Blind rivet: where and why it is used in a car

When it comes to car body repairs, most people immediately think of welding or bolting. But there is a third, no less important method of fastening - blind rivets. These compact metal elements have become indispensable in situations where a strong, but at the same time accurate connection of parts without thermal effects is required. From repairing thresholds to attaching trim, blind rivets solve problems that neither riveting with a classic hammer nor spot welding can handle.

In this article we will look not only design and operating principle blind rivets, but also their key advantages over alternative methods. You will learn in which cases their use is justified, and where it is better to refuse in favor of other technologies. We will pay special attention practical nuances: how to choose the right diameter and material of the rivet, avoid common mistakes during installation and ensure the durability of the connection even in aggressive conditions (for example, when repairing the underbody of a car).

What is a blind rivet and how does it work?

Blind rivet (also called rivet bolt or pull-rivet) is a fastening element that forms a permanent connection due to the deformation of its own body. Unlike traditional rivets, its installation does not require access to both sides of the parts being joined. This makes it ideal for working in hard-to-reach areas, such as attaching interior body panels or repairing arches.

Structurally, the blind rivet consists of two parts:

• 🔹 Housing (sleeve) - a hollow cylindrical part that is deformed during installation, forming a “head” on the back side of the material.
• 🔹 Rod (mandraine) - a metal pin with a thickening at the end, which is pulled out with a special tool, deforming the body.

The operating principle is simple: the rivet is inserted into a pre-drilled hole, then the rod is pulled out rivet gun (manual or pneumatic). The thickening at the end of the rod expands the body, forming a “mushroom” on the reverse side. When the force reaches a critical point, the rod breaks off along a pre-designed groove, leaving a neat connection.

Advantages of blind rivets over welding and bolts

Why do professional auto repairmen increasingly prefer blind rivets rather than conventional welding or bolts? Here are the key arguments:

Criterion	Blind rivet	Welding	Bolted connection
Need to access both sides	❌ No	✅ Yes	✅ Yes
Thermal impact	❌ No	✅ Yes (risk of deformation)	❌ No
Installation speed	✅ 10–30 seconds per rivet	⏳ 2–5 minutes (with preparation)	⏳ 1–3 minutes
Peel strength	✅ Up to 1500 kg (depending on diameter)	✅ High	✅ Depends on the bolt
Corrosion resistance	✅ High (with the right choice of material)	❌ Risk of seam oxidation	✅ Depends on coverage

Main advantage — no heating of the material. This is critical when working with galvanized body parts, where welding destroys the protective layer and provokes rust. In addition, rivets do not require complex surface preparation (cleaning, priming), which speeds up repairs by 2–3 times.

⚠️ Attention: Blind rivets are not recommended for connecting parts that experience dynamic loads (for example, suspension elements). In such cases, priority remains with welding or high-strength bolts.

Where are blind rivets used in a car?

The scope of application of blind rivets in car repair is wider than it seems at first glance. They are used both for cosmetic repairs, and for the restoration of load-bearing elements of the body. Here are typical cases:

• 🚗 Repair of thresholds and arches — attaching patches or new panels without the risk of burning through the metal by welding.
• 🔧 Installation of sheathing and plastic elements - for example, attaching mudguards or wheel arch liners.
• 🛠️ Bottom restoration — rivets withstand vibration loads better than spot welding.
• 🔩 Attaching additional equipment — bumpers, towbars, crankcase guards (if there is no access to the reverse side).
• 🔄 Replacing rotten areas of the body - for example, when repairing the wings or hood in the places where the seals are attached.

Blind rivets are especially relevant when working with aluminum bodies (for example, at Audi A8 or Jaguar XJ). Welding aluminum requires argon and highly skilled craftsman, while rivets provide a strong connection without special equipment.

Another plus - possibility of dismantling. Although the rivet forms a permanent joint, it can be drilled out without damaging the base metal (unlike welding, where the seam must be cut off).

Types of blind rivets: what they are and how to choose

Not all blind rivets are created equal. They are classified by material, diameter, length and head type. An incorrect selection may result in a weak connection or corrosion. Let's look at the main parameters:

1. By material

• 🔹 Steel (galvanized) - a universal option for most tasks. Suitable for joining steel body parts. Marking: A2 (stainless steel) or C1022 (carbon steel with zinc coating).
• 🔹 Aluminum - lightweight, resistant to corrosion, but less durable. Ideal for aluminum bodies. Popular alloys: AD51, AD57.
• 🔹 Stainless — for aggressive environments (for example, underbody repair). Brands: A4 (marine stainless steel).
• 🔹 Monometallic - body and rod made of the same material (for example, Monobolt). Used for critical connections.

2. By diameter and length

The diameter of the rivet is selected to match the thickness of the materials being joined. Standard sizes: 3.2 mm, 4.0 mm, 4.8 mm, 5.0 mm and 6.4 mm. The length of the sleeve must exceed the total thickness of the parts by 1.5–2 times (for example, for two sheets of 1 mm each, a rivet 4–6 mm long is needed).

3. By head type

• 🔹 Flat (secret) - for flat surfaces where aesthetics are important.
• 🔹 Round (semicircular) - a universal option, provides maximum strength.
• 🔹 Reinforced (with side) — for soft materials (plastic, thin metal).

Critical error: Using steel rivets on aluminum parts without an insulating gasket leads to galvanic corrosion after just 6-12 months.

How to check the quality of a rivet before purchasing?

1. Inspect the coating: there should be no chips or rust on the galvanized rivets.

2. Check the markings: quality products are marked (for example, “A2-70” for stainless steel).

3. Break test: the rod should break along the groove, not bend.

Step-by-step instructions: how to properly install a blind rivet

The quality of the connection depends 80% on correct installation. Let's break down the process step by step, including preparation and selection of tools.

Required tools:

• 🔧 Riveting gun (manual or pneumatic). For auto repair, a tool with force is optimal up to 3000 N.
• 🔨 Drill with metal drills (diameter 0.1–0.2 mm larger than the diameter of the rivet).
• 🧲 Reamer or countersink for chamfering.
• 🧴 Degreaser (acetone or alcohol).
• 👓 Protective equipment: glasses and gloves (when working with aluminum).

Procedure:

1. Marking and drilling. Drill a hole in both pieces. The diameter of the drill must match the diameter of the rivet (for example, for a rivet 4.8 mm use drill 5.0 mm). Bevel both sides of the hole.
2. Cleaning and degreasing. Remove the shavings and treat the surface with a degreaser. This will prevent corrosion and improve adhesion.
3. Installation of the rivet. Insert the rivet into the hole so that the head fits snugly against the surface. Make sure that the sleeve protrudes from the back side by at least 1.5 mm.
4. Riveting. Insert the rod into the gun and squeeze the handles until you hear a click (the rod breaks). Do not release the tool for 2-3 seconds - this will allow the material to “settle”.
5. Quality control. Check the connection: the head should be symmetrical, without cracks. Try shaking the parts - play is unacceptable.

The diameters of the rivet and the hole are checked to match|There is no gap between the parts|The rivet rod fits freely into the gun|The reverse side is available for deformation of the sleeve-->

⚠️ Attention: When working with air gun adjust the air pressure! Sufficient for aluminum rivets 6–7 bar, for steel - 8–10 bar. Excessive pressure leads to rupture of the liner.

Common mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes when working with blind rivets. Here are the most critical of them and ways to prevent them:

Error	Consequences	How to avoid
Mismatch between hole and rivet diameters	Weak connection, play	Use a drill 0.1–0.2 mm larger than the rivet diameter
Installation without degreasing	Corrosion, decrease in strength	Treat the surface with acetone or alcohol
Insufficient sleeve length	Incomplete deformation, riveting	Sleeve length = (material thickness × 1.5) + 1 mm
Using Steel Rivet for Aluminum	Galvanic corrosion	Choose aluminum or stainless steel rivets
Intermittent riveting force	Uneven deformation, cracks	Squeeze the pistol grips smoothly, without jerking

Another typical problem is rivet misalignment during installation. This happens if the gun is not perpendicular to the surface. To avoid skew, use guide nozzles or magnetic holders.

Advice from the experts: If the rivet does not break off after squeezing the gun, do not try to tighten it or modify it. This is a sign of marriage - replace it with a new one.

Comparison of blind rivets with other types of fasteners

To understand when to choose a blind rivet and when to choose an alternative method, let’s compare it with other types of fasteners based on key parameters.

• 🔹 Blind rivet vs. Classic rivet
  Classical requires access to both sides and hammering, which is not always possible in the body. Exhaust It is installed on one side and does not deform the front surface.
• 🔹 Blind rivet vs. Spot welding
  

  Welding is stronger, but destroys the zinc coating and requires stripping. Rivets retain anti-corrosion protection and do not heat the metal.

• 🔹 Blind rivet vs. Bolt and nut
  

  The bolted connection is dismountable, but requires space for a nut and wrench. The rivet is more compact and does not weaken over time.

• 🔹 Blind rivet vs. Glue (eg. 3M VHB)
  

  The adhesive is suitable for plastic and light panels, but does not withstand vibration loads. Rivets are more reliable for metal parts.

The ideal scenario for blind rivets is - joining thin metal sheets (up to 3 mm each) in places where shear strength is important, but there are no extreme loads. For example, attaching a door sill or repairing an arch.

- There is no access to the back of the part.

- It is necessary to preserve the zinc coating.

- A quick and strong connection without heating is required.-->

FAQ: Frequently asked questions about blind rivets

Can pop rivets be used to repair suspension?

No. The suspension experiences dynamic and shock loads that the rivets cannot withstand. For such tasks use high-strength bolts (strength class 10.9 and above) or welding.

How to remove a blind rivet if you need to disassemble a connection?

There are two ways:

1. Drill out the rivet with a drill 0.5–1 mm smaller than its diameter, then knock out the remaining sleeve.
2. Use special rivet roller (for example, Rivnut Tool), which “screws” into the sleeve and pulls it out.

Once removed, the hole can be reused if its condition allows it.

Which rivets are best for repairing the underbody of a car?

For the bottom we recommend:

• 🔹 Stainless rivets (A4) - resistant to moisture and salt.
• 🔹 Rivets with sealing coating (e.g. Seal-Riv).
• 🔹 Aluminum rivets with an insulating gasket (if you combine aluminum with steel).

Diameter: no less 4.8 mm, length - 3–4 mm more than the total thickness of the sheets.

Can rivets be painted after installation?

Yes, but subject to two rules:

1. Use epoxy primer before painting - it improves adhesion.
2. Do not paint the rivet head if it is in contact with another part (such as a seal). This may cause the paint to peel off.

Paint is not necessary for stainless rivets - they themselves are resistant to corrosion.

How long does one blind rivet last?

Strength depends on diameter and material:

• 🔹 3.2 mm (aluminum) - up to 300 kg to break.
• 🔹 4.8 mm (steel) - up to 1000 kg.
• 🔹 6.4 mm (stainless steel) - up to 1500 kg.

For comparison: spot welding can withstand 1200–1800 kg to a point, but destroys the anti-corrosion coating.