Bus slipping out of gear - Fixed???

It's been quite a session.

1st off, in August of 2002 I made the decision to convert Bussy over to Subaru power. At that point I assumed somebody else had done it and there would be lots of information available. I was a little bit wrong on that point, as this is a common conversion for late model Vanagons, but not common at all for Bussy-types.

I expected to occupy my buddy's garage for two months, maybe three tops. I was sick almost all winter - Nov to March - and didn't get as much work done as quickly as I had planned. Oh. Did I say planned? Nothing was really planned. It was an Invent-As-You-Go type deal. It all worked, ultimately, although I was not at the point of driving it until July. Eleven months. Former buddy.

I had plans to do an instructional CD to market for a modest fee. I wanted to get everything working perfectly and then I could put the CD out with some confidence. That never happened either. It has never quite worked "perfectly." Although I have received some very high praise from some people that know their stuff, I have never had "closure" on the project due to two items: 1) It slips out of 1st and 3rd gears (2) The cooling system is too efficient for general driving.

The shifting problem has been driving me insane. I have been through every millimeter of that shifting mechanism multiple times, have re-designed my motor mounting system, have even mounted a camera underneath the bus to record what events actually lead up to it slipping out of gear. There were no "events" as it simply slipped out with no apparent reason for it. The nature of slipping out of 1st and 3rd is unique in that they share no components inside the transmission. They share only the fact that each is engaged by moving the shift lever forward which moves their individual shift rods backwards.

Since they only share linkage, and it is apparent that the problem has to be within the realm of what is shared, the problem therefore needs to be related to the linkage. I finally gave up on diagnosing the linkage after proving to myself that there is nothing possibly wrong there, so I made the commitment to remove the engine and transmission and take the transmission back to my transmission man, Gary. Gary had told me many times over the past months to bring it to him, but I kept insisting that it had to be linkage.

Two weeks ago I started the engine / tranny removal. Wednesday of that week I delivered that tranny plus two others I own to Gary's shop. Thursday night, I dismantled the tranny in question (Tranny #2) and found nothing wrong with it. With me doing most of the work and Gary doing the critical measuring and checking, it was determined that the problem cannot be inside the transmission. I put it back together and took it home.

Since then I have been crawling around under there, putting the transmission temporarily in place, hooking up the shift linkage, running it through the gears, etcetera. I installed new shift rod bushings. The shift rod is the main piece of the linkage and its job is to connect the shift lever action from up front to the transmission way back there in the back. For some reason, VW engineers encased that rod inside a steel tube and used 3 tiny badminton birdie shaped nylon bushings to keep the rod centered in the tube. While installing these new bushings, (I had ripped the old ones off without looking at them closely - they weren't that old as I had installed them in about 2000) I looked at "the book" and read the paragraph and looked at the pictures, then installed them. When I did a "test run" on it all, I discovered that I had apparently mis-interpretted the book as I obviously had installed the front bushing backwards. The part that would be the feathers of the birdie was sticking out of the tube slightly. As I layed there cursing the fact that I was going to have to pull it all apart again and do it right, I was envisioning how that tapered part of the bushing was exerting a force, a slight force but still a force, pulling forward on the shift rod. Forward as in "out of 1st & 3rd gears."

Might I have installed the bushings wrong four years ago? Might this have been the problem all along? I don't know. Maybe it was. It makes sense that I would have interpretted the book procedure the same way both times. I had no particular reason to double-check my work back in 2000 as I was only installing new bushings because the opportunity presented itself (the engine and transmission need to be out to do it.) There is a rubber bellows that covers the ends of the tube and that would have hidden it from my view - I still had the stock VW heater tubes in place then, too. If that was the case, then it makes perfect sense that when there is no load on the transmission, as in rolling along on a level road, coasting, that there would be just enough pulling power by that bushing to pull it out of those two gears.

Today I finished up, got the axles back on, the brakes (new) set up and adjusted, double checked anything that I could not remember tightening, and away we went. Test drive #1 was uneventful and test drive #2 went well except for one incident of slipping out of third gear. I am not too disturbed by this as in reassembling the transmission, Gary tightened up the 3rd/4th shift rail so much that it is very stiff and hard to move. I remember when I shifted into third just before it slipped out that I had not shifted "with authority" but had just hap-hazardly stuck it in there. I have about 20 miles of third gear driving since that event and it has stayed like it should.

I have a lot of noise transmitted through the linkage and tomorrow I shall try some adjusting to get rid of the racket. Hopefully I will now have closure on the shift linkage problem. I guess I won't know for sure until that

3rd / 4th rail loosens up some more. -BH
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Busahaulic
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