Posted by Matt Wilson on Thursday, December 14, 2000 at 01:47:53:
Anyone here have experience rebuilding manual transmissions? Especially the old non-syncho, spur gear kind?
I have a '49 flat-fender 1-ton PW. I'm doing a complete rebuild of the tranny. The cluster gear and the 1st/2nd gear (a cast piece that contains both ratios) I received were pretty badly dinged up on the tooth surfaces, and had some rust (NOS parts). Most of this could not be seen, as the gears were coated with preservative.
The place that sold the parts to me gladly exchanged for some different parts. The next cluster gear I received looked way better, with only a couple of small indentations on a few teeth. This was under the preservative, so probably happened at the factory.
However, the next 1st/2nd gear I got is fairly dented on the tooth faces. The gear was really coated well with preservative, wrapped and came in a box that was stuffed with ads dating back to 1939. Judging by this, I have no doubt the scratches and dents were caused at the factory. Funny thing is, the rest of the gear is almost spotless. I wonder if the tool used to cut the teeth could have had some crud that caused the indentations, or if there was some kind of running-in procedure that contained trash and caused the damage.
Anyway, the people who sold me the parts had no way of knowing that the gears looked this way underneath all the cosmoline, so I don't hold it against them. My only concern is whether or not this would significantly reduce the life of the gears.
Since very little of the truck's life will be spent in either 1st or 2nd gear, my gut feeling is that I should install the parts as they are and not worry about it. But since I'm spending the time, money and effort to do this, a part of me wants the "perfect gear." Trouble is, I think it may be difficult to find anything better, if this is what the factory was putting out. I guess they didn't consider it a critical matter to have smooth gear tooth faces back then. Modern thought says indentations are places for pitting and spalling to start.
The indentations are random when it comes to direction and location. Some are in the middle of the tooth face, others are toward front edge, others are near the aft edge. Some lead radially away from the tooth root. Others are roughly the same direction as the tooth width. The lengths vary anywhere from a few thousandths to 1/4". Most of them are a few thousandths wide (probably about 0.010 - 0.015"), and about as deep. There are few that appear to be as much as 0.030" wide, and close to that in depth.
Has anyone else seen gears in this shape? Is this considered normal for this era of gear construction? If I intended to haul heavy loads in 1st or 2nd on off-road hills from now on, it might be an issue. But for my type of usage, as I said, chances are, this is probably not a problem, but I'd like to get some other input. I would send the gear back again, but I think the odds are slim that I will get anything better.
Thanks much,
Matt
P.S. I'm surprised the ads used in the packaging were dated 1939. I didn't know this tranny was made then. Does anyone know anything about other applications for this?
Also, even more interesting is the fact that the gears is stamped with the Ford script logo, plain as day. Why is this?