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Geaux Tigers!!
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Discussion Starter · #1 ·
As always, I searched, but this is a tough one to find the "right" search terms for. Anyway, here's the issue. It's very hard to explain accurately, so bear with me. :popc1:

When accelerating from a stop, I can feel a "clunk" in the rear as the suspension squats. There is nothing audible that coincides with this. If I floor it, you feel only one clunk as the truck squats a lot and quickly. If I give it very little throttle, it's possible to accelerate away with no clunk at all. If I give it a bit more throttle, it clunks.....add another dose of throttle and it clunks/squats more. At speeds where the truck doesn't accelerate very hard, the clunk isn't there.

And as I slow to a stop, the rear suspension seems to spring back and "clunk" upward as I stop aggressively. It's as if something it preventing the suspension from squating under acceleration and then preventing it from extending when stopping.

I removed the rear sway bar thinking the bushings may be binding. No help. I left the bar off, BTW.

I removed the rear shocks and drove it around the neighborhood thinking that perhaps the shocks were gummed up. No help. Put them back on.

Now the only things (suspension-wise) I can think of are the leaf spring bushings (which I can't see causing this) and the shackles. Perhaps the shackles were impacted into place causing the rear to bind? That's my best guess at this point and I'll loosen and re-torque them tonight.

Could it be something in the rear driveshaft? What else could I check? I'm running out of components back there. ;) Is this just axle wrap? This is very noticeable and unlike any rear suspension phenomena I've had in any other leaf sprung truck I've owned.

Thanks,
Tommy
 

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Better check the diff, possible play or damage in the components. I've seen it (heard it)on mustangs and in my bronco (reason why I'm rebuilding), It's a sign that the rearend could be giving out, Bad pinion, bearings, piece out off spider, etc ..., clunks upon fast acceleration and deceleration, but no sound when going slow.
 

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Geaux Tigers!!
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Discussion Starter · #5 ·
Funny y'all should mention the rear gear stuff. The pinion seals looks to have a slight leak (weeping, not accumulation/dripping). The previous owner also said he had the rear u-joints replaced. Looking at the orig. owner's records for the truck, it had the rear ring & pinion replaced about 2-3 years ago (under warranty).

However, if I had to guess, I'd say this clunking is based more on suspension movement than drivetrain. It's hard to tell when driving, though. Please keep the ideas coming. I'd really like to get to the bottom of this this week.

Thanks!
Tommy
 

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Geaux Tigers!!
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Discussion Starter · #9 ·
Larston said:
Are you 100% sure it's the rear suspension? Sounds more like radius arm bushings. Sound can transfer all over the place and make it hard to pinpoint.
Good idea, but I just swapped the front RA bushings for poly units Sat. morning. No change. :duh I agree that it could be coming from a variety of locations, but it really feels like it's coming from the rear end. However, I've been wrong before and will explore all possibilities!

Tommy
 

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Geaux Tigers!!
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Discussion Starter · #12 ·
So I've been paying more attention to this clunking deal with regard to when it happens and it appears it is suspension travel related. There aren't many bumps that I can take where the clunking is very noticeable, but there is one at work that does it. When coasting over it I can definitely feel the clunk and the truck has no power or braking going on when crossing over it. Unfortunately, the power went out last night and stupid me didn't have a key since I always go in/out of my house via the garage. :twak So a few hours later after dinner with the neighbors I got in, but it was too late to check the torque on the shackles. Hopefully I can get to it tonight.

Tommy
 

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What you describe seems to be a Ford thing. I have noticed it in a F150 Supercrew and my Bronco. I know others on here have noticed it too. The general consensus in the past is that it's the rear driveshaft slipjoint. Try giving that some grease.
 

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k1w1t1m said:
What you describe seems to be a Ford thing. I have noticed it in a F150 Supercrew and my Bronco. I know others on here have noticed it too. The general consensus in the past is that it's the rear drive shaft slip joint. Try giving that some grease.
:stupid This has got my vote. Look just drop the rear half of the rear shaft and clean the splines and re-grease it all nice. If that aint the problem....well at least you will know that is one less thing on the maintenance list that needs to get done.
 

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Geaux Tigers!!
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Discussion Starter · #15 ·
Streetgang said:
:stupid This has got my vote. Look just drop the rear half of the rear shaft and clean the splines and re-grease it all nice. If that aint the problem....well at least you will know that is one less thing on the maintenance list that needs to get done.
So pardon my ignorance here, but our driveshafts are actually two pieces with a slipjoint/splined shaft between them? It didn't even dawn on me that would have to be the case since there are bolts on the u-joints on both ends, unlike most cars where the tranny end is just a splined shaft. Hmmm...

So what y'all are saying is that the grease in there may have dried up and the splined shafts are sticking instead of sliding smoothly relative to one another? That makes a lot of sense.

I just looked at the boot and it appears the clamps are one-time-use only. I suppose replacements are available from Ford? I don't think I'd want to use hose clamps there. I'm guessing there's a good chance I'll tear up the boot, too, in the process of removing the clamp.

Thanks!
Tommy
 

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Tommy R said:
So pardon my ignorance here, but our driveshafts are actually two pieces with a slipjoint/splined shaft between them? It didn't even dawn on me that would have to be the case since there are bolts on the u-joints on both ends, unlike most cars where the tranny end is just a splined shaft. Hmmm...

So what y'all are saying is that the grease in there may have dried up and the splined shafts are sticking instead of sliding smoothly relative to one another? That makes a lot of sense.

I just looked at the boot and it appears the clamps are one-time-use only. I suppose replacements are available from Ford? I don't think I'd want to use hose clamps there. I'm guessing there's a good chance I'll tear up the boot, too, in the process of removing the clamp.

Thanks!
Tommy
This is a common problem with bronco.
Just use wire cutters and cut one end of the band off without tearing up the boot.
I just used a zip tie and its held up for 2 years.
pack it with lots of grease, there is a certain type but i just used regular axle grease.
 

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Geaux Tigers!!
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Discussion Starter · #17 ·
It's crazy. I searched using all kinds of terms, but found nothing. Just searched again using "slip shaft" and found all the info I could hope to find. This definitely sounds like the problem I've got. Hopefully, I'll have time tomorrow night to take care of this. :)

Thanks again to everyone for the ideas! So much good info here!

Tommy
 

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I killed Kenny...again
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also check the actual cardan joint at the t-case. mine had the clunks for a week or two, and i get hear it humming a bit down the road. took off from a stop one day, and it all let go. put the trans in nuetral, chock your front tires and spin the rear shaft, inspecting the cardan case. i had a small crack on one of the ears, and thats what let go
 
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