The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Correct clock/phasing/orientation of yokes on '66 C20 2 piece driveshaft

Rust-O-Matic · 09-09-2017, 04:39 PM

Here's an update. I got the shaft back in, pulled one wheel off the rear, and ran the bare drum/axle/driveshaft slowly from 0 to about 65 mph. Still have a vibration. I could see the driveshaft slightly (very slightly, not violently) shaking within the center carrier rubber, so I knocked the center u joint out, and flipped the rear shaft 180 degrees in relationship to the front shaft, and put it back together.

Fired it back up and ran the same test. Driveshaft seems to be smoother, but my eyeball isn't exactly a high precision dial indicator. Regardless, I STILL have a shake with no wheel mounted. So I soaked the brake drum with degreaser and pressure washed the ever loving snot out of it, and scraped some rust buildup out of the inside of the back edge of it. (Keep in mind this is an HO52, not a typical 10/12 bolt that the drum just slides off of).

Fired it up, same test, same shake. After staring at it a while I can clearly see the drum/axle housing/trailing arm vibrating up and down once it's up to speed. I took a short video but I'm not exactly sure how to share it with you guys.

I got disgusted and gave up for the day, and decided to put my new $130 (ridiculous) copper heater core into the freshly restored and painted housing, only to find the copper lines are off just a little bit and it doesn't freaking fit. I tried to flex them ever so slightly to allow the housing to go around them, and one of them broke right of in my gorilla hands. What a crappy finish to a crappy week.

Enough whining though, does anyone have any idea what would cause my drum/axle to vibrate as I explained above? Do they balance those things? Are replacements available? I can't seem to find any exactly like mine, and the couple I have seen cost as much as a good used 14 bolt, which I'd kinda like to swap out anyway for the higher gears. My current 4.56s suck. Just fyi, I had the drums off a while back to rebuild the brakes, and at the time the bearings inside appeared to be in good clean shape, with no signs of gouges, grooves, or galling that I could find.

09-09-2017, 04:39 PM	#11
Rust-O-Matic Registered User Join Date: Apr 2015 Location: Gallatin, MO Posts: 295	Re: Correct clock/phasing/orientation of yokes on '66 C20 2 piece driveshaft Here's an update. I got the shaft back in, pulled one wheel off the rear, and ran the bare drum/axle/driveshaft slowly from 0 to about 65 mph. Still have a vibration. I could see the driveshaft slightly (very slightly, not violently) shaking within the center carrier rubber, so I knocked the center u joint out, and flipped the rear shaft 180 degrees in relationship to the front shaft, and put it back together. Fired it back up and ran the same test. Driveshaft seems to be smoother, but my eyeball isn't exactly a high precision dial indicator. Regardless, I STILL have a shake with no wheel mounted. So I soaked the brake drum with degreaser and pressure washed the ever loving snot out of it, and scraped some rust buildup out of the inside of the back edge of it. (Keep in mind this is an HO52, not a typical 10/12 bolt that the drum just slides off of). Fired it up, same test, same shake. After staring at it a while I can clearly see the drum/axle housing/trailing arm vibrating up and down once it's up to speed. I took a short video but I'm not exactly sure how to share it with you guys. I got disgusted and gave up for the day, and decided to put my new $130 (ridiculous) copper heater core into the freshly restored and painted housing, only to find the copper lines are off just a little bit and it doesn't freaking fit. I tried to flex them ever so slightly to allow the housing to go around them, and one of them broke right of in my gorilla hands. What a crappy finish to a crappy week. Enough whining though, does anyone have any idea what would cause my drum/axle to vibrate as I explained above? Do they balance those things? Are replacements available? I can't seem to find any exactly like mine, and the couple I have seen cost as much as a good used 14 bolt, which I'd kinda like to swap out anyway for the higher gears. My current 4.56s suck. Just fyi, I had the drums off a while back to rebuild the brakes, and at the time the bearings inside appeared to be in good clean shape, with no signs of gouges, grooves, or galling that I could find.