Left-turn snapping noise - Ideas??

[v30crewcab]

dust shields bent and rubbing the rotor under turning stress?

[jdf915]

Have you checked tire clearance? See if there is anything hanging in the fender well.

[SkinnyG]

All the "easy fixes" are not it.

It's not the tires, it's not fender clearance, it's not wheel bearings, it's nothing that should be reasonably obvious. And boy howdy have I looked.

It's not a "tire rub" sound, it's more gawd-awful than that. It's like someone is feeding sheet metal into a fan. Very, very metallic.

Today, because I noticed that the right rear was sitting about an inch or two low, and suspecting that the springs got overloaded with an accidental 1700lb load of sand.....

So, good opportunity to investigate the leafs....


Pretty significant difference between the 2nd leafs. There were other minor variances in other leaves as well.


Re-shaping the leaf.


Reassembled, with a 3° shim for sorting out a driveline vibration.

I also swapped the leafs RIGHT to LEFT, just to see.

No difference with the sound, so I can safely say the entire rear suspension is not at fault. The 3° shim worked wonders with the driveline vibration though.

Figure this one: while it does happen while turning left (but not right), the noise is worse, and more frequent while going straight but in manual 2nd gear. Figure that one.

I've rebuilt two TH350's this past year, and I can't for the life of me figure what the heck could be wrong inside a transmission to cause that. Manual 2 applies a band, if I'm not mistaken, so a dying sprag should not be an issue. Wouldn't I notice a dying sprag?

[jdf915]

This is a long shot but... When your turning left turn off the motor and see if the sound stops, it could be that the anti slosh plate has come loose from the pan and is running into the crank when you turn left.

[SkinnyG]

Oooh. I hadn't thought of that.

I saw that the shield was intact when I rebuilt the motor.

That's a good long shot though, thank you!

[68c10owner]

Originally Posted by SkinnyG

Oooh. I hadn't thought of that.

I saw that the shield was intact when I rebuilt the motor.

That's a good long shot though, thank you!

Have you checked your brake pads yet? I mentioned it before but the sound you describe is exactly what mine was doing. The wear indicator on the left wheel would only hit the rotor when I turned left. I never would have thought that was it but replaced the pads and noise went away.

[SkinnyG]

The brakes were definitely not the cause. I put in new pads just to see.

Also swapped the rotors left-to-right. Nothing.

Absolutely, I can not find the problem.

And then Tuesday, the trans bit the green wiener, and here I am:



And incidentally, the parking pawl looks like it's been trying to engage park at speed. And there is no parking pawl return spring in there at all.

Houston? I think I found the problem.

I'll let you know when the trans is all rebuilt. This, gents, is the LAST part that has not been rebuilt on this truck.

[SkinnyG]

SOLVED!

It was DEFINITELY the missing Park Pawl spring.

Fresh trans, now, to boot!

[Axle]

Mark that one in the unexpected column.

Alex.