Suspension Maintenance and Repair

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The suspension is full of moving parts, but those that require greasing can all be attributed to the steering (see separate section). The only scheduled routine items that are truly suspension-related are the visual inspection of the hydraulic dampers (shock absorbers) for leaks at every 1,000 mile service and the tightening of the rear spring bolts every 6,000 miles.

 FRONT SUSPENSION

The dampers are the “sealed for life” telescopic  type, so are simply replaced when worn out. The various suspension joints and pivots are lined with rubber bushes that, again, require only to be replaced when they are worn, causing excessive movement. The original type of bush tends to perish and shrink with time and although most are sleeved with steel, the shrinkage allows joints to move and the movement itself aggravates the wear and distortion of the bushes. It is best to deal with this sort of wear before the technical inspector forces you to do it. If a visual inspection shows them to be dry, cracked or distorted they need attention. You will be surprised how much this work will improve the handling of the car, which imperceptibly deteriorates over time.

Dismantling the front suspension is a challenging job. It is also potentially dangerous because of the pent-up forces in the compressed spring. Whilst the workshop manual describes a straight-forward process of component removal, it does not describe the difficulty caused by corrosion and seized bolts and split pins. Allow plenty of time for the work because it will take longer than you think! (You may need to refer to the section on dealing with seized and rusted bolts).

Before you start the work in earnest, it is a good idea to give the suspension a thorough clean. A steam clean is best but a good scrubbing and hosing down will do. This will reduce the amount of dust you swallow during the work and will make bolt-heads etc easier to grip. If you have the chance, spray all the visible threaded fixings with penetrating fluid like Plus-gas and leave it overnight to do its work.

The good news is that the dampers can be replaced relatively easily without disturbing the other parts of the suspension. (See Section K.6 of the workshop manual). Replace the top and bottom rubbers at the same time.

To carry out more extensive work it will be necessary to remove the spring. In order to do so, you can make up a spring compressor like the original special tool 18G368, (See Section Q in the workshop manual) which is essentially a threaded rod inserted in place of the removed damper. It has a stepped cross-bar at the bottom that is inserted between the coils of the spring and a plate at the top that sits in place of the damper cover. Using the flats at the top, you turn the rod to draw the cross-bar up against the compression forces in the spring. Once the spring is stable and free of its bottom pan, it is safe to remove the bottom arm and gently release the spring, which will expand to its uncompressed length, when the compressor and the spring can be removed.

An alternative to the special tool compressor is a set of general compressors sold by motor factors. They tend to be the sort that clamp to the outside of the coils and are compressed evenly as a pair. These are, however, inherently more risky because they may become dislodged more easily during use. There is limited space to attach them when the spring is in place.

It is common for the rubber suspension bushes to be seized in place and for the pivot bolts to be rusted to the bush sleeve. In these cases, the solutions range from simply driving them out with a suitable drift, hacking them out with an old chisel and burning them out with a welding torch. If you are faced with this sort of problem, patience and persistence are your best friends. Keep thinking how easy it will be when it comes to reassembly.

Once the suspension is dismantled, the components will benefit from a good clean. If you want to do a restoration-standard job, get them blast cleaned and powder coated but take care that machined bearing surfaces are left uncoated. Otherwise a wire brush, some wet-and-dry paper and enamel paint will do a presentable job.

While the swivel-pin assembly is off the car it is a good idea to dismantle it, clean out all the old grease and clear the grease passages. If you are having the parts blast-cleaned and coated, you need to do this anyway or they will dump molten grease all over the powder-coating oven and you won’t be very popular.

There is a weak-spot in the Magnette suspension and this is the point where the tie rods pass through the brackets attaching them to the body. They are held in place and cushioned by a pair of circular rubbers each of which is held in place by a bell (concave) washer. The rubber "doughnut" to the suspension side of the bracket is also enclosed in a steel ring to control expansion when tightened. Over the years, the rubber deteriorates, the assembly works loose and eventually the tie-rod chafes against the bracket, causing wear and bending of the rod. If you find this sort of damage, it will need repair before re-assembly. Modest loss of metal can be replaced with weld, then ground back to shape. Threads will need to be re-cut. Where heavy corrosion exists, it is a good idea to clean the threads anyway with a die or a spare nut that has grooves cut into its thread with a hacksaw. If the threaded end is completely unserviceable, it can be replaced by cutting it off and replacing it. A threaded hole is created in the end of the rod and a new threaded section made up and inserted into the hole, secured with Loctite. One specialist lists tie-rods as an exchange item, so you may prefer to let them do the work. Click HERE to see the tie-rod repair being carried out on Youtube.

When reassembling the rubber doughnuts onto the tie-rod, you may find they are a tight fit, especially the ones in the steel ring. You can use vaseline as an assembly lube but not grease as it may damage the rubber. Replace the castle nuts and split pins. If you have trouble finding new nuts, Nyloc equivalents are fine. When reassembling, Leave the whole assembly loose until all the suspension components are in place and carrying the weight of the car, then do your final tighten up.

If the hole in the body bracket has ovalled, it will need to be restored by welding on new bell washers. Alternatively, if this work is beyond your scope, new brackets can be obtained from specialist suppliers.

The eye-bolts that hold the bottom of the damper are also prone to shearing when force is applied to the nut, so here again, it may be necessary to replace the part, which is advertised as available from specialists.

You may find, when the crud is removed from the spring bottom pan, that it is showing signs of corrosion. Obviously it must have enough structural integrity to retain the spring and was only a flimsy steel pressing to start with. If in doubt, replace it. Fortunately it is now possible to obtain cast brass replacements that eliminate all future corrosion risk.

If any of the grease nipples are damaged or do not appear to be self-sealing properly with their sprung ball, it is easier to replace them before re-assembly.

When re-assembling the springs, take note that they only fit one way up: the end that is machined flat is uppermost; the stepped one fits into the bottom pan and prevents rotation in use.

Do not fully tighten joints and pivots until everything is in place and you can arrange for the suspension to take the weight of the car by supporting it only at the bottom of the swivel pin. This allows the spring to settle and the joints to be unstressed at the centre of their movement. If you tighten everything before dropping the car, when it settles down all the bushes will be under immediate torsional strain and prone to rapid deterioration.

A number of owners have replaced their suspension bushes with polyurethane equivalents to reap the longevity and handling benefits of this superior material. See the Modifications section for details.

(The previous section updated 21.12.12 following a forum thread and a useful contribution from Trevor Jones). 

REAR SUSPENSION

The rear suspension is a conventional semi-elliptic “cart-spring” arrangement, with a single telescopic damper each side. The spring eyes are held by pivots that are mounted in rubber bushes and there are shackles at the rear to allow movement. The assembly also includes other rubber pads and cushions, which is why the workshop manual stresses that oil must not be applied. The springs are intended to operate dry.

Over time, the rear mounting bushes deteriorate like the front ones and their replacement brings all the same challenges of seizing and corrosion. Here, too, polyurethane replacements are available. The dampers are also mounted with rubber bushes that merit replacement at the same time.

The leaf springs lose their temper over time, leading to the rear-end sag typical of older cars. The wheel should sit centrally in the wheel-arch, so if, viewed from the side, the top of the wheel is noticeably closer to the arch top, then the chances are that sag is present. In days gone by the recommended solution was to have springs re-tempered but the problem now may be to find someone to do the work. A quick Google search revealed a firm in Portsmouth, UK that advertises work on vintage and classic leaf-springs. You could try searching for a local forge and ask if  they can do it. The simpler solution may be to buy a new set of springs from a specialist but it is worth discussing the options first. It is the specialist suppliers that know where the old trades are to be found (though they tend to be a bit protective of their sources!)

The original springs were held together by clips and bolts that allowed leaves to be separated and cleaned individually. However, I have encountered replacement sets that were riveted and therefore not to be separated without much inconvenience. Alternatively, they may have clips that are bent over and need unbending to separate the springs.

Between the springs are rubber interleaving pads that are intended to stop the end of one spring chafing the bottom of the one above it. These deteriorate over time so you may find that chafing has occurred anyway and significant loss of spring thickness means new springs are required. Similarly, you may find that springs are cracked or broken and must be replaced.

Once again, do not tighten the main spring bolts at either end until the springs are carrying the weight of the car.