OK my 4 speed transmission went out on my 1986 f250. It has the 300 i6 in it and a new process 435 transmission. It is also a 4x4. Two questions I'd like to ask. How hard is it to swap out the transmission by myself and second if I can't fin another new process 435 what other transmissions would hook right up to it without a adaptor or having to find other parts?

 

Those transmissions are hard to break. What is wrong with it?

If you run the front up on some high ramps, and then have a floor jack and a piece of plywood to lay on the ground, you can probably do it yourself.

 

It started hissing on me and every now and then you would hear a loud sound like metal breaking or hitting other metal. It would also occasionally pull the truck hard to the right or just act like it didn't have power to move the truck even when your up to speed. All the noise is coming out of the transmission area for sure but also started to think maybe the transfer case was fried. Not a mechanic so not sure to be honest

 

I cant see and bad trany or even the transfer case a cause for the truck to pull to the right.
I would get the truck up in the air, all wheels off the ground and supported good and start checking things.


First would be the front axle more so the axle ujoints being bad and binding.


Then the front drive shaft ujoints being bad and binding and the slip joint for play and if it moves in and out as it should.


Transfer case put trany in neutral and the TF in 4x2 and turn the rear drive shaft checking for noises.
Now put in 4x4 and do the same, the front drive shaft should turn now.


Now for the trany it gets a little harder. I would put the TF in neutral and start the truck put the trany in gear. A gear you hear the noise the most and let it run get under and see if you hear anything.


If nothing put the TF in 4x2 and do the same just know the rear wheel will now be turning.
I would also put the TF in 4x4 and do the same thing but now the front & rear tires will be turning.
With it in 4x4 and front wheels turning turn the steering wheel left and righto see if the noise shows up.


BTW I had a bad ujoint on a front drive shaft on my 02 Durango that would only show up/bind when in 4x2 when making tight turns in a parking garage looking for a spot and would have put money on a bad front axle CV/ujoint.


Oh it never pulled to 1 side or other driving down the road.
Dave ----

 

I agree with the above. A np435 is virtually impossible to kill.

A month or so ago I had quite the ordeal. I was driving and heard a massive bang, followed by clunking then the truck jerking. I thought it was my np435. Turned out to have shattered the ring and pinion in the back.

I'd drain the tranny through a cloth or something and see if any metal comes out. Try the above suggestions, put it up on stands with all 4 wheels off the ground and start playing around with things to narrow down the problem.

Those np435s were used as heavy duty transmissions in vehicles much bigger than a pickup. Have a look on youtube, people are at sled pulls with modified cummins engines, and aren't even breaking them....

 

Are the hubs locked in? If they are, that slip joint in the front driveshaft can make a lot of noise if it's wore out from lack of grease. Sometimes the hubs can give you problems and it will not unlock properly, even though it's in the unlock position. You can jack each front wheel up and turn it by hand and look to see if any of the front axles are turning.

I too have also had them pull to the right or the left from a rusty/frozen front u-joint.

 

NEVER drive the truck on the street or anywhere with good traction in 4x4. It will bind up causing bad noises and pull from side to side until something breaks. Here's what I'd try in order:

1. Tranny in gear, Transfer case in 2wd, hubs unlocked. Turn the driveshaft by hand. If the front axles spin your hubs do unlock fine. Lock in one hub, turn the driveshaft. The locked axle will not spin, do again for the other side. This shows the hubs unlock/lock fine.

2. Put the transfer case in 4wd, make sure the front driveshaft is locked.

3. With the transfer case in neutral, run the engine and "drive the transmission" through all gears. Listen for anything weird.

4. Put the truck on 4 stands. Grab the front tires, one hand on the top on on the bottom, wiggle it checking for play. Do again one hand on each side, and on a 45. "Drive" the truck in the air using all gears and transfer case positions and listen for anything weird. Be careful.

5. Check the ujoints on the front axle shafts the best you can, I can see them somewhat but my truck is lifted... 3 joints in total. Check the driveshaft u joints for play/looseness side to side, up and down, and rotational play. Check the front and rear pinion for side to side play, there should be none (the part the driveshaft attaches to that goes in the axles.)

6. Check crossmember, tranny mount, and bellhousing bolts etc.

7. Drain the tranny through a cloth/fabric. Check for bad oil, or any metal pieces, very small shavings may be normal You may find a bunch on the drain plug if it is magnetic. Refill if it's fine. Do the same for the transfer case. A fluid change never hurts anyway.

8. Pull the rear diff cover, look for bad or excessively dirty oil, metal pieces, weird wear patterns, or damaged gears. If it's ok, clean the mating surfaces, apply good gasket maker, bolt the cover on and refill the diff. Hopefully the problem isn't deep in the front axle as they are a task to get apart and service.

I'm sure you will find something odd after all that........

Let us know how it goes. Good luck.

Jason