Hi,

I have a 1970 F-250 with a New Process 435 trans. The issues:

Shifts into 1st, 2nd and reverse just fine.

3rd gear engages, but the shifter doesn't feel like it goes in all the way.
4th gear won't engage and grinds every time I try shifting into it.
Sometimes the trans seems to get stuck in gear until I let the truck roll slightly, then it frees up.

No idea what the problem could be.

Thoughts?

Thanks for the help!

 

3rd and 4th are on the same shift fork and the same synchro. If this happened all of a sudden I would guess the shift fork and/or it's "shoes". If it's been steadilly getting worse I would guess the synchro and or it's blocking rings are worn out. You can take the top of the tranny off without removing the tranny from the truck. Put the tranny in neutral. 1st remove the cab's floor access panel over the tranny. Then remove the bolts that retain the tranny's top cover. Now grab on to the shifter and pull the assembly straight up. On the underside of the cover there will be the shift forks hanging there dripping gear oil. Now you can check the shift forks and the nylon shoes on them where they slide in to the synchros.

 

Will I see wear and tear on the forks and if so, is it a simple "swap-em-out" job to repair it? This would sure beat hunting for a replacement trans!

Thanks for your help

 

Maybe. If "banging gears" is what caused this you'll prolly find a bent or broken fork. You might check out you-tube. I would sure think there is a video on there about the NP435.

 

It might be easier and cheaper simply to replace the whole tranny. They are excellent transmissions but cheap as dirt...almost.
Eric

 

See parts catalog pic for numbers in bold.

7C430 NP435 4 speed has 2 nylon inserts (shoes) on 1/2 & 3/4 shift forks. These can crack apart, their pieces can fall into the gears jamming them up.

1/2 nylon inserts (D2TZ-7C430-B) different from 3/4 nylon inserts (C2TZ-7C430-B).

7220 (B8T-7220-D) NP435 435 spring (7227) loaded shift lever retainer cap has two notches, is retained to shift tower by two pins (7221).

To remove this cap, it must be pressed down and held down while turning it to remove it.

People unaware use pliers or channel locks to remove it, which tears out one or both of the notches. Now, they aren't going anywhere!

 

Know any good sources? I've tried Craigslist to no success and with ebay, I'm wary of anything I can't see in person or at least get from a trusted source.

 

Don't limit yourself to an NP435. There are several other trannies that will swap in easily and give you an upgrade. I have a T-19 from an '85 F350 diesel in mine, the only thing that I had to change was the front U-joint on the driveshaft, it was a perfect fit otherwise. Now I have all four fully synchronized gears with no granny low first gear (although the T-19 could be had either way) and the spacing between 3rd and 4th isn't such a huge jump. And the T-19 isn't the only option. There are a number of trannies originally installed in Ford trucks over the years that will easily bolt in, this should widen the field of your search quite a bit.

 

Thanks TigerDan. My weakness with old trucks is transmissions as in I don't know what swaps with what, how to tell, etc. I have an inline 300, so would I have to look for specific front ends on a replacement transmission? The more options for transmissions the better. Thanks for the help it's how I learn.

 

I'm not sure what the differences in input shafts were for the various applications, but I believe Fords were fairly standardized. I seem to recall having an input shaft length of 6-3/4", a diameter of 1-1/16 and 10 splines. I won't swear to those dimensions, it's been a while. I think your 300-6 transmission would have the same dimensions as my 360.

In my case I had the T-19 left over from installing a ZF 5-speed in the '85 and got to comparing it with another NP435 I had, and found that the overall length of the tranny, input shaft length and the splines were all the same so I went ahead and pulled the NP435 and installed the T19 in its' place. The only thing that was different was that the output shaft was larger and had a larger yoke on it. I went down to my local NAPA store with the u-joint dimensions and got a crossover u-joint with the two different dimensions on it.

 

2 X Tiger Dan. Looking up a 70 ish clutch for a pick up with a 300, Ford does not ask me which transmission. Just lists part numbers for the 11" disc and pressure plate. Looking up a clutch for a 1985 300,302,351W it does not ask which transmission. Only asks 10" or 11" clutch possible.

 

All this has my brain gears moving.

1. Would putting a C4 automatic in be a huge hassle? My truck has linkage for a column shifter (at some point someone put in a floor-mount shifter), so would putting in an automatic trans be difficult?

2. I have seen 300-6's mated to C4's, but what all would need modding to go from a manual to an auto? The more details the better.

Thanks for all of the help you guys.

 

On your shift rails check for broken roll pins. Also may be syncrhos worn out or weak blocker rings .

 

Best if you found a donor vehicle. Just off the top o' the ol' knoggin', you'll need A/T radiator,fan shroud,tranny cooling lines,flex plate,block/tranny serparator plate,torque convertor,C4,driveshaft,A/T steering column,re-wire for neutral safety switch and backups,tranny mount,steering column to tranny shift link.