- Joined
- January 26, 2004
- Messages
- 6,113
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- City, State
- Mechanicsville, Virginia
- Year, Model & Trim Level
- 2004 Acura TL
I have recently noticed on the board that a lot of people are having a hard time figuring out driveshaft and u-joint problems. The symptoms of driveshaft and u-joint failure/weakness are sometimes hard to find and takes a well expierenced person to know what to look for. I wanted to type up a thread of symptoms, problems, and other things that might help people figure out the current problems in their vehicles.
A failed u-joint or damaged drive shaft can exhibit a variety of symptoms. A clunk that is heard when the transmission is shifted into gear is the most obvious. You can also encounter unusual noise, roughness, and vibration.
To help differentiate a potential drivetrain problem from other common sources of noise and vibration, is is important to note the speed and driving conditions at which the problem occurs. Along with any type of problem, always knowing when it happens, what speed, weather conditions, etc. are all good things to start thinking about when a problem occurs. As a general guide, a worn u-joint is most noticeable during acceleration or deceleration and is less speed sensitive than an unbalanced tire (commonly occuring in the 30-60 mph range or a bad wheel bearing (more noticeable at higher speeds). Unfortunately, it is often very difficult to accurately pinpoint drivetrain problems with only a road test. Therefore, expand the undercar investigation by putting the vehicile on the lift, if accessable, where is possible to get a good view of what is going on underneath.
The first problem most likely encountered is an undercar fluid leak. If there is a lot of lube escaping from the pinion shaft seal, the drivetrain noise could be caused by a bad pinion bearing. To confirm the problem, start the engine and put the transmission in gear, and listen at the carrier: if the bearing is noisy, it is necessary to make one of those difficult judgement calls. if the bearing sounds fine but the pinion seal is still leaking, I suggest you replace the seal immediately.
On some vehicles, like the Explorer, seal replacement is a simple procedure that involves removing the pinion flange and replacing the seal. However, always refer to the service manual for the correct procedure and note any special precautions that are to be taken.
At the other end of the driveline, inspect the transmission's extention housing seal the same way. If it is leaking, the seal itself can be easily replaced. Check the extention housing bushing. That is the most likely reason the seal went bad in the first place. Once the yoke is removed, an internal expanding bearing/bushing puller makes short work of bushing replacement. Before pusing the slip yoke back in after the new seal is installed, make sure the machined surface of the bore is free of scratches, nicks, and grooves that could damage the seal. For that added margin of safety, a little transmission lube or petroleum jully on the lip of seal helps the parts slide in easily.
If the seals pass the test, continute driveline examination by inspecting the u-joint's grease seals for signs of rust, leakage, or lubrication breakdown. Also, check for excessive joint movement by firmly grasping and attempting to rotate the coupling yokes back and forth in opposite directions. If any perceptible trunnion-to-bearing movement is felt, the joint should be replaced.
The runout of the driveshaft should also be checked. if there is excessive runout, determine the cause and make the neccessary repairs. If the runout is fine, check the phasing of the joints and their angle. To check their operating angle, use an inclinometer. This instrument, when attached to the driveshaft, will display the angel of the driveshaft along any point. Your finding from this test should be compared to specifications. Normally, if the angles are wrong, the rear axle has moved in its mounting.
As a final diagnosis inspection point, check the entire length of the driveshaft for excess undercoating, dents, missing weights (not all driveshafts have weights), or other damage that could cause an imbalance and result in a vibration. If no damaged is found, the driveshaft should be removed and its balance checked by a driveshaft/specialty shop.
When a u-joint is damaged or excessively worn, it must be replaced.
Spicer is a very good u-joint replacement.
Here is another site that may help: Dead Link Removed
And one more: Dead Link Removed
Hope this helps some people out
-Drew
A failed u-joint or damaged drive shaft can exhibit a variety of symptoms. A clunk that is heard when the transmission is shifted into gear is the most obvious. You can also encounter unusual noise, roughness, and vibration.
To help differentiate a potential drivetrain problem from other common sources of noise and vibration, is is important to note the speed and driving conditions at which the problem occurs. Along with any type of problem, always knowing when it happens, what speed, weather conditions, etc. are all good things to start thinking about when a problem occurs. As a general guide, a worn u-joint is most noticeable during acceleration or deceleration and is less speed sensitive than an unbalanced tire (commonly occuring in the 30-60 mph range or a bad wheel bearing (more noticeable at higher speeds). Unfortunately, it is often very difficult to accurately pinpoint drivetrain problems with only a road test. Therefore, expand the undercar investigation by putting the vehicile on the lift, if accessable, where is possible to get a good view of what is going on underneath.
The first problem most likely encountered is an undercar fluid leak. If there is a lot of lube escaping from the pinion shaft seal, the drivetrain noise could be caused by a bad pinion bearing. To confirm the problem, start the engine and put the transmission in gear, and listen at the carrier: if the bearing is noisy, it is necessary to make one of those difficult judgement calls. if the bearing sounds fine but the pinion seal is still leaking, I suggest you replace the seal immediately.
On some vehicles, like the Explorer, seal replacement is a simple procedure that involves removing the pinion flange and replacing the seal. However, always refer to the service manual for the correct procedure and note any special precautions that are to be taken.
At the other end of the driveline, inspect the transmission's extention housing seal the same way. If it is leaking, the seal itself can be easily replaced. Check the extention housing bushing. That is the most likely reason the seal went bad in the first place. Once the yoke is removed, an internal expanding bearing/bushing puller makes short work of bushing replacement. Before pusing the slip yoke back in after the new seal is installed, make sure the machined surface of the bore is free of scratches, nicks, and grooves that could damage the seal. For that added margin of safety, a little transmission lube or petroleum jully on the lip of seal helps the parts slide in easily.
If the seals pass the test, continute driveline examination by inspecting the u-joint's grease seals for signs of rust, leakage, or lubrication breakdown. Also, check for excessive joint movement by firmly grasping and attempting to rotate the coupling yokes back and forth in opposite directions. If any perceptible trunnion-to-bearing movement is felt, the joint should be replaced.
The runout of the driveshaft should also be checked. if there is excessive runout, determine the cause and make the neccessary repairs. If the runout is fine, check the phasing of the joints and their angle. To check their operating angle, use an inclinometer. This instrument, when attached to the driveshaft, will display the angel of the driveshaft along any point. Your finding from this test should be compared to specifications. Normally, if the angles are wrong, the rear axle has moved in its mounting.
As a final diagnosis inspection point, check the entire length of the driveshaft for excess undercoating, dents, missing weights (not all driveshafts have weights), or other damage that could cause an imbalance and result in a vibration. If no damaged is found, the driveshaft should be removed and its balance checked by a driveshaft/specialty shop.
When a u-joint is damaged or excessively worn, it must be replaced.
Spicer is a very good u-joint replacement.
Here is another site that may help: Dead Link Removed
And one more: Dead Link Removed
Hope this helps some people out
-Drew