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??

[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

[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.

[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?

[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....

[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.

[tdangle]

New update: Since the rear end is an open diff type, I raised one side off the ground and run it up to about 50 MPH per the speedo. I know the tire is running 2x as fast. Same vibration. if I drop the speed to 25 on the speedo, no vibration. So this leads me to driveshaft speed at 50 is when vibration starts. did the same thing with a factory steel wheel, no change. Tried the other side and same thing.

Took video of the drive shaft at the trans, carrier bearing and rear axle. Nothing looked out of place.

Rear end has a weird noise especially when slowing down during this test. I starting to think something is amiss with the Dana 60 rear end. Oh and incase if was missed in an earlier thread, driveshaft has been fully rebuilt and balanced twice, once when it was rebuilt and the other when it was shortened for my new trans.

[Accelo]

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

This statement eliminates the motor and transmission as they change speed and the vibration remains. Only transmission issue related this this would be the output shaft bushing. I am assuming it is tight, but would like to hear from you on this one.

I unbolted the driveshaft from the rear end and by hand turning the yoke took up all the slack or free play in the piñon gear

This is common, if you are referring to radial play, on an open differential. The spiders have slack. This is from the axial play between the spider gears. The only method to measure gear back-lash is to have the cover off and physically retain the pinion when measuring the ring gear at the outside diameter.

Things you may try;
Sounds like you have had two different sets of tires on the truck with the same results. Let’s assume it's not the tires. The axles have been touched upon. If you look closely at the outside diameter while they are on the jack stands and rotating you may be able to see any axial or radial run-out. Since the road force balance would identify this if it was in the tires or wheels any movement would be attributed to the axles. If you haven't rotated the front tires to the rear also try that. Check for radial & axial play in the axles by lifting up on the tires while the truck is supported off the ground by jack-stands on the axle.

I am assuming you also ran the truck up to speed with both the tires rotating, while it was on the jack stands. This should have reproduced the same vibration. If it didn’t, I would watch for run-out on the OD of the tires. With luck you may be able to tell the difference between driveline induced vibration and tire vibration. As the one frequency will be four times higher than the other. Tires are the usual suspect as they are a much heavier rotation mass.
Check the driveline U-joints are phased correctly. Typically, the spline is indexed so it is impossible to get incorrect but you have done you do-diligence on all the normal items this should be on the list.
If you still have the issue after all this work I would likely go after the differential bearings. Start with the differential. Sometimes the fit will denigrate and this causes looseness with out the rumbling associated with bearing noise.
Changing the 90W and looking for debris in the oil would be an easy first step. You could confirm the back lash at the same time.
Cheers

[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.

[tdangle]

Double checked index. Drive shop put yellow dots when balancing and I have in in correct. I did drain and install new fluid really should have taken my time and checked a few things while open. I’m suspecting play in the spider gears or shaft. Not sure how an axle could be bent as this is a full floating axle, but I will check it also
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