4.36 gears

BGTV8 · 11-18-2014, 09:53 PM

For road course usage, 4.36:1 makes 1st gear redundant and in effect gives you a 5-speed gearbox with reduced Vmax.

With 4.08:1, I don't use 1st to start, which gives me a single gear from zero to 100kph. 4.36:1 would be crazy short ...

Speed in gears with Nissan box and my DD tyres at 7200rpm is:
1st 40mph
2nd 64mph
3rd 91mph
4th 117 mph
5th 148mph
6th 156mph ** at 6000rpm ***

With my 645mm tall track tyres, speeds are

1st 35 mph too slow to be any use, so I start in 2nd
2nd 57mph
3rd 82 mph
4th 110 mph
5th 140mph
6th 159mph *** at 6500rpm ***

In my case, I used to see redline in 5th at Phillip Island GP circuit with the 3.7:1 OEM ratio but ith the 4.08:1 ration I have to use 6th and pull somewhere between 6300 and 6400 rpm down the chute into T1, so the 4.08:1 has made a very significant difference in acceleration and Vmax.

I would reckon that unless you can safely turn your engine to 8000+ rpm (means dry-sump) then a 4.36:1 diff will not help on the track - might be useful on the strip though

I am now playing with options as I have a box with a much taller first gear and a 0.878:1 OD 6th .... so looking at tyre sizes to suit (650mm tall vs 665mm tall vs 675mm tall Dunlop slicks).

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11-18-2014, 09:53 PM	#9 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,515 Drives: 09 Nissan 370Z M6 Rep Power: 39974	For road course usage, 4.36:1 makes 1st gear redundant and in effect gives you a 5-speed gearbox with reduced Vmax. With 4.08:1, I don't use 1st to start, which gives me a single gear from zero to 100kph. 4.36:1 would be crazy short ... Speed in gears with Nissan box and my DD tyres at 7200rpm is: 1st 40mph 2nd 64mph 3rd 91mph 4th 117 mph 5th 148mph 6th 156mph at 6000rpm * With my 645mm tall track tyres, speeds are 1st 35 mph too slow to be any use, so I start in 2nd 2nd 57mph 3rd 82 mph 4th 110 mph 5th 140mph 6th 159mph * at 6500rpm * In my case, I used to see redline in 5th at Phillip Island GP circuit with the 3.7:1 OEM ratio but ith the 4.08:1 ration I have to use 6th and pull somewhere between 6300 and 6400 rpm down the chute into T1, so the 4.08:1 has made a very significant difference in acceleration and Vmax. I would reckon that unless you can safely turn your engine to 8000+ rpm (means dry-sump) then a 4.36:1 diff will not help on the track - might be useful on the strip though I am now playing with options as I have a box with a much taller first gear and a 0.878:1 OD 6th .... so looking at tyre sizes to suit (650mm tall vs 665mm tall vs 675mm tall Dunlop slicks).