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MG MGA - MGA rear springs

I need a set of rear springs for a 59 MGA I am restoring. I keep hearing negative comments about some of the new springs that are being purchased. Has anyone purchased springs that were level and did not have too much arch? Any recommendation where to purchase some good springs is appreciated.
S Rymer

Do you have your old rear springs? If you do any competent spring shop can copy them to make new ones. Most old springs can be made like new again by a spring shop also. There are rarely any reason to buy new.
R J Brown

The springs I got from Scarborough Faire about a year ago look pretty good.
John
John Cline

My rear springs came from Scarborough Faire about fifteen years ago, still seem to be working fine. Marvin
Marvin Stuart

John, -- That looks way too high to me. You should just be able to place your hand flat between the top of the tire and the fender. With the body sitting higher there is little or no travel for the rebound straps, and it screws up high speed handling of the car.
Barney Gaylord

SR, Before buying a new pair I would strongly advise you to check (or ask someone to check) the camber by placing each spring upside down on a flat surface and measuring from the surface to the top face of the smallest leaf. If this is 6.38" the camber is correct. I don't know the exact tolerance you could allow on this but I would suggest no more than plus or minus 0.5".
I'm assuming the leaf thickness on your new springs will be as original viz. 7/32". Mike
m.j. moore

Mike's dimension sounds pretty close. This came up a while back and someone finally found this diagram in a factory manual which shows the dimension for a single main leaf and how they recommended taking the measurment. If you have your springs rebuilt the rebuilder would probably want this information to go by.
On the subject of spring rebuilders, I've heard from other club members that some rebuilders are having problems getting the narrow spring steel stock to create MG springs.

Bill Young

This may be helpful or not: (from a book on Tuning MGB suspension)

Tuning the Suspension

Suspension requirements vary enormously between individual drivers, as standard the M.G.B. has very predictable handling. A lithe roll is evident but this curbs the over enthusiastic. There are logical sequences to follow, to correct, or emphasise road holding points.
Basically the M.G,B. is neutral but when pressed will oversteer slightly. For slight alterations tyre pressures can be varied, where this difference exceeds S lbs./in,2 it is lime to start on the suspension (put the tyre pressures back to normal).
Lowering the rear lessens roll, alters the tyre slip angle and causes earlier bump stop contact. Stiffer springs will result in oversteer. Stiffening the front springs or fitting an anti roll bar (increasing diameter f one is fined) will introduce understeer, s can a lowered front. Before deciding on any work think what the car will be used for.
A road car with occasional passenger for fast road work carrying little weight could have similar to race suspension. The family man/enthusiast with a car for all purposes wants anything but.
Overall weights have to be considered, the racing car may for instance, be lightened with alloy/glass fibre panels etc. Conversely for long distance events its fuel capacity may be doubled.

The standard tourer 15BG/1SGA had a total kerbside weight of 1975 lbs.. split into 1065 front/90 lbs. rear. Add two people, a couple of cases and full tank and this could easily become 1165 lbs. front/1310 lbs. rear, a different kettle of fish. Don't therefore fit the softest rate spring to lower the car willy nilly.

The front coil spring has an easy life with no complications. The leaf rear spring on the other hand controls many factors. It locates the axle laterally and axially, through its design it absorbs torque and prevents 'wind up' a major cause of aide tramp. Oh yes, it acts as a spring? Apart from bump loadings, too soft a rear spring could fracture under excessive torque loadings. Prevent this with a radius arm you say. O.K. but, this can cause axle tramp and the car to skate about in the wet too,

For the front, you must consider the
free lengths and rate, against the weight of
the front of the car divided by two. Here it gets complicated because the front spring does not bear the cards weight directly as the rear springs do. And also you must estimate the unstrung weight to be allowed each side; including wheel, tyre hubs and a portion of the suspension itself.

(Some is self supporting). From a known weight 1065 is 532.2 lbs. less 66.5 lbs. 4 (say) 466 lbs.
Before you jump down and point out that the spring chart shows a working load of 1030 lbs. remember I said it gets complicated. The spring is located less than half way along the bottom wishbones and therefore
becomes a function of the suspension geometry, resulting in the spring being compressed less than half the wheel deflection. Thus the standard springs 348 1b1/ins. rate becomes 73 lbs./ins, at the wheel. Six inch wheel movement from its free length would be equivalent to 2.9 ins. at the spring approx 6.4 x 73 = 467 at wheel. 2.965 x 348 = 1030 give or take a splash of mud.
Some of this movement is of course already taken up in the static fitted height of the spring during assembly. The balance of compression is when the car bears its own weight. From this you can then deduce that fitting AHH 5789 spring will give a stiffer ride without raising or lowering the car appreciably,
CART 21 also stiffens but also effectively lowers the car just over an inch in relation to the normal weight of the car.

At the rear the choice is yours from the many offered. Load and ride height must be considered and again weight is the rear total, less the axle, wheels etc. (approx. 130 lbs.) divided by two,
Early 18G springs AFH 6453 did not have the plastic interleaving and have slightly stiffer rate than the later AHH 1080. AHH 8343 has increased rate (110 Ibs,) but less deflection and is flat at a lower load, ideal for light sprint motor.
AHC 31 is a good high load short moveĀment spring for stiffening and lowering while AHH 7346 has even greater load capacity and movement for rallying etc.
Lastly the competition AHT 20 with similar load capacity but less deflection. Ideal for long distance events demanding lowered cars with a high fuel load. As the fuel load reduces the ride height is not too greatly affected

dominic clancy

This thread was discussed between 15/01/2008 and 16/01/2008

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