Anybody know how to remedy the clunk sound in the rear end, at initial acceleration on a '95 F150 4x4 ORD. The intensity varies dependent on how hard a stop is made, and/or how quick acceleration is made. My sons '96 F150 4x4 ORD did the same thing. Both trucks, under 60K miles. My non-ORD F150 4x4 does not do this, 178K miles. thanks, Rich

 

are you sure its coming from the rear end and not the u-joints on the driveshaft.

I had a similar sound and it was the u-joints.

 

thanks, already checked 'em, their good. Almost sounds like a bad axle slap. It's inconsistant, and kinda feels like loose u bolts on the carrier, their good also. My sons '96 did exactly the same thing and with our limited expierenced eyes and ears, we found nothing.

 

We do have an axle forum, but since we're not really sure what this actually is yet, I'll leave it here.

When you take the rear driveshaft off, and grab the pinion flange, is there any looseness that you can feel? It'll feel pretty tight/unforgiving on a new/rebuilt one, but there shouldn't be a lot of slop.

Have you taken the rear diff cover off yet to inspect?

 

thanks stang, move this if you wish. No, I haven't checked the pinion, and other than chucks and bits I wouldn't know what to look for in the diff., and it drives perfectly, once it's rolling. It almost sounds torque related, like something not lined up right or loose suspension.

I bought used, but the underneath looks like it has never been off the pavement. It is wired with a brake controller and the previous had a boat. What has got me is my son had the exact same symtom on the same style OffRd truck package.

 

How do you say dere, Rich. I have the same thing with my '88, but as you know it's on the rough side anyways. I know a fella who had a '96 named Steve (not the truck) also witda same thing and I think it has to do with axle wrap, u-bolts, or something right there. One other thought is the transmission mount. I still think you should take out those 4" lift blocks in the back though and see what happens....and those rattling hubcaps don't help either.

 

This type of problem is very hard to diagnose over a computer.

Take the driveshaft off as well as the rear diff cover. To unbolt the cover, put a pan under it and remove all the bolts except the top one, leave that loose. Use a screwdriver to gently pry the cover off, fluid will pour out from the bottom edge, and after the majority of the oil comes out, remove the top bolt and take it off.

Get a couple cans of brake clean and a box/roll of scott shop towels, and clean the inside out. Look for metal chips, and look for milky oil coming out. Milky oil indicates water in it.

What you'll want to do is grab that pinion flange (the metal disc with a big bolt in the middle, which the driveshaft bolts to). Turn it (rotate) back and forth, try to push on it left to right (side to side), see if there's any looseness. There are two bearings a few inches inside, moving it left to right will sorta check if they're about gone.

When you try to rotate that left or right, it shouldn't move much. If you can turn that (with tires stationary) more than I'd say about 2" either way, then you've got some major slop in that rear end. Possibly due to worn side/spyder gears, or bearings.

You'll also want to jack the wheels off the ground, and play around with that differential to see if you can get it to **** in the position it's in. There are two bearings on either side of it that have caps holding it in (like big u-bolts almost). Sometimes those bearings go and the carrier can move/**** itself under torque. You can put a wrench on that nut by the pinion flange and see if you can get it to move side to side. It should only spin.

While your in there, you'll see a toothed ring behind the ring gear, check the teeth on that for damage. Thats for your speedometer. Also, the fill plug has a magnet on the back of it, check that for metal fragments. There should only be very very fine pieces of metal on there. Wipe them off before re-installing. Re-fill with fresh diff lube, I think its about 2-2.5qts. On level ground fill it up til it comes out the fill hole.

Scrape all the gasket material off the cover and gasket surface on the rear axle, and use some RTV silcone to seal it up. Use a 3/8" ratchet to torque those bolts down, and tighten them down. Don't need to go crazy on torque, just a good firm tight on the ratchet.

If all of that looks good, then you might start looking into other things that could be causing the problem. Thats a pretty decent check for the rear end.

 

Justin you're a lifesaver. The slop in my 95 rear end is major bad. I can turn the driveshaft anywhere from 1/8 of a turn to a 1/4 turn (cant really tell but its bad.) Think I might tear into the rear end and see what I find. Is all of this rebuildable or would I be better off junk yardin until I find a while axle like I have now?

 

thanks a ton mustang, or I mean a 1/2 ton. I appreciate the inspection process I will keep it handy. Without disconnecting the u joint I grabbed the pinion flange and got nothing but a solid feel, and she didn't even slap me.

 

Hep GP, I am almost sure Steve's truck had the same creaking clunk before he raised his truck. The trans mount is a consideration... Now, you told me I had to leave them there hub caps on so the wheels wouldn't come off, and to keep my alumillum wheels from rustin. good to hear from you here, hotdog. Anybody take any shots at that war wagon of yours up there yet?
RZ

 

yeah, I think you're right about his truck always having it, but I was referring to yours being jacked up in the rear with those cheap blocks. I know you like it like that, but it may be amplifying the problem.

I've only recieved compliments and plenty of looks so far.

 

OK, I don't want to give you a cheap reputation, so let me clear things up here. RRZIELIN doesn't use hubcaps or have his truck raised up at all.

I still think the source is outside the differential housing.

 

Like I said, good to hear from you hotdog. No worrys, I use 3' long air shocks front and rear anyways.

It might be in the spring shackles, or a cracked leaf. I just find it hard to believe it's broken or wore out parts at this point, 51K miles and soo untouched and clean and dry underneath. I am thinking something needs to be shimmed somewhere, or maybe a mount point is weak.

 

I have the same thing on my 1988 F150 4 x 2 extended cab, with about 90,000 miles--had it checked by the Ford dealer: differential had been rebuilt recently, two of the U-joints replaced recently as well, and the metalic clunk was still there. Their conclusion: there is a sleeve inside the drive shaft, which can crack, and will make that sound; doesn't affect driveability. Only solution is a new driveshaft (about $800. for parts/installation)--so I just keep driving with a bit of a clunk.
I would appreciate any other thoughts on this.
Frank.

 

I think your dealer is full of it. They like to make up explanations when they don't have a good answer, make it expensive to fix to discourage you from proving them wrong, then tell you it won't make a difference whether it's fixed or not to further convince you not to do it.

There are a ton of causes for the clunk. I'd say about half the time, the slip yoke out the back of the transfer case is making the noise. That's what it is on mine. Other possible causes are tranny mounts, bushings, cracked crossmembers, loose/cracked springs, and probably about six others I'm forgetting.