Hey everybody, need some help with the good ol’ NP435 4 speed out of my 1980 ranger

Just rebuilt it, brand new… almost everything.

1st through 3rd and reverse all work fantastic. Shift great, spin by hand nicely done it without any concerns.

But 4th gear is giving issues.

Shfiting into isn’t the problem, but after some spinning, it gets stiffer until it jams up by hand.

If i spin it backwards a little bit, i can continue spinning and then the problem happens again. Spinning opposite direction however creates zero issues????

Doing all of this in reverse logic creates that issue for 1st though 3rd.

Any ideas guys???

 

The clearance is too tight?
Shaft end clearance(s)
Does it go in and out of fourth okay right?
Look at putting a thinner select fit washer in it
I might have that trans overhaul procedure in a book
You can get it off AllData at your library
You need the spec and to measure it
Check all the clearances, both shafts, eyeball reverse idler clearance, should have a ton

 

It gos in and out of fourth nicely, engagement doesn't seem to be the problem.

Will have to recheck clearances i guess sadly --

 

Still trying to determine exactly what is happening when you say it binds up
You had all of the roller bearings out of it right?
And put them all back in using grease to hold them in place right?
So, now you put it in gear and rotate the input shaft
All is well until in fourth? right?

 

I shift the tranny into fourth (no problem) and when I spin the input shaft (make sure system spins freely).....

The input (or transmission itself i should say) starts to get tougher to spin over until the entire thing "binds up" -- I cant spin it anymore
If I spin the input shaft a small amount in reverse direction, then I can continue in the original direction but it will happen again
I can spin the input 1st through 3rd and reverse with no issues and none of this binding situation

I am pretty dang forsure im shifting into fourth and not reverse (watches as the output shaft spins in the appropiate direction)


All bearings been properly removed and replaced and lubricated, for certain i didnt miss anything like that.

 

Maybe post a video for us to watch
If the input bearing rollers get a flat spot, the bearing will act like a one way clutch and bind up
It could also be excessive bearing clearance, or something allowing the countershaft to move over and bind up the mainshaft
A lot of people just look at those bearings and never really measure anything (me included)
Maybe measure each roller for diameter and compare to new ones, make sure they roll easily on a flat surface

 

Heres a video!

I went 1st through 3rd then reverse, and 4th last.

Not all top cover plate bolts on since ive been diving deep once again.

Ive noticed that if 3rd gear likes to jump forward as i spin in 4th fast. If i hold it back. Everything spins okay???

 

So i have found something out.

As i spin 4th gear… 3rd creeps towards and pressures against the 4th gear syncro, causing the tranny to JAM!!

I remember the shimming process
i had to put in there at one time, would this have anything to do / fix it???

 

Possibly
Maybe take one out and re measure the clearance

 

Did some more shim adding and deleting.

less is definitely not the answer.

However, my best choice was at 5 total, which at one point it spun perfectly in 4th.

Then all of a sudden, the binding came back?!?!? Has to be something else