Porsche 911 pulling to the left when driving on a straight road not only reduces driving comfort as you continuously have to adjust the steering wheel to keep the vehicle in your lane, but it also signals an underlying fault that can compromise your road safety. In this article we go through all the reasons that can cause your 911 to veer left and how you can fix it.
The most common causes for Porsche 911 pulling to the left when driving are bad wheel alignment, tire pressure lower in left tires than the right tires, uneven tire wear, and defective wheel bearing. Some other issues that can cause 911 to pull to the left are worn suspension and steering components, sticking brake caliper, bent rim, road crown or the road slopes to the left, mismatched tires, and defective tires.
1. Bad wheel alignment
Misaligned wheels is one of the leading cause of Porsche 911 pulling to the left when driving on a straight road. Wheel alignment is an important and often overlooked aspect of maintenance. Potholes and curbs can easily misalign your wheels, resulting in poor control and excessive wear on your tires.
What are the symptoms of bad wheel alignment in Porsche 911?
The most obvious sign of misaligned wheels in 911 is when your vehicle pulls to one side and you constantly have to adjust the steering wheel to drive in a straight line. Some other signs include uneven or rapid tire wear, crooked steering wheel when driving straight and squealing tires.
How is wheel alignment performed on Porsche 911?
Wheel alignment is primarily carried out using electrical diagnostic tools. Using sensors that are attached to the wheels of 911, a computer system recognizes the extent to which the actual values deviate from the target values. The target values are the standardized values specified by the manufacturer. The measured values can be compared on a computer and deviations are interpreted and corrected directly.
How often should wheel alignment be performed on Porsche 911?
In contrast to wearing parts, there are no fixed maintenance intervals or manufacturer specifications for wheel alignment. Therefore, such a review is usually at your own discretion. Nevertheless, it is advisable to check the treads at least as part of the tire rotation every six months or 5,000 to 7,000 miles. Do note that driving habits can heavily influence how often you need to get your 911 wheels aligned.
2. Incorrect tire pressure
Incorrect tire pressure in one or more of the tires can also make your Porsche 911 pull to the left when driving. Lower tire pressure increases the contact area of the tire tread with the road surface which leads to higher road grip and friction. If the air pressure in the left side tires is less than the tires on the right side, your vehicle will pull to the left due to higher drag on the left tires.
If your 911 is equipped with tire pressure monitoring system, also called TPMS, the amber colored low tire pressure warning light may illuminate in the instrument cluster in case of incorrect tire pressure.
Check tire pressure
Reinflate all the tires of your 911 to the manufacturer specified air pressure, which is mentioned on the vehicle placard or tire inflation pressure label usually located on the B-pillar or the edge of the driver door. If you can’t find the label, check the owners manual of your vehicle.
3. Uneven tire wear
Uneven tire wear can also cause your 911 to pull to the left when driving. Uneven tire wear can have many causes, most often it is caused by driving with incorrect tire pressure or bad wheel alignment for too long. If your car is still pulling left with the correct tire pressures and wheel alignment, you should check for uneven tire wear.
How to check uneven tire wear in 911
Spotting uneven tire wear in your 911 is easy. You just have to examine the tire tread for abnormal wear. For example, if the inner or outer edge of the tire is wearing down faster than the rest of the tread, bad wheel alignment is the most likely culprit.
Will replacing the tires fix the issue of 911 pulling to the left?
If your 911 is pulling to the left due to uneven tire wear, replacing the tires should rectify the issue. But, if you replace the tires without finding and fixing the underlying cause of uneven tire wear, the new tires will also wear out unevenly and you may end up with the same problem of car pulling to the left. Therefore, if uneven tire wear is discovered, it is highly recommended to get the wheel alignment done, and check for any issues with the suspension and steering parts before installing new tires.
4. Bad wheel bearing
A defective wheel bearing can be the cause of Porsche 911 pulling to the left. The most common signs of bad wheel bearing are grinding noise in the cabin when driving straight, a knocking noise when cornering, and the vehicle vibrates. The faster you drive, the louder the grinding noise and stronger the vibration.
What causes bearings to fail in Porsche 911?
Even when driving your 911 in a straight line, the bearings have to absorb high radial forces. The entire weight of the vehicle rests on the bearings. When driving, the speed creates additional forces. If a curve is then also driven through, axial forces occur. High impacts on the bearings also occur on uneven roads or when driving through potholes. Impacts of all kinds are much more damaging to bearings than the high loads. Therefore, all wheel bearings eventually fail. However, how soon they fail depends on driving habits.
5. Worn suspension and steering components
Looseness in suspension or steering system components can cause uneven tire wear and can also make your 911 pull to the left. Overly worn ball joints or tie rod ends makes it difficult to properly align your vehicle. Some common signs include vibrations from the front end or through the steering wheel, clunking or rattling noise coming from your front suspension especially when going over speed bumps or when turning the vehicle. In extreme cases, your front end can not only vibrate but also shake violently at high speeds, this phenomenon has been nicknamed “death wobble”.
6. Sticking brake caliper
If the brake pad on the left front wheel or the left rear wheel is continuously rubbing against the rotor when the brake pedal is not depressed, it can not only cause excessive overheating and burning smell, but will also pull 911 to the left side. One of the most common cause of sticking brakes is stuck brake caliper, but can also happen due to other defects in the braking system or improper installation.
How to check for sticking brakes
Since sticking brakes cause overheating, the easiest method is to measure the temperature of the brake rotors with an infrared thermometer after a test drive. If you do not have the instrument, you can splash some water onto the rotors. If the water sizzles and evaporates instantly on contact, it means your 911 brakes are sticking. Be careful not to splash too much water, as it can damage the rotor.
You can also feel the temperature on the outer side of the rims. If one of the rims is significantly warmer than the others, the brake caliper may be dragging. Do not touch the rotor or brake caliper to check the temperature as it may burn your hand.
7. Bent rim
A bent rim can also cause your Porsche 911 to pull to the left side of the road. Such damage usually occurs when obstacles such as curbs, speed bumps or deep potholes are driven over too quickly. This may also lead to vibration especially when driving at high speeds. Balancing the wheels and performing wheel alignment would probably not fix the problem, a bent rim must be replaced.
Even if there is no visible damage, the whole rim could be deformed resulting in uneven diameter. An experienced mechanic can tell if the rim is bent by mounting it on the wheel balancing machine.
8. Road crown
Your 911 may be pulling to the left due to the angle of the road and not due to a fault. Crown is the side to side, or the cross-sectional shape of a road surface. Most common type of road surface designs are center-crowned, in-sloped, or out-sloped. If the slope is towards the left side of the road, your vehicle may veer towards the left side as well, the intensity of the pull depends on the angle of the slope.
The central task of the road crown is to drain surface water from the road surface as quickly and harmlessly as possible in order to protect the road structure from moisture penetrating and to prevent water accumulation and its consequences (aquaplaning, water splashing or black ice formation) on the surface.
9. Mismatched tires
Using mismatched tires can also cause your vehicle to veer to the left. All the wheels and tires on your 911 must be of the same size. If the left side wheels have wider tires than the ones on the right side, the vehicle will pull to the left due to higher friction.
The vehicle will also pull to the left if the diameter of the tires is smaller on the left side than the right. For example, it is common for a car to veer to the direction where a compact spare tire (also called donut tire) is installed in case of a flat tire.
10. Defective tire
Did your 911 start pulling to the left after you installed new tires on the rims? In very rare cases a defective tire could be the cause.
How to check for a defective tire
The easiest way to check if one of the tire is causing the vehicle to veer left is by swapping the left side wheels with the right side. If the vehicle veers towards the right after the swap, it indicates a defect in a tire or a rim.
There are many reasons why your Porsche 911 is pulling to the left when driving. When looking for the reason, you should always start with the most obvious causes, misaligned wheels or incorrect tire pressure.