Fit it once, fit it right: BM Catalysts on why installation practices are key

When it comes to emissions control technology, the spotlight often falls on whether the part in question is type-approved, up to OE standards or available for purchase. But there is an often-overlooked factor at play, one that can make or break the success of a repair, and that is installation practices. 

BM Catalysts advise that often the aftermarket’s biggest missed opportunity isn’t just about the quality of parts being fitted, but how they are being fitted. In a market increasingly driven by efficiency, margins and reputation, this is as prevalent as ever.

The reality is simple, even the highest-quality emissions control product can fail prematurely if installation standards fall short. Reusing worn fittings, ageing gaskets or fatigued clamps introduces risk into what could otherwise be a straightforward repair. The result of reusing such components can lead to leaks, movement, noise complaints and, ultimately, costly comebacks.

James Saunders, Technical Director at BM Catalysts, explains: “Fitting kits are a small but important factor to take into consideration when buying or fitting a replacement emissions control product.”

The benefits of using a new fitting kit outweigh the costs, yet they’re often overlooked in favour of saving time or money in the moment”, he added. 

This is where the concept of the “complete repair” becomes critical. It’s not just about replacing the failed part; it’s about restoring the entire system to a condition that ensures long-term performance. That means replacing all associated mounting components at the same time, from gaskets and clamps to rubbers, springs and fixings.

Take gaskets as a starting point. Over time, they degrade, compress and lose their ability to form an effective seal. Attempting to reuse them is a false economy. In manifold applications, where precision sealing is critical, even slight misalignment can lead to exhaust gas leaks, impacting both performance and emissions compliance. 

The same applies to support rubbers and hangers. These components are designed to absorb vibration and stabilise the exhaust system, but like all rubber parts, they deteriorate with age. 

Reusing worn supports can introduce excessive movement, placing strain on the newly installed unit. In extreme cases, this can lead to detachment and impact damage, potentially destroying the internal monolith and resulting in a second replacement job that could have been avoided entirely.

Even seemingly minor components such as nuts, bolts and springs play a crucial role. Corrosion can weaken threads, while springs can lose tension over time, compromising the integrity of joints. These issues often only become apparent during installation, leading to delays, frustration and additional labour time, none of which are factored into the original job.