Threadlocker or regular tightening: What holds better on the Airholder roof rack?

Every roof rack owner eventually asks the same question: Do I need to retighten the connections every 200 kilometers? The answer depends on how the screw is secured against vibration in the first place. There are two practical approaches: regularly retightening by torque—or applying threadlocker during assembly. Both have their areas of application, advantages, and disadvantages.

At Airholder, we opted for a specific product—INBUS® 79680 high-strength threadlocker—and include it with every roof rack kit. In this article, we explain why this particular product, what the difference between the methods is, and which approach makes sense when.

In short: what is better

• For permanent fastenings (roof tent mounts, baskets, spare tire mounts, attachments that are mounted once and stay for seasons)—threadlocker is clearly superior. Once applied, forgotten.
• For temporary/frequently changed mounts (e.g., bike rack that is installed today and removed next week)—retightening with torque is more practical: nothing sticks, relocation takes seconds.
• For lashing straps and ratchet straps—only tensioning/visual inspection. Threadlocker has nothing to do with straps.
• For the Airholder platform itself on the fixed points—factory mounting kit with built-in securing. It is tightened strictly according to torque, without additional means.

Details follow below.

Where the problem comes from: vibration and self-loosening

Every bolted connection tends to self-loosen under vibration. Especially with transverse vibrations, which are completely normal during driving: winding roads, poor asphalt, curbs, speed bumps.

In the laboratory, this is investigated according to DIN 65151 (Junker test). The results show: an unsecured M8 screw loses its preload force on a vibration test stand within a few minutes. In real vehicle operation, this is of course not minutes—but during a two-week mountain tour, something that was initially tight can indeed loosen.

There are two solutions:

1. Regularly restore torque—i.e., periodically check and retighten the connection with a torque wrench.
2. Block the thread—apply an anaerobic polymer that fills the gap between the threads and prevents loosening.

Both methods work. The difference lies in convenience, reliability, and use case.

Method 1: Regular retightening with torque

How it works

After assembly and every few hundred kilometers, the torque is checked with a torque wrench. For M8 on Airholder mounts, the typical tightening torque is 20–25 Nm.

Advantages

• No chemicals, nothing sticks
• Mount relocation takes seconds
• Works with any bolted connection, even non-standard threads

Disadvantages

• Requires discipline—forgetting to check risks play. On mountain tours, it is recommended: after the first 50 km, then every 200–300 km
• Torque wrench must be carried along, otherwise it will be tightened "by feel"—and M8 will quickly be over-tightened
• Climbing onto the roof with the wrench in rain, snow, or cold is not pleasant
• Does not protect against water ingress into the thread—corrosion can occur over years

When useful

• Bicycle mounts and carriers that are frequently relocated (every one to two weeks)
• Test or temporary configurations
• Emergency scenario: if for some reason no threadlocker was used—works, but suboptimal as a permanent solution

Method 2: Threadlocker

How it works

An anaerobic polymer is applied to the screw thread—a liquid that cures in the absence of air (i.e., precisely in the tightly screwed gap). After curing, the threads are filled with solid material; the screw can no longer loosen due to vibration.

Strength classes:

• Low strength (purple)—weak securing, for set screws and precision mechanics
• Medium strength (blue)—compromise: holds, but can be loosened with standard tools if necessary
• High strength (green or red, depending on manufacturer)—maximum protection against loosening, disassembly requires heating or significantly higher break-loose torque

Advantages

• Applied once—for the entire lifespan of the connection. No torque check needed on the go
• Protection against water ingress: the polymer also seals the thread, no corrosion
• Works regardless of whether you remember to check the torque at the campsite—always secures
• Good for connections in hard-to-reach places (e.g., lower mounts)

Disadvantages

• Requires curing time—hand-tight in minutes, full strength after 8 hours
• Must be applied correctly during assembly—to clean, degreased threads, in the correct amount
• With high strength, disassembly is more complex—heating with a heat gun or significantly higher break-loose torque required

When useful

• Permanent mounts—roof tent adapters, baskets, spare tire mounts, everything that is set up once and lasts for seasons
• Connections in inaccessible places
• Any fastening where safety is critical—i.e., anything that carries a load on the roof of a moving vehicle

Our choice: INBUS® 79680 high-strength

Every Airholder kit includes a tube of INBUS® 79680 high-strength threadlocker, 20 g, Made in Germany. This is a conscious decision for several reasons.

Why INBUS

• Made in Germany—produced by INBUS Werkzeug GmbH in Breckerfeld. Stable quality, transparent technical data
• Suitable for M6–M20—our M8 on the B-profiles is right in the application range
• Green color (ColorCap)—differs from classic Loctite colors (blue/red), quickly identifiable in the workshop
• +OneDrop bottle design—precise dosing, no dripping, no smudging
• Additional sealing against water ingress—crucial for a roof rack exposed to rain, snow, and road salt for years

Why high strength, not medium strength

This is the most common question. The logic:

• Airholder mounts are a permanent installation, not changing accessories. Once set for your roof tent or bike rack—it runs for years
• On the roof of a moving vehicle, the risk of loosening is critical in its consequences—a mount flying off with 100+ kg of load at 130 km/h is not the same as a loose screw in a cabinet
• High strength provides maximum reserve against vibration, especially on mountain roads
• Disassembly with high strength is indeed more complex—but this is a rare operation, every few years, and it is solved with local heating by a heat gun (about 250 °C)

For connections that need to be frequently disassembled (quick-change adapters), there is medium strength—for example, INBUS® 79560. This is a matter of scenario, not dogma.

What's in the kit

Every Airholder roof rack kit (VW T6 Short Wheelbase, Defender 110 and other platforms) includes a tube of INBUS 79680—20 grams with reserve for all standard mounts in the kit plus two to three relocations. Nothing needs to be purchased separately.

Which method when—by scenario

How to properly apply INBUS 79680

1. Clean threads—brush screw and nut, wipe with cloth, degrease (alcohol or acetone)
2. Apply 1–2 drops to the screw thread (about 2–3 threads, towards the screw end)
3. Screw within a few minutes—before the liquid sets
4. Tighten to 20–25 Nm for M8 on Airholder mounts
5. Allow to cure—hand-tight after 2–10 minutes (for active metals like steel), full strength after 8 hours
6. Do not subject to full load before full curing

Practically, this means that mounts with INBUS 79680 should be installed at least one day before departure, preferably two. A newly assembled carrier that goes directly into the mountains is bad practice.

Checklist before installing mounts with threadlocker

• [ ] Screw and T-slot nut threads cleaned, degreased
• [ ] INBUS 79680 tube not expired (date on packaging)
• [ ] Torque wrench set to 20–25 Nm
• [ ] All mounts to be installed in this session prepared (parallel curing for multiple connections)
• [ ] Allow at least 24 hours of rest before full load
• [ ] When reassembling (if mount was previously removed)—check threads for old polymer residues, clean mechanically if necessary

What we do NOT recommend

• No Loctite 222 or comparable low-strength (purple) for roof rack fastenings—too weak for vibration stress in the mountains
• No self-locking nuts as a substitute for threadlocker in our system—the mount design is for normal M8 + polymer, not locknuts
• No mechanical counter-nuts on the T-slot of the B-profiles—the slot is designed for T-slot nuts, a counter-nut will damage the profile
• Do not mix threadlockers from different manufacturers on the same thread—chemically different formulations will not react correctly with each other