The OFFICIAL clunk/thunk driveshaft thread (1 Viewer)

[dfinn]

has anyones clunk gotten worse after greasing?

U joints each took less than 5 or 10 pumps before grease started flowing. Rear prop shaft took what seemed like more than the suggested 20-30 pumps but grease did finally push past the seal. Front prop shaft took way more than 30 pumps with no sign of grease coming past the seal, I gave up when I couldn't stand to be under the vehicle contorted any longer. I only get the clunk when shifting from R to D. Shifting between D and N does not clunk. I don't get any kind of clunk when the vehicles is moving or coming to a stop so I don't think it's something in the suspension.

 

[abuck99]

Sounds like worn splines on the cv and drive flange. The cv should move instantly when you rotate the wheel

Thanks Ben-

Neither axle moves instantly when you rotate the wheel- there is definitely some play. I need to dig in and check it out. If the splines are worn on the drive flange, and the axle splines are worn- is there any additional harm that comes to the drive line by continuing to drive it? At this mileage ( 168k) my eventual resolution would be to replace the CV's, flanges, wheel bearings, and prob control arms. (looks like no rear bumper for me anytime soon)

 

[benc]

Thanks Ben-

Neither axle moves instantly when you rotate the wheel- there is definitely some play. I need to dig in and check it out. If the splines are worn on the drive flange, and the axle splines are worn- is there any additional harm that comes to the drive line by continuing to drive it? At this mileage ( 168k) my eventual resolution would be to replace the CV's, flanges, wheel bearings, and prob control arms. (looks like no rear bumper for me anytime soon)

No harm, the axels and flanges already need replacment so you will be fine. The worst that will happen is the splines will strip and you will have to drive with the center diff locked to get it home.

 

[RobRed]

CV's are one of the systems that contribute to the thunk condition.

 

[feddomw]

CV's are one of the systems that contribute to the thunk condition.

Which ones?

 

[RobRed]

Which ones?

Not sure I understand your question.

There are multiple contributors to the "driveline thunk" concern. Worn splines and worn joints will contribute to the issue.

I spent considerable time on this issues for my truck. Started with the easy stuff like lubing the drive shafts, bushing in sway bars, replacing CV's, then replacing rear control arms. Each of these routes yielded improvements. The rear control arms (ostensibly bushing in the arms) cured to thunk to factory new levels.

 

[fjfowdie]

^ this. Mine only has the rear links left to replace but the new shafts and flanges made a huge difference

 

[RobRed]

^ this. Mine only has the rear links left to replace but the new shafts and flanges made a huge difference

Your point as well... There is no one thing that fixes the issue. For example my flanges etc are fine.

 

[abuck99]

There are 3 different mounting bushings located around the front diff which might also add to excessive play in the front drive line. The rubber pucks on from & rear of the diff and then the differential support.

If I am checking these for play with a prybar, how much movement should one expect out of the front & rear rubber pucks (pictured red circles)? And how much movement should one expect out of the diff support (pictured red square box)?

The pucks have very little movement. But the diff support (red square) seems really sloppy. Is that the nature of that particular bushing, very soft?

 

[kevine]

following this thread. I installed a 2.5" OME lift with the diff drop kit. I have a clunking noise when I shift into drive or reverse. I can see the front diff move up and down about 1" when it's shifted into D or R. The diff drop kit added a 1" spacer to the diff support on passenger side (closest to pass tire). Wonder if I should take spacer out? A friend said he used a shorter bolt for that spot. I checked and it's tight as is and has a nut on top of that bolt (used original bolt, which worked with spacer). Not sure what to do.

 

[shibubba]

There are 3 different mounting bushings located around the front diff which might also add to excessive play in the front drive line. The rubber pucks on from & rear of the diff and then the differential support.

If I am checking these for play with a prybar, how much movement should one expect out of the front & rear rubber pucks (pictured red circles)? And how much movement should one expect out of the diff support (pictured red square box)?

The pucks have very little movement. But the diff support (red square) seems really sloppy. Is that the nature of that particular bushing, very soft?

View attachment 1265129

View attachment 1265135

I am also very curious, would really like to figure my clunk out

 

[BillZ260]

is there a specific smaller diameter grease gun fitting I should be using for the U-Joints? I have a smaller and larger gun, both have the same diameter tip and they just fit in there, but don't wiggle enough to snap onto the zert. What are you guy's using? Did I just not try hard enough or?

 

[abuck99]

is there a specific smaller diameter grease gun fitting I should be using for the U-Joints? I have a smaller and larger gun, both have the same diameter tip and they just fit in there, but don't wiggle enough to snap onto the zert. What are you guy's using? Did I just not try hard enough or?

Standard size. The zerks on ujoint & prop shaft have the same fitting size. Sometimes the fitting on the end of my grease gun doesn't stick to the zerk- wiggle or press harder till it locks on.

 

[Greenbean]

I wanna throw this question in here,

My clunk has lessened after I greased my u-joints, and pumped grease into the slip yolks BUT I pumped quite a bit and haven't seen grease yet come by the slip yoke seals.

Here's the interesting part, when the vehicle is fresh and cold it's almost gone. No thunk at all, or drivetrain slack as I'm calling it. After the vehicle is driven and things are warmed up it seems to come back. Let it sit overnight and it's gone until warmed up again.

Is this a common symptom to something I'm missing?

 

[bucfl]

It could it be the grease is thicker when cold? And thins out while warm?

 

[2001LC]

There are 3 different mounting bushings located around the front diff which might also add to excessive play in the front drive line. The rubber pucks on from & rear of the diff and then the differential support.

If I am checking these for play with a prybar, how much movement should one expect out of the front & rear rubber pucks (pictured red circles)? And how much movement should one expect out of the diff support (pictured red square box)?

The pucks have very little movement. But the diff support (red square) seems really sloppy. Is that the nature of that particular bushing, very soft?

View attachment 1265129

View attachment 1265135

You doing a good job move through the different component of drivetrain and suspension. You'll get this solved soon and have safer, tighter and better feeling rig when done. Keep it up!

You should see very little movement, but some in your front diff bushing. Also inspection should be done by looking at condition of bushing and brackets.

The propeller shaft slip yoke clunk, is mostly associated with acceleration and deceleration, coming to stop and take off and speed bumps.

As far as clunk being from wheel hub flange to axle spline teeth back lash, it's very common to find this. The fist sign is N to D or N to R shifting you'll hear the clunk. It has to be very worn to hear just by letting off gas. Lag in movement as stated as well as pulling off wheel hub grease cap and snap ring gives good visual inspection. If axle (front drive shafts) aren't to bad you can swap from one side to other and just replace wheel hub flange with new ($50 ea). Axle seem to be harder steel then flange, so flange gets the worst of it. Not best practice but cost savings if budget is tight. Keep in mind this condition is most often caused be loose wheel bearings & wide snap ring gap.

 

[Greenbean]

It could it be the grease is thicker when cold? And thins out while warm?

I'm hoping so as I haven't seen grease yet through the slip yoke seals. I'm going to hit them again tomorrow and try and get it past the seals. At least that's what my FSM says, lol...

 

[2001LC]

Using thinner grease like #1, #0 or even #00, is a good way to start when dealing with tight seals. This works well to get grease to pass seals, once flowing you can step up to #2 over time in the heat of summer is best. Additionally cleaning and priming outer rim of seal is good practice. Once cleaned & primed, I found great trick, recently, to aid flowing of grease past seals. I learned to pulse grease in while wheels on ground. By this I mean pump in grease until yoke start to extend, building a little pressure. Then give an addition pump so it moves out just a little more and hold. You'll see it start to collapse. As it collapses give a little pump expanding again. Keep repeating, without getting overly extended. This can take minutes and may even need to be over time, possible days or even weeks. The pulse primes the seal from the backside. Eventually grease will pass or welch plug will give way. Either way pressure will be relived, shaft lubed and clunk gone.

 

[abuck99]

I know it's been debated and debated but I feel that less is more when it comes to prop shaft greasing- I have yet to get grease to pass the seal- and I could have pumped nearly the whole tube but out of curiosity when removing the zerk the grease spewed out for a few moments to equalize the pressure. I don't believe there should be any significant positive pressure.

If the sole purpose of lubing the propshaft is to keep splines greased, then a few pumps every 3000 miles should do it.

 

[2001LC]

^^Removing the grease zerk^^ when grease will not pass, and keeping wheels on ground are/is good insurance. Both reduce risk of damage to transfer case/differentials keeping pressure neutral.