[SF335]

I am planning to put an LSD into my 2011 335i 6MT and am debating whether to change the final drive ration from the 3.08 to a 3.46. It looks like doing the 3.46 is about $800 cheaper, which is quite nice. The car is my DD but will see a lot of track time.

I would love to get some input from those who have done this, how you use the car, and whether you would do it again/recommend it.

Thank you.

[feuer]

How many of these threads are you going to start? Your questions have been answered already.
http://www.e90post.com/forums/showthread.php?t=1455561
http://www.e90post.com/forums/showthread.php?t=1455560

[SF335]

Originally Posted by feuer

How many of these threads are you going to start? Your questions have been answered already.
http://www.e90post.com/forums/showthread.php?t=1455561
http://www.e90post.com/forums/showthread.php?t=1455560

This is rude. I am not looking for an answer to a question, I am collecting impressions so I can make this decision. If you notice, the last two threads I started on this topic only had two comments from people who actually did this (neither of whom track their cars). I also realized that this is probably the right forum for this question, since it is the drivetrain forum for both the n55 and n54 and gets the most viewers.

I saw your reply in the other thread and thank you for sharing your thoughts but you did not even mention if you've tried the 3.46. Perhaps it offends you that you shared your opinion and yet I am still seeking more opinions, in which case I am sorry.

If there is a way to merge the threads, or if there is a rule against double posting, I would be grateful if someone let me know.

[feuer]

Originally Posted by SF335

This is rude. I am not looking for an answer to a question, I am collecting impressions so I can make this decision. If you notice, the last two threads I started on this topic only had two comments from people who actually did this (neither of whom track their cars). I also realized that this is probably the right forum for this question, since it is the drivetrain forum for both the n55 and n54 and gets the most viewers.

I saw your reply in the other thread and thank you for sharing your thoughts but you did not even mention if you've tried the 3.46. Perhaps it offends you that you shared your opinion and yet I am still seeking more opinions, in which case I am sorry.

If there is a way to merge the threads, or if there is a rule against double posting, I would be grateful if someone let me know.

rude or not your questions have been answered sufficiently for you to make a decision. From cost perspective to performance. I have done probably over 50 track days in my 335i MT and therefore, I don't really need to drive one with 3.46 ratio to know how it will behave. I know well what the change of ratio will do. But hey, by all means, if you think isn't enough continue duplicating the same thread. I sincerely hope you will figure it out soon.

[SF335]

Originally Posted by feuer

I sincerely hope you will figure it out soon.

Thanks. I have to purchase the LSD soon so I have to figure it out ASAP!

I hope this bickering doesn't dissuade others from sharing their actual experience with a 3.46 on an MT so please share your thoughts. Thank you!

[ASBSECU E93]

Originally Posted by feuer

How many of these threads are you going to start? Your questions have been answered already.
http://www.e90post.com/forums/showthread.php?t=1455561
http://www.e90post.com/forums/showthread.php?t=1455560

@feuer - so, same question but a different application.

I'm going LSD as well for a high WHP 135. As you know, the lag on a 6780 is unavoidable (unless I use nitrous to spool quicker).

[feuer]

Originally Posted by ASBSECU E93

@feuer - so, same question but a different application.
I'm going LSD as well for a high WHP 135. As you know, the lag on a 6780 is unavoidable (unless I use nitrous to spool quicker).

I would keep 3.08 on MT n54. Turbo engines like load and I don't like peak power at low RPM. Might be better for track on ST n54 but for drag I don't think so.
Originally Posted by Terry @ BMS
FWIW we made these gearing changes to both of our N54 MT development cars... And then later regretted it and changed back... Mainly due to track gearing. MTs need those 3.08s to avoid the 4-5 shifts in the 1/4 and 5-6 shifts in the 1/2 mile at higher power levels.

[SF335]

I talked to TC Kline today and in their opinion there is no doubt that 3.46 is the way to go on a track oriented vehicle.

Drag racing is obviously a different application.

[marcvtec]

@ Feuer - Relax bud.
This gentlemen is asking questions, and its not your mom asking you questions.
Take your tampon out.

@SF335 - Keep asking questions, who cares about this guy and his superstar keyboard responses. Your car, your way ! - enjoy.

[SF335]

Originally Posted by marcvtec

@ Feuer - Relax bud.
This gentlemen is asking questions, and its not your mom asking you questions.
Take your tampon out.

@SF335 - Keep asking questions, who cares about this guy and his superstar keyboard responses. Your car, your way ! - enjoy.

Thank you so much! Reading this was certainly uplifting after the unnecessary bashing from Feuer - and funny! I'll continue researching and calling around - as I gather more information I will post here for everyone's benefit.

[marcvtec]

Originally Posted by SF335

Thank you so much! Reading this was certainly uplifting after the unnecessary bashing from Feuer - and funny! I'll continue researching and calling around - as I gather more information I will post here for everyone's benefit.

Please do post your information, thats what keeps this community alive.
I've been here for 12 years and there is a reason why.
Do your thing, and let others respond as they think is needed.
Cheers.

[feuer]

Originally Posted by marcvtec

@ Feuer - Relax bud. Take your tampon out

Very good I like it

[Chris@VargasTurboTech]

Kinda depends on the power range and capability of the vehicle. On stock turbos it'll likely make the car feel more lively around town but obviously first gear is going to be less useful than normal. Since you track the car, you have an idea of the fastest speeds you'll pull on the straights -figure out if that will cause an extra shift and if you care.

I also have a 6MT, and I'm going 3.14 (M3 diff) when I upgrade. You can get a used M3 diff, with upgraded axles, for cheap. You will need a custom driveshaft though. Still, it ends up being like $200 more for me to go custom driveshaft and all M3 parts including axles than to just swap rear diff with new. (I sweet talked Tony into selling me his carbon driveshaft for cheap).

Chris

[SF335]

The M3 LSD is a cool option. It's nice to stay with BMW parts although it seems like a bit of a hassle.

I just talked to Harlod at HPA. His advice is that if the car is driven on the street, to stay with 3.08 because first and second become too aggressive and the advantages at the track really depend on the particular track.

Interesting how divided this is...

[V8bait]

I already think the 3.08 is too short and was considering a 2.84 from the 335d. 3.46 would suck if you're anything other than bone stock without a tune IMO. 3.15 is the shortest I'd go with bigger tires.

Look up the gear ratios and calculate speed vs rpm to see when you'd have to shift, if you can be in the ideal gear for the 1/4 or 1/2 mile, freeway rpm etc to decide.

[feuer]

Originally Posted by V8bait

I already think the 3.08 is too short and was considering a 2.84 from the 335d. 3.46 would suck if you're anything other than bone stock without a tune IMO. 3.15 is the shortest I'd go with bigger tires.

Look up the gear ratios and calculate speed vs rpm to see when you'd have to shift, if you can be in the ideal gear for the 1/4 or 1/2 mile, freeway rpm etc to decide.

You tune these cars so know them definitely better then me, but never the less my track experience makes me agree with you. Shorter gearing would result in more gear changes, more boost drops, more bogging. Turbo engines need load so is better to stay in gear longer.

[drunkenup]

Get to the track and make this decision for yourself. You don't need the LSD yet if you don't know what final drive is right for you. 2 years of doing DE's and I don't want to trade overdrive for a stronger 3rd gear.

I'd never go with a faster rear end on a high HP build. You're shifting the torque curve right and losing spool, why would you reduce your time in gear?

[SF335]

I appreciate everyone's feedback. From these replies and from reading old threads it's interesting to see that people who haven't done the switch to 3.46 don't recommend it and people who have, do. I guess we see this mental bias quite often when it comes to doing mods.

It would still be great to hear from those who have switched to 3.46 - I know there must be quite a few people here who have.

On a related note, does anything need to be changed in the programming/tuning of the car if changing the final drive ration?

[berns]

3.46 all fucking day. I ran a 3.08 on my E90 street/track car and now running the 3.46 in my 135i track toy, I'll never go back. Car finally feels lively, in every gear. I recommend buying your fully built pumpkin from Dan @ Diffsonline.

[langsbr]

Originally Posted by berns

3.46 all fucking day. I ran a 3.08 on my E90 street/track car and now running the 3.46 in my 135i track toy, I'll never go back. Car finally feels lively, in every gear. I recommend buying your fully built pumpkin from Dan @ Diffsonline.

What is your setup though?

I have to agree with V8Bait - I don't see how a 3.46 would be livable or useful. I sure wouldn't want to drive it on the highway either.

OP - why is the 3.08 $800 more than the 3.46? Do you have a welded diff and have to purchase the whole assembly or something? I just don't see the ratio having anything to do with price.

[berns]

Originally Posted by langsbr

What is your setup though?

I have to agree with V8Bait - I don't see how a 3.46 would be livable or useful. I sure wouldn't want to drive it on the highway either.

OP - why is the 3.08 $800 more than the 3.46? Do you have a welded diff and have to purchase the whole assembly or something? I just don't see the ratio having anything to do with price.

Liveable? Why are BMW forum dudes such pussies about everything?
Have you ever driven an S2000 or Evo on the street?

3.46 is both livable and useful. Sure, RPMs are higher at 80mph than they were before. Also, the OP asked what is better on the track. Those building cars for street & track have to choose which they care about more. I'm willing to make sacrifices in comfort, MPG, coasting RPM, for a better car on the track. Everything we do to our cars is preference.

The 3.46 pumpkins wouldn't sell as quickly as they do if they sucked. For drag racing, street driving, runway pulls, keep your 3.08. For track fun, canyons, auto-x, 3.46 all day, in my opinion of course, which is what this thread is about.

And as far as $$ is concerned, not sure where the OP is getting his prices. The 3.46 is usually +$800 on top of the diff itself.

[V8bait]

Originally Posted by berns

Liveable? Why are BMW forum dudes such pussies about everything?
Have you ever driven an S2000 or Evo on the street?

3.46 is both livable and useful. Sure, RPMs are higher at 80mph than they were before. Also, the OP asked what is better on the track. Those building cars for street & track have to choose which they care about more. I'm willing to make sacrifices in comfort, MPG, coasting RPM, for a better car on the track. Everything we do to our cars is preference.

The 3.46 pumpkins wouldn't sell as quickly as they do if they sucked. For drag racing, street driving, runway pulls, keep your 3.08. For track fun, canyons, auto-x, 3.46 all day, in my opinion of course, which is what this thread is about.

And as far as $$ is concerned, not sure where the OP is getting his prices. The 3.46 is usually +$800 on top of the diff itself.

I'd agree with this. Not necessarily faster or friendlier to drive but for playing around in lower gears a 3.46 would be more fun if you're not blowing the tires off with spin.