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Rear end backlash?

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Old Jul 29, 2021 | 12:46 PM
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Rear end backlash?

I occasionally hear a ping coming from the rear end when first starting out cold. I went under to check out the u joints today, no movement there. There’s some backlash in the driveshaft which I believe is normal but I’d like some other opinions. Here’s a video.

https://drive.google.com/file/d/1yyK...w?usp=drivesdk

Also, I was expecting a zerk on the u joint, didn’t see one. What am I missing.
 
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Old Jul 29, 2021 | 12:51 PM
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Can't see the video, you need to grant rights.

Not all U-joints have zerks, "lubed for life". Without hearing it, could it just be the rear brakes sticking a little? Mine do that some times after first backing up.
 
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Old Jul 29, 2021 | 01:08 PM
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Originally Posted by ALBUQ F-1
Can't see the video, you need to grant rights.

Not all U-joints have zerks, "lubed for life". Without hearing it, could it just be the rear brakes sticking a little? Mine do that some times after first backing up.
Oops…rights granted.

Brakes are a possibility, I’ll check them.
 
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Old Jul 29, 2021 | 01:33 PM
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Does this driveshaft have a slipyoke? Possibly need to grease it if so, I've seen a lot of them ping as the splines move from rest to power.
That amount of backlash is normal, have seen many with a lot more.
 
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Old Jul 29, 2021 | 02:14 PM
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I agree, not bad. Is the diff oil up to proper level?
 
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Old Jul 29, 2021 | 02:56 PM
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Originally Posted by mechmagcn
Does this driveshaft have a slipyoke? Possibly need to grease it if so, I've seen a lot of them ping as the splines move from rest to power.
That amount of backlash is normal, have seen many with a lot more.
i don’t know if it has a slip yoke, I guess I gotta climb under and look. I’m trying to lube everything but it seems like there’s 1000 zerk’s.
 
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Old Jul 29, 2021 | 02:57 PM
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Originally Posted by ALBUQ F-1
I agree, not bad. Is the diff oil up to proper level?
I thought it was normal, but you can’t be too safe. Yes, I changed the diff oil about a month ago, checked again today, it’s good.
 
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Old Jul 29, 2021 | 06:08 PM
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I don’t see a slip yoke. I found the zerk on the u joint, but I can’t get a grease gun on it, no room. I’ll figure it out somehow.

I suspect there’s nothing wrong, just the normal noise from a 73 year old truck.


 
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Old Jul 30, 2021 | 02:00 PM
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I took a video to let folks listen to this ping, nothing to see, but listen at about 20 seconds in. I moved up and down the driveway and it didn’t repeat.

https://drive.google.com/file/d/1mwv...w?usp=drivesdk
 
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Old Jul 30, 2021 | 02:25 PM
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Sorry, my end, I finally got the videos to play, see my later post.
 
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Old Jul 30, 2021 | 02:29 PM
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Originally Posted by 1956_F100
I cannot get any of the videos to play. But my guess is the ping is the driveshaft itself ringing. Probably too much wear in the rear axle, you know, a little in the ring and pinion, a little in the side gears and pinion gears, It all adds up.

What trans is in the truck, and how high is the warm idle speed and cold idle speed?
that’s odd, I gave permissions for everyone to watch. You should just click the link and it should play.

the tranny is a 4 speed spur gear. Idle speed is consistent warm and cold at about 550.

I agree it sounds like the driveshaft pinging, I just don’t know what’s causing it.
 
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Old Jul 30, 2021 | 02:35 PM
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I finally figured out how to play the videos. First thing I would to is removed the driveshaft, check, and probably just replace the U-joints. In the second video it almost looks like the rear U-joint is loose or one of the cups on the driveshaft yoke itself is worn oblong allowing a U-joint to move around a little.
 
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Old Jul 30, 2021 | 03:23 PM
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At the 11 or 12 second mark on the video it really looks like the U-Joint is worn pretty good.
 
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Old Jul 30, 2021 | 04:12 PM
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Originally Posted by rpaxton939
At the 11 or 12 second mark on the video it really looks like the U-Joint is worn pretty good.
I know…right? But I was just now under her checking the u joints, even with a pry bar I can’t get any movement out of either u joint, only the diff. I lubed both for now, perhaps next week I’ll pull the driveshaft and change them. I haven’t done a u joint since maybe the late 70s, but if I remember right, it was pretty easy using the proper tools. Advance usually has tools to loan.

Does anyone know the correct u joints? I’m sure they’re fairly generic.
 
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Old Jul 30, 2021 | 04:40 PM
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Get the u-joint off and take it to the supply store. They can make a good match if you have it with you.
 
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