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Topic Summary

Posted by: macrisel
« on: April 17, 2015, 01:06:24 PM »

Quote
You may run into a hydraulic lock problem by sealing the ends of the shift rails where they weren't originally sealed. When oil migrates to the end of the shift rails it has no place to go when a shift is attempted. Cut a thin slot in the shift rail so the oil can get back to the transmission during a shift.

Bob makes an excellent point on this....one that I didn't know when I rebuilt my transmission shift tower the first time.  I sealed the front caps on my shift rails with RTV sealant prior to driving them in.  Two days later I had the trasmission installed and was taking it for a test drive without the shift tower covers and boots on. 

After about 5-6 shifts going down the gravel road, it was becoming more difficult to shift between gears.  That was when the pressure built up enough in the shift rails to cause the cover to pop off, bounce off the bell housing and end up directly in my lap!

My Dad was riding with me at the time and just gave me one of those "What the heck was that?!?" looks.  I just shrugged and kept driving...

That made it a lot easier to change gears!
Posted by: Ryan_M
« on: April 14, 2015, 03:54:06 PM »

Unfortunately I do not have a spare M38 tower kicking around and the dozen or so pictures I have of my last M38 tower overhaul offer no clues. I'll be venturing back out to that M38 in the woods I posted about a couple days ago. I'll try and take a look at that one.
Posted by: athawk11
« on: April 14, 2015, 01:22:27 PM »

Thanks Ryan!  I have an M38 shift tower on Whitey, but I don't want to take it apart.  Your growing parts stash...do you have an M38 Shift tower you can open?  I'm really curious how they sealed this unit, but still were able to accommodate the issue described by Bob W.  I can't see a grove in your photo, but it may be cut on the side not shown from the bottom.  Or, did the bore itself have a groove?  This makes more sense to me.  It would match what I think I saw on the front side of the 3A shift tower.

Tim
Posted by: Ryan_M
« on: April 13, 2015, 12:30:41 PM »

Disregard the comment in the pic but here's the underside of an M38 tower.

Posted by: athawk11
« on: April 13, 2015, 11:16:03 AM »

That is an excellent point.  I did read about this extra step, but I didn't do this.   The rods didn't seem to fit super tight in the bores, so I thought the oil would still be able to migrate back.  I cruised for about 20 miles and didn't seem to have any ill affects, but I'm not sure this short trip will tell me anything.  Time will tell.

Did the M38 have grooves cut?  I have an M38 shift tower on Whitey.  It got a new shift fork and poppets, but I didn't pay attention during the refurb.

Tim
Posted by: Bob W
« on: April 12, 2015, 06:02:42 PM »

You may run into a hydraulic lock problem by sealing the ends of the shift rails where they weren't originally sealed. When oil migrates to the end of the shift rails it has no place to go when a shift is attempted. Cut a thin slot in the shift rail so the oil can get back to the transmission during a shift.
Posted by: JeepFever
« on: April 12, 2015, 12:33:02 AM »

.
Thanks for the tips!

Hopefully someday I can start working on mine again . . I will keep these in mind.
Posted by: athawk11
« on: April 11, 2015, 11:40:54 PM »

I'm only a few years beyond my rebuild, but have always been disappointed that my green Willys leaked.  I pulled the drive train, determined to seal it up better than the first time around.  I was surprised how greasy the shift tower was when I pulled it to drop the tranny.  I decided to decrease the chance that this will leak. I added a seal plate to the rear of the shift rods.  I've seen others do this with some success.  I drilled and tapped the tower (1/4" x 20) so I could hold the plate in place.  I added some RTV gasket maker.



I was missing one of the caps on the front of the shift rods too.  I wanted to get it all back together today, so I was a little bummed.  Turns out, 1/2" copper caps are a perfect fit.  I shortened them, added some Permatex, then drove them in.  A perfectly workable solution...




The jury is out as to whether these steps will help seal it up, but it's a relatively easy approach, so it may be worth a try.

Tim