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How to: How to: Diagnose Driveshaft and U-Joint Problems

ExplorerDMB

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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: Driveline 101
And one more: Driveline Angle


Hope this helps some people out

-Drew
 


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unclemeat

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Good info.
 




IZwack

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i dont mean to hijack this thread but id like to add something ive ran into..
the thing that gave away a bad u-joint one day was this periodic squeeking that happened from stand still up to about 10 or 15 mph. and how frequent the squeek was repeating itself was relative to how fast i was going - in other words, the faster i went, the more often it would squeek - that is up to about 15 mph at which point the squeek went away.

so i looked under the truck and i saw the rear differential flange, u-joint and part of the driveshaft (the one right in front of the rear differential) had this fine red powder covering it, i was like wow WTH IS THIS!!!
Dead Link​

well i disconnected the driveshaft from the differential flange and i moved the u-joint around and sure enough, it produced the same squeek... oh and it also had some "hard spots" when I cycled it through its movements.. after i removed the u-joint, it fell apart and this is what came out:
Dead Link​

so what was happening was the roller bearings were grinding themselves to a fine powder and this powder was what was all over the joint, driveshaft and flange.

.
 




Longjohn119

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Looks like you were just a couple of days away from dropping a driveshaft ..

No a lot of fun at highway speed or under heavy acceleration ....
 




ExplorerDMB

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Having a u-joint break at any time is horrible. Those driveshafts spin at incredible revolutions, and can hurt someone, something, or a vehicle. Glad you caught it in time.

-Drew
 




Rhett

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this should be in the list of useful threads.

I hope I'll be able to find it when I really need the info.
 




DB_1

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I'd like to add my 2 cents if I may regarding the front driveshaft.

On a wheelin' trip last month I was getting a chriping sound from the front end of my rig that was really annoying. At first I thought it might be a wheel bearing going out but I took it out of 4wd and it stopped so then I thought it must be a u-joint going bad in my front driveshaft. I was half right but I didn't know it until I got home and had a chance to tear apart the driveshaft.
I had the forethought of ordering 3 new Spicer u-joints fron Randy's R&P...I couldn't find and local parts stores that carried Spicer joints. So, I get all the joints out of the d-shaft and on the CV, double cardan (whatever you choose to call it) end there is whats called a circulating ball between the 2 joints in the CV. The seal around the ball was flopping around and for good reason because is was bone dry in there. The circulating ball assembly also has a small spring inside so becarefull not to lose that if are reusing it. Spicer also has a direct replacement assembly if yours is shot and has grease fittings that requires a needle adapter for your grease gun. Napa has a good selection of these needle adapters.
A couple notes on replacing the joints in your front d-shaft...1. if you choose the run the kind of joints that have zerk fittings you will only be able to use 2 of them because the end joint that mates to the t-case wont work. The zerk fitting rubs/hits on the circulating ball assembly...2. to get the joints out of the CV end, get a flathead screwdriver between the u-joint and the circulating ball/assy. then pry on it until you can slide the caps of the u-joint then proceed to pound/pry the joint out as usual.
 








Rick

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If someone would like to add a step-by-step on installing U-joints that would really make this thread complete :thumbsup:
 




ExplorerDMB

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I may be changing some u-joints soon in my explorer or my jeep soon. I will try to remember to take pictures of what I do and blah blah.

-Drew
 








Rhett

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Sometimes, DeRocha comes in handy, and so is DMB for finding it :D
 




explorersport86

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Same problem - flexplate/torque converter?

I recently purchased a 96 Sport with 65,000 miles. The truck has excellent dealer maintenance records. All fluids look/smell great and it idles and accelerates well. However, I have the exact same annoying problem. Slight vibration at idle that peaks at or about 2500 RPM. It almost feels as if the exhaust is grounded to the body or in a bound state. I have also read to check the transmission cooler lines to make sure they're not interfering with the frame/body. I have yet to check this.

I experimented on a lift last evening and ran the truck with all 4 tires up, noting vibration/noise. Unfortunately, all externals appear visually normal as after perfoming a normal "hands-on" pull/tug, etc. I've checked exhaust, hangers, driveline balance, u-joints, motor mounts, etc. etc. The ONLY thing odd was a harmonic vibration/noise coming from the rear engine/front of transmission. I believe I have isolated mine to a flexplate/torque converter issue.

I have an another 4.0L OHV with the same engine/trans combo and 150,000 miles it's smooth as silk with no such noise/vibration.

If anyone has suggestions, please chime in. Thanks.
 




IZwack

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explorersport86 said:
..I experimented on a lift last evening and ran the truck with all 4 tires up, noting vibration/noise...
thats interesting ...ur experiment with the tires up in the air could suggest a bent wheel or a bad tire.. even though there might not be any signs of a wobble when the tires are up in the air, a bad tire could still cause vibration once the weight of the vehicle is on it. i would probably look at getting the tires/wheels balanced before looking at that flexplate ;)
 




explorersport86

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New Tires

Thanks for the thought. I've replaced the tires with new Michelin LTS. Wow what a difference. It's amazing what a good set of tires do for this vehicle. I still have the annoying noise/vibration that's present at idle, during acceleration up to about 2500 RPM where it starts to disappear.

To clarify what I'm feeling - a general "roughness" and "booming" that sometimes excites and resonates the inner panels. It is more pronouced if the engine is under a load and after things come fully up to operating temperature.

It almost feels like a powertrain component/exhaust is grounded against the body, but I have yet to discover anything.

The truck is smooth and silent at coast, deceleration and even while crusing on the highway (no load).

Based upon mine own testing, I think I've narrowed the source to one or more of the following:

Loose nuts/bolts on torque converter
Cracked Flexplate (TSB for this)

Bound Exhaust System
Bound Body Mounts

Thanks in advance for any responses, ideas, similar problems/solutions.
 




griggs

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I had the same kind of slight vibration problem in a 96 X with 4.0L OHV V6 as Explorerscout96. Tried many things to fix and never did. Was something in the engine or flywheel or ???. Had Ford shop test drive and they said that's the way they are. I test drove one on a used car lot - same thing. Sold unit and replaced with a 97X with 5.0L V8 and AWD. Much smoother but it had a different vibration problem - slight driveline vibration near 60 mph that beat in and out every mile on the freeway. I suspected the driveshafts were each out of balance a very slight amount and I would only feel vibration when the shafts were aligned. Just living with it.
 




DeRocha

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Rick said:
If someone would like to add a step-by-step on installing U-joints that would really make this thread complete :thumbsup:
Ok...step by step info with pics is contained in the U-joint link in my sig line.
 




Albino 94LTD

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I'm in the process of refreshing a D35 TTB and an 8.8" for installation in an '88 Bronco II, including all the U joints for stub shafts and Drivelines.

I'm finding confusing information about the part/model #'s

The front stub shafts seem to use Spicer 297's. A call to Drivelines NW informs me that Spicer is replacing the 297 with the 760-non greasable.
Other manufacturer #'s;
Precision 371
Neapco 1-0297
TRW 20193
Alloy 1758
A.E.C. 297
Warner 114-645
Wesco 201-297

Anyone care to confrim the above????

Now, what about the drivelines?

Do they use a different U Joint?? like a Spicer 153x, 625x or 433-1x
Other manufacturer part #'s
Precision 396
Neapco 1-0153
TRW 20049
Alloy 1004
A.E.C. 521HD
Warner 114-513
Wesco 201-520

Correct?
 




DeRocha

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These are the U-Joints # for (Brute Force)
1-0297BF (Qty = 3) Front Axle
1-0153BF (Qty = 3) Front Shaft
1-0153BF (Qty = 2) Rear Shaft

The front and rear shafts use the same U-Joints held in place with those outer spring clips.
Dead Link

The Front axle U-joints are held in place by Inner "C" clips (for a better pic see the U-joint link in my sig)
752408100009.jpg
 


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ExplorerDMB

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A Bad U-joint Can't Do Any Damage

Well, at work today we had to pull out the transfer case out of a late model silverado because they front driveshaft binded and cracked the t-case horribly. The double-cardan joint on the driveshaft has a ball and spline type deal in the middle of the u-joints and well it basically shattered in there. We think the d-shaft was the problem for the tcase problem. Here are some pictures:

-Drew
 

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