Knocking Noise

[arctcknight]

i have a very nasty knocking noise coming from either my t-case or rear axle i re lubed my joints in the axle but nothing there is a little bit of play in my axle and i havnt a clue what could be causing it.

 

[Ziggy]

Is the knocking noise consistant? Or does it come and go as you speed up or slow down? Check your drive shaft for straightness/alinghment. Are you sure it's coming from the transfer box or drive shaft?

 

[arctcknight]

it only comeswhen im accelerating and whencoasting down hill.

 

[dirt]

i have heard that there is a slip yoke at the rear of the t-case that is suppossd to use a special teflon grease to eliminate this slight bind. this info came from a former ford factory technician.

 

[Seabronc]

I'd suspect that the U-joint or Double Carden joint is beginning to bind up. Usually that causes a lot of vibration before it actually goes.

Good luck,

>-

 

[Seabronc]

Also, if it sound's like a pissed off Leprechaun beating on the floor boards, it could be caused by spring wrap which in this case would be due to weak leaf springs.

What happens is they distort out of shape and cause the drive shaft angle to shift outside of it's designed limit's. Or in other words be at an angle that the joints can't handle.

So if you find the joints all perfect check this out. It is usually caused by the engine torque being too high for the rear end it's hooked up to, but weak sprigs will give the same result.

Good luck,

>-

 

[Ziggy]

It wouldn't be spring warp as he gets the noise going down hill. Since noise accures when the drive shaft is under load, I would suspect the u-joints. Best way to check these is to jack the back axle up, support the truck with stands, then put the transfer case in "N" and rotate the drive shafts by hand and watch or feel for any slop in the u-joints. If you need to replace any, might as well do them all. It will a little expensive, but I suggest going with a good quality u-joint like Spicer and get them with grease fittings so you can keep them greased.

 

[Seabronc]

I respectfully disagree that spring wrap can't happen under a down hill situation. I can invision reverse wrap with the engine trying to hold the truck back with weak leaf springs, as far fetched as it may be . However, I do agree, based on the description of the problem, that the most likely problem is one or more of the joints being bad as I stated in my first post. Also, like Ziggy said, if changing one, go for all of them.

Good luck,

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