NP435 to Toploader swap idea

Hello,

I have a 1983 F-150 with a 300-6, NP435 four speed, and NP208 transfer case.

Unfortunately, my NP435 is getting worn out. Third gear sounds like shopping cart wheels, first gear sounds a little harsh, and when I sit in neutral and let off the clutch I can hear a main bearing squealing away. The shifter needs a rebuild too. As much as I like the toughness and gear spread of the NP435, this one needs rebuilt or replaced before I manage to break something. I know the bad bearings aren't doing any favors for my gear teeth in the meantime.

With my 3:08 rear gears, I can manage highway driving without overdrive. The granny gear in the NP435 is nice for hill starts, but it's way too low to be practical 99% of the time. What would really make my truck more driveable is another gear within my usual speed range -- which makes me wonder if I could pull the NP435, and run a 4 speed toploader!

This seems feasible; the 3-speed manual available in these trucks is almost identical to an original 4-speed toploader -- except with only three gears inside the case. The SROD 4-speed overdrive is also closely related to a toploader and was optioned in trucks just like mine.

Here's what I'll have to consider:

>Will a toploader bolt up to my 300? Would I need to get its bellhousing or use my NP435 bell?

>Can I adapt a toploader to mate with my transfer case? The SROD is a modified toploader and was factory optioned with four-wheel drive, so it seems feasible. Can the toploader's tailshaft come off or be switched with whatever's at the end of a SROD?

>Transmission mount -- NP435 mount and crossmember compatible? Or would I need to pull a 3 speed or overdrive crossmember/mount?

>The driveshaft. I don't expect overall length to be the same. A SROD/4x4 truck's driveshaft might be the right length.


Obviously I have a lot of loose ends to tie up if I actually want to do this; this is a speculative idea.
Feel free to turn this into a discussion thread -- I'm just throwing ideas and seeing what sticks.

Thanks,
can0fspam.

The SROD uses a different style of shift lever for the transfer case, so you would definitely need that if you're serious about this swap. There's one available on Ebay right now:

https://www.ebay.com/itm/6586-1982-1983-FORD-F150-TRK-4X4-4-SPD-MAN-TRANS-W-OD-TRANSFER-CASE-SHIFTER/282650451716?hash=item41cf479f04:g:pwgAAOSwbdpWT~jj

can0fspam wrote

Feel free to turn this into a discussion thread -- I'm just throwing ideas and seeing what sticks.

Thanks,
can0fspam.

Not considering a 5spd at all? The ones from the 1988-1996 trucks are very easy to swap in, and everything pretty much bolts right up with little or no modifications.

I've thought about it before. Aren't you the guy who converted a 3.03 to a Mazda 5 speed?

I was considering a five speed, but I think I want to keep this truck more old school. It has a factory mechanical clutch and I know the firewalls in these trucks doesn't hold up to a master cylinder without reinforcement.

I also used to own a Ford Ranger with the Mazda 5 speed, and I had nothing but trouble with the internal hydraulic release bearing. The transmission itself was not all that bad -- I've heard of them lasting 250k+ miles in some cases -- but my experience with the hydraulic clutch setup kinda tarnished that box for me.

With my tall gears, I don't really need an overdrive anyways -- and I like the old school cool and simple toughness of a toploader.

can0fspam wrote

I've thought about it before. Aren't you the guy who converted a 3.03 to a Mazda 5 speed?

That would be me, yes. In my case the truck was already equipped with a hydraulic clutch, so it was an easier swap for me. My existing driveshaft fit as well as my existing speedo cable. I also have a 3.08 rear diff, so it's nice on the highway with the OD, and of course I still have 4th gear, so I can leave it there and get the same 1:1 ratio as a 4spd or a 3spd if I want to. To make mine look more old school, I grafted a curvy NP435 shifter stick on to a Mazda shifter socket, so the truck will look like a factory 4spd when it's all done. I personally haven't had any issues with the hydraulic clutch, but I don't drive the truck much either;).

If youre wanting to stick with the original mechanical clutch linkage then I get it. I was just curious if a 5spd was an option or not.

Carry on.

If it were me, I would stay with the NP435 or a the Borg & Warner T18 or T19 as th Ford top loaders would move the shifter over to the side so you would have to cut a new hole in the floor plate or getting a different one. A diesel NP435 would give you a higher 1st gear making it more usefull in your truck per your use.