Larry -
I've seen several things cause 'jumping out' whilst on overrun in gear,
though because of leverage and usage reasons it seems to most often occur in
second or third. I haven't really seen the syncro (baulk ring) itself
causing this problem, rather in my experience there are two other things
that often cause popping out:
- The syncro hub assembly (the slider that moves between 3-4 gears) has 3
locking dogs [aka "shifting plates"] inside; if the springs or dogs
themselves are worn this will easily cause it to pop out. When the slider is
installed on the hub and the springs and dogs are in place it should be
pretty tough to slide it by hand if things are good and tight as they should
be - if it slides easily you've got a problem. Wear on the shifter plates
occurs on the 'pips' on the top faces. Wear on the springs can be most
often seen where they contact the shift plates - look for shiny spots on the
springs and measure with a micrometer to determine if there's any
significant wear/shrinkge - when in doubt, replace them if you can.
- The selector shafts on the shifter mechanisim have ball & spring detents
that latch the shift sliders in position by using axial loading to prevent
inadvertent movement - these detents can be clagged up with sludge, dirt or
decaying grease or may have weakened springs and this will offer little
support for the normal gear position. It's important to test the axial
loads on these shafts, and although it's easliy done with a spring scale
it's rarely done on most rebuilds. You can adjust the loads with shims.
(Also check the shafts to ensure that their detent grooves are symetrical
and uniform, as well as the balls themselves... wear on either can cause
popping out.)
Give this a try ans see if it helps.
Regards,
Kevin McLemore
1967 Sunbeam Alpine (rebuilt my gbx & O/D two years ago)
1949 Triumph Renown
----Original Message Follows----
From: "lauri lehtinen" <lauri.lehtinen@pp.nic.fi>
Reply-To: "lauri lehtinen" <lauri.lehtinen@pp.nic.fi>
To: "Jarrid Gross" <JGross@econolite.com>
CC: "Alpine" <alpines@autox.team.net>
Subject: Re: Jumping third
Date: Thu, 13 Jun 2002 12:04:22 +0300
> Larry,
>
> Jumping third means there is a bent third/fourth
> shifter fork. Also the third gear might have
> severe wear on the dog clutch.
>
> Jarrid
thanks again, Jarrid.
For me this sounds to suit very well to the sickness, because there is odd
whirll if sift lever is pushed too much when shifting to 3rd. There are no
difficulties or noise when shifting any gear, so synchro rings seem to be
ok. And yes, all dogs and synchro teeth were ok as long as I could see
between the shifter safts and forks. I tried to check them without
dismanteling the box.
BTW you learn very quick to avoid motor braking with 3rd. Even then when it
jumps off only about every 10th time...
Larry
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