If you have never driven an SM the steering comes as a bit of a shock at first. Two turns lock to lock, variable power against speed and self centering it’s all unusual. However within a day or two though every other car will seem odd and heavy!
Corrosion can occur on the high pressure pumps and metal pipework, fluid leaking can cause the system to fail. If you see the car in its normal place of residence look for evidence of green stuff on the floor – not alien blood but LHM fluid!
When started the car should promptly assume its normal ride height. Move the suspension height control (to the left of the driver’s seat) to all positions and make sure the ride height changes. It won’t be instant but it should be prompt.
Check for wear in the front ball joints resulting in the front suspension rattling although this could be the anti roll bar bushes. Because the steering always returns to straight on check that it has been set up properly on a straight section of road, it’s a small adjustment to put it right.
The LHM mineral oil used in the braking system does not corrode pipes as conventional systems can so these shouldn’t give any problems, although the system should be cleaned and flushed and then replaced with new LHM.
It’s wise to fit genuine Citroën brake pads as the car is heavy and takes some stopping.
TYRES: The Citroen SM was designed with Michelin XWX tyres originally 195/70 VR 15, unfortunately this size of Michelin is no longer available. From the 1973 model year or the introduction of the EFi SM the tyre size changed to 205/70 VR 15, which is still available as a Michelin XWX.
Other makes are available at differing budgets and are listed below with their overall diameter and section width:
Michelin XWX – overall Diameter 669mm – section Width 205mm
Blockley Radial – overall Diameter 670mm – section Width 195mm
Verdestein Classic – overall Diameter 658mm – section Width 201mm
Pirelli Citrate CN12 – overall Diameter 670mm, – section Width 206mm
Avon CR28 – overall Diameter 670mm – section Width 203mm