Ultimate Guide: Can You Swap Crotch Straps Between FIA 5/6-Point Harness Brands?
At GSM Performance, one of the most common questions we get asked is:
“Can I use a crutch strap from one harness brand with a lap or shoulder strap from another?”
It might seem like a small detail, but this is a critical question with serious implications for safety and compliance. In this definitive guide, we’ll break down everything you need to know about crutch strap compatibility, FIA regulations, harness design, and what your options are when replacing a damaged or worn-out strap.
Mixing Harness Brands: Why It’s Not Allowed
The short answer: No, you cannot mix harness components across brands. Here’s why:
FIA Homologation Rules
FIA harnesses are tested and approved as a complete unit — shoulder, lap, and crutch straps must all match and share the same homologation number. Mixing parts immediately invalidates the approval.Incompatible Hardware
Even though many buckles look similar across Sparco, TRS, OMP, Schroth, or Sabelt, the internal locking mechanisms are brand-specific. Misaligned buckles could jam, not lock correctly, or even release under stress.No Swapping or Re-Webbing
FIA rules state that once any part of the harness is worn or damaged — especially the sub-strap — the entire harness must be replaced. Replacement or re-webbing is only allowed through the original manufacturer and is rarely supported.Expiry Dates Must Match
Even if one strap is still “in date,” it cannot be used with a different homologated harness. All parts must come from the same original set.
FIA 8853-2016: What Changed?
The updated FIA 8853-2016 standard introduced some important changes to harness design:
All FIA harnesses must now be 6-point only — 5-point systems are no longer legal for motorsport.
Crutch straps are now permanently fixed to the camlock buckle.
You can’t purchase crutch straps separately — they’re built into the full system.
Brands like TRS, Sabelt, and Schroth integrate their sub-straps into the buckle housing, making them non-removable.
These changes improve anti-submarine safety and eliminate the chance of tampering.
What If My Crotch Strap is Worn or Broken?
You’re not alone — this is a common scenario.
Your options:
Replace the entire harness with a new matching set.
Contact the manufacturer directly — but replacements are only offered in rare cases where the serial matches and compliance isn’t broken.
Do NOT attempt to substitute parts from other brands, even if they look compatible.
Remember: the sub-strap is your last line of defence in a crash to stop you from sliding under the lap belt.
The Role of the Crotch Strap in Your Safety
Also known as the “anti-sub strap,” this part plays a critical role:
Keeps your body correctly positioned during an accident.
Prevents submarining under the lap belt.
Helps secure the central camlock and shoulder/lap belts in the correct location.
This isn’t just a “bonus” strap — it’s essential for your safety. Tampering with it by using a mismatched replacement can lead to failure during high-impact crashes.
So, Can You Replace Just the Sub Strap?
| Question | Answer |
| Can I use a crutch strap from another brand? | ❌ No |
| Can I replace just the sub-strap? | ❌ Only with an exact manufacturer match (rare) |
| Can I mix harness parts from different brands? | ❌ No |
| Can I upgrade from a 4-point to a 6-point system? | ✅ Yes, but only with brand-approved kits |
| Are 5-point harnesses still legal? | ❌ Not under FIA 8853-2016 |
Explore Our FIA Harness Range – Stay Compliant and Safe
At GSM Performance, we stock a wide range of complete FIA-approved harnesses from top-tier motorsport brands. These are all tested, homologated, and safe when used as complete sets.
Our Most Popular FIA 6-Point Racing Harnesses
If you’re ready to upgrade to a fully FIA-compliant 6-point harness system, we’ve got you covered. At GSM Performance, we stock the most trusted motorsport harnesses in the industry, all designed to meet the latest FIA 8853-2016 standards and deliver the best in driver safety and comfort.
Here are some of our most popular options from leading brands:
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From £168.89 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
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From £209.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
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From £195.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Final Thoughts: Safety First, Always
If you’ve got a damaged sub-strap or are building a new track car, the best advice we can give is simple:
Stick with a full matching harness set from the same manufacturer. Don’t mix brands. Don’t swap components.
Harness systems are not modular — they’re integrated safety systems, and treating them as such is essential. A small mistake with compatibility could mean your harness fails during impact. For the cost of a new harness set, it’s simply not worth the risk.
Have questions or need help picking the right system? Contact our GSM Performance team — we’re here to help with expert advice and a wide range of in-stock harness kits.
Stay strapped. Stay safe. See you on the grid.