55+ vibration - Help

[tdangle]

OK, I have searched and found lots of posts about vibration, most either fixed by something obvious or no solution found.

I have a C20 leaf springs dana 60 2 wheel drive long bed. GM performance crate motor (SP 350/357) with a newly built 7004R from Bow Tie Overdrives. 2 Piece drive shaft rebuilt, shortened and balanced by a drive line shop. 265/75R16 tires with aftermarket rims. New tires road force balanced. Operating u-joint angles .2,1.9,3.7 per spicer app calculations. Tire pressure 40 front, 45 back. New disc brakes up front, new drums in back. New front end rebuilt and alignment.

Vibration is same in 3rd or OD or neutral. Accelerating or decelerating no change.

Very smooth below 50 MPH. Braking is very smooth with no shutter. Mainly feel it in my stock bench seat, do not feel it in my feet on the floor, center rear view mirror shakes

Anyone have ideas

[tdangle]

forgot to add: 4.10 gears and fairly new shocks

[Getter-Done]

My first guess is the tires and rims.
Was it reputable place that balanced your tires?
And not afraid to say (Hey you got a bad tire or rim).

My second guess is a bad (New) rotor or drum.

[tutone]

I would look closely at the front wheel brgs even though you probably have new ones. The test would be to brake during the vibration. That will stabalize the brgs and transfer the load to the calipers. I had the exact thing going on with a late model gmc. When you jacked it up, you would have sworn it was fine. But that was the culprit.

[tdangle]

Originally Posted by tutone

I would look closely at the front wheel brgs even though you probably have new ones. The test would be to brake during the vibration. That will stabalize the brgs and transfer the load to the calipers. I had the exact thing going on with a late model gmc. When you jacked it up, you would have sworn it was fine. But that was the culprit.

Braking during the vibration does not affect it.

Yes front bearings are new and adjusted correctly.

[tdangle]

Originally Posted by Getter-Done

My first guess is the tires and rims.
Was it reputable place that balanced your tires?
And not afraid to say (Hey you got a bad tire or rim).

My second guess is a bad (New) rotor or drum.

Same rims, new tires. The old tires were rebalanced multiple times with little effect. The new tires were balanced poorly and the place I just took it to ripped the previous person who balanced the tires, They gave me how much each wheel tire assembly was off, and the load balance readings for the tires itself. Thats what road force balancing does. Also confirmed my rims are right on with no imbalance or out of round. After the rebalancing it did help some, but still have a vibration.

[tdangle]

I did notice something I thought was odd. I unbolted the driveshaft from the rear end and by hand turning the yoke took up all the slack or freeplay in the piñon gear to ring gear and if I tried to continue to turn it (sitting on the ground with parking brake set I could hear and feel a slight clunk coming from inside the housing holding the gear set. Normal??

[Steeveedee]

Originally Posted by tdangle

I did notice something I thought was odd. I unbolted the driveshaft from the rear end and by hand turning the yoke took up all the slack or freeplay in the piñon gear to ring gear and if I tried to continue to turn it (sitting on the ground with parking brake set I could hear and feel a slight clunk coming from inside the housing holding the gear set. Normal??

I'd have to hear it, but pretty much I would not expect a noise in this situation. Backlash would be the suspect. If you can, pop the cover off the diff and give us some photos.

[BlackZ]

At that speed, since you eliminated engine rpm and transmission gear selection, the only two things it could be is your driveline or tires. Have them rebalance the driveshaft, I've had brand new shafts come out wrong before.

[tutone]

I know this sounds like a dumb question, but when the vibration starts, and your mirror begins to shake, does the frequency increase with speed? The rear end has a small amount of play built in, so without pulling the cover and looking for issues in the housing, it's just a guess. One more cheap thing to try is to get a good tire and wheel and put it on each corner an drive it 4 times. You could have a perfectly balanced set of tires with one bad belt in one of them and that would do it to. Good luck

[Richard]

Do not understand your stated operating angles? As I see it nothing is even close to being in spec? Does not seem right. Think you need to put some time into investigating operating angles for two piece drive shafts.

[duallyjams]

I had a vibration problem with my truck.

If you feel it in the seat the vibration is coming from the rear. If possible try rotating the tires to see if the problem follows the tire.

I tried every type of tire balancing there is, static, road force, balance beads, nothing corrected the problem, all it did was change the speed the vibration started. The only thing that help was putting 800lbs in the bed of the truck. The belts in the tires were causing the vibration.

If possible see if any friend has a set of wheels and ties that you can barrow to eliminate the tires from the problem.

I put on new wheels and tires and now my truck is smooth from 0 to 80 mph.

[Bigdav160]

At that speed it is wheel/tire related

[Davidf]

I chased a vibration for a while thinking it was center support bearing. Turns out it was a loose pinion yoke and worn u-joint locating tab that allowed the u-joint to slid back and forth on the yoke. Tightened up the pinion nut and built up the tab with weld and machined for a tight fit. Now I have a vibration around 65 that seems front end related…so?

[BigBird05]

Although very rare, I have seen a bent axle shaft cause a rear end vibration.

[72c20customcamper]

Did the shaft come apart at any time prior to install?

[jimijam00]

Originally Posted by BigBird05

Although very rare, I have seen a bent axle shaft cause a rear end vibration.

Happened to me on another vehicle. Most over look this.

[Seanext]

Driveshaft should have been balanced together. It should have been marked by the shop that balanced it so it could be clocked back to the same position that it was balanced in. If it was taken apart and not put back correctly that could cause the vibration

[Grumpy old man]

I started noticing a vibration at 55+ at 57 + it turned into a creaking sound ,Now at 60 + it's just a limp ...

[diggerbob]

I chased a rear end vibration on my 1970 c-10 shortbed for years. It came in at 62 mph and subsided somewhat at 64. Over the years, this vibration caused me to make quite a few changes. I got new tires and rally wheels; a new 700R trans along with a new aluminum driveshaft; dialed in the required operating angles for rear pinion and trans output shaft; rebuilt the rear end (I needed positraction anyway) - along with a new pinion shaft. After doing all of the above, the vibration was still there. By this time, several years had gone by and my tires were dry rotted so I ordered some new ones and while I was at it, I had some new rally wheels made. This time around, I had them made by Wheelsmith because of their reputation for making a superior wheel. The tire shop told me that the new wheels and tires balanced easily on their Hunter Roadforce balancing machines.

I left the tire shop and went straight to the highway. It got to 62 and was nice and smooth so I took it on up to 80 and it rolled nice and smooth all the way. Eureka!!!

When I got my first set of rally wheels (from a well known manufacturer), the tire shop pointed out to me that the lateral runout on a couple of them were as much as 0.041" so they put them on the rear. The better pair of wheels went on the front. I tried to get a better pair of wheels (from the same manufacturer) for the rear and in doing so, I managed to get a pair in which the maximum rear wheel runout was 0.029". Nonetheless, I couldn't find a tire store who could do a roadforce balance on any of these wheels. When I got my newest set of rally wheels from Wheelsmith, they told me that they wont ship a wheel with more than 0.02" of lateral runout. They also machine the mating surface of each finished wheel where it mates to the hub. The guy at the tire store said that they had no issues doing a roadforce balance on my new tires and wheels. It certainly made a difference in the way my truck rolls down the highway. My new Wheelsmith wheels are beautiful to look at too.

One last thought: These old C-10's don't have their rear shocks mounted vertically enough to work as effectively as they should. Besides making them a little rough riding in the rear, I think that this also makes them less able to dampen vibration due to imbalance in the rear wheels and rims. Although my truck is at factory ride height, I am thinking about getting a shock relocation kit from No Limit Company which is designed to bring the shocks to a more vertical orientation. I understand that this kit will smooth out bumps in the road much better and if that is true, I would suspect that it might help to smooth out any imbalance induced vibration coming from components bolted to your rear end as well. I'll be interested to see what the experts think....

['68OrangeSunshine]

Originally Posted by Grumpy old man

I started noticing a vibration at 55+ at 57 + it turned into a creaking sound ,Now at 60 + it's just a limp ...

They say whiskey is good for that.

[HO455]

I had a lot of NVH in my Burban when I first got it running. A rebuilt drive shaft with an aftermarket carrier bearing took care of about half of it. The rest was coming from the rear end.

In the end we found the posi carrier case and the spider gears were disintegrating. (Photo below) In addition one axle had had a bearing fail at some point and it had a speedi-sleeve installed over the bad spot on the axle.

Fortunately I got it fixed before the ring and pinion or the housing were damaged.

As previously mentioned it would be worthwhile to pull the cover off for an inspection. Personally I would pull the axles and inspect the bearings at that point for peace of mind.

Good luck and please keep us in the loop.

[Moore87]

Did you install the 2 piece shaft in the correct phase?

[Richard]

FWIU ideal for two piece is your front shaft should match the trans angle within 1 degree to keep u-joint working angle at trans almost non-existant. Middle u-joint after carrier and pinion u-joint should have same working angle within 1 degree. The angles should match to cancel out. Have no idea what your trans angle is. The working angles are what matter not the trans, driveshaft and pinion. Those angles just determine the working angles.
Maybe I am totally off here, but as I see it three different angles will most likely cause a vibration. One operating angle needs to be 1 degree or less and the other two need to be within 1 degree. You have two angles that are close and one at almost 4 degrees.

[tdangle]

As far as the working angles of the u-joints are concerned, I removed the shim I put in to lower the center carrier support and it's all as it came from the factory now. Stock ride height. No change in the vibration. Still fighting it. Wish I had access to 2 stock steel rimmed tire assemblies. I would love to bolt them on and see if there is a difference, once and for all eliminating tire & wheels.