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MG MGB Technical - A-Arm Geometry

Have just finished a complete rebuild, with largely new parts, of the front suspension for my 1972 stock roadster- king pins, upgraded dampers, springs, a-arms, spring pans, pivots, bushes all around etc. etc. Down on all four for the first time in months.
The lower a-arms are not quite parallel to the ground - is this right?

I see the v-8's all seem to ride parallel, but the 1800cc have a slight angle down from the pivot - it this correct? I want to get right before setting to torque all around.

Any input appreciated!
Ray Walsh

Give the car a really good bounce then roll back and forward to settle the suspension, then tighten the inner control arm bushes. You did leave them loose to neutralize the tension when loaded ?? Denis
Denis4

Thanks, Denis. I've only hand-tightened at the moment. So, the a-arm should be parallel in the end?
Ray
Ray Walsh

In my experience the front suspension, unlike the rear, needs driving over sleeping policemen or similar to settle. The coil springs also settle over time, but new ones seem to be very variable in free height and compression under load. Ideally the A-arms would be parallel to the ground, angled downwards slightly towards the outside with new springs, to settle closer to horizontal over a short time.

Distance from the bottom of the bright trim strip to the centre of the axle is the usual arbiter of ride height, with 14" to 14.5" seemingly the norm for 'settled' springs. Replacing them on my 73 was 16" initially and looked awful. A tour over the many sleeping policemen around Solihull got them down to just under 15.5" - still pretty awful. Two years and 5-6k later they were just over 14.5".
Paul Hunt

Many of our cars have had new springs by now, more often rear. But modern replacements are of very variable temper. If yours are angling down to start with, that's fine but keep your fingers crossed that they don't continue "settling". Pointing up will start to give bump steer.
It seems it's not only classic springs that are suspect. I work sometimes in a local garage and the place is littered with broken springs off "modern" vehicles.
Allan Reeling

Alan, I'll bet the majority are European springs, not Japanese. Or it was a few years ago.

European springs did not have a pig tail design and tried to overcome it with the cup fittings at each end. Some of the worst were BMW and Audi! (I was MOT tester)
Michael Beswick

Paul/Allan/Michael -
Thank you for the commentary. A good 20 minutes bouncing on the front corners and it finally settle perfectly parallel to the ground. All torqued up and now on to an alignment.
Cheers!
Ray
Ray Walsh

Absolutely right Michael.
Allan Reeling

This thread was discussed on 07/02/2015

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