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Location:
Adelaide
Registered:
August 2003
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final drive 5.1
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Mon, 27 October 2003 13:02
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hey guys...
what is final drive 5.1? anyone got a picture of it..??
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Location:
Brisbane
Registered:
May 2002
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Re: final drive 5.1
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Mon, 27 October 2003 13:16
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Hmmm. I'll bite my tongue. 
The final drive is the ratio of teeth in your crownwheel and pinion gears, inside the differential. A 5.1 ratio means the ratio of the teeth is 5.1:1. This is very low gearing, which means good acceleration off the line but very poor top speed and lots of revs on the highway.
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Registered:
August 2002
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Re: final drive 5.1
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Mon, 27 October 2003 13:25
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Its the day you try dorifto and start with
"hey watch this..."
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Location:
Adelaide
Registered:
August 2003
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Re: final drive 5.1
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Mon, 27 October 2003 14:05
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| BlackSupra wrote on Mon, 27 October 2003 23:55 |
Its the day you try dorifto and start with
"hey watch this..."
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i'm blur..
Norbie: yeah i know its good in acceleration and lose alot in high end....but how much will it lose in topend??
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: final drive 5.1
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Mon, 27 October 2003 14:57
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You're probably getting to the point where the gearing is that short that you'll be forever changing gear and the car will be slower.
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Location:
South Australia
Registered:
July 2002
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Re: final drive 5.1
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Mon, 27 October 2003 15:49
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Yeah - when you get to about 5.1 final drive, you need something that changes pretty quick, button-clutch, lightened flywheel etc etc, probably a close ratio dog-box wouldn't go unmissed either, and an engine with a good spread of torque.
Okay, you don't need these things, but without them you would be changes gears too often to actually be going quicker than if you had something between a 4.5 to 4.8:1 diff.
And your top-speed will have a (near) direct relation with the change in ratio of the diff. So say your previous top speed was 200km/h and you initially had a 4:1 diff (for example) and you changed to a 5:1 diff, you would have 4/5 of 200km/h (20% loss of top speed) which is 160km/h.
In reality, this isn't quite the case due to various non-linear factors (air-resistance being one of them) so you'd probably lose somewhere between 15 to 20% of your top speed in that example.
Your fuel economy will be shot to **** too 
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Location:
Adelaide
Registered:
August 2003
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Re: final drive 5.1
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Mon, 27 October 2003 16:27
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ah..thanks for the info guys..
i guess there's always a tradeoff in getting a better acceleration or a better top speed..
cheers
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Location:
Sydney
Registered:
May 2002
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Re: final drive 5.1
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Mon, 27 October 2003 21:29
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Top speed of a sprinter with 5.1 diff, close ratio gear box and 195/45/15 tyres with a 100KW engine (63KW at the wheels) is about 180K's at the redline.
I know this as thats what the terratrip said going down mountain straight at bathurst 
Cheers
Ben
AE86 Trueno 4AGE
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Location:
Montrose, VIC
Registered:
May 2002
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Re: final drive 5.1
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Mon, 27 October 2003 22:02
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*puts on best advertising testosterone-filled voice*
Final Drive five-point-one - a revolution in driver training and testing. Contact your local Road Train Driving School for more details, or call 1902-456-123 (calls charged $4.95/minute, higher from mobile, public, foreign and shoe-based phones)
5.1 is probably going to make your sprinter feel a bit like a mountain goat - unless of course you have an engine with a 12,000rpm redline!
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