tim124
Part of things
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Cortina estate with 120 /140ish BHP, TD XUD9 engine & 5 speed box R380), I have a choice of ratios for the axle, 3.77:1, 3.44:1 or 3.00:1 would the 3.00: 1 work the best? thanks
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squonk
Part of things
Posts: 858
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That would depend on the size of the wheel/tyre combo and the final drive ratio (5th being an overdrive ratio). You should probably aim for a drive train that gives about 30mph/1000rpm in 5th.
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Last Edit: Aug 6, 2014 18:31:07 GMT by squonk
2004 Chevrolet Avalanche Z71
2005 Mercedes CLK320 Cabriolet
1996 Mercedes C180 Elegance Auto Saloon
1996 Rover 620Ti (Dead fuel pump)
1992 Toyota HiLux Surf
1987 Range Rover Vogue (Rusty)
1992 Range Rover Vogue SE (More Rusty)
2006 Chrysler Grand Voyager
2008 Corsa 1.4 Design
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bortaf
Posted a lot
Posts: 4,549
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3.00-1 ? you meen a 3.09 from a capri ?? I'd probably use the the 3.44, i allways run a 3.75 with a TD under the hood BUT i run 90 BHP ford 1.8TDis and they struggle round town with that diff, yours will be better in that respect with a fair bit more power. A said do the maths on the rolling radius of your wheel tyre combo and top gear, if you intend to use it on the motorway you should be aiming at 30MPH per 1000 rpm as said for a comfy and frugal drive  |
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R.I.P photobucket
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turbo xud9 pugs run 3k rpm @ 80mph give or take a few, the hdi 306 runs a few hubdred less and is a common swap onto the xud
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tim124
Part of things
Posts: 128
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3.00 from a mustang, slightly too wide but would fit ok,the 3.44 is a straight bolt in affair so i think that will be used, thanks for your help!
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squonk
Part of things
Posts: 858
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You will need to use a relatively large diameter wheel and tyre combinationto make this ratio work properly. Ideally cruising at 60mph in 5th you want the engine to rev below 2000rpm. The R380 gearbox appears to have a 5th gear ratio of 0.792:1. For ease of calculation lets say you are going to fit 15" wheels with 205/60 profile tyres. This gives a combined wheel and tyre diameter of about 25 inches. Using a 3.44 diff a quick calculation suggests that at 60mph the engine will be spinning at 2200rpm. Not too bad but it would be more suited to the 3.00 ratio as that will give an engine speed of 1900rpm for 60mph.
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2004 Chevrolet Avalanche Z71
2005 Mercedes CLK320 Cabriolet
1996 Mercedes C180 Elegance Auto Saloon
1996 Rover 620Ti (Dead fuel pump)
1992 Toyota HiLux Surf
1987 Range Rover Vogue (Rusty)
1992 Range Rover Vogue SE (More Rusty)
2006 Chrysler Grand Voyager
2008 Corsa 1.4 Design
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tim124
Part of things
Posts: 128
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Yeah, I've done the numbers too, 3.44 & 15" 195/80/15 tires or bigger will work for me, this is a work vehicle so no interest in low profile rubber......thanks
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