SOT: Question for the REAL gearheads!! (VW Jetta Gearbox)

[robspeed]

im finally putting the Jetta back together, and am fooling with the throwout bearing cover, etc, changing the bearing and the cover. Anyways, i notice just inside there, that there is PART OF A GEARTOOTH laying there, being *really* annoying. I pinch it out with a needlenoze, and decide to pull the fifth gear cover to see if its the fifth gear. It has to be a fairly fine gear because the tooth is pretty small. Anyways, i take the cover off, and sure enough, one of the two gears in there is missing part of the tooth. My question is this:

This is a pretty low overdrive (numerically .75), and the car is a relatively peaky VW 16v, so the only time its going to be in fifth is in total cruise mode. It will always be necessary to downshift to pass or put any load on it. SO, do you all think i could just put the cover back on, fill it with MTL and just drive on? Im fairly certain I got all the loose pieces out. Its about $240 for a new fifth gear(set),,,,, as you can see in the pic there is a curious "DIMPLING" on each of the teeth, probably damage from the loose bits when they were still loose.... i think that score mark on the gear was a loose bit caught between it and the case.... im betting you all are going to say bite it and buy the new gears... :/

(For those that dont know/remember, this is the $450 ebay tranny supposedly rebuilt and with that extra-low overdrive "upgrade"... )

[Guest Anonymous]

Sorry to say it but it looks like about 60% of that tooth is missing. I would definatly replace it. If it was just a corner it would probably be OK.

[f1reverb]

at some point, you can run it. Something isn't aligned right for the edges of those teeth to be scored, or someone did a bad thing when shifting. I just put in a new (used) diff in my 533i, and when I took the diff cover off to switch it to the newer diff (mounting point different for the rear diff mount) I find a pin sitting on the bottom of the case. Not broken but scored slightly, so I'm sure that when this pin fell out it led to whatever failed in the old unit. I drove it humming and vibrating for years so I knew it would fail at some point. Also, the speedo sensor in the diff cover, being magnetic, had tons of filings on the old diff, so whenever that pin fell out it led to metal getting scraped off somewhere. I do have to say that the new diff is fantastic, and my 5er finally feels right after 4.5 years of ownership. It shifts a hell of a lot better too as the rubber mount was broken as well, so I replaced that (cost as much as the whole diff, fifty bucks).

[jerry]

only my opinion. it looks like it initiated at the root of the tooth at the corner. it looks like the surface finish quality is poor on the edge of the gear with what appears to be several tool marks. you'll get just as much information by looking at the mating gear for evidence of uneven witness marks or what is referred to as spalls (small material breakout on the loaded surface).

i don't see any spalls from your photo, but my judgement is limited by the clarity of the photo. it appears that you just happen to have 'dumb-luck'. as this is not a single engine helicopter or airplane, drive with it. you'll probably hear a whine, but it's worth a try.

[robspeed]

anybody think i should pull the gears *JUST* to polish the sides? seems stupid without actually swapping the gears. I think I *will* swap in some good used gears if I can find some... sucks to be me!