What causes a car to shake at 40 mph?

A shudder or vibration may develop while driving at speeds between 35 and 40 MPH. Our technicians tell us this condition is commonly caused by a failed automatic transmission torque converter. It is recommend to replace the torque converter and install an updated powertrain control module (PCM) to correct this concern.

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226 people reported this problem
89 comments

Acura MDX Vehicles With This Problem

15 model years affected
Average mileage: 116,773
(360–2,248,989)
General Diagnosis : $110 -$139
The average cost for a Acura MDX General Diagnosis is between $110 -$139. Learn More
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Viewing 1 — 20 of 89 comments
2001 Acura MDX 100,000 mi,
Visitor

Vibration or shudder between 35 and 45 MPH while lightly pressing on the gas. Immediately goes away if you let off the gas pedal.

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2006 Acura MDX 135,000 mi,
Visitor

Shuddering usually between 25-40 mph when slightly depressing gas pedal, cruising or slightly accelerating. Shuddering stops when letting off the gas pedal or by de-pressing to accelerate quickly. I called the Acura dealership and my vehicle did not have a recall for a Powertrain Control Module (PCM) software update to resolve issue. Acura technician mentioned it could be the torque converter or another software update needed.

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2013 Acura MDX 74,000 mi,
Visitor
When I excelerate over 40 there is sometimes a vibration, what is this?
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2004 Acura MDX 99,000 mi,
Shuttering at low speeds, off and on. Not continuous, nor consistent, but obvious.
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2014 Acura MDX 21,000 mi,
Visitor
Hesitation upon acceleration. Car studders while accelerating.
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2002 Acura MDX 120,000 mi,
Visitor

2002 MDX upshifts from 4th to 5th gear at 35-45 mph, resulting in lugging, shuddering/vibration and a LOUD, annoying growling/grinding noise. The problem is absolutely gone if I shift to D4 (not allowing it to shift to 5th gear) or if driving over 55 mph (and 5th-gear rpms > 1600).

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2001 Acura MDX 52,000 mi,
Visitor

I noticed the ‘shudder’ described here and brought it in to the dealer and told them of this noise. On first visit dealer could not find a problem. After driving some more I detected that this ‘shudder’ occurred in the 40-50 mile range and brought the car back to the dealer. After two rides in MDX 2nd mechanic finally correctly diagnosed the problem ( one would think that this would be the first thing they should suspect). When paying $1800 repair bill ( that’s with ‘discount’) I complained that the internet had numerous complaints about torrque converter problem and that quite a few customers did not pay for this defect repair. I also voiced my concern over possible future transmission problems. The manager disregarded the numerous internet documentations and claimed the model had no transmission issues. Months later I was at my local mechanics shop with another car & I described the MDX ‘shudder’ and he immediately told me that it was a torque converter without my telling him anymore. I was not happy with the stonewalling or lack of knowledge that Acura showed in dealing with me. I’d prefer to have my car serviced by Acura however this kind of treatment has driven me away.

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2005 Acura MDX 138,000 mi,
Visitor

Have the same shutter / washboard sensation when driving at city speeds. This just started last week. We have owned since new and have religiously maintaned the car at Ron Tonkin Acura. Very dissapointing as we researched reliability at the time of purchase and the MDX was highly rated. I will report back when we have a diagnosis and repair. Have read other threads, stating this is a safety issue as the drive wheels (front) can all of a sudden lock up and not spin while driving car. If this happens on a freeway, imagine what would happen.

11 Main Reasons Why Car Shakes When Braking

Driving safety always comes first in a dictionary of all drivers. Do you feel relaxed and trust your driving skills when your car shakes when braking? Of course not! In such a situation, my stomach becomes turning, palms sweating, and I have a feeling of discomfort and insecurity. Sounds familiar?

If you want to avoid a car accident and the breaking down of your car on the remote road, you should take a look at eleven reasons for this particular problem I listed below. Once any of them occurs, it is always a good idea to talk with your mechanic to discover what is wrong. Let’s avoid to pay more due to inattention and slow responding.

Eleven Primary Reasons Why Do Car Shakes When Braking

1. Tires are out of balance

If your car shakes when driving 50 to 60 mph (80.5 – 96.5 km/h), but the shaking stops at higher speeds, you should check your tires. When they are out of balance, there is a high possibility to feel the disturbance of your vehicle. Fortunately, it is not a big deal, and you just need to have your tires appropriately balanced as soon as you discover a problem.

Keep in mind that worn tires can cause the same disbalance and, consequently, shaking when driving and braking. Moreover, in some cars, it may happen that wearing off the tires is uneven. Therefore, you should replace them with new or second-hand, but better ones.

2. Brake rotors out of round

In case you step on the brake and feel trembling, especially at high speeds, it can be the rotor problem, well-known as ‘out of round’ rotor. It happens quite often. Once it occurs, you will feel the shaking through your steering wheel while braking. Try to find the closest expert for the braking system to assist you in need.

Keep in mind that the warped brake rotors often appear as the consequence of wear and tear. Since the rotors suffer a great of heat and deform during the braking, you need to replace them occasionally.

3. Uneven adjustment of a rotor

Sometimes, a mechanic may tight rotors unevenly after servicing your car. Therefore, it is one of the first things you need to check once the problem with shaking when braking occurs.

4. A problem with a caliper

In some cases, you can feel your steering wheel vibrates, and it gets even worse when you add more speed. Therefore, you should check if the cause of the problem is a caliper. I will reveal a little secret to you. When you smell the burning odor while driving, your car likely has a problem with this car-part.

To avoid complications, take care to check for an issue with caliper sticking after driving 70 000 miles (130 000 km). It is especially crucial in situations when you have recognized that the front brake is thinner and more worn out.

5. Suspension problems

Brake system is not a simple part of your car. Actually, there are many pieces, such as tie rods, wheel bearings, and ball joints, causing the shaking when braking when they work inappropriately. If you feel car shakes when turning suspension, then you have a problem with one or more of these parts.

6. Wheel bearing and steering wrack

Both of these parts are essential in the wheel mechanism. Therefore, when experiencing the shaking when braking followed with noise, you should check if you have a problem with one of them.

The sound can be quiet and soft in the beginning. Later on, it starts to rumble, especially when driving 40 mph (64 km/h) or swaying a bit to one side of the road. It would help if you had your car checked right away.

7. Problem with axles

Bent or arched axles connected to the steering wheel may cause the problem with shaking when braking. Over time, they lose their perfect manufactured shape due to the bumpy roads, a lot of driving, and accidents.

The noise you can experience is some kind of clicking when turning or braking in the turning process. Often, it is followed by vibrating.

8. Bent rim

If you feel the shaking behind, or underneath your seat, that can all be the sign of bent rim. As the tire no more has the perfect circle shape, its parts may not touch the road anymore. Depending on where you experience the shaking, you can conclude which part of the rim is not ideally shaped anymore.

9. Flat brake pads

When stepping on the brake, your barking pads experience pressure and heat. After a while, you will need to change the old brake pads since they tear and wear.

If not, you will hear a high-pitched sound and feel uncomfortable shaking. If the pads are 1/4 of their regular size, then it is time for new ones. The regular check and change will prevent shaking affected by worn pads.

10. Problems with engine

Not so often, the car engine can cause shaking. Usually, you may have a problem with spark plugs and engine air filters. Try to check and change both of them regularly since they can’t last forever.

On average, the spark plugs can last for 80.000 to 100.000 miles (130.000 – 160.000 km) before you need to replace them. If you want your engine to work impeccably, always take care to follow instructions in the manufacturer manual.

11. A problem with dry guide pins

Even though the problems with dry pins sound simple and basic, they can make your car shakes, and the steering wheel vibrates when you brake. Since they are a part of brake calipers, you can expect them to cause an issue when becoming too dry or dirty. In such a situation, the best you can do is to take them off, clean, and lubricate. That’s it!

Conclusion

Whatever the reason for your car to shake when you brake, you need to check and deal with the cause. The safety of you and your dearest ones is on the stake, and you should prevent any possible danger appearing. Use the tips I have described here, and keep driving safely and without any worries.