Dana 18 Gear Set Questions

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My father-in-law is a machinist and generally they won't touch it once they know the hardness. If someone is already setup and experienced with this process than there is no reason for a professional to take the risk.

 

I'm no machinist but I would take those instructions to simply mean make sure you are machining the new cuts in precisely line with the original bore. This should be obvious. Maybe it means to make sure the bore isn't worn or damaged or something.

I may have an extra an extra gear or two if you need them for practice. Let me know and I'll look to see what I have.

 

Thanks a lot man! I'm no machinist either, but I think you're right.

Well I cleaned all the gears that i hope to replace from Debella. They are all worn, have some pieces of gear missing, corrosion etc... What I now understand is that the ID of the intermediate gear is the race for the shaft bearing and wears out no matter the hardening. Once the intermediate bearings go bad there is already wear of the other half of the bearing assembly. So, when you get the Novak shaft or whatever, the roller bearings and spacers, you're just throwing new parts at wore out junk.

To that end, what AA states as making sure the bore of the intermediate gear is concentric from one side to the other is that the internal gear wear may be great enough to throw off your ID centering on your boring jig enough to make one side a couple thousandths off from the other.

This may be why the guy with the video of cutting the ID of the intermediate gear is doing it on a lathe in a special made jig. He doesn't need to find the center to bore it when he turns it over to cut the other ID. His process ensure that no matter the wear, it should be concentric one side to the other.

My intermediate gear is in poor condition and even though I rebuilt it with new Novak stuff, it can't fix wore out junk.

To that end, in my opinion, the quality of the hardening for the intermediate shafts may be less of a factor than has been stated. The intermediate gear may have been worn enough internally to cause premature failure of the new parts. The bearing clearances or even the roundness of the ID of the intermediate gear may be suspect.

 

It can be done....

 

Yeah, that's what i am referring to. Im going to try this on my mill, as I have a boring head. I also have a 13 or 14" chuck for my lathe, but no soft jaws. See how this works out.

 

The guy in the video is hoping that the gears are concentric from one end to the other, they are not. I have machined several that were off center from each end by about .010". By measuring the teeth with a boring head you can sort of make them closer. He has no option for that with his soft jaws, if the teeth are wore any he is screwed beyond belief. While he has some knowledge of what he is doing (not trying to be mean here) he is at best an amateur machinist. You are gonna crap when you realize how hard these gears are.

If you want soft jaws make them, I never buy them. I simply make them out of aluminum or mild steel. Bolt them on your lathe chuck and true them up.

 

in my 15 years on this forum this is the best line I've ever read.

Mike what is the going rate to expect to get this work done by someone? I don't think a 7" southbend is gonna do this for me.
Thank you!

 

My expeience is that you will wear out 2 or 3 1 1/4" shafts before the inner bore of the intermediate gear is too worn, but this can vary if you just keep running it with a flat-spotted shaft and all the rollers ground up. By then, , the thrust washers can't control the "twist" of the gear in the case. When this happens, the gear mesh gets chewed up, wearing the teeth both gears meshed with the intermediate gear.
If reusing an intermediate gear, examine the edge of the gear teeth to see if there are sharp edges, indicating the gear may have run cocked slightly sideways in worn thrust washers.
Hey Mcruff, have you ever tried grinding through most of the surface hardening with something like a toolpost grinder?
-Donny

 

I charge $65 to machine the gears plus return shipping. I would guess most shops that might take this would charge 2hrs labor plus set up since they don’t or haven’t done one before. So figure around $240. I’m cheap because I do it for Jeep and play money and I already know what to expect. I have a 9” Soutbend lathe and I normally wouldn’t do it on my lathe. I might make another set of soft jaws and try one though, just to see, especially if it already checks concentric from end to end.

I don’t have a toolpost grinder, so no I haven’t tried that. These gears are case hardened about .050” deep, that’s a lot of grinding on a toolpost grinder. That guy took lite cuts on his lathe. I usually take .030” passes with my boring head. I have also played with the shape of my carbide to make it cut better.

 

Received my gears from DeBella. They are all NOS. some in Seal Tested boxes, one has a dana gear inside, the other just stamped made in USA. The shaft came from London Ontario and looks to be Canadian surplus. The intermediate gear is NOS, Made in USA and has a stamp on it ion 2 V's on top of each other so it looks like WM. There is some slight surface flash rust on some of the parts not wrapped in anti rust paper/foil or cosmolone.

I even got new shift forks.

I did not buy a new case, bearing retainers, bull gear or shift shafts. I even got gaskets that seem to be made in USA.

640.00 and change to my door. Im pretty pleased so far.