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Ok guys im building my nv4500 and the updated mainshaft uses the split 3 piece washer on the fifth gear but when i put the nut on the outer ring of the washer stays loose  is this normal or is there a spacific nut i need

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I just put on of  these in my truck last summer and i believe mine was the same way.  I think the outer washer is to keep the inner pieces from falling out if it gets loose.  It still keeps the gear from backing off because of the slotted shaft that the inner pieces fit into.   

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In 415k miles I've never had a 5th gear nut issue. 

  • Stock transmission never had a issues.
  • First Rebuild was with a upgraded main shaft and standard nut. The torque is pretty high like 550 Ft/lbs
  • Second rebuild again upgraded shaft and 5th gear towing never bothered it. Still going...

One of the big causes is the oversize tire puts a lot of stress on the 5th gear. Then the gear starts to rock on the splines. Being I've never ran oversized tires and been undersized the entire life of my truck I've never had one issue with 5th gear nut. Even with the current power level with 500 HP. Never came lose once.

 

Still running Mobil 50 SAE Gear Lube GL-4 Synthetic no issues with the lube oil either. I've had a few batches of defective syncros but that is it.

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I agree with you that oversized tires do make a big difference on drivetrain wear. I have only had the nut fail once and that was on the original transmission with 175000 miles.  Once i put the updated shaft in the nut itself never failed.  I stripped a couple teeth off the gear last summer.  i got lucky and they just fell into the bottom without damaging anything.  The guys at inland truck said they see that a lot.  You might be on to something with the undersized tires. 

 

Steven the guys over at torque king can probably answer any questions you might have.  Its a local shop for me so I always go and pick their brains they are pretty helpful.  They seem to be the NV 4500 experts, probably had one of the best mainshaft fix kits ever.  Not enough demand now so they quit making them. 

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Ok Ill try to contact them i picked this trans up from a guy  it was a 2wd and input bearing failed breaking teeth on the counter shaft im swaping it in my truck after im done it now has been changed to 4wd new larger input shaft and retainer nee counter shaft new updated mainshaft ne bearing including  needle bearings new syncros new 5th gear  and all going in a truck rarly tows more than a bass boat and is stock as far as power just want reliable  

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