1936 Terraplane Gear Box Issues

philster

I have an issue with second gear.  All of a sudden, it wants to jump out of second gear when accelerating.  If I hold the gear lever up when accelerating, it jolts the gear lever and makes a very loud noise but stays in gear.  If I do not hold the gear leaver up, it jumps out of gear despite the side slide locks working correctly?

Any ideas of what has caused the problem and a fix solution?

Regards
Phil

Jon B

Not sure, but I'm curious:  do the sliding lockout bars (one on each side of the transmission) work?  They are what hold the transmission in gear and prevent shifting until the clutch pedal is depressed.

Frankvintagefullflowcom

I'd like to say it's just a broken lock-ball spring (this would cause the problem to occur quickly) or something else simple, but my guess is that the second/high shift sleeve clutch (w/external "teeth") and the internal teeth of the second gear on the mainshaft are worn to the point of becoming "rounded-off", thus tending to push the sliding clutch out of engagement. Once this begins to happen, there's no stopping it as it only gets worse each time it "pops" out. This wear occurs slowly over time and is the result of operators who aren't familiar with the shifting technique necessary to prevent that damage in these unsynchronized transmissions ("crash boxes"), i.e, "double clutching" on both up and down shifts. My guess is that it doesn't push out of gear upon slowing down(?). The detent ball ("lock ball") can't hold it in gear against that force when the wear gets to a certain point.....too much force.

Second (intermediate) gear is usually the first victim and I'm afraid the only way to correct it is by replacement of the worn parts.

I hope it's easier than that.

F 

Jon B

If you determine that parts need replacement, and you either can't find the correct part (or don't have the expertise, or don't want to pay someone who does), you could consider finding a good used transmission.  I believe these interchanged over several years in the 1930's and -- though they're not "a dime a dozen" -- chances are that you could find one inexpensively.  In fact, you might buy a "parts transmission" and use it as the donor for any parts you need.

PaulButler

philster,

I see from your location details that you're in Australia (Melbourne?).

It might be worth having a word with @barrysweet52 ; I think he had some transmissions lying around if you need one. I have tried for a long time to find a cost effective way to ship parts from Australia to the UK and haven't succeeded yet.

I'm sure he'll tell you otherwise if I'm wrong!

Geoff

Phil, Frank is on the button.   Your transmission needs rebuilding.  The drive dog teeth and the second gear are worn beyond redemption.   Coupled with the probable disintegration of the rear thrust washer and wear of the main  thrust washers, plus end play in the main and output shafts and the white-metal in the second  gear worn out. .  Don't let anyone near this transmission if they are not familiar with it, they will stuff it up for sure.  Sorry to be such a joy-germ, but I have seen  many of these boxes done incorrectly, and they inevitable fail.  I have rebuilt many of these over the years, but parts are getitng difficult now.

Geoff 

philster

Thank you to all your comments and as soon as I read Franks comments, I thought, yep, that's it.
I was hoping that it was a worn spacer or something similar.
It's been 15+ years since I pulled gear boxes apart and replaced gears (in my other Terraplanes & not the one giving me grief now) so I guess I will have to brush a few cob webs out of my seniors brain and fix this one.  I do have a NOS second gear on the shelf so that's a start!

Phil

Geoff

You will need the shift sleeve as well, it will be correspondingly tapered.  You have a workshop manual?

Geoff 

ken1962

And as the current owner of Phil's "other terraplane" I can say Phil can certainly be proud of his transmission as it's still "sweet" for me to drive Cheers ken

barrysweet52

I have some NOS parts and recond second gears in Adelaide.  ozhudson@gmail.com

bob ward

Geoff, what sorts of things do non-experts get wrong when they rebuild these boxes?

WayneC

I have a complete '36 Terraplane transmission sitting in my shop, shift handle and all (maybe even the pressure plate, friction disk, and the flywheel). A couple of the attaching legs are broken, but the trans case looks like it's never been opened.  I took it out of my '36 Terraplane that was last registered in New Mexico in 1952

Geoff

Bob, -  things like replacing the white metal insert with bronze, layshaft bushings,  incorrect thrust washers, incorrect end play, basic setting of   shafts, drive sleeve mesh, wrong circlips, etc. etc.   For instance, a common one is interpretation of instructions.  Motors manual states "End play of main shaft is adjusted by shims.   Most people interpret this as saying you remove shims to  compensate for  too much end play.   Hudson workshop manual says more specifically "Insert necessary number of shims to  enable end play .008" - .0012".   thsi is when fitting new parts.  if you just remove shims you move the entire input shaft rearwards, which alters the  relationship of the  tooth contact with the shift sleeve. This usually results in jumping out of second gear.    The workshop manuals do not tell you how to allow for over 80 years of wear.   I could go on!

Geoff