Differentials

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10-19-2006 | 06:42 PM

vegastrashed

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My Ride: 2007 E63 AMG | Obsidian Black | Schwarzes Nappa | Black BirdEye Maple | Premium II Package | Electronic Trunk Closer | Parktronic Engine: RPi/Powerchips custom ECU tune, RPi Ram Air Kit (BMC filter, scoops), RennTech Sport exhaust, secondary cats, charcoal and resonator delete, custom AAA x-pipe Exterior: 50% side windows / 35% rear window Formula One Pinnacle Series | Flat AMG hood emblem Suspension: Renntech Lowering Module Wheels/Tires: Radenergie R10, Falken FK452 245/30/20, Yokohama ADVAN Sport 285/25/20 ----------------------------------------- 2005 545i Sport SMG | Ti Grau | Schwarzes Dakota | Anthracite Maple | Logic 7 | Nav Engine: Custom AFE CAI, Superchips ECU remap, Sprint Booster, RDSport Dual Exhaust Conversion with Quad Pipes and X-pipe, 3 resonators deleted, 90mm tips! Exterior: M-Tech Aero kit | M5 Mirrors | M5 Rear Bumper | Trunk Lid Finisher | Vorsteiner decklid spoiler | 50% Formula One Pinnacle Tint Suspension and Brakes: Bilstein PSS9 coilovers, JBT BBK: 16" cross-drilled rotors, 8 piston and 15" cross-drilled rotors, 4 piston Wheels: VIP Modular VR 02 20x9F, 20x10R | Toyo T1R 245/30/20F, 285/25/20R Lights: PIAA 4150K Xtreme White Plus fog lights, AIB v3 MOST IMPORTANT: Hardwired V1; =) ED Date: 4/7/05, Re-delivery date: 5/21/05

I have been wondering why the manuals and SMGs have a lower final drive ratio (2.91) than a Step (3.46)? Znod and grogan545 both agree that the final drive ratio of the Step is a contributor for their excellent timed runs. Why can't BMW just outfit the manuals and SMG with the same 3.46 as the Step?

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10-19-2006 | 07:18 PM

EBMCS03

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Ya it has to be the first and second gear ratio + rear differential which gives the Step the edge on acceleration.

Well with a higher final drive ratio you get less top end speed... maybe thats why BMW chose to give the manuals a higher final drive ratio... so they can drive faster on the autobahn...

Thats prob not the only reason... but a combination... RPM when crusing in 6th along with the avilability of a manual gear box that has the same gear ratios as a auto tranny so they changed the final gear ratio to make the crusing rpms similiar?

Fuel Economy... we dont care but BMW does.. and needs to make them similiar also...

I dunno. just my guesses... thats all i can guess for now. brain is stuck and fried.

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10-19-2006 | 07:33 PM

ImolaRedM

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That's a good question. It would be nice if at least BMW offered more agressive gearing on the sport package as they did with the E39.

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10-19-2006 | 07:33 PM

vegastrashed

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Even more confused as ever...

EDIT: In response to EBMCS03's reply.

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10-20-2006 | 07:19 AM

UUronL

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Quote:

Originally Posted by ImolaRedM' post='346877' date='Oct 19 2006, 10:33 PM

That's a good question. It would be nice if at least BMW offered more agressive gearing on the sport package as they did with the E39.

Well, luckily for the 530i owners here... the diff is a lot better than what our V8 manual brethren get...

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10-20-2006 | 07:48 AM

vegastrashed

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Quote:

Originally Posted by UUronL' post='347017' date='Oct 20 2006, 07:19 AM

Well, luckily for the 530i owners here... the diff is a lot better than what our V8 manual brethren get...

UUronL,
I was hoping that you would answer the question... You and Znod had answered regarding diffs awhile back ago explaining the ratios but why did BMW stick the manuals and SMG with crappy ones?

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10-20-2006 | 11:31 AM

AlexFW

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My Ride: 545i SMG with Limited Slip Differential

Model Year: 2005

645ci (3.23) : 5.6s
545i (2.93) : 5.8s

Technicians @my dealer are searching infos from germany for change the differential ...

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10-20-2006 | 01:22 PM

vegastrashed

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Quote:

Originally Posted by AlexFW' post='347112' date='Oct 20 2006, 11:31 AM

645ci (3.23) : 5.6s
545i (2.93) : 5.8s

Technicians @my dealer are searching infos from germany for change the differential ...

Are you quoting the reported 0 - 60 times?

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10-20-2006 | 02:15 PM

AlexFW

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My Ride: 545i SMG with Limited Slip Differential

Model Year: 2005

Quote:

Originally Posted by vegastrashed' post='347142' date='Oct 20 2006, 10:22 PM

Are you quoting the reported 0 - 60 times?

No, 0-100 kmh, obviously

.

Anyway ... 545i and 645ci have the same weight but with different differential there is a difference of 0.2s .

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10-20-2006 | 02:46 PM

#10

BetterMakeWay

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Confused...so that means that the steptronic is better at 1/4 runs or so?!

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