DCT 3.15 differential into 6 speed

[Inflame]

I'm curious if anyone has downgraded their 6 Speed 3.85 to a DCT 3.15 differential.

The cost would be nearly zero, just labor, as you can sell the 6mt unit for exactly what you paid for the DCT unit.

Lowering overall RPM per gear per mph is the goal. I understand the car would be a bit 'slower' but a supercharger would help with that

Thank you!

[Patrón]

Originally Posted by Inflame

I'm curious if anyone has downgraded their 6 Speed 3.85 to a DCT 3.15 differential.

The cost would be nearly zero, just labor, as you can sell the 6mt unit for exactly what you paid for the DCT unit.

Lowering overall RPM per gear per mph is the goal. I understand the car would be a bit 'slower' but a supercharger would help with that

Thank you!

i have a dct and would be willing to swap

[doogee]

If you got an M3 and are trying to save fuel, you got the wrong car lol.

This swap doesn't make a lot of sense I don't see a benefit?

[Richbot]

Might make sense on a Harrop car? Otherwise yeah, that's a lot of gear for a teeny engine to pull around, might make a little bit of sense paired with a 285/30-18 rear tire

[doogee]

Originally Posted by Richbot

Might make sense on a Harrop car? Otherwise yeah, that's a lot of gear for a teeny engine to pull around, might make a little bit of sense paired with a 285/30-18 rear tire

If he's going for top speed and fuel economy sure.

Otherwise he's just slowing the car down for no reason.

[Inflame]

My reasoning is personal, I own this car for other reasons than it's performance, it is the slowest car in my fleet. My E36 M3 makes more whp out of an NA v8.

Please only comment if you've thought about doing the swap or have done it, i'd like to hear from personal experience from people who have done a ratio swap to a manual car to a lower ratio.

[e92Mjunky]

I will have a diff available for E92 with a 3:62 in it, may make a good compromise

[deansbimmer]

Nobody with a 6MT has gone to a 3.15 because it's a batsh!t crazy idea.

[Inflame]

The 3.62 is a good compromise to my end goal, it'll keep great acceleration and lower RPM's on long highway trips... I may consider it.

Ideally changing the final drive is not what I want to do, but it's easier than developing a lower ratio 6th gear. I am looking for a blown transmission I can dismantle and possibly machine my own 6th gear....

[Green-Eggs]

Originally Posted by Inflame

I'm curious if anyone has downgraded their 6 Speed 3.85 to a DCT 3.15 differential.

The cost would be nearly zero, just labor, as you can sell the 6mt unit for exactly what you paid for the DCT unit.

Lowering overall RPM per gear per mph is the goal. I understand the car would be a bit 'slower' but a supercharger would help with that

Thank you!

Yes it's been done. We installed a 3.15 in Robert's stroked, supercharged E92 Texas Mile car. We both found it very drivable with the 3.15 when the supercharger was installed. Not so much when we put the stock engine back in. Today the differential is back to stock 3.85 with a stock motor.

[BadBoostedBMWM3]

Originally Posted by Green-Eggs

Yes it's been done. We installed a 3.15 in Robert's stroked, supercharged E92 Texas Mile car. We both found it very drivable with the 3.15 when the supercharger was installed. Not so much when we put the stock engine back in. Today the differential is back to stock 3.85 with a stock motor.

Do you mean pencil geek's car?

If so, what happened to it?

[Green-Eggs]

Originally Posted by BadBoostedBMWM3

Do you mean pencil geek's car?

If so, what happened to it?

Yes. It was turn totally back to stock so it could become the BE Bearings test vehicle.
http://www.m3post.com/forums/showthread.php?t=1337998