|
|
SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS! |
Post Reply |
|
Thread Tools | Search this Thread |
02-03-2011, 08:26 AM | #1 |
Private First Class
9
Rep 120
Posts |
Differential Question
Hey,
Any point swapping to a 3.91 LSD. I believe my 06 auto-manual has a 3.73 stock. Is it worth it to swapping for such a small difference? Thanks.
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
02-03-2011, 08:40 AM | #2 | |
Lieutenant General
2282
Rep 12,565
Posts
Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT
iTrader: (99)
Garage List F15 X5 xDrive35i [8.75]
E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.22] |
Quote:
I would've done a 3.73 which was about an 8% change but the price was even HIGHER for 3.73 over a 3.64 so I didn't bother. The Quaife + rebuild was already putting me at the end of my budget. The upgrade was worthwhile but not for the cost. So if your installer is not going to charge you anything more for taller gearing, I'd go with the 4.10s... Other things to consider, at what speeds do you typically drive your car? Does it see alot of freeway miles, is this a dedicated track car, etc? But given the lack of mods for the n52, I think torque multiplier effect from taller gearing is really your best mod (plus the limited slip). |
|
Appreciate
0
|
02-03-2011, 12:28 PM | #3 |
Private First Class
9
Rep 120
Posts |
Its not a track dedicated car. Daily driver really .... spirited driving now and then. Some autocross ....
the reason i was thinking 3.91 was because i thought 4.10 would make it impossible to drive daily (too jerky and i would be at higher RPM's all the time) .... what do u think??? oh and 4.10 is the same price ....
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
Appreciate
0
|
02-03-2011, 12:45 PM | #4 |
Colonel
886
Rep 2,736
Posts |
hey their! id stick with your 3.73 gears, your already higer than the rest of the z4's but a 4.10 rear will kill your gas milage and youll be reving way higer on the higeway, could be a 1000 rpm increas in some cases was with my 1971 charger anyway.
your rear diff is already a real good number for fuel and performance, at least you can say you have a higher diff out of the box than a stock M and SI's for that matter. For the cost youll get more of a difference and way cheaper going with that 3 stage intake mod anyway. oh yea teh 3.91 you wont notice anything and youll be pi$$ed you spent all that money! either way you slice it changing the rear diff will be over a grand to possably 2K depending on labor and parts. |
Appreciate
0
|
02-03-2011, 02:13 PM | #5 | |
Lieutenant General
2282
Rep 12,565
Posts
Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT
iTrader: (99)
Garage List F15 X5 xDrive35i [8.75]
E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.22] |
Quote:
easiest way to solve your question is look at how you drive now. look at your current shift points and your typical cruising speed/gear, and then compare the effect of taller gearing. the change in rpms is linear, so 5% change in gearing is a 5% change in your rpms. few members here went with taller gears, and the only regret is those who didn't go high enough. search around and you'll see threads on this. if you're only going 5% change, i say don't even bother then and save your money. the limited slip alone would put a big smile on your face. Last edited by 3002 tii; 02-03-2011 at 02:19 PM.. |
|
Appreciate
0
|
02-03-2011, 02:59 PM | #6 | |
Colonel
886
Rep 2,736
Posts |
Quote:
Yea I guess I was not really being apples for apples as my experience with my 4:10 rear on my charger was always making my motor sing on the high way so extended drives got a little worried about my engine grate for stop light take offs though. I was just saying his rear end is a good rear end for a daily driver that's all. So yea it be like knocking it over to sport mode. |
|
Appreciate
0
|
02-03-2011, 04:50 PM | #7 |
Private First Class
9
Rep 120
Posts |
-C- .... I actually just got a huge scholarship from Boeing ..... So, I can, if I want, get the manifold swap done as well as put in a diff .....
I'm trying to see if the diff is a good idea. If not ill get KW coilovers.
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
Appreciate
0
|
02-03-2011, 05:08 PM | #8 |
Captain
55
Rep 815
Posts |
Ah, the familiar refrain... I remember when I got my fellowship in grad school the first thing I did was run out and blow the entire first months pay on comp tires for my Autox car. A year later I was doing my first engine swap in my department secretary's garage. The bug never quit's biting.
|
Appreciate
0
|
02-03-2011, 09:52 PM | #9 |
Private First Class
9
Rep 120
Posts |
Oh and what about recalibrating the speedo?
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
Appreciate
0
|
02-03-2011, 11:27 PM | #10 |
Colonel
479
Rep 2,782
Posts
Drives: ESS/G-Power Z4M, VF Z4, 996tt
Join Date: Sep 2009
Location: Los Angeles
|
You don't need to recalibrate about the speedo. Dubbedown is correct.
|
Appreciate
0
|
02-04-2011, 12:25 AM | #11 | |
Private First Class
9
Rep 120
Posts |
Quote:
Also it seems 4.10's are the way to go .... no jerkiness/insane increase in gas mileage then?????
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
|
Appreciate
0
|
02-04-2011, 07:58 PM | #12 | |
Private First Class
9
Rep 120
Posts |
Quote:
any further inputs ..... about the speedo and the jerkiness??? i tried lookin up posts but didnt find anything to answer the questions ....
__________________
BMW Performance | SuperSprint | 17" M3 CSL Replica's | Active Autowerke | Stop Tech | RPI | 3.0I to 3.0SI Conversion
|
|
Appreciate
0
|
02-24-2011, 11:06 AM | #13 | |
Supreme Allied Commander
3839
Rep 54,348
Posts
Drives: F80 M3
Join Date: Mar 2007
Location: Santa Barbara, AP, Brembo, GIAC, Koni, Ohlins, Performance Friction, www.hpautosport.com
|
Quote:
The only jerkiness I can see happening is if you were to have a clutch type LSD that is engaging and disengaging all the time. If you ever driven a car with a detroit locker, you will know what I mean. You will never have such a thing with the Quaife, it's super quiet, you wont' even know it's there. |
|
Appreciate
0
|
Post Reply |
Bookmarks |
|
|