I towed a trailer with my Hyundai Elantra across three provinces recently, and probably exceeded the car's towing limit. Could this do any permanent damage to the car's suspension or any other parts?
Assuming your car still operates fine, there probably wasn't any damage done. As I've said in the past, cars are tougher than we give credit. However, this is not to say that you may have damaged the transmission.
The transmission most often takes the majority of abuse in these situations, so most of the attention to making towing modifications focuses on the tranny. Your question is made more difficult not knowing if the transmission is manual or automatic so I'll give both scenarios.
1. If the transmission is manual, then the transmission itself may be fine. What you may notice is a lack of original performance in the take-up of the clutch. Towing is very tough on clutch materials if the gross towing capacity of the car is exceeded. During the course of your trip, you would have smelled a sweet, burning odour. That would have been your clutch disc letting you know that the task you were asking it to perform was outside its ability to accommodate.
2. On the other hand, if you have an automatic transmission, damage can be done a couple of ways. First, the fluid that couples the engine to the transmission can be burned, much in the same manner as a clutch. Second, the friction materials that connect the various gear sets inside the transmission can burn up also. These devices operate in precisely the same way that a clutch operates.
A typical towing modification is an auxiliary transmission cooler, but this is making the assumption that the towing capacity will be observed – not thrown out.
As for the suspension, it usually bounces back – that's its job – and unless you have noticed a difference in the ride height, you are probably okay.
Have the transmission and clutch inspected, and have the engine oil changed for peace of mind.
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