[Mgs] [MG-MGB] MGB leaf springs

PaulHunt73 paulhunt73 at virginmedia.com
Wed Jan 11 01:59:49 MST 2017

I've replaced front and rear springs on both cars at various times.

On the counter the new front ones were nearly 1/2" longer than the stated free height in the manuals, and had different heights!  I asked nicely and the counter chap did select two the same height for me, but said 'it won't make any difference'.  Incidentally on removal the old springs - given the amount of crusty corrosion almost certainly original with 30 years and 150k on them were also slightly longer than the spec free height.  Despite only tightening the A-arm pivots once the full weight of the car was on the suspension (!) here was 1/2" difference between the sides (none before) and the measured height was 1.5" and 2" higher than before, and looked ridiculous.  They settled about 1/2" after going over several of our local sleeping policemen, but even after 2 years of use were still about 1/2" higher than they should be for a CB roadster.  Ideally with normal loading the A-arms should be parallel to the road surface.

As you say some years ago there were very many complaints about rears being too high, either from over-arching or from simply being too hard.  So much so that they would not compress enough in a fully-equipped car to get the rear rebound straps fastened without significant extra weight in the boot.   Originally from America (complaints) but then in the UK as well.  Given the size of so many people today I have wondered if it was deliberate, given that the factory only allowed 150lb/11 stone per occupant!

I've not had that problem in the UK despite three sets at various times on two cars, in fact I've had to extend the CB roadster shackles by 1.25" to control the bottoming and grounding when touring fully laden.  Even so, there is still a curve in the rebound straps with no load in the car.  The V8 is an RB so higher ride-height anyway, and harder springs so I didn't have that problem, but again I still have a curve in the rebound straps unladen.

For some years springs were in short supply when the main British manufacturer stopped production.  Currently CB Springs in the UK (http://www.gbsprings.co.uk/heritage-car-springs/) list 'Heritage Car Springs' for most if not all the original OEM types to original specs.  Whether this is with BMHs approval I don't know, but normally they are pretty hot on misuse of their trade marks.

Incidentally the axle being offset to one side is almost universal and (apart from one claim I saw) always to the left giving typically a 1/2" narrower gap between tyre and arch on that side compared to the right.  It's not the springs (same offset on mine with three sets) or misalignment of the mounting points (having carefully measured using lines dropped to a flat and level surface and measuring the diagonals as well as track and wheelbase) so can only be original jig alignment of the several panels between the chassis rails and the outer wings and the shape of those panels.

This can result in tyre/arch rubbing on CB cars particularly with wider tyres, and almost guaranteed with wire-wheel conversion hubs on a stud-wheel axle.  There is some scope for compensating for this by slackening the U-bolts, giving the body a good hard shove to the left and holding it there while you retighten.  I've got mine pretty-well central now, but with 175 tyres and a pukka wire wheel axle I still get slight rubbing of tyres on arches - both now - on enthusiastic cornering fully laden.

Can't comment on the Moss US springs.


  ----- Original Message ----- 

  Has anyone installed leaf springs recently? ...

  That brings me to my 72B. I replaced the leaf springs about 10 years ago....
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