Rear drums clanking?

[Chris_North]

So I changed my beaten and battered rear end for a newer, nicer junkyard one. I was pretty sure the loud clanking/clunking I would almost always hear when accelerating hard or switching from park into drive or reverse or from reverse to drive and vice versa was from the slop in the rear and would go away. Not so. Some searching suggested it might be the slip yoke and that greasing it should cure the problem, at least for a while. However by pure happenstance with the wheels off I rotated the brake drum, and to my surprise I heard the same, albeit fainter, clank sound. So I am now 89% sure this very annoying noise is just from the initial torque applied to the wheel studs slamming against the brake drum causing a bell-like resonation.

Some searching I can't find anything similar happening to anyone else. All the lugs are tight. I didn't check with a torque wrench but any tighter and I don't think I would be able to get them back off in a few weeks without a pipe on the end of a breaker bar or a big impact wrench. AFAIK the brakes are set up well and shoes definitely catch but don't drag. The drums are definitely old ones (I had to beat the ones off that came from the JY axle because they froze to the shoes which destroyed them so I used the originals, which haven't been changed for at least two years), but even the other set seemed loose like this. Am I missing something? The obvious solution is to change out the drums, but I don't want to spend $90 and then find out it was something else. Any suggestions?

 

[alwaysFlOoReD]

Check your driveshaft u-joints.

Richard

 

[shane96ranger]

So I am now 89% sure this very annoying noise is just from the initial torque applied to the wheel studs slamming against the brake drum causing a bell-like resonation.

If your lug nuts are torqued properly, this ain't happening. The drum is not going anywhere when sandwiched between the wheel and hub. There is some slight play in the axle shafts (in and out) that is normal, which makes a little clunk. My Mustang does it all the time when I pull in my driveway.

I would tend to agree with alwaysfloored's assessment. Check the U joints. While the driveshaft is out, grease up the yoke with a teflon grease only, no lithium based.

 

[Andy D]

Is the diff full?

 

[brokemechanic3000]

Did you check the retainers for the shoes? If they've rusted away the shoes will move and cause the noise you heard.

 

[Chris_North]

As far as I can tell everything looks good with the shoes. I'm not very familiar with drums.

I'm pretty sure the u-joints are fine. You'd feel a bit of rotational or up-down/side to side play in them if they weren't, right? As far as that goes everything is rock solid. I know it defies logic, the wheels should be pressing so hard against the drum that they should have no chance of moving, but it definitely (from inside the cab, anyhow) sounds like it's coming from the far back end and sometimes even from the right or left side. I bought the grease and was set to do it before I found this so I will probably be greasing the slip yoke anyhow, but I don't believe that is the problem. I get the clank only when moving into gears, and occasionally during hard acceleration, but never when stopping.

Also I forgot to mention that if I hold the brakes hard (as if coming to a short stop) when shifting I don't get the noise. I am going to have someone operate the truck while I stand outside to see if I can pinpoint the noise a bit better, but they will have to wait till tomorrow. I would guess that if it is the brakes I should also see rub/wear marks, so I will check that out too. Now that I think of it I don't recall seeing any...

Edit: The diff is also full, and has a comparable fluid for that ford whatever number friction modifier.

 

[alwaysFlOoReD]

Just in case you didn't know when checking the u-joints;
Block a wheel
Make sure you're in neutral.
Now check the u-joints, there should be absolutely no movement side to side, up and down, or rotationally between the shaft and either end.
Another possibility is the pinion nut has come loose, that has happened to me.
Also perhaps excessive ring to pinion clearance.
Good luck,

Richard

 

[Chris_North]

Double checked for any slop. The driveshaft itself is rock solid, no play up-down, etc, and no apparent rotational play. However, I can rotate it about an 1/8 turn (probably less) but with all the play being in the rear end. I know its not the same thing as if something loose was calling the noise, but hitting the driveshaft produces a similar, but much more hollow sounding clang noise.

I will check the pinion nut and grease the slip yoke later tonight. I'm assuming the pinion nut is just behind the driveshaft to diff connection and that it is really just some kind of big hex nut? What torque should that be at?

 

[PanamaExpat]

Less than 1/8th turn on a rear diff isn't anything I would worry about. Sure you don't have an E-brake cable hanging a bit?

 

[shane96ranger]

FWIW, I could not tell the U-joint in my F150 was toast until I pulled the driveshaft. The joint by the pinion flange was very stiff, and I had checked several times priory. thinking it was the suspect.

Posting whilst sitting upon the throne.

 

[alwaysFlOoReD]

Double checked for any slop. The driveshaft itself is rock solid, no play up-down, etc, and no apparent rotational play. However, I can rotate it about an 1/8 turn (probably less) but with all the play being in the rear end. I know its not the same thing as if something loose was calling the noise, but hitting the driveshaft produces a similar, but much more hollow sounding clang noise.

I agree with expat, tho I don't know what he means about the e-brake.

will check the pinion nut and grease the slip yoke later tonight. I'm assuming the pinion nut is just behind the driveshaft to diff connection and that it is really just some kind of big hex nut? What torque should that be at?

Yes, a big hex nut.

FWIW, I could not tell the U-joint in my F150 was toast until I pulled the driveshaft. The joint by the pinion flange was very stiff, and I had checked several times priory. thinking it was the suspect.

^^^You have to remove the driveshaft anyway, so check the u-joints again. They should be fluid throughout the range of motion. If they feel dry, they are, so then replace.

I'm interested in seeing what's up,

Richard

 

[Chris_North]

Okay so, another few hours of wrenching, greasing, and painting, and this is what I have learned.

It is definitely not the slip yoke. I pulled that apart, and to my surprise it is plastic, and well-lubed. Threw some more grease in there anyhow.

I don't think it is the U joints. With the drive shaft off I checked all the ranges of motion. All smooth.

I also can't see it being the pinion nut. I had to have someone hold the brakes, and even then I was moving the truck forward trying to tighten it.

It's not the brake drums. Frankly that was a stupid suggestion, I don't know who even brought that up.


Before leaving work I had my buddy shift from neutral to reverse and so on while I looked and listened under the truck. I think I found the problem, or at least the cause of the noise. When shifting, the drive shaft and diff jump up or down (depending on drive or reverse) a lot, I'd say over an inch. Couldn't see the transfer case or transmission at the time. It seems that that jump causes one of the round ends of the U-joint to hit the u-joint plate piece, thus clunking. Why would this happen? I went creeping around under the truck looking for drivetrain mounts to see if maybe they were loose or broken, but except for the engine mounts (just two?) I only found one other mount at the end of the tranny. All the bolts I could get to seemed tight. In fact, the only ones that I could get to move a little were the bottom-most ones, where the mount attaches to the frame piece. I tightened those two up a few cranks. I was tired and so didn't go nuts checking to see if it made a difference, but the clank doesn't seem as loud. I can't say with certainty this is truly the case though.

I never considered it a possible symptom until now, but when in overdrive and only when accelerating uphill, my whole truck shakes pretty hard until it downshifts and then no more shaking. It will never shake except in that situation. I have a burnt exhaust valve and probably an otherwise tired engine, I was told and accepted that it was just the engine running rough, and that it is probably more noticeable in OD because of the torque converter locking up. Is it plausible that this is not the case?

 

[shane96ranger]

Well, for future reference, you're lucky that pinion nut wouldn't turn. That could result in damaging your gears if you got them out of spec.

About the movement, are your axle u-bolts loose? Is the suspension moving with it?

Your trans could also be on it's way out based on your last paragraph.

Posting whilst sitting upon the throne.

 

[GentleRF]

Chris:

I got to thinking on the s clanking issue and figured out it may be inside the rear end. There are two places it can be inside there. One is the pinion to ring gear play and the second is in the spider gears. It could be even a combination of the two. You will need a dial indicator with a magnetic base to check them. I had a similar problem in an '89 with the A4LD trans. The rear had excessive play there too.

Rick in East Bremerton

 

[Chris_North]

I'm not thinking it would be anything inside the rear. I know it's possible and I'm keeping an open mind but the exact same noise with two diffferent rears would lead me to believe it's something else.

Well, for future reference, you're lucky that pinion nut wouldn't turn. That could result in damaging your gears if you got them out of spec.

Nobody told me that. I'm a look before you leap kind of guy. My motto is I will either make it a lot better or a lot worse.

About the movement, are your axle u-bolts loose? Is the suspension moving with it?

Your trans could also be on it's way out based on your last paragraph.

Posting whilst sitting upon the throne.

I don't think so, the entire rear was changed a few days ago and I made sure to put the nuts on tight. I am going to re-torque them again soon to be sure as suggested. I don't know about what is exactly moving, I will look again tomorrow.

I wouldn't be surprised if the trans was ready to give out. The truck hasn't had a hard life since I've had it, but before me I think some firefighter guy used it and beat the hell out of it. It's on its second engine and the tranny is original with 150k miles on it. Other than an occasion thunk (felt not noise) every once in a while when loaded and accelerating, the tranny seems to be in impressive condition.

I did take it out to the grocery down the road and I think the noise is definitely quieted. I don't think it made it a few times either. Will definitely check tomorrow. Is that all for powertrain mounts though? Two engine and one in between the transmission and the transfer case?