NP435 to Toploader swap idea

[can0fspam]

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.

[salans7]

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

[Rembrant]

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.

[can0fspam]

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.

[Rembrant]

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.

[Frank Wyatt]

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.