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Weird Vibration - Bad DOJ?


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On a long road trip this past weekend, the car started to vibrate strangely. Front end, feel it through the steering and the rest of the car.

 

I have had a few problems with the passenger side axle, first finding a replacement that fit, then it lost a lot of grease due to a missing heat shield on the cat. So I figured it might be the DOJ going west due to a lack of grease. However, when I checked it, it was just as tight as the driver side, and just as hot, too.

 

The vibration went away, but I don't trust it. I have another long trip coming up, so I don't want to risk it.

 

Can bad DOJ's act this way, with the vibration coming and going? Any good way to tell it is bad without waiting for it to fail completely?

 

Vehicle is a 1993 5sp 4WD Loyale.

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I had a DOJ (inner joint) fail on my '88 on a camping trip years ago. It was a very strange thing, shook the whole car. It could be "felt" in the steering wheel, but it didn't actually turn the wheel or cause the car to pull at all. It was not, however, intermittent at all. Whenever I was above about 40mph, it started to shake.

 

I ended up diagnosing it through elimination...it was obviously coming from one corner, everything else seemed fine....had to be that. When we got back to the campground, I pulled the axle, pulled out a maul and broke the outer joint, slipped the spindle back through the bearings and drove home in RWD smooth as could be.

 

 

Now, there was no noticeable play in the axle, nor a torn boot in that case. BUT, that was on a car with about 5" of lift (4" kit, plus adjustable front struts for another inch), which put about 2" of strain on the front axles. I think similar failure would be very unlikely at stock ride height, but still possible.

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This one has been abused. It is low on grease.
yes, easily could be the DOJ. if it's low on grease then that's probably what it is.

 

i had both inner axle boots (new MWE axles) break on a 4,000 mile road trip out west. they had sat a couple years and were dry rotted. they vibrated madly for thousands of miles, coming and going, and would shut up when i stuffed grease in the joint by hand at gas stops.

 

made it home - cleaned, regreased, and rebooted those same abused axles 2 years ago and they're now working perfectly in my 2" lifted XT6.

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The typical symptom for a DOJ failure is that the vibration happens at acceleration; as soon as you lift off the gas, the vibration stops. If you have a torn boot at the DOJ, it's pretty certain that the DOJ there is the cause. Re-greasing and re-booting is a pretty likely solution for it. Otherwise, an axle replacement will fix it. I've had better luck with used axles from a wrecking yard than rebuilt. That being said, MWE in Colorado has always sent me quality rebuilt axles.

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The boot is not torn, but heat from the cat caused the DOJ to spew grease, even after putting in a make-shift heat shield.

 

When it vibrates (currently, it is OK), it is only on the throttle that it happens: accelerating, or steady state at highway speed. It goes away with my foot off the gas.

 

There were no apparent problems with the axle when the car was jacked up and everything shaken and moved, as Nipper suggested. Tie rod ends seem OK.

 

I guess I will have to peel back the boot and fill it with grease, then replace the clamp. Messy job!

 

Any tips on installing a better heat shield? The cat is a used one, installed back in the spring when a rock ripped out the old one, along with mangling the tranny crossmember. The entire front half of the exhaust system was replaced, from the exhaust ports to the flange downstream of the cat, but it didn't come with the shield. Right now, I have some sheet metal jammed between the cat and the frame, but it doesn't seem to work very well. There is a good air gap between the cat and the metal, so I don't see why it doesn't work. Maybe I should use something shinier.

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Looks like you've identified the problem; if the DOJ was spewing grease the boot has to have a hole in it, or the clamps have loosened up to allow the grease out. In any event, you've seen the classic symptom of a bad DOJ--vibrates under acceleration and stops instantly when you let off the gas. Sometimes the vibration is so slight it's hardly noticeable; other times it can be so bad that you think the transmission is about to fall out of the car.

 

As to a solution. I had "macguyvered" a solution on my old brat. I had taken an old license plate and strapped it around the cat with a huge hose clamp. I had made a spacer so that I had a 1/2" pathway between the cat and the license plate. I also arranged it so that the front portion would act as a scoop to guide more air around the cat for cooling purposes so the heat from the cat wouldn't cause the DOJ boot to fail on that side. A little hard to do since there were some potential clearance issues for my "heat shield." I'd take a picture but I sold that brat a few years ago.

 

However, the other half of the solution was to adjust the fuel mixture properly. If the mixture is too rich, raw unburned fuel gets to the cat and will burn there running up the cat temperature significantly and causing premature boot failure.

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From the track of the thrown grease, it was leaking out from under the boot. The boot itself is in perfect shape, no pinholes.

 

I clipped the clamp, pulled back the boot, filled the joint with moly grease, and put on a new, no-tool type clamp. It still seems a bit loose to me, so I am keeping a gear-type hose clamp handy in case it starts to spew grease again. It seems like the boot won't fit into the groove in the joint, so it moves around on the joint and may not seal well.

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