy. If, however, you do most of your miles cruising on the hwy, I'm not sure why your driving a V8 M3.

How many of those who attempt to discount the benefit of the 3.62 have actually driven a car equiped with this FD ratio? I have and it's awesome.

I think every owner of the 3.62 FD ratio tends to agree with your opinion.

Really depends on what is important to you - I have no doubt that the car feels quite different in nature to drive with the 3.62 FD, but the reality is that the performance gains are negligible if you are looking at street/drag/track racing. So if you are looking to spend your money wisely, then I don't think this upgrade is necessary. Sure the car will be more responsive in gear, so as a daily driver it will feel much better. Given most people use the M3 as a daily driver 95% of the time, then perhaps this is a worthwhile upgrade, purely for the difference in how the car feels.

I don't agree it should have come with 3.62 from the factory, my personal opinion is that it should have come with 3.45 from the factory.

[eeeboy]

I love the3.62...omg, i love it.
i don't drive hwys

[stylinexpat]

Originally Posted by eeeboy

I love the3.62...omg, i love it.
i don't drive hwys

Since you are in Irvine, I would love to see yours one day. I drive in the city and on the highways.

[turbo8765]

Mixja, you're correct in noting that most e90/2/3 drivers do the vast majority of their driving on the street. Any mod that improves street performance is, therefore, more likely to be a better mod.

Furthermore, I've seen no reasonable direct comparison that shows the 3.62 is slower at the dragstrip. I've heard an INCREDIBLE amount of heresay about a single individual who allegedly ran slower at a different track, under different conditions on his first time out with the 3.46 as compared to the 3.15. There is a tendancy on internet forum for information to become fact after two or there repetitions irrespective of any actual validity.

It's is exceedingly unlikely that a M3 DCT with 3.62 FD is slower than an M3 with 3.15 at the dragstrip. In a couple of years when there is significantly more data from a number of different cars at different tracks it will become apparent that the 3.62 is not slower at the dragstrip.

Note that the 3.62 may be slower on a road course....maybe

[stylinexpat]

Originally Posted by turbo8765

Mixja, you're correct in noting that most e90/2/3 drivers do the vast majority of their driving on the street. Any mod that improves street performance is, therefore, more likely to be a better mod.

Furthermore, I've seen no reasonable direct comparison that shows the 3.62 is slower at the dragstrip. I've heard an INCREDIBLE amount of heresay about a single individual who allegedly ran slower at a different track, under different conditions on his first time out with the 3.46 as compared to the 3.15. There is a tendancy on internet forum for information to become fact after two or there repetitions irrespective of any actual validity.

It's is exceedingly unlikely that a M3 DCT with 3.62 FD is slower than an M3 with 3.15 at the dragstrip. In a couple of years when there is significantly more data from a number of different cars at different tracks it will become apparent that the 3.62 is not slower at the dragstrip.

Note that the 3.62 may be slower on a road course....maybe

Have you tried a top-speed run?

[swamp2]

Guys, there has been a lot of debate about differentials. In short a higer FD ratio does produce more wheel torque and more wheel power however, the trade off is less time accelerating in each gear (i.e. you have to go to 2nd which is much lower acceleration than 1st while the car with the stock diff is still pulling hard to a higher speed before the 1-2 shift, similarly across all gears). There has also been a lot of debate (mostly in the past) about physics based simulation for determining a vehicles performance. In short simulation is pretty well accepted and has been shown to be quite accurate across a large range of vehicles. I finally decided to run some sims of the M3 (M-DCT) with the stock FD (3.15) vs. a 3.45 and 3.62. This is actually one of the best cases to simulate since it essentially washes out any baseline effects, the only changes to each set up is the FD ratio and therefore even though you might see some inaccuracy on an individual run the RELATIVE results between these results and any apples to apples real world test should be excellent.

In short the 3.45 FD has little to no effect (except at very high speeds) but the 3.62 has a combination of positive effects with few downsides. #1 is stock, #2 is 3.45 and #3 is 3.62. I think this goes against much of the guesses and common wisdom on the topic. Personally, I trust simulation as much or even more than test. Tests often get obfuscated with many non controlled/controllable factors leading to a non apples to apples scenario.

[stylinexpat]

Originally Posted by swamp2

Guys, there has been a lot of debate about differentials. In short a higer FD ratio does produce more wheel torque and more wheel power however, the trade off is less time accelerating in each gear (i.e. you have to go to 2nd which is much lower acceleration than 1st while the car with the stock diff is still pulling hard to a higher speed before the 1-2 shift, similarly across all gears). There has also been a lot of debate (mostly in the past) about physics based simulation for determining a vehicles performance. In short simulation is pretty well accepted and has been shown to be quite accurate across a large range of vehicles. I finally decided to run some sims of the M3 (M-DCT) with the stock FD (3.15) vs. a 3.45 and 3.62. This is actually one of the best cases to simulate since it essentially washes out any baseline effects, the only changes to each set up is the FD ratio and therefore even though you might see some inaccuracy on an individual run the RELATIVE results between these results and any apples to apples real world test should be excellent.

In short the 3.45 FD has little to no effect (except at very high speeds) but the 3.62 has a combination of positive effects with few downsides. #1 is stock, #2 is 3.45 and #3 is 3.62. I think this goes against much of the guesses and common wisdom on the topic. Personally, I trust simulation as much or even more than test. Tests often get obfuscated with many non controlled/controllable factors leading to a non apples to apples scenario.

I seem to like the DCT with the 3.45 numbers..

[ecksreturns]

Originally Posted by stylinexpat

I seem to like the DCT with the 3.45 numbers..

Even though the 3.62 is better in almost every test in that analysis ?

[stylinexpat]

Originally Posted by ecksreturns

Even though the 3.62 is better in almost every test in that analysis ?

My guess is that since you are located in India you may not be doing a lot of highway driving. India is pretty populated with most likely city driving so for you the 3.62 may be a better option for you in India but out here in California the 3.45 may be the better option for me for city driving and highway driving.

PS: I don't think the 3.62 is better in almost every test in the analysis but that depends on where you spend most of your time driving the car.

[ecksreturns]

99% of my driving is city driving , so I guess 3.62 is suitable for my M3.

[BarryC]

Originally Posted by Lemans_Blue_M

Start by reading this thread...

http://www.m3post.com/forums/showthr...ht=3.62&page=2

You will find several reasons (evidence) to why this is a bad idea.

This will explain why this particular ratio is not ideal for this car. (and the DCT transmission)

Bottom Line: You won't get your 'bang for the buck' out of this proposed modification.

Just trying to save you from making a very costly mistake, that won't really make any difference in your overall performance.

If your heart is truly set on doing this modification anyway...you would be much better off in the long run with a 3.45:1 ratio.

A differential simply gives you a slight advantage off the line in 1st and 2nd gear, after that...the advantage is gone. The disadvantage is that you will burn more fuel with a 3.62 ratio, as your cruising rpms will increase to maintain your normal highway speeds.

In all honesty, you'll get more performance out of exhaust mods + pulley swap + custom tune at the end of the day.

I don't quite understand the purpose of the thread attached above other than to spout anecdotal comments rather than empirical data.

For example - where is it stated the 1/4 mile time is the end all measure of the benefits of a particular mod? Has any one measured how much faster or slower the car would be at the 1/2 mile or 1 mile mark? Also, how does this mod affect road course performance? IMO a road course test is probably more relevant as I think most would agree this car is designed more for road course use rather than drag strip performance.

My own anecdotal experience is this car is in its current form is every bit as fast or faster as my E46M3 with a VF Stage 1 S/C with 390whp with a track GC suspension and stoptech brakes on full course VIR. I routinely hit about the same or higher speeds on the front and back straights in a heavier lower hp car.

So I think for someone to say the 3.62 on a DCT car is a failure is not correct. My personal experience has been a very good one as I haven't experienced increase fuel consumption, annoying rpm at highway speed (btw, the rpm at 80mph is still less than the stock '95M3 I own), and other negatives being thrown around.

I'd do this mod again as it is a lot of fun!

Thx,
BC

[swamp2]

Originally Posted by stylinexpat

My guess is that since you are located in India you may not be doing a lot of highway driving. India is pretty populated with most likely city driving so for you the 3.62 may be a better option for you in India but out here in California the 3.45 may be the better option for me for city driving and highway driving.

PS: I don't think the 3.62 is better in almost every test in the analysis but that depends on where you spend most of your time driving the car.

It is better in precisely 25 of 42 of these metrics and almost universally better less than 120 mph. In general the 3.62 is "better" for WOT runs at lower speeds that would make the 3.62 "better" in some sense for you.