This weekend i will swap the diff from a 2,93 to a 3,91 (e34 m5) I need to know torque (NM) to tight the 18 bolts to the shafts?
Diff. Swap
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Why would you put a 3.91 on a 5-speed when you have a supercharger? You'll end up at 2700 rpm at 100 kph. And you'll top out at ~230
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I want it quickly from the start. I have no need to drive my car in over 200kph on the miserable norwegian roads,(especially where i live.) Also i am pretty sure my top speed will increase now, because there is not enough road or power to drive my 2,93 ratio to 212mph (341kph) as it theoretical can. Also i have 22" wheels. Found this one on this forum:
Changing to a quicker ratio provides faster acceleration in all gears at all rpm's. It does not affect engine emissions or idle speed and can make up for changes in tire diameter. Some BMW models were originally geared very long for increased fuel mileage. These cars benefit the most from quicker ratios.Generally, longer ratios yield better fuel mileage and shorter ratios offer more acceleration and higher fuel consumption. In practice, the fuel difference is often slight. If you have such a long ratio you must frequently downshift to pass or accelerate quickly, then in reality you do not get the theoretically higher fuel mileage that the longer ratio would have you expect. And, if you switch to a shorter ratio for more acceleration, you may not burn much more gas than before, as you are now able to upshift more quickly into the higher gears.
In a similar way, you would expect that changing to a shorter ratio for more acceleration will reduce your top end speed a you would run out of revs in high gear. However, few cars have enough top end torque to pull full revs in high gear. Changing to a shorter ratio will usually enable the engine to pull more revs against the high speed drag resistance. Though you will turn more revs per mile, your actual top end speed may be as good or better than before, especially if you have added some additional performance improvements.
The following formula will enable you to calculate your possibilities, but keep in mind actual results will vary. Drag, rolling resistance, tire characteristics, spoiler packages and engine modifications all affect acceleration and achievable top end speed. And don't forget road conditions, speed limits, and radar! It is usually more practical to gear for greater acceleration than higher top end speed. You can enjoy it more often with fewer penalties.
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I think what Adrian was saying is that the very short ratio will limit your top speed due to the maximum revs of the engine. With the 6-speed box and a 6th gear ratio of 0.831 you will hit maximum revs (6200 RPM) at 145 MPH.
Cruising at 80 MPH, your engine will be turning over at 3400 RPM which is excessive for comfort.
More importantly, you will need to hack through 5 gear changes to reach 100 MPH whereas an 840ci will still be in 3rd gear and probably ahead of you!
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What was the legal speed limit in Norway again?
80mph is what they legally can only dream of
I seem to remember signs saying 70 all over the place... 70kph mind you
Everything else said makes sense though. With a 3.91 backend you will have no need for 1st gear anymore. You´d not be the first one to swap in such a ratio and for the purpose of being relatively quick off the line or spin your wheels it´ll be the best choice there is off the shelf.
In terms of achievable top speed (if you find a Norwegian place to try) you may be in for a nasty surprise since there seems to be yet another rev limiter either in the gear box or by way of the DME which just jumps in your face with a "Trans Fail Safe" message once exceeding a certain engine rev in highest gear.
Show us your 22" rims! I have seen 20´s but not 22´s so far.Cheers
Reinhard -
Zitat von reinhard;93490Alles anzeigen
What was the legal speed limit in Norway again?
80mph is what they legally can only dream of
I seem to remember signs saying 70 all over the place... 70kph mind you
Show us your 22" rims! I have seen 20´s but not 22´s so far.
Cheers
Reinhard
Guess this is the ones ? In his album by the way
And for the speed limits well you know hove we struggle
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looks like pure alloy evaporated with a little rubber 
Terje, would this be the ultimate winter 8-series for norway?
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Zitat von Timm;93486
Cruising at 80 MPH, your engine will be turning over at 3400 RPM which is excessive for comfort.
At that RPM the supercharger will be on constant boost, not giving you any advantage of the increased low end torque. With norwegian fuel prices that is the last thing i'd want.Zitat von Timm;93486
More importantly, you will need to hack through 5 gear changes to reach 100 MPH whereas an 840ci will still be in 3rd gear and probably ahead of you!
This is what i thought. I know the 5-speed is a fairly quick auto box, but i don't think you will hack that much of 0-100 mph times. With the supercharger you have the perfect blend of gear ratios at 2.93, maybe 3.15, with the five speed. But i wish you good luck on your 3.91 voyage.The 8-series is no racer. It's no supercar. It's a Grand Tourer, please treat it as such.
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Zitat von 8Harry8;93492 looks like pure alloy evaporated with a little rubber
Terje, would this be the ultimate winter 8-series for norway?
Ha ha it actually look's a bit cool
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3.64 and 3.15 is hard to get a hold of with lock, most of them are open. 2.93 is a lot easier
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Where i bought the 3,91 also has a 3,64 and a 3,15 with lock.
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It is time to put it in. (dirty car
)
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