Zf5 Grinding

[Dummy99]

1986 F250 6.9idi

A couple weeks ago I finished swapping my 2wd C6 for a 4x4 zf5 with the Borg Warner 1356. Donor truck had a south bend solid flywheel in it so I had the flywheel resurfaced and bought new south bend clutch, pressure plate, and throw out bearing.

I replaced the syncros and resealed the ZF and resealed the transfer case as everything else looked fine to me. The shifter for the tcase is not installed as I haven’t cut a hole in the floor for it yet but the tcase shifter is held in 2wd with zip ties. Brand new master and slave cylinders with adjustable push rod.

My issue… I have a pretty loud grinding noise coming from the drivetrain when decelerating, this happens in every gear (Not sure about reverse I’ll try that after work). If I let off the throttle gradually, or quickly, until about 0 input the grinding starts until I give more throttle, this is especially bad in overdrive. Also more often then not when downshifting the noise is there when a gear is selected until I let out on the clutch and apply throttle. No noise in neutral.

I am a green driver, yes I swapped a manual trans into my truck not knowing how to drive stick

Any ideas on this one? I read somewhere it could be the planetary gears in the tcase but I’m not certain.

 

[franklin2]

Did you check the main shaft and countershaft end play specs when you tore into it? The way the gears are cut at a angle, they will shift to the rear or shift forward in the case when they get a pull or are decelerating. If there is too much end play, they move too much and cause problems. You may even hear it banging in the case if you blip the throttle on and off while in gear going down a level road.

 

[Dummy99]

I don’t recall there being much of any play but I’m not certain so that could be possible. I was able to find clearance specs but having trouble finding a play specs the service manual.

 

[beechkingd]

Dumb question but did you install a pilot bearing in the flywheel/crank shaft? Also, you installed a solid flywheel, they do make a loud/awful sounding rollover growl sound when there is little to no load at various rpms.

 

[YJMike92]

Did you replace the dual mass flywheel with a solid flywheel? If so you may be hearing transmission noise because of a flywheel swap. The transmission will be louder with a solid flywheel.

 

[Dummy99]

Yes I am using a solid flywheel and have never heard this growling noise before I did this swap. I did install a pilot bearing. Driving yesterday I was having trouble replicating this noise and wasn’t able to make it happen. I’m just going to keep driving on it and I’ll come back if I learn anything else.

 

[MtnHaul]

If the noise is most pronounced when RPMs are ~1300 or below then the sound is likely related to the solid flywheel. Cruising ~1900 RPM should be quiet, relatively speaking.

 

[Brody]

Is your driveshaft stretched to it's limits? I know when I did my ZF5 swap I had to have my driveshaft lengthened around 4 inches