1999 230K 4L 4x Rear metallic clicking or bang noise during acceleration or takeoff.

[trader007]

Dead stop. Hit gas moderately to hard, BANG BANG BANG like metal bolts are snapping clean off. It doesn't sound good. If i baby it off the stop it doesnt make any noise.

At no point does anything appear to be physically wrong. I can feel the clicking in general, but its not like its in the pedal or anything. Fairly sure its in the rear end, maybe broken brakes although I did a full brake job 3 years ago...

I've had this truck for over 100k miles, done all the work myself. Basically, the rear end is completely stock besides brake drums, shoes and hardware. And shocks.

About 4 years ago, I did a drain and fill on the rear diff. Added special limited slip compound.

I have been doing lots of research since I don't have access to a shop until saturday, but without even looking at I'm thinking it might be the limited slip clutch packs worn so bad that they make this noise. It appears to be a known issue with limited slip rear ends. Think I'm close?

 

[adsm08]

Limited slip won't do anything like that, especially not in a straight line.

I would suspect a u-joint over anything else from your description. Get under, grab the drive shaft and try rocking it around in all directions. Do that at both ends.

 

[trader007]

I doubt it's the shaft, because I check it every oil change. It's stock as far as I know, but it's never felt loose by any means.. I've seen so many u-joints go bad with 1/4 the mileage as mine and i even have 2" of lift. Build Ford tough man.

I'll definitely check it though. And like I said, I have never had any issues with the rear end at all, even when I changed the fluid at 160K miles it was clean inside and the metal magnet wasn't even very dirty. It hasn't leaked a drop since either.

 

[509lifted]

trader my u-joints went bad and did exactly what yours is doin and my driveshaft wouldnt even move when i checked then a week later it went

 

[Frank The Tank]

Drive it till the U-joints fall out just to be sure... that's what I like to do.

(also could be the driveshaft is bent.... mine did that same thing then once also and no matter how hard you shake it the U-Joints wont rattle, lol)

 

[trader007]

thanks guys! i figured that could be possible, but i didnt know if it was likely. i suppose on saturday i will take the drive shaft off and replace the u joints. even if they appear good to me, which i doubt once i get to the bearings, i will replace them no matter what. quarter million miles, they did their job.

im pretty much at that point with this truck. anything that is original and is in any question of being OK, i just throw out and replace it. i figure only a few grand more and more then half the truck will be new

 

[wildbill23c]

thanks guys! i figured that could be possible, but i didnt know if it was likely. i suppose on saturday i will take the drive shaft off and replace the u joints. even if they appear good to me, which i doubt once i get to the bearings, i will replace them no matter what. quarter million miles, they did their job.

im pretty much at that point with this truck. anything that is original and is in any question of being OK, i just throw out and replace it. i figure only a few grand more and more then half the truck will be new

Yeah, I'm at the same point on my 84 B2 which in fact will be a project no way around it, PO didn't do it any help.

Definitely look at your drive shaft's u-joints like other's have said, check your suspension components too that can cause some noise if those components are lose such as springs shocks, etc. Usually if you have an actual rear differential problem you will hear a howling noise rather than banging.

Its better to replace suspicious parts than ignore them and find out the hard way that you should have replaced them. I look at it as an insurance policy, if I know I put a new part it its most likely going to be ok, on these older vehicle's replacing old parts is pretty much the normal thing to do especially when you don't know if the PO ever did or not. I do the same thing with all of my fluids on a used vehicle immediately have them changed the first chance I get.

 

[trader007]

success!

one bearing in the rear u joint was dry and stuck. the joint felt fine on the truck, but after i took it off it was obvious it only moved one way

new premium joints in, and it actually does feel smoother back there. i also tweaked my left torsion adjuster, because i was hitting bumps all crooked and weird. i could tell the left tire had no strength in the spring. i got just barely 1/8 turn but it made a huge difference. truck doesnt nosedive on that side now, but it has made the worn wheel bearing on the passanger side get real loud. so i guess next paycheck that is getting replaced...

 

[Andy D]

Yah, that was all the Rat needed was the rear U- joint.