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MG MGB GT V8 Factory Originals Technical - Front Springs

The gap between the coils, that is each wire coil is approx. 5mm, makig tha approx upward travel of the front suspension 30 to 35 mm, which to me seems too little,would appreciate any comment.
The distance from the wheel centre to the curve of the wheel arch is 335 mm which by all accounts appears to be normal.
The car is a R.B GT with CAHT21 front springs and inverted eye rear springs.

Rgds Trevor Burnett
t burnett

335mm/13" is a little low for 'normal', it's typically 14", but then CAHT21 are competition lowered. The loaded height is given as 6.14", so if you take the number of coils, the wire thickness, and do the sums that should give you the free space between coils and hence how much they can be compressed before binding. But because the springs are inboard of the wheels and closer to the suspension arm pivots the movement here is significantly less than at the wheels, and any measurement error here is proportionally larger.
PaulH Solihull

Many thanks your input Paul, please advise your thoughts on replacing these springs with part no.AHH 5789 or even BHH 1077, your advise will be much appreciated.

Rgds Trevor B.
t burnett

AHH 5789 was for the pre-72 GT, had a free height of 9.1" and a loaded of 6.6".

BHH 1077 was for the 72 and later CB GT and all V8s, had a free height of 9.32" and a loaded of 6.84". Both have the same rate as the competition lowered at 480lb/in.

However what you actually get now could be quite a bit different from those figures, some of the latter I bought a few years ago had a free height of 9.75" i.e. quite a bit higher. I also had to politely request two the same height (the first two he brought out were different) which he did but saying it wouldn't make any difference. When fitted, the car ended up with one side lightly higher than the other, after a shake-down run, even though it had been level before. The same spec of spring that had been on the front of my roadster for a few years ended up with a free height of 9.125" i.e. a considerable loss, and the front had got quite a bit lower in that time, with the A-arms angled upwards as they moved outwards and I couldn't get the hydraulic jack under the cross-member anymore. So not only are the heights erratic, but the resistance also, let alone how long they will keep those figures i.e. the temper. It's all a bit of a minefield.

Incidentally, I'd be interested to know how many 'free coils' your C-AHT 21 have. The start of the free coils is where the first flattened turn is left behind, and ends where the last flattened turn is reached. It's a bit difficult relating the spec numbers to springs I have, so perhaps a photo would be best. For example the above are supposed to have 7.2, but all three of mine that are supposed to be the same spec are less than 7 and different one to another.
PaulH Solihull

Thanks, not much info appears to be available(based on actual experience)of which springs to use in this application, I am going to try the BHH 1077 and if I am happy with the height in front and if there is any marginal difference between front and rear I could always fine tune it in a number of ways.
My front ride height at the moment(330mm/13 inches) is far too low and I need to increase this height to at least 14.5/15 inches regardlees of what Moss's tuning manual states.
Will keep you updated.

rgds Trevor B.
t burnett

This thread was discussed between 02/08/2011 and 04/08/2011

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