The wishbones are fabricated from relatively thin-wall steel tube and corrode, especially after a winter. This guide collects what owners said about protecting them. It is opinion, not testing, and owners disagree, so the options are laid out as they were argued.
Wishbones are tube. One owner who has seen many says almost every one he has seen was only surface rust, though he has seen pictures of worse. The parts that go thin first are the flat plates where the suspension mounts on the rears, and the flat part of the upper fronts. Because the tube is thin-wall, one plater says it is worth catching corrosion early. For where to look when stripping, see Suspension refresh.
Before coating
- Blast first, with fine sand or glass bead, to remove oxidation (one owner's advice). Another left his in a deoxidising bath for a few days before powder coating.
- Take the bushes out before powder coating, because they can't take the baking temperature. Take the ball joints out before blasting too, and replace them while you are there. See Wishbone ball joints and bushes.
- You can't blast or powder coat the hubs. The uprights can be done once the hub is removed. See Wheel hub replacement.
- Ball joint and bush eyes and the threaded holes in the uprights need masking, or cleaning out afterwards.
The options as owners described them
| Treatment | What owners said |
|---|---|
| Powder coating | The most popular, and fairly cheap. Hard protective coating if applied properly after blasting. Drawbacks: it can chip, and then rust underneath unnoticed for some time (one plater says it can hide corrosion); it is also "a paint to remove" once rust gets under it. One owner (a supplier, 2005) says it effectively lasts forever. |
| Zinc plating plus passivating | One plater with a long engineering background says this is the best compromise: it replaced cadmium plating when that was banned, and any new corrosion is visible almost from the start so it can be caught early. A bare plated finish isn't pretty, but as one owner said, "it's all hidden". Can be painted or powder coated over it, which keeps protection on any masked areas. |
| Zinc-nickel plating | An electroplating process like normal zinc plating, said by one plater to offer around five times the corrosion resistance of ordinary yellow passivated zinc. A relatively new process in 2014. |
| Hot-dip galvanising | Very good protection, but awkward for these parts. The tubes are closed, so there is a risk of explosion in the molten zinc bath unless there are holes to let air out and zinc drain, and the thick coating means the bush and ball joint eyes and threaded holes need reaming or cleaning afterwards. One owner who galvanised all his parts and top-coated them says he would avoid it: hard work. |
| POR15 | Easy to do on all parts, though the finish isn't as good as powder coat. One owner found it the best of those he had tried; another says it has lifted where it was disturbed, such as bolt holes, so "still not ideal". One owner who used it plans to add a wax coat over it. |
| 2-pack paint | One owner 2-pack painted his suspension and says it still looks new. Another had his done in a 4-coat offshore paint system (ISO 12944 C5M) at work, which has lasted about eight years. A third mentioned an Australian study of bikes which, he says, found painting more durable than powder coating over the long term (second-hand, not checked). |
| Hammerite | Judged the worst by one owner: "chips and lifts easily". Another noted it chips if applied too thickly. |
| Wax or grease on top | See below. |
One owner heard that the Elise parts supplier uses a newer type of powder coat or paint on its wishbones, said to be better than powder coating, but could not recall what it was. Ask the supplier if it matters to you.
The 15-year-old standard paint on the originals was pointed out in the thread as a sign they may not need anything special, though nobody tested a simple coating.
A combination, in one owner's view
One owner with a coatings background says the best result usually comes from three steps: de-rust (chemical or electrical), zinc plate (hot-spray or electro), then a topcoat such as POR or powder coat. The zinc stops rust spreading under the topcoat if it chips, and a rust inhibitor base layer under any paint is a good idea. Other owners made the same point about plating first. This is his opinion; nobody in the threads reports testing it on wishbones.
Protecting them without removing them
- Waxy coatings, twice a year or so. Spray the wishbones and the exposed bolt threads and fasteners with a clear wax such as Waxoyl, Dinitrol or Tectyl. It forms a weatherproofing layer, seals threads and joints, and wipes off with brake cleaner and a rag. It looks messier than paint and needs topping up.
- Which wax. One owner who has used most of them says Dinitrol is the best, and that Waxoyl is fine inside boxed sections but dries out and becomes permeable too quickly where it is exposed. That is one owner's experience.
- Mike Sander's grease (or similar ship and 4x4 grease). One owner uses it to stop rust on his wishbones where he wants to deal with them later. He says it excludes water and degreases easily, but attracts dirt "like there is no tomorrow".
- A plater's version of the same advice: after plating, spray them from time to time with something oily or waxy and they will probably last forever.
Help wanted
These are opinions from 2011 to 2015 and nobody has run a comparison. If you have coated wishbones, we would like to know what you used, how it has lasted and how many years, and any supplier that does the coating well.