Differential Ratios

Ratio-Speed Set Ups

Diff Ratios & Speed Set Ups		Warm			Hot			Hotter			Smokin'
		#1A	#2A	#3A	#1C	#2C	#3C	#1D	#2D	#3D	#1F	#2F	#3F

Input:
Engine Size:		1380	1380	1380	1380	1380	1380	1380	1380	1380	1380	1380	1380

Horsepower:		110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp	110bhp

Tire/Wheel Size:		175/70x13	175/70x13	175/70x13	195/60x15	195/60x15	195/60x15	175/70x13	175/70x13	175/70x13	195/60x15	195/60x15	195/60x15

	No of Teeth on:
Back Axle:	crown wheel	38	39	41	38	39	41	38	39	41	38	39	41
	pinion	9	10	11	9	10	11	9	10	11	9	10	11

Speedo Drive:	3rd motion shaft	5	5	5	5	5	5	5	5	5	5	5	5
	take off pinion	13	13	13	13	13	13	13	13	13	13	13	13
Speedo available/fitted:		1472	1376	1280	1472	1280	1280	1472	1376	1280	1376	1280	1280

5 Speed/OD Ratio:		1	1	1	1	1	1	0.85	0.85	0.85	0.85	0.85	0.85

Output:
Wheel turns per mile		910	910	910	833	833	833	910	910	910	833	833	833
Axle ratio:		4.22	3.90	3.73	4.22	3.90	3.73	4.22	3.90	3.73	4.22	3.90	3.73
Speedo ratio:		0.38	0.38	0.38	0.38	0.38	0.38	0.38	0.38	0.38	0.38	0.38	0.38
Speedo turns per mile		1478	1365	1305	1353	1250	1194	1478	1365	1305	1353	1250	1194
MPH per 1000rpm		15.6	16.9	17.7	17.1	18.5	19.3	18.4	19.9	20.8	20.1	21.7	22.7

RPM @ 70 mph (in top)		4483	4141	3957	4103	3790	3622	3810	3519	3364	3488	3222	3079

% speedo error		0	-1	2	-8	-2	-7	0	-1	2	-2	-2	-7

Top Speed at 6,500 RPM		102	110	115	111	120	126	119	129	135	130	141	148

Notes/Variations:		diff ratio change only	diff ratio change only	diff ratio change only	diff ratio & tire & rim change	diff ratio & tire & rim change	diff ratio & tire & rim change	diff ratio & 5speed	diff ratio & 5speed	diff ratio & 5speed	diff ratio, tire & rim size & 5speed	diff ratio, tire & rim size & 5speed	diff ratio, tire & rim size & 5speed