MG Model	Chassis #	Front Spring Part Number	Spring Rate, lb/in	Coil Dia, in.	Wire Dia, in.	Free Length, in.	Number of Active Coils	Static Laden Height, in.	Static Laden Load, lb.
MGA 1500	to 15151	139105	348*	3.238	0.498	9.75	7.5	6.6	1095
MGA 1500	from 15152	AHH5546	480*	3.28	0.54	8.88	7.2	6.6	1095
MGA 1600	all	AHH5546	480*	3.28	0.54	8.88	7.2	6.6	1095
MGA MK II	all	AHH5546	480*	3.28	0.54	8.88	7.2	6.6	1095
MGA "Deluxe"	all**	AHH5546	480*	3.28	0.54	8.88	7.2	6.6	1095
MGA Twin Cam	all	AHH5789	480	3.28	0.54	9.09	7.2	6.6	1193
MGB Roadster	to 293446	AHH6451	348	3.238	0.498	9.9	7.5	7	1030
MGB Roadster***	from 293447	BHH1225	348*	3.238	0.498*	10.2	7.5	7.24	1030
	to 410000
MGB/GT	to 296196	AHH5789	480	3.28	0.54	9.1	7.2	6.6	1193
MGB/GT***	from 296197	BHH1077	480*	3.28	0.54*	9.32	7.2	6.84	1193
	to 361000
MGB Competition	n/a	C-AHT21	480			8.63*		6.14	1193
Notes: * Figure not shown in factory manuals, but calculated from other known factory values. ** Data for "Deluxe" cars show same figures as for Twin Cam in factory manuals. However, the "Deluxe" models carry the lighter pushrod engine, so should have same springs as the 1600 models. *** Coincides with introduction of radial tires as standard equipment, 1972

In the middle is the original standard spring from a MKII Deluxe (same for all pushrod engine cars after 15151). On the left is the AHH6451 spring from Moss, which they claim is a suitable replacement for standard MGAs. It is actually an MGB spring with lower spring rate (similar to early spec MGA springs). And on the right is the correct AHH5546 spring from MGOC. Wire diameter of the AHH5546 spring and the original spring is identical, 0.54". The MGB spring is 0.498". While it has same spring rate as the earliest MGA spring, it is slightly longer free length. When installed in the MGA it will have the softer early spring rate, but it will also sit 0.15" higher at the spring, or 0.30" higher ride height. The factory knew the softer front springs were not good for the MGA, which is why they were changed to higher spring rate in early 1500 production after the first 5051 cars.

There is also the MGB competition spring C-AHT21 (if you can find it), which is correct 480-lb/in spring rate for MGA but 0.25" shorter, which will lower the front ride height of the MGA by 0.50".