Follow our guide to keeping tinworm away from the rear suspension on most front-wheel-drive classic Fords.
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Get your ’80s or ’90s Ford ready for winter with our guide to rust-proofing the rear suspension set-up.
Front-wheel-drive (FWD) Fords ranging from a Fiesta to a Mondeo all seem to suffer from corrosion in the rear suspension. One of the biggest threats concerns the rear coil springs, especially those that are separate to the telescopic damper. They usually sit on a spring pan, which may be part of a lower suspension arm, or part of a beam and trailing arm set-up. Whatever the arrangement, those spring pans often fill up with dirt and water, so they eventually corrode. At worst, the coil spring becomes dislodged or even fractured because it too has rotted away.
Taking the approach that prevention is better than cure, the following steps show how to rust protect these spring pans to help avoid corrosion. In some cases, the work can be conducted in situ, providing the coil spring can be safely removed. If it can’t, then removal of a spring pan/arm can be timeconsuming and potentially problematic with seized fastenings, so it may be easier to overhaul a used spring pan/ arm, then swap it over afterwards.
There are a number of safety points to note when completing the work shown. The most important concerns raising a vehicle and supporting it. Position the vehicle on level ground and use axle stands – do not rely on a trolley jack or similar lifting device to support a raised vehicle. When removing coil springs, make sure they are not compressed before touching them, and keep your fingers out of the coils in case they get trapped.
If you have an angle grinder and a selection of wire wheels, brushes and cups to be able to quickly clean rusty metal, remember that this equipment will propel metal and other debris everywhere, so protect yourself with a full-face mask, gloves and overalls. Lots of dust will be generated, so wear a breathing mask and most angle grinders are noisy, so wear ear plugs or ear defenders.
There’s no quick fix to rustproofing the rear suspension on a FWD Ford, so take your time and allow a long weekend to complete all of the work.
Once each mounting bolt has been slackened, continue undoing them with a ratchet, or if you have an impact driver, this will be much quicker. Wind the bolt in and out to help clean the thread.
When the rear of the vehicle has been sufficiently raised to release the tension in the rear coil springs, position axle stands underneath the back of the sills. Do not rely solely on a trolley jack.
With the rear dampers detached, carefully raise the rear of the vehicle to release the coil springs. Raise the vehicle underneath the sills, not under the rear suspension. Visually check the coil springs are not trapped.
Catching the corrosion before it goes too far is essential and this work can be done in situ by extracting the coil springs. Start by spraying penetrating fluid over the lower mounting bolts for the dampers.
This is a typical trailing arm rear suspension beam used on many front-wheel-drive Fords.The biggest threat is corrosion of the coil spring pans, which can cause the springs to dislodge.
You probably won’t be able to remove all the rust, so any surface corrosion should be treated with a rust inhibitor, which turns the remaining iron oxide to iron tannate. It cannot fix rusty holes.
An angle grinder with a selection of wire cups, wheels and brushes can help to speed-up the job of removing rust and dirt. Wear a full-face mask, breathing mask and ear plugs/defenders.
It may be easier to use a metal decorator’s scraper to remove rust and dirt from the spring pan and surrounding area.There’s no quick method, but thorough preparation for rustproofing is essential.
Using a breaker bar, try to undo the lower mounting bolts for each rear damper.They may be threaded into a captive nut, so make sure they have been soaked in penetrating fluid.
Carefully extract each rear coil spring, but only do this if they are not compressed. Keep your fingers away from the coils — only touch the top and bottom sections of each coil spring.
Use a wire brush to remove any flaky rust, road dirt and anything else that shouldn’t be inside the spring pan. Clean the underside and surrounding area as well. Check any drain holes are clear.
Use a blunt screwdriver to poke around inside the spring pan — the area where the bottom of each coil spring sits.This needs to be structurally sound, so scrape and poke it to check the metal is solid.
After refitting the mounting bolts for the dampers, lower the vehicle back onto its wheels, checking the coil springs are seated properly.Tighten those damper mounting bolts to the recommended torque setting.
The horrors of corrosion are often only evident when a component such as this spring pan/arm is removed.The corrosion in the arm on the right cannot be repaired and will fail the MoT test.
The same rust protection procedures can be applied to a spring pan/arm as outlined in steps 12-15. With the component removed, there’s the potential to do a better job and take your time.
Swapping over a spring pan/arm can be a nightmare of a job, especially if fittings are seized, so it may be one for your local garage. At least you can do the preparation work on the replacement arm.
Once all the rust protection has dried, reassemble the rear suspension. Check how to refit the coil springs, ensuring the ends are correctly inserted into any grooves in the spring pan, along with any rubber mounts.
Use a screwdriver to align the mounting holes for the bottom damper mounts. It may help to carefully lower the rear of the vehicle back onto its wheels, but check the springs remain correctly seated.
A quicker method of cleaning a spring pan/arm is to use an angle grinder with a wire brush or cup. Wear protective clothing (see step 11) and secure the arm in a vice to keep a grip of it when cleaning.
After painting, further protection can help, such as a wax or similar rustproofing liquid. We used a heavy grade lubricant called Prolan, which is from Witham Oil & Paint. It remains tacky and helps protect the spring pan.
Leave the rust inhibitor to dry. It should turn from white to blue and finally black. A second coat may be required.This acts as a primer, so more paint will be required to protect the metalwork.
Some FWD Fords, such as this Mk4 Escort, have removable rear spring pans/arms, which are just as prone to corrosion, but at least they can be swapped for a pair that are in better condition.
It may be easier to buy a used spring pan/arm, then clean and paint it prior to the swap. A wire brush and scraper are the basic tools you’ll need, but it may take half an hour or more to do this.
Apply a hard-wearing paint. We sprayed a thick stonechip protective paint over the spring pans and also along the rest of the rear suspension, applying several thin coats and leaving it for 24 hours to fully dry.