After warmup 1st hard to get into and reverse grinds: FIXED!

[kinggeorge13]

So my 1978 Westfalia (Persephone) has only been on the road for a couple weeks now other than the odd test drive over the past while.   And just as I thought I had most of her work done and was on my way to Speedy Auto Glass to get a new windshield put in and suddenly she would not easily go into first gear.   Sometimes as a traffic light went green it was all I could do to push the shifter hard to get it into gear.   No grinding, just would not move into that position.  Going back into neutral, letting out the clutch, clutch back in, still the same problem.    Turning off the engine and restarting presented no different results.   Up until this point her gear changing had been flawless.   

I get to Speedy and go to back into a parking spot and as I tried to go into reverse, my gears start to grind.   I instantly push in the clutch and try again and more grinding.   Nothing I could do to get it not to grind so I finally did the awful thing and just pushed down the shifter and forced it through the grinding and into reverse and parked.   I was sweating profusely by this point.   Turned off the engine for a few minutes, started up and just as an experiment tried to go into reverse and the second I heard/felt the grinding, I stopped and shut her down.    Later that day (new window gleaming away) I did every move possible to avoid having to go into reverse.  The problem with hard first gear never got better.   The next day I tried again and the exact same problems so I parked it.

I did a bunch of research and hoping like heck it was not the clutch itself or even something more nefarious, I decided the two courses of action were to adjust the clutch cable and replace the transmission gear oil.    Since I'd never touched the gear oil yet on this bus and had no idea when anyone previous to me did, I decided that was something I should do regardless of fixing the problem or not.   Some have reported similar problems fixed by new transmission oil but it seemed most often it was a clutch cable adjustment (clutch/gears still spinning when stopped and trying to go into reverse when the reverse gear expects no spinning opposition).   After a million posts were read and questions asked, I finally decided a good/safe gear oil was Lucas SAE 80W-90 Gear Oil which was designed for both GL-4 and GL-5 and had the all important MT-1 designation to protect my soft metal in the gears.   And of course it's designed for hypoid gears.

The black goop that came out of the transmission and the rock-hard crap that was inside the socket head of the drain plug that took some severe cleaning with a small sharp screwdriver before my 17mm driver could even get into it tells me it's been a very, very long time since anyone changed that gear oil.    Got it all drained out and in went the Lucas fresh oil.     Multiple test drives, long and short, cold engine and hot engine over the past couple days and I have not had a problem getting into first gear at all.  Shifting into reverse once again produces a nice clean plunk right into reverse that I would expect and no more grinding.  No grinding at all.

So you just never know.  Sometimes it's all about the fluid being clean and new.   

[Bruce]

Don't count your chickens just yet.
Your problem cannot have been fixed by changing the oil.  Something else changed to make the problem temporarily go away.

Grinding going into reverse while the car is stationary means the input shaft of the trans is turning.  Usually due to a dragging clutch or a tight gland nut bearing.  Changing the gear oil won't affect either of those.

In order to engage reverse without any grinding, the input shaft and the pinion shaft have to both be stopped.  When you push the clutch pedal in, the drag of the gear oil causes the input shaft to stop.  This takes 1-2 seconds.  Old nasty oil isn't going to cause the input shaft to continue to spin indefinitely.

The next time it happens and you have to back up, shut the engine off, put it in reverse, then start the engine.  Until you find the real cause.

I've seen this problem before. In the case I saw, the manufacturer of the gland nut installed the needle bearing too high up in the head of the bolt so that the rollers were starting to touch the radius up to the splines when it got warmed up.

[bwaz]

and he adjusted the clutch cable, which is more likely the reason it's better?

[Bruce]

I'm not sure he adjusted the clutch freeplay, Brian.
Perhaps George can confirm this.

[kinggeorge13]

When I first got under the bus I did a minor adjustment on the cable  (like only 1.5 to 2 full turns at the most) and decided before I went any further, I'd change all the gear oil first so I'd know that was done and out of the way.   So maybe I lucked into that helping/fixing as well but for sure my first gear shifting continues to be wonderful as well as no problems getting into reverse.    One thing that was interesting I thought is that with the clutch out (i.e. nothing on the pedal), my clutch cable is plenty tight and no play at all.   I had thought it should have a little play but with all gears working nicely again, I was hesitant to play with something that was finally working.

One thing I do want to say to Bruce is thanks for the great suggestion of turning off the engine and then clutch in and put into reverse and then start the engine to save from having to grind into reverse if this ever occurs again.  Makes total sense when I think about it and it's a great thing to remember.