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NP435 bearing question

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Old Dec 9, 2022 | 10:44 AM
  #1  
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Laughing Gas
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From: Lacey, WA
NP435 bearing question

Hi,

Truck is a 1970 F250 Highboy with a 390.... yes a 390 I built from the 360 when I purchased it.

So, about 10yrs ago I rebuilt the NP435 due to popping out of 3rd gear. Purchased an overhaul kit from Novak. Replaced all bearings, seals, and synchro's. Tranny has worked flawlessly for 22,000miles until recently I started to notice a bearing "howl". Makes zero noise in neutral or reverse with the clutch out. Just makes it in forward gears with 4th being the worst. To trouble shoot the issue I have removed the short drive shaft from between the Tranny and the transfer case. No change in noise so it's not a U-joint or the input bearing of the transfer case.

I'm guessing the output bearing on the main shaft. Question of the day is.... why would this bearing prematurely fail? I read somewhere that over torqueing the nut on the rear of the yoke may cause this.

Comments / suggestions are greatly appreciated.
 
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Old Dec 17, 2022 | 09:23 AM
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Laughing Gas
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From: Lacey, WA
Update: Pulled the tranny and removed the rear extension housing to access the rear main bearing. First thing I noticed is the extension housing bushing came out with the yoke. It was clearly spinning in it's bore. Supposed to be a press in fit. Pulled the bearing and it feels fine but, since I'm already into it going to replace it. Have ordered seals, gaskets, and the bearing.

 
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Old Dec 17, 2022 | 03:17 PM
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f5fordgirl
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A new bushing might not fit tight enough in the tail housing to stay there, might need a different housing.
 
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Old Dec 18, 2022 | 08:30 AM
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Agree, when the new bushing arrives I will test fit it. If it slides right in I am going to use some Loctite 609 Retaining Compound on it.
 
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Old Dec 27, 2022 | 07:48 AM
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UPDATE #2.

Received the replacement parts from Transmission Parts Distributors.. Output main shaft bearing, seals, extension housing bushing, and gaskets.

Test fit the new bushing in the extension housing and also on the yoke shaft.

Results: Original bushing is a little bid tighter in the housing, but loser on the yoke. New bushing is loser in the housing but tighter on the yoke.

Going to install new bushing in the extension housing using Loctite 620 Retaining Compound.
Top
 
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Old Dec 28, 2022 | 11:29 AM
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mark a.
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Originally Posted by lee
UPDATE #2.

Received the replacement parts from Transmission Parts Distributors.. Output main shaft bearing, seals, extension housing bushing, and gaskets.

Test fit the new bushing in the extension housing and also on the yoke shaft.

Results: Original bushing is a little bid tighter in the housing, but loser on the yoke. New bushing is loser in the housing but tighter on the yoke.

Going to install new bushing in the extension housing using Loctite 620 Retaining Compound.
Top
If there is a machine shop around you could get the bushing's od knurled.
 
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Old Jan 6, 2023 | 07:22 AM
  #7  
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Laughing Gas
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Update: Took the housing to my local Transmission shop. They knurled the bushing and the bore of the housing. Pressed in the bushing with Loctite added. Just have to put it all back together.
 
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Old Jan 7, 2023 | 06:03 AM
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Sounds like you have a solution and I honestly hope its the fix you need, that it doesn't require more attention anytime soon.
 
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