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Discussion Starter #1
would rather not have another shift before 60 ticks....i know, i know im talkin straight line here....but please throw me a bone. found a cheap 3.46, but why did bmw only install a 3.07 on the zhp tho?
 

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Keeping it surreal
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would rather not have another shift before 60 ticks....i know, i know im talkin straight line here....but please throw me a bone. found a cheap 3.46, but why did bmw only install a 3.07 on the zhp tho?
So why don`t YOU explain what`s the BFD about shifting to third at 55 or so, rather than 61 mph? Most guys around here would love to have that 3.46....
 

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Living Life At The Beach
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would rather not have another shift before 60 ticks....i know, i know im talkin straight line here....but please throw me a bone. found a cheap 3.46, but why did bmw only install a 3.07 on the zhp tho?
Because it has a six speed transmission instead of a five speed?
 

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Discussion Starter #4
Because it has a six speed transmission instead of a five speed?
so 3.07 is only avail in six speed trim? i was wondering because i hadn't seen a 3.07 yet to buy. it seems OEM is usually kinda conservative with ferocity on upgraded cars like the zhp. or am i wrong is 3.46 avail on something from BMW? not to say that 3.46 is like a flux capacitor or anything....
 

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Discussion Starter #5
So why don`t YOU explain what`s the BFD about shifting to third at 55 or so, rather than 61 mph? Most guys around here would love to have that 3.46....
because most guys around here autocross...c'est la vie
 

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Is it Trackday yet?
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so 3.07 is only avail in six speed trim? i was wondering because i hadn't seen a 3.07 yet to buy. it seems OEM is usually kinda conservative with ferocity on upgraded cars like the zhp. or am i wrong is 3.46 avail on something from BMW? not to say that 3.46 is like a flux capacitor or anything....
3.46 is on auto E46's. The one I put in my car was likely from a 325i.

Here's a great site on BMW diff ratios...

http://www.bokchoys.com/differential/GearRatios.htm
 

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Discussion Starter #7
3.46 is on auto E46's. The one I put in my car was likely from a 325i.

Here's a great site on BMW diff ratios...

http://www.bokchoys.com/differential/GearRatios.htm
that's a great link! thanks man. so what i gather from that sheet is that 3.46 is quite conservative as well...and that it wont have much loss in terms of drivability. can i guessimate -2 mpg was what i had read, and actually better low speed drivability in 2nd gear instead of having to use 1st. more downsides though? rpms cant be that much higher at 80 right?
 

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that's a great link! thanks man. so what i gather from that sheet is that 3.46 is quite conservative as well...and that it wont have much loss in terms of drivability. can i guessimate -2 mpg was what i had read, and actually better low speed drivability in 2nd gear instead of having to use 1st. more downsides though? rpms cant be that much higher at 80 right?
It's not radical. My neighbor has an E36 M3 LTW race car with a 4.10 in it. He also has a bunch more revs than me. His car is a face stretcher when he gets on the loud pedal.

Overall the 3.46 a slight difference in fuel economy, but as KrisL and others have commented, the extra "get up and go" makes you get on the loud pedal more than you were before cuz it's so much more fun to drive.

I find 3rd gear to be more usable with the 3.46 for the mountain driving I do most. You're always in the power band this way. Sixth gear is now more usable on the freeway too. I can pass without having to downshift to 5th.

On the race track I find I run out of 4th on long straight aways with the 3.46. So, my top speed at the end of the front straight at Thunderhill, for instance, may be down a little cuz I should probably shift to 5th, but by the time I get that done, it's time to shift back down to 4th for Turn 1. The solution is to get out of the turn before the straight faster so I can shift to 5th sooner. :D

I'm not racing so I'm not too concerned about that anyway. At the track I have more power to dig myself out of slower corners with the 3.46. There is one turn, Turn 11, at Thunderhill that I would always feel like I was dragging a train car behind me trying to get out of it. With the 3.46 I have a little extra oomph in 2nd and can get out of that corner much better now.

I think it transformed my car's performance and I know others who have done it agree too. None of us regret it, especially for the killer deals we got last year. I paid under $250 for the diff and about $200 to have it setup and installed. Putting a 325i diff in a 330i required swapping the flanges. I figured I put a lot of stress on the diff, I rather not learn a hard lesson at the track by doing it myself. Some things I just prefer to leave to the pros.
 

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Discussion Starter #9
It's not radical. My neighbor has an E36 M3 LTW race car with a 4.10 in it. He also has a bunch more revs than me. His car is a face stretcher when he gets on the loud pedal.

Overall the 3.46 a slight difference in fuel economy, but as KrisL and others have commented, the extra "get up and go" makes you get on the loud pedal more than you were before cuz it's so much more fun to drive.

I find 3rd gear to be more usable with the 3.46 for the mountain driving I do most. You're always in the power band this way. Sixth gear is now more usable on the freeway too. I can pass without having to downshift to 5th.

On the race track I find I run out of 4th on long straight aways with the 3.46. So, my top speed at the end of the front straight at Thunderhill, for instance, may be down a little cuz I should probably shift to 5th, but by the time I get that done, it's time to shift back down to 4th for Turn 1. The solution is to get out of the turn before the straight faster so I can shift to 5th sooner. :D

I'm not racing so I'm not too concerned about that anyway. At the track I have more power to dig myself out of slower corners with the 3.46. There is one turn, Turn 11, at Thunderhill that I would always feel like I was dragging a train car behind me trying to get out of it. With the 3.46 I have a little extra oomph in 2nd and can get out of that corner much better now.

I think it transformed my car's performance and I know others who have done it agree too. None of us regret it, especially for the killer deals we got last year. I paid under $250 for the diff and about $200 to have it setup and installed. Putting a 325i diff in a 330i required swapping the flanges. I figured I put a lot of stress on the diff, I rather not learn a hard lesson at the track by doing it myself. Some things I just prefer to leave to the pros.
ok cool im probly gonna go that route. i already found one from bav auto recyclers on ebay, for the price you mentioned. hopefully i can get labour for that much as well. so on a 5spd is a flange swap required as well? thanks, great excerpt btw.
 

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Speaking of the 3.46 diff, I find that mine 'screams' a lot when I punch it while in 2nd from roughly 5500rpms to redline. This only happens in this gear and was wondering if any of you guys who switched experience the same. Both my indy and the dealer claim they don't see anything wrong, but I'm not convinced. Problem is I can't remember how my 3.07 used to sound in similar situations before the switch to offer a comparison. I wonder if a fluid switch (to Redline which I will perform in the next 5 days) will mitigate this 'noise'?

Other than that, as everyone has commented, second gear is much more usable when taking-off from a dead stop on a flat road and fourth - I call it the crazy zone - bacause I can just about manouver with easy in any tight situations, including curves and ramps...
 

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Speaking of the 3.46 diff, I find that mine 'screams' a lot when I punch it while in 2nd from roughly 5500rpms to redline. This only happens in this gear and was wondering if any of you guys who switched experience the same. Both my indy and the dealer claim they don't see anything wrong, but I'm not convinced. Problem is I can't remember how my 3.07 used to sound in similar situations before the switch to offer a comparison. I wonder if a fluid switch (to Redline which I will perform in the next 5 days) will mitigate this 'noise'?

Other than that, as everyone has commented, second gear is much more usable when taking-off from a dead stop on a flat road and fourth - I call it the crazy zone - bacause I can just about manouver with easy in any tight situations, including curves and ramps...
Come on guys, someone ought to have an idea...? :mad:
 

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Come on guys, someone ought to have an idea...? :mad:
Nope, mine's as quiet as stock. Changed the fluid lately? I had the fluid changed when my 3.46 was installed.

I sold my 3.07 locally for $100.

If I had a 5spd instead of a 6spd, I may have opted for a 3.23 or something to keep the highway revs a bit lower.
 

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chillen
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OP, I have a 3.23, the previous owner installed. Its got pepp in its step. The noise isnt all to bad, while doin 80 mph the car is @ 3500rpms, and I dont need to downshift to 4th hardly ever for a normal pass. just my 2 cents.
 

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If you've got a 5 speed your rear gear is going to be spinning faster for a given RPM v.s. A 6 speed. I had a 533i and went from3. 25to. 3. 73. Awesome acceleration but 1st gear was almost useless especially in the rain.
 

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Nope, mine's as quiet as stock. Changed the fluid lately? I had the fluid changed when my 3.46 was installed.

I sold my 3.07 locally for $100.

If I had a 5spd instead of a 6spd, I may have opted for a 3.23 or something to keep the highway revs a bit lower.
I'm planning on changing the fluid this weekend. That was my first suspicion since I started experiencing that 'noise' lately.

Just in case it's not the diff, what else could cause such a high pitched gear when in second gear? Maybe it's in my head, but I swear it doesn't happen in any other gear.. :dunno:
 

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I'm planning on changing the fluid this weekend. That was my first suspicion since I started experiencing that 'noise' lately.

Just in case it's not the diff, what else could cause such a high pitched gear when in second gear? Maybe it's in my head, but I swear it doesn't happen in any other gear.. :dunno:
Well, if something is only happening in one gear, I'd suspect the transmission.

You should be able to run through the same speed range in 3rd gear (albeit with less tq) to see if it's the diff..
 
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