np 540-go

Wes · Post by **Wes** » Thu Apr 10, 2008 2:30 pm

Just found a 64 gmc 400 w/ 305c and a np 540-?? in it. I am wondering how well it will work in a high boy.Any one have any info ??

averagef250 · Post by **averagef250** » Thu Apr 10, 2008 2:52 pm

The 540's a real nice tranny. I like them a lot. Just like a 435, but much bigger bearings and a dream to work on.

If the 540 was overdrive it would be hot deal, but they aren't. The shift pattern is a little strange for a 5 speed and the ratios aren't necessary unless you're pulling big weight.

I rebuilt a Ford 540 last week and re-ratiod it and removed second gear to make it a 4 speed and added a ranger splitter in front of it all behind an isuzu 6BD1T in a 77 F-350.

averagef250 · Post by **averagef250** » Thu Apr 10, 2008 6:39 pm

I got to thinking how I might be wrong about the non-overdrive and I was. The 540 was made in an OD version, the 540-O, but they aren't very common and they didn't hold up well. The 540-O was a 540 with a different input-cluster ratio for a .82 overdrive. Apparently the larger diameter input gear puts about 18% more load on the input shaft which thends to snap them off behind engines with any real grunt. The downer is you can't buy NP540-O input shafts anymore.

If you found an NP540-O or just a 540 or 541 you can swap the guts directly into your NP435. I don't know how it would work, the top shift plates are different and AFAIK, Ford never used the 540-O, only GM and dodge so the 540-O's that are out there can't work with a Ford clutch.

Wes · Post by **Wes** » Fri Apr 11, 2008 2:57 am

Cool thanks for the info I saw that there was only 1 od unit listed out of @ 7 diff gear ratio combinations. This tranny has re builders tag on unfortunately the re builder went out of business. So I suppose it could be any ratio now.