Running a 3.62 diff with a DCT

[SYT_Shadow]

Originally Posted by bigjae1976

The point is the DCT shifts fast enough to have a negligible effect on acceleration.

Exactly. That's the beauty of the DCT. All the pros of shorter gearing and none of the cons

Very frustrating it's so hard to get good info on whether 3.62 and DCT will be happy with OEM GTS dct software and the stock ECU tuned

[MSY]

My point was the shift time is only part of it. If you have to shift into 4th earlier than you lose a much larger amount of gear multiplication than you gain from a shorter ratio in 3rd for example but depending on the track it may or may not be an advantage.

[bigjae1976]

Originally Posted by MSY

My point was the shift time is only part of it. If you have to shift into 4th earlier than you lose a much larger amount of gear multiplication than you gain from a shorter ratio in 3rd for example but depending on the track it may or may not be an advantage.

Gotcha. But does that make a difference?

[driftflo]

yes, msy is right in general. but 3.15 is too long even for nordschleife. so i guess you will not find a single track in the world where you will be quicker with a 3.15 fd.

we can argue if 3.45, 3.62 or 3.85 is the perfect fd for a certain track, 3.15 is not!

[wyatth]

I loved the Dinan 3.91 in my 6MT 46M, and I’m sure I’d love a shorter FD in my DCT 90M 10x more. 3.45 sounds perfect.

[MSY]

3rd is perfect at laguna seca in my view in a duct as is

[peter de la mare]

Still not had any luck with sorting my missing downshift blips on the standard ECU. I may just try re-flashing the GTS software to see if that does anything.

[nycplumber]

Originally Posted by peter de la mare

Still not had any luck with sorting my missing downshift blips on the standard ECU. I may just try re-flashing the GTS software to see if that does anything.

Sorry to hear that. I'm really close to pulling the trigger on a 3.45 with a wavetrac but I don't want to run into issues later.

[peter de la mare]

I can’t believe other people when they say there’s no impact on shifts when they make this modification, there’s a big impact.

[Redd]

Just ordered my 3.45 and OS Giken LSD. Will report back when I get it all installed.

[SYT_Shadow]

keep us updated Peter

[nycplumber]

Originally Posted by peter de la mare

I can’t believe other people when they say there’s no impact on shifts when they make this modification, there’s a big impact.

What tune is on your DCT? have you tried stock or the OEM GTS TUNE?

[peter de la mare]

Originally Posted by nycplumber

What tune is on your DCT? have you tried stock or the OEM GTS TUNE?

It has the proper GTS tune on it. I could just try re-flashing it.

[warp10]

Changing the diff ratio with out somehow telling the ecu that it's changed is not a good idea. Over revs can happen. The ecu is expecting a certain ratio so it rev matches based on that. If you change the ratio it is still going to assume the stock ratio. Just my .02. I have been researching this for a while. Syvecs allows for the change.

[nycplumber]

Originally Posted by peter de la mare

It has the proper GTS tune on it. I could just try re-flashing it.

Have you tried the stock version?

[peter de la mare]

Originally Posted by nycplumber

Have you tried the stock version?

No.

[bigjae1976]

Originally Posted by warp10

Changing the diff ratio with out somehow telling the ecu that it's changed is not a good idea. Over revs can happen. The ecu is expecting a certain ratio so it rev matches based on that. If you change the ratio it is still going to assume the stock ratio. Just my .02. I have been researching this for a while. Syvecs allows for the change.

I've been told that the ECU has no final drive setting like the MSS54 has.

[peter de la mare]

It seems this is the byte that needs changing. I hope to get it done in the next couple of weeks.

[Redd]

Any update on this? Has changing the byte fixed your shifting issues?

[peter de la mare]

Originally Posted by Redd

Any update on this? Has changing the byte fixed your shifting issues?

Not yet, still getting my ass in gear.

[Adrian g.]

Originally Posted by peter de la mare

I need to update this. The downshift blips are all messed up. I finally got some good track day time last night and with the shift speed set at 6, the downshifts were mistimed and way too low.

Luckily my car is getting a Syvevs ECU installed and mapped in a couple of weeks' time which will resolve this.

Originally Posted by peter de la mare

On track I only ever use manual mode and in setting 6. The downshifts do not rev match at all, and it’ll drop into gear and match revs once the gear is engaged. I’ll upload a video of my trackday on Monday and you’ll see.

So for those of us with a dual purpose car, the 3.62 diff (for DCT cars) is a no go?

[peter de la mare]

Originally Posted by Adrian g.

So for those of us with a dual purpose car, the 3.62 diff (for DCT cars) is a no go?

No, it's fine in D. Hopefully once this map tweak for the final drive is done it'll be ok in manual also. It's totally usable now, just lacking the downshift blip from 3rd upwards.