1974 C10, mystery vibration

[jchav62]

Hi all! It's been a while since I posted on here. I have a question:

I recently acquired a 1974 C-10 longbed and got her back running and on the road. The issue I'm having is a weird vibration. What happens is I can drive the truck and it will run super smooth for about 10, sometimes 20 miles.... then some weird vibration starts. My first thought was the driveshaft center carrier bearing. Replaced that. Took for a cruise and it seemed to fix it... around mile number 15 of the test drive, the vibration came back?

Any ideas? I'm kind of stumped.. can't think of anything that will start vibrating only after a few miles of driving...

Thanks! JC62

[69Tom]

U-Joints?

[jchav62]

Originally Posted by 69Tom

U-Joints?

That's what my buddy and I were thinking. Just wanted to get other opinions since it only happens after a few miles of driving.... not constantly.

Thanks...

[GOPAPA]

Just a thought .,, I had a vibration in my old Chevy car and first thought it was the tranny and then u joints and it wound up being my rear end,, pinion gear and spider gear ..the car did not do it all the time and mainly after I got it going awhile

[69Tom]

Originally Posted by GOPAPA

Just a thought .,, I had a vibration in my old Chevy car and first thought it was the tranny and then u joints and it wound up being my rear end,, pinion gear and spider gear ..the car did not do it all the time and mainly after I got it going awhile

Would that be the pinon bearing going bad, or did someone get in there and didn't shim it to correct specs? Not a bad thought though.

I'd definitely start with u-joints, however, as it's an easier fix. I actually just shortened my 74 C20 and dropped off my drive shaft for shortening, new u-joints, and balancing. The u-joints definitely had not been replaced in my truck, so it was time.

[GOPAPA]

Originally Posted by 69Tom

Would that be the pinon bearing going bad, or did someone get in there and didn't shim it to correct specs? Not a bad thought though.

I'd definitely start with u-joints, however, as it's an easier fix. I actually just shortened my 74 C20 and dropped off my drive shafted for shortening, new u-joints, and balancing. The u-joints definitely had not been replaced in my truck, so it was time.

Just gone bad and by accident showed up at the same time as I was over hauling the tranny ,,and I had the drive line shortened and balanced too,,so it through me what the heck was causing the vibration ,,,

I jacked up the rear end and started the car and looked at the rear end while it was running and seen that it was vibrating at that point.

[Dead Parrot]

Tires getting warm and changing a bit. Especially if they are mixed set.
One set of brakes pads/shoes rubbing until they get hot.
Differential with not enough oil and getting warm after several miles.

Intermittent vibrations are a PITA.

[geezer#99]

I chased a vibration kinda like that on a 76 sb.
Did everything possible. New tires, rims, u-joints, balanced driveshaft, wheel bearings, steering box, all of the suspension parts. Everything I could think of.
I thought I had it fixed several times until I’d hit a bump or turn around in the street.
Turned out to be a cracked frame. Right by the steering box. Covered in grime and impossible to see.
Check your frame.

[jchav62]

Thanks guys! The diff oil is one of the first things I checked. It was full and looked pretty clean. I also went and bought new brake shoes for the rear... will be putting those in first chance I get... along with u-joints.

I just got a "new" steering box as well. That's on the 'to-do' list for this weekend. I will inspect the greasy frame when I do that. To me it feels like the vibration is in the rear, but you never know.

I'll post up my findings... if I ever find it.

[Corts60]

Hey glad to see you’re back!

Rear brakes my friend. One or both of the shoe sets is probably sticking when it heats up. Just went through this on my 86. Tool me a couple weeks to figure it out. Go run it until it acts up again and then jack up the rear end in neutral and hand spin the wheels to see which one is sticky. you’ll probably find the culprit right away.

[jchav62]

Originally Posted by Corts60

Hey glad to see you’re back!

Rear brakes my friend. One or both of the shoe sets is probably sticking when it heats up. Just went through this on my 86. Tool me a couple weeks to figure it out. Go run it until it acts up again and then jack up the rear end in neutral and hand spin the wheels to see which one is sticky. you’ll probably find the culprit right away.

Hey bud! I plan on getting out there this afternoon...hopefully. I have the new shoes. I hope that does it! I'm looking forward to driving the truck. She feels real solid for the most part. Thanks!

[Corts60]

Originally Posted by jchav62

Hey bud! I plan on getting out there this afternoon...hopefully. I have the new shoes. I hope that does it! I'm looking forward to driving the truck. She feels real solid for the most part. Thanks!

Let us know how it goes. Just FYI, my truck was doing this with brand new pads on. I never had that happen before on all my trucks. I guess I set the initial adjustment too tight.

[LT7A]

Good info here.

[jchav62]

I went to put in the new rear shoes.. upon removal of the left rear drum, the brake adjuster and related springs/parts all fell out! That was the problem... got the new stuff in and we're good to go!

Thanks all for the advice!! Have a great Thanksgiving...

[Corts60]

Originally Posted by jchav62

I went to put in the new rear shoes.. upon removal of the left rear drum, the brake adjuster and related springs/parts all fell out! That was the problem... got the new stuff in and we're good to go!

Thanks all for the advice!! Have a great Thanksgiving...

Ha! That’ll do it. Glad you got her all fixed up!