Regarding the somewhat common problem of the 5th and reverse position detents hanging up or sticking ; Has anyone ever tried drilling a small hole in the end caps of the manual tranny 5th gear and reverse detent spring and plunger locations to allow an application of a silicone spray? Thereby avoiding trans. removal.
the problem is.. aluminum case that has a steel plunger. The aluminum case contracts in cooler weather while the steel plunger does not (or to a lesser degree). What was once a bore perfectly sized for a plunger, after getting really cold, is now a bore that is too small for the plunger. You shift into 5th gear, mash the plunger into the bore while doing so and there it stays until the trans case warms up enough to swell a little bit and release the plunger. I doubt that silicon spray would help. My 330ci had the same problem. In winter the plunger would stick when cold. After a warm up or in summer - no problem. The first part of my drive to work has a lot of stop and go driving. In cold weather the first shift into 5th hung the plunger up. As I would drive, the plunger would free up. I finally caught the plunger just as it would begin to move back - still sticky and slow to return the gate but just starting to loosen up. It was at that point (if I was waiting at a red light) I would work the plunger by pushing the stick into the 5th gear gate.I figured if the case was aluminum (soft material) and the plunger was steel ( hard metal) sooner or later I'd wear the bore out. Over time it worked. I have always used Redline MTL in my 5 speed and that may have helped, but basically I think I wore the bore in enough to allow free shifting even when cold. I accomplished this over the first winter with the car. Here in Houston we rarely see temps go below freezing but if I took my car to Alaska it might loose the 5th gear gate again - significantly cooler there, perhaps the case would contract enough to give me that problem again. I emailed Jim Blanton (BMW gearbox guru) about this and he told me that he pulled the trans out, removed the plunger, sanded the hell out of it for a very loose fit and then reinstalled the trans. That's a lot of trouble - BMW would actually install a new trans under warranty to fix the problem and all it was a poorly machined plunger. Amazing. Sorry for the too long post but that's how I got my car out of it. Cheers!
I wouldn't recommend drilling. Just do the detent spring modification when it's time to replace the clutch.
I had the same problem with my E39 528i. I was able to pull the cap out with the tranny still in the car and then pull out the plunger. It was a tedious task and required bending and making some tools to do it. It took about five hours to do the job, but I still think that it was better than pulling the tranny. I did have to drill the plug and pull it out with a screw and a pry bar. Then I coaxed the spring and plunger out. The plunger was very tight. Then I chucked the plunger into my drill press and sanded it with emery cloth. I'm not sure how much I really sanded off of it, but it fit back into the hole easily and has worked perfectly since. Good luck!
