How to remove rust from your front forks! A complete guide to surface rust, precautions, and prevention methods

Types of Rust that can Form on Front Forks

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Many motorcycles are made of metal, and they are also heavily exposed to rain and wind, making them susceptible to rust.

Front forks, mostly made of metal, are also prone to rust, specifically pinpoint rust and red rust.

Pinpoint Rust

Pinpoint rust is a fine, spot-like rust with a diameter of about 1mm, and it tends to occur on the inner tubes of front forks that have been chrome-plated.

Chrome plating has microscopic, invisible holes, and red rust develops from these holes in the chrome plating.

Pinpoint rust often appears in large quantities, and if left untreated, it can spread and often develop into red rust.

Red Rust

Red rust is a reddish-brown rust that primarily develops from corroded iron. Even fine pinpoint rust will develop into red rust if left untreated for a long time.

The inner tubes of front forks are made of iron, with nickel plating applied, and then chrome plating on top. Rust that forms on the base iron layer moves up to the upper layers and eventually appears on the surface.

If pinpoint rust appears, do not leave it untreated. Addressing it with rust remover or similar products can prevent it from developing into red rust.

What Happens if Rust on Front Forks is Left Untreated?

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If rust forms on the front forks and is left untreated, it can progress through the following stages:

Pinpoint rust turns into red rust.
The oil seal gets damaged.
Oil leakage occurs.

Let's explain each point in detail.

Pinpoint Rust Turns into Red Rust

The inner tubes of front forks are prone to microscopic pinpoint rust, and if left untreated, this pinpoint rust can grow and consolidate into red rust.

While the chrome plating on front forks might seem impervious to rust, its surface has countless tiny holes. Water, dust, and other elements can penetrate these holes, causing rust to form underneath.

Rust that forms beneath the chrome plating eventually emerges through these holes, appearing as pinpoint rust. If this pinpoint rust is left untreated, it will eventually develop into red rust.

Oil Seal Gets Damaged

The formation of rust can create small irregularities on the surface. When the front fork strokes, these irregularities can hit and damage the oil seal.

The oil seal is responsible for sealing the oil inside the inner tube. If rust becomes significant, it can damage the oil seal, sometimes leading to oil leaks.

Oil Leakage Occurs

This is more likely to occur when rust has developed significantly. When the front fork strokes, it can damage the oil seal, causing it to tear or pull, leading to oil leakage.

Oil leaks due to a damaged oil seal require the replacement of the oil seal. If the oil leak or rust is severe, an overhaul (disassembly for inspection and parts replacement) of the front fork will be necessary.

The estimated cost for a front fork overhaul at a shop is around 24,000 yen for conventional forks and around 26,000 yen for inverted forks. Cartridge-type forks will incur an additional 5,000 yen.

How to Remove Rust and Pinpoint Rust from Front Forks

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The procedure for removing rust from front forks is generally as follows:

Roughly remove rust
Polish with steel wool
Polish with wet sandpaper
Use compounds and other abrasives
Apply rust-preventative treatment

For all rust removal steps, care must be taken not to polish the oil seal or get chemicals on it. Depending on the situation, protective measures such as masking the seal area may be necessary.

Step 1: Roughly Remove Rust

First, use a scraper or similar tool to roughly remove as much rust as possible.

At this time, be careful not to scratch the base material by forcing the rust off or rubbing too hard.

Once the rust has been roughly removed, if rust has formed near the seal, mask the seal with masking tape to prevent the subsequent rust removal treatment from affecting the seal.

Step 2: Polish with Steel Wool

Once the rust has been roughly removed, use steel wool to remove any loose rust.

Steel wool is used by gripping it by hand, which can make it difficult to apply pressure. In such cases, a brass brush with a handle may be easier to use.

Use either or both, as appropriate for the location of the rust, and rub off the loose rust on the front fork. When polishing, move horizontally, not vertically.

Step 3: Polish with Wet Sandpaper

Wet sandpaper is sandpaper that can be used when wet. The higher the grit number, the finer the abrasive. For removing rust from front forks, you should have sandpaper of about 1,000 grit, and for finishing, 1,500 to 2,000 grit.

Dip the wet sandpaper in water (lightly wet it) and polish to remove the rust. Polish horizontally, not vertically, along the front fork.

Start with coarser 1,000-grit sandpaper, and as the rust comes off, finish with finer 1,500-2,000-grit sandpaper.

Step 4: Use Compound

Once the rust has been removed and polished with wet sandpaper, use a compound to further smooth the surface.

Polish with the compound, then wipe it off with a cloth and check with your finger to see if it's smooth.

As it becomes smoother, the surface will develop a mirror-like shine and luster, which will be visually apparent.

Step 5: Apply Anti-Rust Treatment

Once the front fork surface has been smoothed with compound, spray it with a silicone spray that has rust-preventative properties.

At this time, be careful not to get the silicone spray on the oil seal, as it can affect the rubber, such as causing it to harden.

Spray the silicone spray and thoroughly wipe it off with a cloth to complete the rust removal process. Applying anti-rust treatment will also make future maintenance easier.

Precautions When Removing Rust from Front Forks

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When removing rust from front forks, proceed with caution regarding the following points:

Do not treat the oil seal.
Treat horizontally, little by little.

If these precautions are not followed during rust removal, it could potentially damage the front forks, and in the worst case, an overhaul may be necessary.

Do Not Treat the Oil Seal

The oil seal has the role of sealing the front fork oil filled inside the inner tube of the front fork.

Damage to the oil seal can lead to oil leaks, so before starting rust removal, protect the oil seal by masking it.

The front fork acts as a suspension, but if oil leakage progresses, shock absorption will worsen, and the motorcycle may become unstable while riding, which is dangerous.

Treat Horizontally, Little by Little

If the inner tube of the front fork is abraded, it can lead to poor sealing with the oil seal, causing oil leakage.

Therefore, instead of grinding vertically (perpendicularly), grind horizontally (in a side-to-side motion).

How to Prevent Rust on Front Forks

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There are four methods to prevent rust from forming on front forks:

Do not leave it wet after riding in the rain.
Use a motorcycle cover.
Park/store indoors.
Wash regularly.

Being mindful of these practices will help suppress rust formation, and even if rust does occur, it will be relatively minor.

Method 1: Do Not Leave it Wet After Riding in the Rain

Rust forms when moisture and oxygen chemically react with the metal surface. Therefore, avoiding situations where water droplets remain, such as after riding in the rain, can suppress rust formation.

After riding in the rain, wipe off any remaining water droplets from the motorcycle as much as possible, and wash it promptly to remove dust and mud that may have adhered with the water droplets.

Method 2: Use a Motorcycle Cover

Rust on front forks is caused by moisture, as well as dust and oil. Therefore, covering your motorcycle with a cover when parked will help block out external air and dust.

However, if the motorcycle is not ridden for a long period, moisture rising from the ground can get trapped inside the cover, becoming a cause of rust.

If the motorcycle is to be stored for a long period, it is recommended to occasionally remove the cover to air it out, or use a cover that is resistant to moisture and water.

Method 3: Park/Store Indoors

Storing your motorcycle indoors, protected from rain and wind, can reduce rust on the front forks compared to outdoor storage.

Parking or storing indoors with a motorcycle cover offers even greater rust prevention and protects the motorcycle from dust and other dirt.

Method 4: Wash Regularly

Whether you park your motorcycle outdoors, or indoors with a cover, dust from the ground can accumulate and cause rust. Therefore, regular washing can prevent rust formation.

Rust is particularly prone to forming due to salt contained in water and sea breezes if you ride in the rain, or ride near the sea regardless of the weather, or park near the sea.

If you ride your motorcycle in such environments, wash it as soon as possible and apply rust-preventative treatment.

FAQ Regarding Front Fork Rust Removal

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Here are common questions and answers about rust on motorcycle front forks.

If you are looking to remove rust from your front forks or prevent rust from forming, please refer to this section.

Can Pinpoint Rust or Small Rust Spots on Front Forks be Removed with Pikaru?

Pikaru is primarily used for polishing stainless steel and brass and is not suitable for rust on front forks.

To remove rust from front forks, it is recommended to use glass wool (such as Ponsta) or a fine brass brush, then finish with wet sandpaper and polishing compound.

Can Aron Alpha be Used to Fill Rust Holes or Repair Front Forks?

If the surface of the front fork is pitted due to rust, removing the rust can sometimes reveal that the chrome plating in the center of the rust has completely peeled off, leaving a depression.

In such cases, you can fill the depression with Aron Alpha and polish it to seal the hole. However, a bond specifically designed for metal or chrome plating would offer better compatibility and durability than Aron Alpha.

Please note that this is only a temporary fix. Always inspect the treated area before riding to ensure no new depressions have formed.

How Much Does Re-chroming Front Forks Cost?

The market price for re-chroming front forks is around 20,000 yen per fork for conventional forks and around 25,000 yen per fork for inverted forks.

If you also request an overhaul in addition to re-chroming, the total cost would be around 32,000 yen per fork for conventional forks and around 36,000 yen per fork for inverted forks.

Most repair shops cannot perform re-chroming in-house, so they disassemble the front forks and send the parts to a specialized plating company. This involves disassembly labor costs and transportation costs, making it somewhat expensive.

Please tell me how to polish without removing the tires or fenders.

You can polish off rust with wet sandpaper without removing the tires or fenders, but you'll be limited to working within arm's reach, and efficiency won't be very good.

If you're polishing with wet sandpaper without removing the tires or fenders, start with coarser 800-grit sandpaper, then gradually switch to finer grits like 1,000, 1,200, and so on.

Should rust on chrome-plated parts be removed in the same way as front forks?

To remove rust from chrome-plated parts, first remove dust and dirt from the surface, then apply a rust remover suitable for plating and polish.

Apply the chemical to a cloth or rag and gently polish to remove the rust from the plated area. However, if the removed rust adheres to the cloth, it can scratch the plating.

If rust adheres to the cloth, switch to a new cloth or rag to prevent scratches on the plated part as you wipe it clean.

Summary

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We have explained the causes of rust on motorcycle front forks and how to treat it.

Rust on front forks often begins as pinpoint rust on the chrome plating, but if left untreated, this pinpoint rust will eventually develop into widespread red rust.

Leaving red rust untreated can damage the oil seal, sometimes leading to oil leaks. If an oil leak occurs, an overhaul of the front fork will be necessary, so if you find pinpoint rust, remove it as soon as possible.