ruckman101 wrote:It's crap like this that drives people to sell their VWs.
neal
Neal,
I agree with you. It is disheartening. I am also sticking with my original assessment that you have an internal issue that relates to the synchro assembly + potential bearing issue. I wish I had my scanner with me, and I could draw you a simple diagram of the likely issues.
Did you read my bearing plate installation in Chloe saga? That bearing plate is steel. It helps to keep the mainshaft from knocking back and forth. In the factory build, the bearing that holds the mainshaft is held by the soft magnesium nose cone housing. Over time, it gets hammered (like an engine crankcase), and the whole shaft can move just enough to help start throwing you out of gear.
The recommendation to look at mounts was mostly to catch some egregious *failure* that could shift the whole engine/transaxle fore and aft and throw it out of gear. But the factory engineering is pretty good. You have shift rails with detents. The detent grooves are under about 30 lbs of pressure from the spring and balls that hold it in position. You only have to be "somewhat near" gear engagement for the detent to spring the rail into exact alignment. In this detent-dictated position, the fork is held precisely between the grooves of the rapidly spinning synchronizer slider. It has to be thus (and this is why we do not hold our hand on the gearshift) to prevent wear.
So, how on Earth can little fore-and-aft movements of the engine/transaxle, or little movements of the stop plate adjustment affect the fact that your transmission is disengaging 4th gear on the other side of this detent (meaning that the *fork* is pushing the *rail* against 30# of detent far enough to take it out of gear)?? Wait! I'll tell you! The only way that the transmission can generate enough force to overcome the detent is if it is damaged, either inside the synchro assembly (keys, spring, teeth) or the entire input shaft is able to move back and forth too damn much because of a damaged bearing.
Now then, Personal Opinion:
I personally think that your rebuilder might have decided not to replace your Expensive Pinion Bearing, or did not replace your Important Input Shaft Bearing, or did not check the slider/synchro hub or did not control the critical clearances required. I think he is in a pickle because his gamble did not pay off, and he is loath to invest in the parts required to make it work properly. Have him drive the car. Note that if 1st gear holds, if 2nd gear holds, if 3rd gear holds, we can't blame the shift coupler or mounts. What kills 4th gear would also kill 2nd gear if those parts had anything to do with these symptoms. If you could not find 3rd gear or 4th gear, then we would possibly have to look inside the nose cone for worn bushings or damaged interlock/hockey stick ball, etc. But, if I have this right, you have only 4th gear popping out under load, right?
I do not know what to tell you as far as maintaining a working relationship with this rebuilder. You have exerted a lot of effort, you have paid your money in good faith, and you are owed a functional transmission.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles