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Title: missing third gear Post by: CHR!S/DVK on May 22, 2012, 13:47:24 pm last year i bought a gearbox to replace my worn gearbox in my 69 beetle with one that was revised by a friend of the seller, i believe internally only the synchromesh rings were replaced and the nosepiece was replaced.
it's a AB gearbox that came from a 72 beetle, i don't know much about gearboxes and i'm not able to check the exact code right now. i took the axles from my old tranny and mounted them on the new one. before installing, i checked the shifting rods under the nosepiece and they looks good to me (as far as i could see), i aligned them so the hockeystick could move freely through the holes. after some trouble with my engine i finally went for a drive last week, only to find out that the third gear is "missing". 1st, 2nd, 4th and reverse work, but when i shift into third and release the clutch, the gearbox is like it's in neutral, no noise, just no gear. i checked the gear lever adjustment, the coupler under the backseat is in good condition and well mounted. with the backseat and plate above the coupler removed, i see the coupler and rod moving well into the gearbox when i shift into third, just like when i shift into first. i contacted the seller and he is asking advice to fix this together but also mentioned something about two M10 bolt underneath the gearbox that hold something in place.. can anyone help me on this issue..? ??? Title: Re: missing third gear Post by: CHR!S/DVK on May 23, 2012, 22:43:20 pm any guesses or opinions here..?
Title: Re: missing third gear Post by: Bruce on May 24, 2012, 08:33:17 am ...... two M10 bolt underneath the gearbox that hold something in place.... The only M10 bolts under the gearbox are the front trans mount. If it is loose, the trans can move around. Title: Re: missing third gear Post by: 61SNRF on May 24, 2012, 20:44:57 pm Third gear on the input shaft is a two piece assembly that is pressed together, the gear itself and a syncro hub. It is a tight enough fit that the two parts will stay together under stock applications.
When you select third gear, it becomes locked with the input shaft and power is transferred through the assembly and drives the piniion shaft. The problem you describe sounds like the syncro hub has loosened and is spinning on the gear itself, thus a lack of drive in third. For Hi-Perf or heavy duty use, people will weld the two halves together so this can't occur. Fourth gear is configured the same, and is also welded for the same reason. It sounds like you need to take it apart for an internal inspection and repair. Title: Re: missing third gear Post by: CHR!S/DVK on May 25, 2012, 06:33:18 am thanks for the replies!
i have been asking around a lot and indeed the synchro hub seems to be the problem. i am not driving stock 1500, but i hope to finish building my 1679 somewhere in the summer. do you advice to weld the third gear? i'm now inquiring for a professional to take a look at it. do you guys thinks it's a big job to fix this? i hope i can work it out with the seller and don't have to spend much money on the transaxle.. Title: Re: missing third gear Post by: delux67 on May 25, 2012, 10:19:57 am last year i bought a gearbox to replace my worn gearbox in my 69 beetle with one that was revised by a friend of the seller, i believe internally only the synchromesh rings were replaced and the it's a AB gearbox that came from a 72 beetle, i don't know much about gearboxes and i'm not able to check the exact code right now. i took the axles from my old tranny and mounted them on the new one. before installing, i checked the shifting rods under the after some trouble with my engine i finally went for a drive last week, only to find out that the third gear is "missing". 1st, 2nd, 4th and reverse work, but when i shift into third and release the clutch, the gearbox is like it's in neutral, no noise, just no gear. i checked the gear lever adjustment, the coupler under the backseat is in good condition and well mounted. with the backseat and plate above the coupler removed, i see the coupler and rod moving well into the gearbox when i shift into third, just like when i shift into first. i contacted the seller and he is asking advice to fix this together but also mentioned something about two M10 bolt underneath the gearbox that hold something in place.. can anyone help me on this issue..? ??? The 10mm bolt that bolts into the gear carrier housing secures in the housing the needle bearing race that supports the 4th gear end of the pinion shaft. This is a most puzzling problem. I've built many gear boxes and haven't had this happen. Does the tranny make any whining noises like the main bearing may be worn and when shifted toward third the main shaft pulls away with the slider hub when the fork is moved toward 3rd? Perhaps the 3rd and 4th gear shift fork was improperly adjusted, this would require a significant error on the part of the builder. Sounds like the box needs to be re-overhauled or at the very least taken apart to observe. If memory serves you can access the 3rd and 4th slider by removing the gear oil filler on the side of he case. You may be able to get your finger in there to see if the slider has any play when it is between gears. If there is no play when the slider is not engaged in either 3rd or 4th gear you may again have an adjustment problem. At least its an IRS gearbox vs. a swing axel. its easier to get out of the car. There are some other things that come to mind but they all involve R&R the transmission. So Sorry! Title: Re: missing third gear Post by: Bruce on May 25, 2012, 16:09:44 pm ........ you can access the 3rd and 4th slider by removing the gear oil filler on the side of he case. No, it's the 1-2 slider that's right at the filler plug hole.Title: Re: missing third gear Post by: Cheesepanzer on May 25, 2012, 23:03:07 pm The problem you describe sounds like the syncro hub has loosened and is spinning on the gear itself, thus a lack of drive in third. This would be my vote. However, I've also seen a sheared keyway act the same way. Either way, it has to come apart to fix it. Sorry... :-\ Title: Re: missing third gear Post by: mr horsepower on May 26, 2012, 16:01:27 pm Maybe he fliped the slider there are two different thootpaterns on that
or you have to much axial clearance on your shaft can be lots of things ,but one thing is shure you have to open it up and check it good luck henri |