Hunting Down Vibrations
Our customers often call us about vibrations, so we thought we’d make a check list of items to help you nail down a vibration in your car or truck.
The bellhousing isn’t dialed in correctly or at all.
__ Did you neglect to dial-in your bellhousing?
If you haven’t dialed-in your bellhousing, don’t even go on a test run. First, failing to dial-in the bellhousing will void your warranty. Second, you’re at risk of not just a few vibrations, but you could cause severe damage to your transmission. If it’s too late, you’ve already driven the car without dialing it in and you now have a vibration, check it. Even if it’s not the bellhousing, you can rest easy knowing you’re not destroying your transmission.
The vibration is felt through the steering wheel.
__ Do you feel the vibration the whole time you’re driving?
The culprit is most likely your tires or wheels. If your tires are in good shape and inflated properly, the wheels can be damaged or be out of balance. Even a small bump or pothole could have damaged your wheel and it’s relatively cheap to get them checked.
__ Does the vibration occur mostly at speeds under 30 mph?
This is almost always a tire or wheel problem. A tire with a bad belt, tread separation, or flat spots from sitting too long can go out of round and cause vibrations. A damaged, out of round wheel will also vibrate more at this speed. Also, make certain the wheel is properly tightened to the hub.
__ Does the vibration only occur in the 55-60 mph range?
Most likely, the tires are out of balance. It could also be a missing wheel weight or something stuck to the wheels causing the wheels to be out of balance.
__ Does the vibration only happen when you apply the brakes?
It is most likely the brakes causing the vibration. Check for warped or out of round rotors.
__ Does the vibration only happen when you’re turning?
If your car has power steering, this is a very good sign that the power steering is malfunctioning or out of fluid. It should vibrate whether you’re sitting still or rolling when you turn the steering wheel if this is the case.
The vibration is felt at idle.
The car shudders or jerks during acceleration.
Fast vibration, as if you drove onto a rumble strip, that only occurs at a certain speed.
Drives fine at first, but after warming up begins to shake.
These symptoms are probably related to engine performance. A few things to check:
__ Replace old spark plugs and check for damaged spark plug wires
__ Are all the cylinders putting out equal power?
__ Is the air filter dirty, robbing the engine of oxygen?
__ Is the fuel filter clogged, starving the engine of fuel?
After confirming the above, you’ll want to check your engine mounts, especially on an old car. Rubber mounts can deteriorate over time and will no longer isolate the vibrations of the engine from the frame of the car. If they’ve rotted, you’ll want to replace these.
If you recently replaced the mounts with poly mounts or other performance mounts that are made from a harder material than rubber, these mounts will transfer more vibrations than you are used to from the engine to the frame. You’ll have to decide if you’re willing to live with the vibration or if you’d rather go back to rubber mounts.
Vibration doesn’t go away when you push in the clutch pedal on a manual transmission.
__ The problem is with your flywheel or engine
Pushing the clutch pedal in will tell you if the problem is clutch back (if the vibration goes away) or clutch forward (if the vibration stays). The wrong flywheel or a flywheel that isn’t balanced will cause a vibration as will all the engine problems listed above.
The vibration picks up intensity the faster you go and it’s not the tires or wheels.
__ One of your axles is bent.
If you have a bent axle, you’ll have a bad vibration that only gets worse with speed. Check for damage from a collision or from bottoming out the car.
__ Your driveshaft angles are bad.
You should check this first if you have a brand new driveshaft and the vibration just started. You can check your angles using our new app.
__ Your u-joint isn’t lubricated.
A large clunk when you accelerate or go into reverse could be a sign that the problem is in the u-joint. If your driveshaft is at 0 degrees, the u-joint will not be able to self-lubricate. Even at the proper angle over time, the grease could evaporate or fling off as well. You can extend the life of the u-joint by having it serviced to avoid metal to metal contact.
__ Your driveshaft has clearance issues.
You’ll feel the vibration under the vehicle, you may hear knocking, a rattle or scraping sounds as the driveshaft hits the tunnel. If the tunnel shows witness marks, but it seems the driveshaft has plenty of room, get some friends to sit in the car and load the car down while you check for clearance again. It is possible the floor has some flex which is causing the issue. You’ll have to create extra clearance for the driveshaft.
__ Your driveshaft is damaged or out of balance.
Check the driveshaft for dings and dents. Take your driveshaft to be tested for balance.
__ Check your differential fluid.
Your differential could be low on fluid or have water in the fluid. Fill or empty and replace the fluid if there was water. You’ll need to find the leak and repair it or you’ll have the problem again.
The vibration seems to come from the transmission
__ Your automatic transmission is low on fluid or the fluid is in bad condition.
Check the fluid and replace if it’s dirty. Fill if it is low and check for leaks.
__ You have a manual transmission and the clutch is slipping.
If you overheated the clutch and caused a slick or glazed spot on the clutch disc, it will slip and can sometimes cause a vibration. You’ll have to replace the clutch disc.
__ You don’t have enough clearance leading to body contact.
Just like the driveshaft, your transmission may have clearance without anyone in the car, but put in a driver and some passengers, and now the tunnel touches the transmission or the exhaust pipes touch the floor panel or crossmember. This will cause vibrations.
When you’re under load, the engine rotates and could rotate just enough to make your exhaust touch the undercarriage or the crossmember, or the transmission could touch the undercarriage. In any of these situations, the vibrations of the car will be transferred into the cabin.
You have tried all of the above and still have a vibration
If you still have a vibration problem, be diligent in your observations to give the mechanic more clues. For instance, do you hear any noises associated with the vibration? Is it only at a certain speed or RPM? Did it suddenly occur or gradually worsen? Does it only occur at idle? Any change if you release the clutch?
Any rotating assembly can cause vibrations, so it’s important to rule out the simple, cheap, and most likely causes first and to note any other symptoms that might help you rule things out.