Goof of the Month: Subframes Are Important, Yo.

Welcome to Goof of the Month! Every month, we ask for stories from our technician pals which highlight the need to understand one’s vehicle, how to maintain it, and how it works.

This month’s story comes to us from Brian Early, an automotive technician in Oshawa, Ontario. Early’s story illustrates the importance of two things: the potential importance of applying rust protection to your ride if it’ll be used during Canadian winters, and the importance of taking your mechanic’s advice seriously.

The Complaint

Early describes a customer who arrived in their 2005 Pontiac Grand Am, complaining of steering that felt “funny” and was behaving oddly. According to Early, this customer and several family members are semi-regular visitors to his shop – though they’ll often service their rides elsewhere too, if convenient.

“We’ve seen this car, on and off, for quite a while,” Early says. “This time, the customer described the problem to me, as being as if ‘the car was drunk.’ This was an accurate description, and my brief test drive was eye-opening.”

The vehicle’s handling, and directional stability, were substantially reduced – and just a quick test drive was enough for Early to determine that something was drastically wrong. This was a serious problem, and a real safety concern too. Early says there was more than a quarter turn of free play in the steering wheel.

After looking beneath the Grand Am on his hoist, Early quickly found the problem.

Old frame out

“The sheetmetal tab holding one side of the steering rack had broken off, allowing the whole thing to pivot upwards on the other horizontally positioned mounting bolt. So, instead of pushing the rear of the front passenger tire to the right as normal, to turn left, the steering rack would first deflect upwards until it hit the body, causing dramatic toe angle changes, and a highly variable response to steering inputs.”

In simple terms, the steering rack in this Grand Am was only partially attached to the car. Why? Rust. Corrosion had, literally, eaten through the subframe of this Grand Am, and in particular, at the location where the steering rack mounts to that front subframe. Proper steering requires a vehicle’s power steering rack to be fixed firmly in place, but because of corrosion, this steering rack was free to move around a great deal.

“We’re big proponents of oil-spray-style rust prevention, even though we don’t sell it here,” Early adds. “But we’re realistic that it only slows rust, and doesn’t stop or outright prevent it, particularly if the vehicle wasn’t treated right from new. For several years, we’ve suggested to this car’s owner that she have it sprayed, because it was getting scaly and dry in places. But the car gets driven less than 10 km per day, so maybe the customer didn’t think it was a worthwhile expenditure. And to be fair, the visible parts of the car still look to be in good shape. This is not unusual.”

Early notes that in many cases, components like vehicle subframes only use paint as a means of protecting them from corrosion, unlike vehicle body panels, which are typically galvanized or have additional corrosion protection built in. This is why a visual check of the surface of the car is no substitute for a periodic check underneath for more excessive rusting.

Old frame corrosion detail

The Outcome

The customer’s Grand Am was repaired with a used subframe sourced from a wrecker, and Early also changed a long-broken stabilizer bar with a new unit as part of the overall repair, while he was at it. In this case, the customer got lucky – an issue like this can often wind up writing a vehicle off.

“I’ve personally replaced several subframes and cradles, and have condemned quite a few other cars that weren’t worth repairing,” Early says. “This 2005 Grand Am has just under 100,000 km, and the owner decided it was better to spend the money on the repair than to shop for another used vehicle.”

Perhaps due to our climate, Early says this is a fairly common occurrence.

“Since this Grand Am, we’ve also had a first-time customer’s 2008 Chrysler Pacifica in, which we condemned the subframe on. Brake and fuel lines are a far more frequent failure, but subframe and underbody structural rot is a more common of an issue than you might suspect. We also had a Ford Windstar in last week, which had a previous subframe rust repair, but is now rusting through elsewhere. This one will likely be condemned, too. A good oil spray treatment, especially if applied since the vehicle was new, could have delayed or prevented these problems.”

Car with subframe removed

Money-wise, Early figures that annual rust-proofing, which runs about $120 to $160, is a worthwhile investment, compared to repairing a rotted subframe.

“You’ve got to figure about $300 to $600 for a decent used part, and anything from $300 to $1,000 in labor to replace it; plus whatever things break or die or have to be replaced during the swap – including fluids, and exhaust components. This doesn’t even take the safety into consideration. This Grand Am’s steering could have fully detached and caused a loss of control.”

Lesson Learned

The Grand Am customer had made the right choice – taking the vehicle into the shop within days of detecting the unwelcome sensations from the steering system. Thing is, a little rustproofing as per Early’s suggestion, and a more regular, detailed check of the vehicle, could have greatly helped to address this problem before the vehicle’s safety had been so badly degraded. That didn’t happen, in this case.

Given the relative health of the rest of the vehicle, it’s not a stretch to assume that a few bucks a year worth of rustproofing could have offset this repair for years, or prevented the need for it to happen at all.

All said, if you’re driving an older ride, especially if it’s never been oil-sprayed, a regular check-up from your favourite mechanic can help detect and address problems like this one, before they become dangerous. And, if you’re buying a new ride, according to Early, regular rust spray treatment, from day one, is a great idea.