Manual trans experts, look at my gears please

I'm putting a used transmission into my 63 truck. It's an NP435 GM trans from a 69 truck. The truck was a driver before the trans was pulled, but I have no idea of how well it shifted. I popped the lid off to look at it before I installed it and there are two things I see in there that worry me.

1) This gear, I think it is second gear. Should the edges of the teeth be rounded over like this ? And if not, do I need to disassemble the trans and put a new gear in it or is this one still good enough to run ?




2) This is the reverse shift fork. It looks pretty tore up to me. Does this need replacing too ?





I figure if I need to change the gear, I will go ahead and get a rebuild kit and do the bearings and such at the same time, but then I will have 300-400 dollars tied up in this old gearbox. I have no problem with disassembly and pressing and replacing snap rings, gears and bearings and whatnot that come with the rebuild kit, but when it comes to the gear wear, I just don't know what is good enough to run and what really needs to be changed.

I'd sure appreciate some input here from guys who have built this kind of stuff before.

 

I'm no expert but it doesn't look too bad to me. As far as the wear on the teeth I've put much worse back together and had no problems at all. The engaging ends of the teeth are usually beveled so your rounded off is not that far from spec. Also doesn't look like much wear on the face of the teeth either.

On the shift fork it's hard to tell from the pic on what is wear and what was originally machined. Looking at the first pic of the shift fork from right to left, is that first large step machined into it or is it wear (looks machined)? Then the second smaller step (top corner) looks like wear but it is uneven. I would think that wear should be more concentric about the radius end (like the bottom pic is).

In general, if the shift fork is worn excessively the gears will not mesh completely and it will cause it to pop out of gear and also accelerate the rounding off of the teeth.

Do you have a zoomed out pic of the trans case so we can see more of an overall on the shafts and gears? Also some more pics on the shift fork?

 

that's reverse, not second. your forward direction gears are helical. a lot of heavy duty applications use a straight cut reverse gear. it's all chewed up like that from engaging the reverse idler gear. probably not a problem as you don't use reverse as often as your forward direction gears. might grind but make sure you're not moving forward when you go to put it into reverse.

 

In a NP435 that sliding gear is First and Reverse. Somebody was grinding it, probably trying to shift while moving. The gear slides back to mesh with the counter shaft for first. The reverse idler slides forward to engage that gear and the countershaft for reverse.

I'm not an expert on how good it will still work. Price a new gear and see if its worth changing before you go through the trouble of installing the trans.

 

Fellas, thanks for the great replies so far. After studying it awhile, I had decided it was the first/ reverse gear like ya'll said. My buddy who is very much more experienced than me in this area agreed that it seems runnable in this condition as it wasn't synchronized anyway, it's pretty typical.

Now, the reverse shift fork is pretty pricy and not a real easy change. I have to drive out some soft plugs and roll pins and the shaft to change it. It cost about 70 dollars for the part.

The one side seems to be machined originally. The other side was the troubling side to me. There seems to be a notch worn into it. I've got an idea to clean it real well, weld up the notch and machine it back to original shape. I figure with a nice weld and some quality file work I could make it shape up pretty decent. Does this seem like a good plan ?

 

The low/reverse slide won't give you any trouble. If the wear on the fork bothers you, weld the worn spots & file back to original thickness, then heat it up with a torch til cherry red & throw it in a bucket of used oil ... no sense putting $300 in a trans that's selling for $75-$100 in wrecking yards.

 

Fellas, I can't thank you enough for your time answering these questions. If any of you are going to the drags, find me and I will buy each of you a cold drink.

 

If you guys come to St.Thomas, Ill by all of you a drink. Down here boose is cheeper then coke or pepsi so when you order a drink they rip you off and load it with rum and hardly any coke. LOL Ice man