Two Flavours of Catalytic Converters

Growing up when catalytic converters were introduced, I remember the scepticism many drivers of high performance autos felt towards these emission-cutting devices. No one liked them and most, if not all, people felt that all they did was rob cars of power. It was well known that many DIYers with muscle cars would substitute the catalytic converter with a straight pipe as soon as they drove their new vehicle off the dealer’s lot.
Thankfully, those days are long gone as everybody realizes that the catalytic converter is an essential part of a healthy car. While catalytic converter problems are not too commonplace, they still occur and manufacturers offer replacement units in two product streams.
The direct fit catalytic converter is the more expensive of the two options as it comes complete with the mounting pipes and brackets. “The direct fit you just unbolt it at the service joint and bolt it back in,” said Pat Haynes, manager, North American Aftermarket Emission Technology for Walker Exhaust, a division of Tenneco. The universal fit catalytic converter is just the converter body itself. A less expensive option to purchase but the costs can be increased to your customer because there is more installation labour involved. “The universal converter is just the converter and you have to put everything else onto it. You may have to try and salvage the pipes,” said Haynes.
“With the universal fit you have to cut and weld to install it,” said Joe Mercanti the Ontario & Western Canada regional manager for Bosal Canada Inc. “What you are finding these days is that the converter is made specifically for the vehicle as opposed to being universal. When you are putting in a universal converter you have to check and make sure that the holes are correct, that the flow is correct. It is not as simple as installing the direct fit converters. Now with the advanced electronics and with the O2 sensors, it is not as simple.”
The danger exists when a customer comes in with a catalytic converter that has failed that a technician will simply replace the converter, with a direct fit or universal, and that will be all. “You still have to repair the thing that made the converter fail in the first place. You can’t just throw a new one in and hope that it solves the problem,” said Corey Smith, training manager with AP Exhaust.
“The installer or technician makes a determination which type of catalytic converter to install after testing the operating system and makes a determination why the converter failed,” he said. “They repair that area of need and then (he) makes a determination weather to install a direct fit or universal converter. If he goes the direct fit rout, he just purchases it and unbolts the old one and bolts in the new unit. Installing a universal is a bit more work.”
Deciding which unit to install is predicated on many things. Cost is a factor. “You need to assemble the universal fit most of the time,” said Cam Young of Cam’s Auto Service. “The cost of the product is quit reasonable but cost of the labour is more extreme. When you go to a universal fit you have to cut the pipes and weld. Not all technicians are expert welders.” The service station also has to have all the equipment to do a proper job. “The direct fit is a nicer product, you will always get a good fit with it,” he said. “What we are finding, more often than not, is that direct fit converters give us less problems than a universal fit converter. We always give the customer the option. Let the client decide. The cost difference can be half price but that does not include the installation.”
It is important to note that the performance and the specifications of a direct fit and universal fit catalytic converter are identical. “The same converter bodies are used in the direct fit and universal units,” said AP Exhaust’s Smith. “The difference is that we make the whole direct fit assembly as opposed to somebody making it in their shop – cutting and welding pipe.” The converters are made for the specific vehicle. A universal converter is still specifically made for that class of vehicles. You cannot install a catalytic converter that is not made specifically for that car, be it universal or direct fit.
Where the decision is made weather to use a direct fit or universal is in terms of access to the converter. “It’s a job by job thing,” said Smith. “If you take a Ford Taurus or Mercury Sable, that is a very intricate configuration on most of their models. It is nasty enough that you would opt for a direct fit. Very few would choose to use a universal. It is less time consuming and less labour intensive. However, if you take a Chevy Cavalier and work at the converter there, it is easy to get at you cut the back pipe off the converter and replace the unit. It can be easily done. It is an application by application decision.”
Direct fit converters are gaining market share because of car design. “There is a more complex and smaller area to work in – where converters are sometimes put into new cars,” said Walker’s Haynes. “Typically, on newer vehicles, the catalytic converters tend to be closer to the engine and there is less area to work in.” Bosal does not make universal fit catalytic converters due to the complexity of installation. “Now where converters are placed, the configuration that they are in and the access a technician has to them, it is not as easy as it used to be to mount the universal fit catalytic converters, said Mercanti. “They can be tucked up in the engine bay, where the converter used to be mounted on the underside of the body with good access to it.”
The industry is moving towards more direct fit catalytic converters because of the complexity.” Haynes said that the universal fit’s share of the replacement catalytic converter market was 82 per cent in 2006 and in 2010 it dropped to 57 per cent, losing 15 per cent market share in just four years. “Over the next ten years you will have a total inversion of the mix when it will be 80 per cent direct fit and 20 per cent universal.” He adds, “General repair shops will tend to want to go with the direct fit converters because they usually will not have the equipment to do all the cutting and welding and sizing the converter to fit.”
Direct fit catalytic converters give a distinct advantage to the general repair shop over that of a dedicated “muffler shop.” “Many of the highly skilled exhaust guys are not equipped to do a proper diagnostic on the engine operating system,” said Smith. “They put on a new converter, they change a few O2 sensors and they hope they have the problem solved. That balances with a full repair facility, that have all the scan tools and equipment, where they can do a thorough diagnostic on the vehicle and find out what really went wrong and fix the problem that caused the converter to fail and then determine what kind of converter needs to be installed.”