The Stovebolt Site Forums The Shop Area Driveline Odd Popping

Try using a set of big wheel chocks, at the front and rear of both front wheels to keep the truck from going anywhere, and see if you can duplicate the noise on a paved surface such as a driveway or parking lot, with someone watching the suspension from a safe distance to the sides as you try to move the truck forward and back. We found the source of a bad shudder coming from a motorhome that way- - - -the surge brakes of the 2-wheel tow dolly being used to haul a small car behind it were locking up repeatedly during a stop due to a broken damper spring. It felt like the rear end on the motor home was about to come apart every time the brakes were applied. We got the rig home several hundred miles by opening the bleeder valves on the tow dolly to disable the surge brakes, and planning stops carefully to accommodate the reduced braking ability.
Jerry

My apologies, I wasn't asking about the slop to go down a rabbit hole. It was just a question. I am still trying to pinpoint the noise. Last night was the first time I clipped the gopro to the a cross sill of the bed and took it for a drive. It's a little limited on where it can be pointed as it doesn't swivel. To start off I pointed it at the rear end. Took it for a drive, and it did pop, not a big loud one, but it did pop, twice. Unfortunately it wasn't apparent in the video when it happened. I have to dress nicely for my job, so crawling under the truck before and during work to mount the camera is not good at staying clean. However, I brought the camera with me today along with an old sheet to lay on the ground so I can mount it pointing towards the trailing arm-to-frame connections next.

If the video footage doesn't show it, I will definitely try this.

Mounted the camera towards the trailing-arm-to-frame connections at lunch time, and ran out of gas going to the gas station...lol... Since my lunch got cut short I watched the video at work and those connections are solid. However, since the popping didn't happen, and I wasn't able to drive it around until it did pop, I will be doing this exercise after work. The camera will get mounted in the same spot, and I am certain it will pop at the one left turn up the street. If not, it will at one of the many traffic lights when I go to take off.

One thing I did notice, though, is I either need a different yoke for the transmission, or the front shaft has a slight bend in it. There are no vibrations whatsoever, but you can see the front of the driveshaft is not turn a nice smooth, centered, rotation.

Just read thru this whole thread and one thing I didn't see was checking the driveshaft slip joint at the transmission (except for your last post). On Ford Superduty trucks, especially those with 2-piece rear driveshafts, it was common to get a pop on takeoff if the slip joint dried out. The cure was to lube the splines on the slip joint. Ford recommends a teflon based grease for that purpose. You may be experiencing the same thing.
If the splines are worn (you did mention some wobble at the front of the driveshaft), that could be the cause of your noise.

This is a completely different driveshaft that was in it when I bought it. This popping happened while I test drove it before buying it. The driveshaft I took out was a mess. It had the slip into the transmission, and well as a slip between the center bearing and axle. It was sloppy, sloppy, sloppy. But both slips were tight into the transmission, no slop in those splines.

But I could lube the splines just for the fun of it.

I would definitely try that. It can't hurt, and may solve your problem.

Well crap, my response from last night is gone. Oh well. I'll have to try and recreate it, but it'll have to be later. Have to get ready for work

Playing catch up on your thread. I was thinking that since it seems to only happen at low speeds and while turning left.. have you thought about an axle? Just snow balling here so don't shoot me. If the axle shaft was broken and the break lined up most of the time, it would pop when under load such as in a turn ( I had a crank shaft do this). This could also be true if the carrier had a bad bearing or "C" clip. Just thinking...

You may be on to something. Let me try to recap what I had written out last night. Will try to write it verbatim, but I have slept, so some may have gotten lost in the last 10 hours.

Okay, I covered the lunch time incident. Lets jump to after work yesterday. I mounted the camera in the same spot. Armed with a full tank of gas this time, I hit the normal paths that this popping will happen. Nothing. I was more heavy on the throttle too, although I did some normal take offs as well. No popping. Took turns left, right, tight ones, normal ones, turnarounds, three-point-turn, nothing. Was going to stop and get some juice for me but decided to head home instead. But since it hadn't happened yet, and going home is a string of traffic lights, and I wanted a more fluent motion and the ability to turn left and right on the short segments of downtown, I retraced some steps. I drove past the post office and the next stop it popped.

That was about 16 minutes into the video. The entire time the trailing arm connections did not move at all, no slop in those whatsoever. Driveline, except for the minor wobble at the transmission, nothing. Frame, solid. But the pop could be heard from behind the camera. So to give you guys a hint as to where I mounted the camera, the camera mount is a heavy-duty clamp, and I clamped it to the cross sill just behind the center bearing, and the camera pointing down at the connections. On Tuesday I clamped it to the cross sill above the rear u-joint area. This camera takes wide view shots, so it also picks up the space between the bottom of the bed and cab, so you can see all the way up to the transmission when it's facing forward, and the entire axle when pointing backwards.

It's kinda neat to see the underside of the truck while in operation. Definitely a perspective you don't ever get to see.

With that said, and from the videos I have shot thus far, I believe it is coming from the axle. On Tuesday night, it popped, but mildly and you couldn't tell because it happened right at the time of a rough spot in the road. Rough spots don't cause it, it is completely sporadic. The video from lunch yesterday, and last night's video, all indicate the axle is making noise. I owned and daily drove a '65 C20 from 1987 to 2005. It had a 350/SM420 setup. When I got it, it had the HO52, but I found a 1968 Dana 60 and put that in, in 1991. The SM420 is beefy and not quiet. When I bought this truck, it was and still is running the Saginaw 3 Speed, since I had never operated a truck with the 3 speed I figured they were noisy like the SM420. Granted, the transmission needed to be rebuilt when I got it, and while it was being rebuilt I ran a different 3 speed in it and the truck made the same sounds, so I chalked it up to truck transmission gear noise. I may have mentioned it before, but I restate it, this truck has been on many 1,000+ mile trips and not a hiccup. Yes it will pop, but that's it. No loss of fluids, nothing overheats, just the occasional pop.

That said, Tuesday's video had the camera pointing towards the axle and the gear noise was louder than the gear noise with the camera pointing towards the center bearing. The PO did tell me he rebuilt the rear end, so perhaps he did it wrong.

Could it be a broken axle shaft? I don't know, because on tight turns in a parking lot it doesn't do it, the no-spin is locked up pretty good and turning makes the truck lurch not pop. Pushing in the clutch you can here everything finding its happy spot as you finish the turn and turn it straight. Left or right in a parking lot the same, but if using a little throttle it acts normal. Hot Rod Lincoln mentioned something like that earlier in this thread. I prefer to drive slowly in parking lots and let the dummies drive fast and pull out in front of you. Heavy-footed launches, no popping. Just light-footed take-offs and usually after the truck has gotten up to operating temperature.

I have been enjoying this setup, the three-on-the-tree/HO52, but I have the SM420 and Dana 60 still, and have been wanting to install that 420 & D60. So it might be time to get the bearing kit and rebuild it. I have the seals, and other items for it, I have just been enjoying the current setup. The D60 is 3.54 gears, and I do not plan to buy a gear set to re-gear it to 4.57. If it goes in, the 420 has to go in too, or the take-off gear will be too high with my current 3 speeds.

I will take more videos today and tomorrow, all concentrated on the axle and taken from various angles, and I will report back what I see. This turned out to be longer than last night's post, but also has a little more info.

Did one video at lunch, and two after work. It is the axle. The first pop was loud but nothing visually jumped or anything on video. It was felt in the cab.

Since it did it early on in the video and the camera was mounted to the cross sill, between the left rear tire and the frame, I could reach under to stop it easily when I stopped to get some "juice", and the mail. Each video it popped once, and the second time, although not too loud on the video, there was a visible jolt in the left rear drum. Very minor in appearance yet very loud in the cab and it did cause a minor change in direction during the right turn. Each pop happened while taking off tonight, but the second one was at the beginning of a right turn, barely 1 foot of roll.

Also, this axle is really loud while moving. How there wasn't shavings in the oil the times I've changed it, is beyond me. It has been this loud since I bought it in 2015, how it hasn't failed on our long trips, also baffles me.

This is a 3/4 ton rear end with full-floating hubs, right? (axles can be removed from the center of the hub) Try pulling both hubs off and inspecting the inner and outer wheel bearings. It's beginning to sound like you've had a bearing roller come adrift and it's trying to lock up the hub occasionally. If that's the case, most of the metallic debris will be trapped in the hub with the bad bearing. Hub bearings can get VERY noisy and still keep rolling.
Jerry

That makes sense. If it's just axle bearings, that is easy enough.

I just read out your reply to my wife, and added, "With all of the places we have been in that truck with a bad bearing, and didn't breakdown ".

Blessings come in various forms.

Those old rear ends are as tough as woodpecker lips! Lots of us dirt track racers in the 1970's ran them behind 500+ HP small block Chevy engines, turning over 7K RPM down the straightaways through a Muncie 4 speed locked in 2nd. gear. That's one reason the 4.10 gears are so hard to find- - - -that ratio was perfect for a "long quarter mile"- - - -a track that measured 1/4 mile around the infield. A "short quarter" measured around the outside wall, needed a 4.56 gear to get the right engine RPM.

We ran at Merced, Watsonville, and Antioch California, in the San Joaquin Valley back then. Merced was a "short" track. The others were longer, and we had to swap rear end centers to run them.
Jerry

They are tough, that's for sure. Sounds like fun!

I used to race at Watsonville, we had a Hobby Stock that DeAnza College Votech sponsored. We ran a 65 Mercury Cyclone, the only F%#d in the class.