New Drivetrain Vibration...?

[smitty3500]

Truck as stated in my sig has 66k on it. Just installed Con OFE 500 Miles ago. Once installed and back on the road I now have a slight vibration from 65 - 72mph. No vibration before or after those speeds.



I can depress clutch and put it nuetral and let coast. Vibration is still present... hence ruling out anything to do with clutch and flywheel. I would think this is driveshaft related?



Learn me Drivesaft tech. What should I start off doing or replacing to try to get rid of this small vibration. It is not tire balance. Already tried that. Does the driveshaft need to be re-balanced after being taken off the truck? U joints look fine... . but... . ? Center driveshaft support?



Just looking for some pointers/thoughts.

 

[Slow Six]

If you have not changed U joints yet they would be suspect. They will look good but they can be toast. The main problem with the joints is they are dry. Do a search on here about U joints as there are many posts on the topic.

 

[SierraRam]

Do you have a lift on your truck?

 

[smitty3500]

Do you have a lift on your truck?

I do not. Suspension is stock except for Bilsteins.

 

[05mxdiesel]

When my first u-joint went out, I had a vibration at 20mph or under. Replaced all three u-joints and the middle one was the culprit. I'd start by removing the front driveshaft and see if the vibration goes away. Then go from there since it is at a much higher speed.

There was a lot of complaints when the 3rd gen came out about the 70mph vibration and most of them were from the front driveshaft.

 

[leaky gasket]

Just a thought that may or may not work you might want to take your drive shaft and rotate it 180° on the yoke and see if that makes a difference.

 

[Vetteguy70]

Rotating the driveshaft 180 is work not needed. Shaft is independantly balanced, off the motor, and out of the transmission, so it wouldn't make a difference if it was put in the tail shaft in a different position. ((Unless the balance weight is gone. Spot welded on usually))

U-joints are suspect as usual since none of stock joints can be greased. Sealed factory units. I had to replace ALL of them in my 03 within a year due to Upstate N. Y. Winters. I did NOT drive it harsh, 4x4 off road, or anything 'hard'.

HOWEVER: Depressing the clutch at speed, in neutral does NOT rule out a balance issue on the flywheel or clutch. They are STILL a centrifugal mass, rotating at high rpm. If the flywheel was not put on with the counterbalance in the correct position, then you have an issue! Regardless of U-joint problems. The flywheel and clutch assembly, pressure plate etc. are still rotating, and will STILL cause vibration to be felt IF that is an issue.

I don't know what the "Con OFE" is that you refer to, but surmise it may be clutch related from the rest of your post words. Just a heads up that depressing the clutch and going to neutral does NOT rule out vibration coming from there.

You said "500 miles ago". Does that mean the problem has occured SINCE 500 miles have passed since the work was done? IF so, then it may not be related to the work, which makes the U-joints more suspect by process of eliminating WHEN the vibration started to be noticeable. Even though tires and etc have been balanced recently, CHECK to see that the weights are STILL on the tires/rims. Glue ons fall off. Hammer ons fall off, and sometimes slide. Even after you JUST had it balanced. Pot holes, curbs, you name it. If it's mag wheels, glue ons are FAMOUS for not being prepped correctly and falling off. 70mph is famously the RPM for tires to throw weights.

Hope this helps.

STEVE

 

[smitty3500]

CON OFE is a Clutch made by SouthBend. If traveling at 68mph and depressing the clutch and putting the trans in nuetral the vibration is exactly the same. That does rule out the flywheel or clutch b/c the rotational mass of the two is very much changing from 2100 RPM down to Idle. The vibration is the Same. If related to the clutch/flywheel the vibration would change with RPM.



This is deff driveline related.

 

[cbmkr]

U-Joints Bad

Joints are where to look mine was the same,I had a spicer wharehouse and driveline shop for about 10 years and new it when the vib first appeared. rear was first @44K followed by middle @ 53K. front @53K.

Dealer did first one out of warranty but covered it anyway ,I have done the rest myself.

Use a good Hd joint with a Zerk and use good Grease ( amsoil is my Choice).

If you have the plastic insert joints you might want to have your shaft balanced after the new joints are installed. ( the assembly procedure for the plastic injected joints has something to be desired as being most of the shafts are not round after setup and require a lot of weight to Balance. Thus installing a new joint with clips will make the shaft run true and be out of balance.

 

[sag2]

If the vibration was not there before you removed the shaft, before you spend any money, re-index the rear of the shaft first and see if it helps. Most likely you have a flange that only can be bolted up two ways. The best method is to measure the run out of the shaft with a dial indicator. I like to see them less than . 007 at the ends. The shaft may be balanced, but any assembled run out at the flange joint in the rear or yoke in the front will cause a vibration because the shaft is not spinning true. The spec should be . 015-. 020 but from my experience that is too much. less is always better.

For anyone that has not removed their shaft yet, it is always a good idea to mark the flange so it can be assembled back the same way it came out. Although if you're changing the joints it is not as critical a step.

 

[Vetteguy70]

If the vibration was not there before you removed the shaft, before you spend any money, re-index the rear of the shaft first and see if it helps. Most likely you have a flange that only can be bolted up two ways. The best method is to measure the run out of the shaft with a dial indicator. I like to see them less than . 007 at the ends. The shaft may be balanced, but any assembled run out at the flange joint in the rear or yoke in the front will cause a vibration because the shaft is not spinning true. The spec should be . 015-. 020 but from my experience that is too much. less is always better.

For anyone that has not removed their shaft yet, it is always a good idea to mark the flange so it can be assembled back the same way it came out. Although if you're changing the joints it is not as critical a step.

BINGO! You hit it on the head. The shaft WaS taken out when I replaced the clutch. There was a question in my log book about the center "carrier" because it appeared to be tweaked a little (manufactured that way) and I didn't realize it could only go in one way, otherwise, it would throw off the rotation by a few milimeters. WHICH IS HUGE at high speed, and vibration goes nuts from there. SECONDLY, the rear tail shaft mount was BROKEN< and the rubber torn. So, between the vibration, U-Joint being frozen, (center) and the vibration, it was actually rotating so badly that it was LIFTING the tail shaft, and rotation was opening up the rear seal and dumping trans gear fluid! What a mess under there. I found THAT problem when it started hitting hot exhaust. Good thing we didn't have a fire. Just a lot of smelly smoke.



SO: I think we have the problem solved. THANK YOU EVERYONE! It's been a long thread, but it goes back to my "intel days"... ... "It's the little things in life that come back to bite you harder!" Thanks again for everyone who helped.

Steve

 

[Vetteguy70]

CON OFE is a Clutch made by SouthBend. If traveling at 68mph and depressing the clutch and putting the trans in nuetral the vibration is exactly the same. That does rule out the flywheel or clutch b/c the rotational mass of the two is very much changing from 2100 RPM down to Idle. The vibration is the Same. If related to the clutch/flywheel the vibration would change with RPM.



This is deff driveline related.

Got it..... THanks for the info!

Steve

 

[Vetteguy70]

Joints are where to look mine was the same,I had a spicer wharehouse and driveline shop for about 10 years and new it when the vib first appeared. rear was first @44K followed by middle @ 53K. front @53K.

Dealer did first one out of warranty but covered it anyway ,I have done the rest myself.

Use a good Hd joint with a Zerk and use good Grease ( amsoil is my Choice).

If you have the plastic insert joints you might want to have your shaft balanced after the new joints are installed. ( the assembly procedure for the plastic injected joints has something to be desired as being most of the shafts are not round after setup and require a lot of weight to Balance. Thus installing a new joint with clips will make the shaft run true and be out of balance.

I had to do the fronts at 20K or there abouts. Did some others, (can't remember which ones) at 40K, but the dealer told me it was because it was so cold out and I was using 4 wheel drive to plow out driveway. (24 below zero F, 1500 ft driveway with eight feet of snow plus) Even though it was straight line driving, I never thought it was the cold that broke them. Maybe cause the grease got thick, and there was no way to re-grease them? Anyway, I have new joints to put in. So, thanks for the input. I have always wondered WHY they would put Ujoints on something that can't be lubed... ... . and no way to drill, tap and add zerks.

I feel much better knowing I can do this now, and things are not going to keep going down the same road.

Later

Steve