Rattlecan ZF5 at high rpm?!

[Rusgo]

Have a zf5 with single mass flywheel behind the 6.9 that makes a consistent rattling noise above 2500 Rpm. Sounds like high speed gear rollover/chatter. Definitely internal. Seems a bit better on warm days.

Transmission shifts great. No other noises or hiccups. It was rebuilt because of old syncros. Funny thing is it didnt rattle before the rebuild.

I'm thinking gear preload? Since setting it is so touchy.

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[79jasper]

What fluid you running?
Sounds like maybe the preload was set a little too far one way or the other.

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[Rusgo]

Fluid is the synthetic ford stuff it calls for. I did add some synthetic Mtf treatment to see if the sound would change. It stayed the same.

I've never heard of someone with issues from incorrect preload. Makes it tough to diagnose.

Would guess too loose of a preload.

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[79jasper]

That's what I mean. Just loose inside.

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[Rusgo]

Comprehensive troubleshooting guide for the ZF5.

Looks like my issue is either needle bearings or preload.

Since it was fine before, going with preload. Need to source some shims for it.

Gonna have to crack it open when I pull the engine. Fun!


https://www.google.com/url?sa=t&sou...FjAEegQICBAB&usg=AOvVaw0c51JPeDRqNXstd4YzAt6O

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[ClifFord]

Simplest things first. Lift the boot and see if there is anything loose that will rattle on the shifter, also look at the slave cylinder and linkage. I could be wrong but it seams that high rpm will make a solid noise, not a rattle. And at high gear, everything is quieter and you can hear road noise and other stuff better.

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[Garbage_Mechan]

My transfer case shifter lever does that above 2500 rpm due to pinion angle is off. Can you feel it in the shifter or transfer case shifter? Any chance you got the driveline out of phase on reassemble?

 

[Garbage_Mechan]

Preload applies less when trans is in 4th.... power glows straight through...countershaft and gears not loaded. Is it different in 4th? Unless mainshaft bearings are trash most bearing type noises go away cruising in 4th.

 

[Rusgo]

My transfer case shifter lever does that above 2500 rpm due to pinion angle is off. Can you feel it in the shifter or transfer case shifter? Any chance you got the driveline out of phase on reassemble?

Wow, you guys nailed it! It was the transfercase lever. Sounded like the transmission was going to shake itself apart, I grab and tilt the transfer case shifter and it goes away. Now baby quiet at high RPM. Never thought to check something so simple.

Dont think pinion angle would be off with factory suspension? No vibrations present. Might just be sloppy linkage or engagement mechanism?

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[Rusgo]

I just cant believe how quiet it is now. For a year I thought I bungled the rebuild.

3000 rpm and it sounds like a bat out of hell and not a bucket of bolts.

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[Rusgo]

Who has swapped an NP205 into the bull nose trucks? Anything to look out for? Thinking this will be a two birds type way to solve the rattle problem.

Junkyards have them all day long for $200 from late 70s ford trucks. What a steal.

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[IDIBRONCO]

For one, they are extremely heavy. You'd better build an extra support. I doubt that the aluminum piece that it bolts to would hold all that weight for very long. At least the remote mounted ones that I've seen had their own "crossmember" to hold them.