If the DCT GTS tune is so good, why don't we have it from the factory?

[dparm]

Originally Posted by redpriest

It's the correct fluid. Fluid is relatively brand new - they had to change it out a year and a half ago because I had the infamous DCT oil pan and side gasket leak at 50k miles.

No idea about the filter.

Okay, just wanted to check. I have Motul Multi DCTF which is a bit more stout than the OEM stuff, but I doubt that your issues are the result of the fluid overheating. Is there a temp sensor in the DCT that can be queried?

[rjd598]

why does bmw hold back everything from us on stock cars? nothing new, but this one is more acceptable. i didn't see too much of a difference with the flash. can't really remember at this point.

[dparm]

Originally Posted by rjd598

why does bmw hold back everything from us on stock cars? nothing new, but this one is more acceptable. i didn't see too much of a difference with the flash. can't really remember at this point.

I've driven both. If someone hadn't told me the car had a GTS tune, I probably wouldn't have noticed. I suppose the "faster shifting into R" is nice, and maybe some prefer it to start in D2, but those are fairly minor.

[okusa]

Originally Posted by redpriest

Yes, it doesn't happen often, and only on certain tracks where there are a lot of turns which require frequent gear changes. I'm not blaming the tune, necessarily. This has happened to me at Buttonwillow and Thunderhill a couple times. I am talking about > 1-5 seconds between pressing the lever and getting a reaction. I will definitely be investing in a DCT cooler upgrade.

Save your money. The CSF unit offers absolutely zero benefit.

[drwankel]

Originally Posted by dparm

It's a balance between reliability, drivability, and performance.

The GTS software is more aggressive. That equates to better performance, but at the expense of drivability and reliability. GTS owners may be using their cars on the track more often than a standard M3 owner, so they're willing to sacrifice drivability and reliability to get that extra bit of performance.

I think it also comes down to BMW wanting the GTS to be just a little bit better than a regular M3, so they dial everything up to 11. If I paid all of that extra money, I'd want it to be noticeably different.

The thing that confuses me, is that nearly every review of the GTS DCT tune seems to imply that all aspects of the dct are improved. From hard driving to stop and go city driving.

You say drivability is compromised with the GTS tune. Why exactly would it be compromised? Can anybody else here corroborate that? Every review I've read of this kind of tune seems to imply the opposite.

[Sellout]

The only thing that may be compromised is the life of the clutch disks. Shifting faster means more aggressive scrubbing of the disks with each shift. (I'm talking about full throttle shifts) It's a very minor change. The standard DCT software is already pretty fast. The GTS software is faster. We're going from maybe 140ms to 110ms (using Alpine's version which is slowed a bit from the GTS 80ms time)

Honestly, for me, those "minor" changes someone else mentioned are the real reason that the GTS software is enjoyable.

[drwankel]

Originally Posted by Sellout

The only thing that may be compromised is the life of the clutch disks. Shifting faster means more aggressive scrubbing of the disks with each shift. (I'm talking about full throttle shifts) It's a very minor change. The standard DCT software is already pretty fast. The GTS software is faster. We're going from maybe 140ms to 110ms (using Alpine's version which is slowed a bit from the GTS 80ms time)

Honestly, for me, those "minor" changes someone else mentioned are the real reason that the GTS software is enjoyable.

And yet people out there are claiming the opposite. Some people are saying that its the slipping of the clutches that wears them most, and by shifting faster, you are limiting the wear on the clutches due to less slipping.

Which is actually true?

[Sellout]

Originally Posted by drwankel

And yet people out there are claiming the opposite. Some people are saying that its the slipping of the clutches that wears them most, and by shifting faster, you are limiting the wear on the clutches due to less slipping.

Which is actually true?

Both. Clutches are wear items, even in a wet-clutch application like this one. They are going to slip a little bit every time you shift. The more aggressive the shift, the more likely it is that the slip wears away some of the surface. It's not a black and white thing. Slipping always wears the clutch, and the clutch always slips some.

[drwankel]

However, the slower shift allows for more slip. Wouldn't the slower shift wear the clutches faster than the faster shift, if slip is what wears the wet clutches?

[Sellout]

Sure, if the actual load were always the same, but the world doesn't work like that. Slipping at low load for a long time while pulling away from a stop sign isn't the same as slipping at high load with the engine at 7000 rpm.

If we speed up the shift at 7000 rpm, then the actual time spent slipping may be less, but we may be subjecting the clutch plates to a higher load while that slip is happening. At best it's a wash and no additional wear is happening. I'd say that's unlikely. Especially considering that the GTS clutch plates are thicker than the ones we have. BMW didn't install thicker clutch plates in that car for no reason.

We can't dumb it down enough to say something like, "GTS tune makes the clutch plates last longer" and be accurate. Or vice versa.

[e90///M3]

Originally Posted by Sellout

Sure, if the actual load were always the same, but the world doesn't work like that. Slipping at low load for a long time while pulling away from a stop sign isn't the same as slipping at high load with the engine at 7000 rpm.

If we speed up the shift at 7000 rpm, then the actual time spent slipping may be less, but we may be subjecting the clutch plates to a higher load while that slip is happening. At best it's a wash and no additional wear is happening. I'd say that's unlikely. Especially considering that the GTS clutch plates are thicker than the ones we have. BMW didn't install thicker clutch plates in that car for no reason.

We can't dumb it down enough to say something like, "GTS tune makes the clutch plates last longer" and be accurate. Or vice versa.

correct me if I'm wrong, but wasn't there a thread explaining how d mode would wear the clutches more if applying too much throttle (WOT).

[dparm]

Originally Posted by drwankel

The thing that confuses me, is that nearly every review of the GTS DCT tune seems to imply that all aspects of the dct are improved. From hard driving to stop and go city driving.

You say drivability is compromised with the GTS tune. Why exactly would it be compromised? Can anybody else here corroborate that? Every review I've read of this kind of tune seems to imply the opposite.

"Compromised" is a bit strong. It's all about trade-offs. More aggressive shifting is not as comfortable and smooth, that's all.

A lot of it is subjective. What I am saying is that from my perspective, the "benefits" just aren't significant enough for me to swoon over it. The stock programming is excellent and the GTS one just doesn't feel different enough to justify the cost (as cheap as it is).

[Sellout]

Originally Posted by e90///M3

correct me if I'm wrong, but wasn't there a thread explaining how d mode would wear the clutches more if applying too much throttle (WOT).

There may have been. I don't know. I've seen it posited that driving around in S5 or D5 is less likely to wear the clutches than D1 or S1 due to less slip, but I have a very hard time believing that it's really that simple. I feel like there's more going on to make a D/S1 shift smooth than simply slipping the clutch plates.

I also believe that we're picking nits when we talk about this stuff. It's easy to guess that there's some unknown amount of wear being increased or decreased, but who actually knows the standard life expectancy of an M-DCT clutch pack? How many of them have been replaced due to worn plates? I've never seen a DCT with clutch plates at the end of their service life.

[redpriest]

Originally Posted by okusa

Save your money. The CSF unit offers absolutely zero benefit.

Ugh. What cooler do you recommend? Or is this something we just have to deal with.

[okusa]

Originally Posted by redpriest

Ugh. What cooler do you recommend? Or is this something we just have to deal with.

I wish I had an answer. I installed the CSF radiator and DCT cooler and neither offers any benefit over stock as supported by AIM data.

[Shredicus]

Originally Posted by redpriest

Ugh. What cooler do you recommend? Or is this something we just have to deal with.

If it were my money I'd check out the DO88 unit from Germany. They went the extra step and increased the aperture feeding the enlarged cooler to take advantage of the extra surface area.

http://www.m3post.com/forums/showthread.php?t=1173298

[drwankel]

Originally Posted by dparm

"Compromised" is a bit strong. It's all about trade-offs. More aggressive shifting is not as comfortable and smooth, that's all.

A lot of it is subjective. What I am saying is that from my perspective, the "benefits" just aren't significant enough for me to swoon over it. The stock programming is excellent and the GTS one just doesn't feel different enough to justify the cost (as cheap as it is).

However, Steve Dinan says for his own DCT tune that the shifting is smoother than stock? People say one thing and then someone else says the complete and total opposite. I'm kind of at a loss as to who is actually correct here. I hear its smoother, then less smoother. Wears the clutches more, wears the clutches less. Night and day difference, and not much difference at all.

"It makes shifts faster, but does not change shift rpm. Shifting is actually smoother than stock." - Steve Dinan

http://www.dinancars.com/product/d90...ries&mid=1114/

[M43S7RO]

I had the tune done by Alpine and it feels like a good subtle difference in that acceleration feels smoother (not the shifting neccesarily). The shifting does feel a little more direct.

I don't always drive like I'm qualifying for the Monaco
GP so for me simply having D as the default engagement was worth it enough as I drive most in that mode. Previously I found it a nuisance to always have to double tap the selector.

Alpines cost made it an easy choice, if I had paid substantially more then I wouldn't feel it is worth it.

[Redd]

More slip - ie slower shifts - wears the clutch plate more. It's why you're told not to ride the clutch pedal in a manual car.

Faster shifts shock the transmission more and accelerates wear in the entire power train including engine and transmission mounts.

DCT tune - I have the Alpine tune and tbh did not notice much difference from the stock DCT tune. Then again my M3 is Euro spec. That said, upshifts are indeed faster and the car leaps forward at WOT upshifts. It's like dumping the clutch at WOT shifts in a manual car.

[dparm]

Originally Posted by drwankel

However, Steve Dinan says for his own DCT tune that the shifting is smoother than stock? People say one thing and then someone else says the complete and total opposite. I'm kind of at a loss as to who is actually correct here. I hear its smoother, then less smoother. Wears the clutches more, wears the clutches less. Night and day difference, and not much difference at all.

"It makes shifts faster, but does not change shift rpm. Shifting is actually smoother than stock." - Steve Dinan

http://www.dinancars.com/product/d90...ries&mid=1114/

"Smooth" is subjective. (until someone pulls out an accelerometer and proves otherwise)

If you guys want the GTS tune, go for it. I'm simply putting out my opinion.

[narkotic]

Originally Posted by Shredicus

All DCTs use 2 stage cooling:

http://www.m3post.com/forums/showpos...1&postcount=26

Also faster shift speeds should mean less friction and therefore less heat if I understand the wet clutch setup correctly

I stand corrected! Good to know.

[oolas3]

Originally Posted by drwankel

However, Steve Dinan says for his own DCT tune that the shifting is smoother than stock? People say one thing and then someone else says the complete and total opposite. I'm kind of at a loss as to who is actually correct here. I hear its smoother, then less smoother. Wears the clutches more, wears the clutches less. Night and day difference, and not much difference at all.

"It makes shifts faster, but does not change shift rpm. Shifting is actually smoother than stock." - Steve Dinan

http://www.dinancars.com/product/d90...ries&mid=1114/

I have the Dinan DCT tune and it's way better than stock in daily driving duties and around town. Worth every penny IMO. Much smoother and less clunking around. Although for performance driving I would say there is less of an impact over stock as stock is pretty good to begin with.