[updated:LAST EDITED ON 23-Aug-02 AT 05:23 PM (EST)]I think my U-Joints in my rear drive shaft just froze up. When I give it gas, it starts clunking loudly (my buddy say it makes a KER-CHUNK sound), and the back end of the bronco would dip down. Would a forzen u-joint do this? Or is it something more serious?

Thanks!

 

A frozen u-joint will not do that usaully they will cause a vibration, however a throughly trashed u-joint will cause that sound.

The easiest way to check is to block the tires so the truck can't roll, then put the t-case in neutral and get underneath and try to turn the driveshaft back and forth by hand. That will tell you where the Ker-chunk sound is coming from.

Brian:-)

 

My Bronco, as well as another I know of does this same thing. When taking off from a stop, as the back end of the Bronco goes down, there is a clunking from the rear, if you give it a bit more gas and the back goes down more, it'll clunk again.

I have, however, removed the rear driveshaft and verified that the double cardon and rear u-joint are a-ok. I have just put the whole thing off as being the leafsprings, as the axle twists on them, they move and bind slightly, causing the sort of clunk, as the axle twists. If you notice next time, it feels like it is binding, and then when it gives, it makes the noise, and happens in steps.

If anybody else has experienced this, and knows the cause FOR SURE, and how to fix it, SPEAK UP!!! Thank you

 

Just replaced my back set ($23 with labor)--I pulled shaft and took it to a shop. My recommendation---it takes about 5 minutes to break the four bolts on the rear end and then you can see what you really have. And if that is not enough, it takes another 5 minutes to take the four bolts off the front part of the shaft and out it comes--easy. Also, mine started vibrating at about 30 mph and got worse in time, plus I could hear them squeaking at low RPMs.

 

I have the worst luck. My driveshaft and U-joints were fine. It looks like I have a blown rear-end!

Thanks for the responses!

 

I have a vibration when I step on the gas could this be my problem?

 

For some of you if it's not the rear end, Sorry eddy!! you guys may want to take the slip yoke apart from the drive shaft and grease it good. I had the same problem, a thud when stopping and taking off. I use a white grease and haven't had the thud since. I am getting a slight vibration sometimes bad some times not at all. I am thinking it's my u joints and cv joint. So here pretty soon I am going to take it all off and rebuild it.

 

I am getting a vibration sometimes bad some times not so bad could it just be U-Joints?

 

It could very well be U-joints. It could also be that your driveshaft is out of balance, or a hundred other things causing it. I would pull the driveshaft and take it to shop that specializes in them, and have them check it out. No sense replacing the U-joints if they really aren't bad.

 

A bound u-joint will not show itself by putting the truck in neutral and moving the shaft. You have to take the shaft off and rotate the u-joint around, then you will be able to feel if it is bound. Mine was, I paid $300 exchange for a rebuilt and balanced shaft, it was well worth the money. The truck drove a hundred times better with the new shaft.

 

I got 35's w/ 4" lift, when i take off theres a creaking kind of noise, im betting like most of you that whats causing it is the tristing of the rear axle, i was wondering if ladder bars might correct this. There rear end also dives down a good 4" too and pics the front up... i have a the 351 not sure if its stock, but i put stock 2wd 5.4 supercrews, and extended cabs w/ exhaust to shame along w/ my friends 78' w/ new 310hp motor...his truck doesn't dip down in the rear at all and his rides so stiff, i bet add aleafs might get rid of it too, but ladder bars just look moer functional.-rem

 

[updated:LAST EDITED ON 01-Sep-02 AT 03:42 PM (EST)]I've got a little click-e-t-y sound (at the rear of the truck) sometimes when I take off from a stop, and just about always when I turn into my driveway thats on a hill. I'd bet the farm it's the u-joints, and I'd bet the farm it's your u-joints too.

 

 

>My Bronco, as well as another I know of does this same
>thing. When taking off from a stop, as the back end of the
>Bronco goes down, there is a clunking from the rear, if you
>give it a bit more gas and the back goes down more, it'll
>clunk again.
>
>I have, however, removed the rear driveshaft and verified
>that the double cardon and rear u-joint are a-ok. I have
>just put the whole thing off as being the leafsprings, as
>the axle twists on them, they move and bind slightly,
>causing the sort of clunk, as the axle twists. If you
>notice next time, it feels like it is binding, and then when
>it gives, it makes the noise, and happens in steps.
>
>If anybody else has experienced this, and knows the cause
>FOR SURE, and how to fix it, SPEAK UP!!! Thank you

 

>>My Bronco, as well as another I know of does this same
>>thing. When taking off from a stop, as the back end of the
>>Bronco goes down, there is a clunking from the rear, if you
>>give it a bit more gas and the back goes down more, it'll
>>clunk again.
>>
>>I have, however, removed the rear driveshaft and verified
>>that the double cardon and rear u-joint are a-ok. I have
>>just put the whole thing off as being the leafsprings, as
>>the axle twists on them, they move and bind slightly,
>>causing the sort of clunk, as the axle twists. If you
>>notice next time, it feels like it is binding, and then when
>>it gives, it makes the noise, and happens in steps.
>>
>>If anybody else has experienced this, and knows the cause
>>FOR SURE, and how to fix it, SPEAK UP!!! Thank you

I also have a Ford bronco 1991. 218k+ miles. When ever It makes these clunking sounds I have the drive shaft rebuilt. I also see where a gentleman mentioned removing his driveshaft to check for end play. I also did this and found the drive shaft joints to be tight as can be. However you can't possibly simulate the same stresses that the rest of your drivetrain puts on the driveshaft which is several tons of torsional twist. It is only under these severe conditions that your drive shaft components will make sounds or show fatigue. Also make sure that you use an extremely high quality EP grease with no soap bases of any kind. The reason for this is that greases with these soap bases tend to wash out of the bearing when subjected to any kind of water submersion leaving your U-joints or other bearings completely unprotected.