460 engine swap
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Trailering
Joined: Mar 2025
Posts: 17
Likes: 2
From: Virginia
460 engine swap
Hello, I have a 460 7.5L that I plan on putting in my 1985 F150. The f150 came stock with a 300i6 and a 4spd manual 4x4 transmission (it is an NP435 im guessing). I was luckily able to find a bellhousing to match the 460 to the original transmission 4 speed transmission. The Issue that I have come to realize is the stock transmission input shaft has a diameter of 1 1/16. The reason this is a problem is because the correct clutch size for the 460 flywheel is 12.25 with and is only made for input shafts of a 1 1/4 diameter so my input shaft is 1/8 to small.
I am not exactly sure what to do now so I am asking for help. I would like to keep it manual and 4x4.
Question:
- is it possible to replace the input shaft with one slightly larger?
- is there a transmission that would bolt up to my 460 that matches my crossmembers and driveshafts lengths?
or
I could buy a 4x4 zf5 to swap in but then I have to come up with fabricated crossmember and transmission mount to hold it in and also have to get custom driveshafts to match the length to each differential
I don't know much, i am a younger guy learning as i go. any and all help/ advice is appreciated. All the best. Dawson
I am not exactly sure what to do now so I am asking for help. I would like to keep it manual and 4x4.
Question:
- is it possible to replace the input shaft with one slightly larger?
- is there a transmission that would bolt up to my 460 that matches my crossmembers and driveshafts lengths?
or
I could buy a 4x4 zf5 to swap in but then I have to come up with fabricated crossmember and transmission mount to hold it in and also have to get custom driveshafts to match the length to each differential
I don't know much, i am a younger guy learning as i go. any and all help/ advice is appreciated. All the best. Dawson
Moderator
Joined: Jan 2001
Posts: 56,999
Likes: 2,747
From: Virginia
I looked up a 1985 f250 with a 460. I looked in the clutch section, ALL the clutch kits have 1 1/16 10 tooth shafts. You can get a 11 inch, or a 12 inch clutch, You are not looking at something correctly.
FTE Legend
Joined: Nov 2015
Posts: 30,948
Likes: 4,126
From: Angier, NC
I say that because I cant see BW T18 or NP435 making different transmissions for the 300 and then 302 / 351 and then 460 motors, that would be 3 different transmissions for each manf. and that would never happen.
Dave ----
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