1993-940 Driveshaft's plastic laminated splines:

[84B23F]

So, there is some delamination, which means both driveshafts can not be connected together.

Remove "plastic" how?

thx

 

[MasterBlaster]

The who what where now?
I know not of these "plastic splines" of which you speak.
Be there photographic evidence of such strangeness?

 

[84B23F]

Be there photographic evidence of such strangeness?

I'll attempt to take a photograph today; a thin plastic-like laminate layer was laid over the steel splines. A file will get gummed up, so I tried a wired wheel on half of it last night.

Here's a photo of a splined shaft coated with something: Spicer Drivetrain Products Driveshaft Components 2-40-1701

 

[84B23F]

Be there photographic evidence of such strangeness?

This material is not clay, but a plastic/epoxy coating...I cleaned out all channels, etc.

 

[2manyturbos]

The who what where now?
I know not of these "plastic splines" of which you speak.
Be there photographic evidence of such strangeness?

I have seen what he is describing only on 7-9 driveshaft splines. I've never seen it torn up like it is on his splines.

 

[84B23F]

I've never seen it torn up like it is on his splines.

360k plus miles & 30 years old...U-Joints are fine [no zerks on them]...carrier bearing's grease had clay residue. One different bolt/nut on transmission flange.

U-Joints may have been replaced, transmission worked on, etc.

Separating shafts went smoothly, but they would not reinstall. Epoxy/plastic delaminated...all of it removed now.

 

[PCH]

I think if you remove the plastic coating the free play is going to create some problems.

 

[84B23F]

I think if you remove the plastic coating the free play is going to create some problems.

Dammed if you do, and dammed if you don't, but if one drives like Grandpa, there should be no issues.

Singular Problem - In time, spline slapping might cause some minor damage. Examine a transmission's end shaft, and rear end's input shaft on a 30 year old vehicle...they all have extra rotational play. Hence, where's the beef?

Footnote - There was black grease on splines when shaft was removed...don't know if OEM put grease on splines.

 

[2manyturbos]

Dammed if you do, and dammed if you don't, but if one drives like Grandpa, there should be no issues.

Singular Problem - In time, spline slapping might cause some minor damage. Examine a transmission's end shaft, and rear end's input shaft on a 30 year old vehicle...they all have extra rotational play. Hence, where's the beef?

Footnote - There was black grease on splines when shaft was removed...don't know if OEM put grease on splines.

They were greased at the factory. It was a black grease.

 

[culberro]

The spline coatings are pretty thick, and I'd only remove the flaking parts to ease insertion.
If you remove all of the coating, there's a very good chance that you'll have excessive driveline vibrations.

 

[84B23F]

The spline coatings are pretty thick...If you remove all of the coating, there's a very good chance that you'll have excessive driveline vibrations.

I believe centrifugal force is involved, which is different from an out of balanced shaft. The epoxy coating is a low mass substance that was evenly spread, so removing it would not affect shaft's balance. Water over the dam now...

"A commonly used demonstration of circular motion laws by physics teachers is spinning a bucket full of water in the vertical plane further explaining why the water did not spill out when the bucket was upside down"

 

[2manyturbos]

I believe centrifugal force is involved, which is different from an out of balanced shaft. The epoxy coating is a low mass substance that was evenly spread, so removing it would not affect shaft's balance. Water over the dam now...

"A commonly used demonstration of circular motion laws by physics teachers is spinning a bucket full of water in the vertical plane further explaining why the water did not spill out when the bucket was upside down"

It will be out of balance. You have allowed enough play for the yolk to move off of it's axis of rotation where it was balanced. It takes so little you would be surprised. With something that heavy .003" shift can result in one heck of a vibration. Don't be surprised if you end up with one hell of a harmonic vibration as that yolk goes through different frequencies. A physics teacher would bring up the parallel axis theorem when describing what the outcome of removing that coating will result in.

 

[culberro]

I believe centrifugal force is involved, which is different from an out of balanced shaft. The epoxy coating is a low mass substance that was evenly spread, so removing it would not affect shaft's balance. Water over the dam now...

"A commonly used demonstration of circular motion laws by physics teachers is spinning a bucket full of water in the vertical plane further explaining why the water did not spill out when the bucket was upside down"

Have you been around a well worn driveline slip from loose splines? You can easily wiggle the driveshaft 1/8"+ perpendicular to the DS axis, a little bit of spline slop creates for a large angular deflection between the inner and outer splines. That angular deflection is the amount the two halves of the driveline will be out of alignment.

 

[84B23F]

Have you been around a well worn driveline slip from loose splines?

I did not perceive slop....in regards to your question, I believe older heavy duty trucks with drive-shaft carrier bearings have been down this road.

Waiting on U-Joints.....I suspect those with older 7s/9s Volvos will have this issue...something screwed the coating

One possible solution - Wright Coating Technologies

 

[2manyturbos]

I did not perceive slop....in regards to your question, I believe older heavy duty trucks with drive-shaft carrier bearings have been down this road.

Waiting on U-Joints.....I suspect those with older 7s/9s Volvos will have this issue...something screwed the coating

One possible solution - Wright Coating Technologies

Even easier would be to just buy a good used driveshaft.

 

[84B23F]

A physics teacher would bring up...

Spinning top - While the spinning top may seem very simple, there is actually a lot of advanced physics and mathematics that go into making a top spin. The spinning tops illustrates several physics concepts including angular momentum, inertia, momentum, centripetal force, potential energy, kinetic energy, torque, friction and gravity.

 

[2manyturbos]

Perhaps, if the Physics teacher was describing rotational motion to children he/she would use a spinning top analogy. A driveshaft is much more complex than a spinning top as far as the forces acting on it. When it is no longer spinning on the axis through its center of mass really bad things happen. Especially, if it is not constrained, which is the case now that the coating has been removed.

Parallel axis theorem - Wikipedia

en.wikipedia.org

Parallel Axis Theorem

 

[84B23F]

Perhaps

There are heavy duty trucks have that sliding spline shaft setup, and on them there is a grease zerk.

Wright Coating has suggested, "Uncoated drive-line splines used on light duty pickup trucks and SUVs generated a clunking noise when the truck would start or stop. Applying a conventional fluidized bed nylon eliminated the noise by protecting the spline from corrosion while lubricating the surface."

In order to hear a "clunking" noise suggests spline slop, but apparently, some OEMs did not use nylon (which now I think Volvo did). I suppose that noise happens with higher mileage vehicles. I would suspect on semi-trucks, this slop also happens, especially when not greased.

Thus, use a heavy duty grease. I don't know if the rubber cap on one end could contain extra grease, but a little extra grease in the hollow end might be prudent. On CV shaft, I understand the grease re-circulates, but the rubber boot is secured with two clamps.