So I have a 79 f-250 4x4 with a 460 NP 435 tranny and np 205 'case, the tranny pops out of reverse and is starting to make bad noises (grinding) in first, I posted about this earlier, but figured nothing out. I allready made sure that the belhousing bolts were tight, and checked any others I could find while I was under there. this has gotten progressively worse since I got the truck, but only now has it become bad enough that I can't just hold it in gear. thanks in advance for any help.

 

You likely don't want to hear this but it sounds like it's time to pull the trans, unbolt the lid and have a look.Does it make noise in any other gears besides 1st and reverse?Are any other gears hard to shift into or out of?

 

it shifts PERFECT, it is obveously not just worn out, it shifts much better than my dads truck, which has the same tranny. I think first and reverse are the only ones that sound bad, more than usual for these trannys, since first and reverse are always a little noisy. How hard would it be to rebuild this thing? I've done all my own work on it so far, but wondering how in depth it is where would I get a kit?

 

Ther was another thread on these recently.I'm gonna go try and find it because I can't remember what forum it was under.As I stated in that thread NAPA can supply gaskets and bearings then another member posted a link to trans parts supplier.

 

They are a easy simple box to rebuild, go in without fear.
How does it sound (ear on the shift **** when at idle in neutral?
Sounds like crap they do.
The 308L bearing on the mainshaft next to 1st gear gets hammered do to the mismatch of tapered bearing and ball on same shaft.
There is a 11 ball vs 7 ball 57% stronger with my math.
Nylon pads in the shifter forks wear over time, less if the rings are polished like almost chrome.
With proper taper bearing clearance set check synchro spacing as there are shims you can add, go a little below minimum spec.
Input bearing clearance should be just detectable, too loose you have a milk truck loose box, too tight when everything inside expands which runs hotter than the case will bind up causing hard shifting.
If a high mileage box the cluster end shims might allow the cluster to have excessive end clearance.
New tight shifter top make shifting a pleasure.
Use a dummy shaft to hold the rollers inside the cluster, make sure the steel washers are in the right order inside the cluster.
If you have time take a dremel and dress the drive dogs and slider teeth allowing for smoother shifting plus dress reverse idler and that big 1st gear. You want more of a point on the side of these gears, this allows for less of a hard time going into reverse or 1st as those contact areas of time they are rounded down. Don't be crunching 1st and reverse you'll be good.
What oil to use depends on the climate you live in like morning temps.
Check the disc on the input shaft for wobble, new throwout bushing and lube it. Get a new pressure plate, even they are crap these days with thin basket material vs thick of years ago.
Check the fingers for looseness on all three after pressure plate is bolted up.
Long toothed here i'll stop now.