Rob Reilly <reilly@admail.fnal.gov> writes:
> The 120 got its first test drive with the original JH trans. Seemed a little
> difficult to get it into first and second, tendency to pop out of second.
> After
> about half a mile of driving around my neighborhood, it got stuck in first
> gear! Arrgh! Drove home 3 blocks in first, and into the garage. Fortunately I
> hadn't bolted the trans tunnel down yet, so I pulled it and the trans top
> cover
> off. The first gear was all the way back and the second gear synchro sleeve
> was
> all the way forward, allowing the six spring-loaded balls and one
> plunger/ball
> to come partially out and prevent the gears from returning to where they are
> supposed to be. I got lucky in that none of the balls fell out. With a hammer
> and prybar I got the gears back to neutral position without damaging
> anything.
Rob,
First, let me congratulate you on getting the 120 back on the road--well
done!
Second, I am writing to commiserate with you on your gearbox woes--my '64
E-type shares the same (flawed) gearbox design as your 120 and has the same
"stuck in first" problem as yours (sorry about the delay in answering, but
I had to first check my catalogs to confirm that it is in fact the identical
unit, which it is, and not appear to be a complete ass). You may remember
that I tried to start this thread about half a year ago.
I agree with Scott Fisher when he writes that the second gear problem may
be a separate problem altogether--I'll return to this later--now I'll
discuss the first gear problem. My best guess is that the "stuck in first"
problem is due to wear in the interlock mechanism, which should prevent the
synchronizing sleeve from moving forward when first gear is engaged. I believe
what happens is that when first gear is moved forward (disengage), the syncro
sleeve moves forward too--just a bit--which wedges the interlocking ball and
plunger between the main shaft and first gear. Additional force on first gear
now gets transferred through the interlock ball and plunger to the sleeve,
which adds even more wedging pressure to the ball and plunger. Now the whole
mess is locked up solid and no amount of reasonable force is going to make
first gear budge. My workabout solution in the E-type is to shove the gear
selector all the way back in first and rattle it back and forth (with a little
more force on the "back") until it suddenly is able to go to neutral as if
nothing had happened at all. Kind of like an AC signal with a small DC
component. From the amount of force that results in no action, you'd be
surprised at how light a shaking unsticks things. Something else to try if
you're stationary is to rotate the main shaft 180 degrees in case the align-
ment of the interlock with gravity is important; moving the car forward or
backwards about a foot should do this--I don't know the final drive ratio
of the 120 offhand... Occasionally first unjams just enough to move, but
still binds a bit. I can drag it to neutral, where the problem disappears
completely. This is consistent with the interlock jam theory, but not the
balls out of whack, described above.
While you have the gearbox cover off, now is a good time to recheck a few
things. First, when first gear is fully engaged, the six spring loaded balls
and the one interlock ball should protrude a bit from the syncro sleeve. After
opening my gearbox, my balls appeared out of whack, but on closer examination
they where just shy of poking out halfway, which is how they should look.
My manual has a sectioned view of the gearbox, which is a scale drawing, and
you can measure what Jaguar designed in, and it's a frighteningly large
percentage that hangs out! As long as the ball's point of contact is inside
the syncro sleeve, I believe you're okay. I was never able to duplicate the
"stuck in first" problem with the gearbox cover removed, but I hadn't
adequately devoted myself. Here's a few things to try:
1. Align mainshaft so interlock ball is accessible
2. Engage first gear
3. Determine interlock plunger play (maybe use a magnet)
4. Pry first gear forward while lightly pulling the syncro sleeve
forward. Does it bind? What is the play in the interlock
plunger now?
5. Pry first gear forward while pushing syncro sleeve backwards.
Is the shift easier?
You may wish to confirm also that the syncro sleeve can't move all the
way forward when first is engaged. Take careful measurements between
the syncro sleeve and second gear both in first, and while pressing the syncro
sleeve forward (in neutral). Only in the later case should the sleeve be
all the way forward. I would be surprised to find that interlock had failed
to keep the syncro sleeve back. I think the spring loaded balls look out of
whack even on a good gearbox, and you were taken by surprise to even see them
at all--I was. Lots of force is required to move things around; remember
the shift selector is a pretty good lever--so I'm not too surprised at the
pry bar and hammer (...you weren't using the 20# sledge, were you?).
> Scott Fisher wrote:
> >2) Over-Engagement of first gear:
>
> >Another warn part..however this time there is an in-situ fix...but it's a
> bit of a pain of a job.
>
> >Take the top off the box and roll the car forward in 2nd gear...rotating
> into
> view you should see a soft metal pin/rivet/stop which is the over-engagement
> stop. This is likely to be considerably worn.
>
> Me: There is no stop pin/rivet at all, nor never was there. I understand what
> you are referring to, probably added on later boxes to correct the fault I am
> now experiencing.
No stop pin on the '64 model gearbox either. With the selector fork removed,
first gear travel is limited by the gearbox case itself. I'm not sure what the
clearance should be with the selector fork installed--probably on the order
of about .010 - .020".
> George Haynes wrote:
> >There seems to be a propensity for those Moss boxes to stick in first gear.
> >There may have been a design error or machining error somewhere. You'll
> need a
> spacer (washer) at the back of the case to keep first gear from moving along
> the mainshaft too far. It's crude but effective. A friend has done it to
> the
> Moss box in his 1951 Morgan. No more trouble. Of course it requires
> removing
> and dismantling the box to install the spacer, whose thickness will have to
> be determined. I think it was in the .100" range.
> George Haynes
>
> Me: I have discovered a spacer/washer on the 1st/2nd fork actuator rod that
> isn't in the parts list. It has the effect of reducing the rearward travel of
> the fork into 1st. Also, the locking wire on the setscrew for the 1st/2nd
> fork
> is a different color than all the others. Aha! Some PO has been messing with
> the fork, maybe to fix the same problem. Now to figure out what he did, he
> must
> have added the washer, maybe he replaced some parts with newer parts? Stay
> tuned. Rob
I too was told that this is a common problem and that the easy solution was
to install a spacer on the 1st/2nd striking rod to limit rearward travel. I
grudgingly resorted to this quick-fix and choose a spacer thickness so the
first gear detente on the actuator rod was still partially engaged (don't want
to trade that "won't get out of first" problem for a "won't stay in first!").
Crude, yes. Effective, well--no. Not completely anyway. I got this "fix"
from the owner of a shop that exclusively worked on British cars, so you
can probably guess lots of shops were willing to do this. To correctly fix
this problem, you're going to have to pull the gearbox and rip into the guts.
For me, it looks like living with the problem is the lesser of evils. Maybe
when I get a 3.8 engine I'll deal with the problem (Come on! Hasn't anyone out
there seen Jaguar RA3357-9?).
Second gear. First make sure the problem isn't caused by the PO trying to
solve the first gear problem. Has the striking rod plunger spring been cut
short? Plunger okay? Fork bent by excessive force to get out of first? You
may be able to check this out by shoving first gear forward, shifting the
gearbox top assembly to second, and then fitting the top to the gearbox and
noting alignment problems. Otherwise, it could be worn engagement splines on
second gear, or worn roller bearings, which you can probably feel for in play.
Good luck, and please keep me posted. If I had to guess, I would bet your
second gear problem is a bent fork from some gorilla trying to force it out of
first. You can solve this easily enough without removing the gearbox. And
remember to rattle your way out of first when it sticks; force will not work.
-greg
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