Peter :
I'm afraid it doesn't sound good. The ball is supposed to be 5/16"
diameter, just large enough to seat against the end of the passage that the
plunger moves in, and seal it off against the operating pressure from the
pump (when the OD is not engaged). Someone has obviously substituted the
wrong ball, with the result that the OD (at least at one time) tried to
engage in all gears, including reverse. However, there is a sprag clutch
in the tail housing which is supposed to prevent the input (to the OD) from
ever turning faster than the output, so it doesn't 'slip' while shifting in
and out of OD. The bad news is that that clutch will be destroyed if the
OD engages in reverse. The fact your OD seems to slip indicates that
clutch is not working (and the two operating clutches are slipping as
well), plus the grinding noise in reverse is probably the remains of the
clutch grinding around.
Unfortunately, parts for the sprag clutch are hard to find and expensive.
At the very least, you need to disassemble the OD and clean out all the
broken bits. I don't know of any reason it can't be put back together
without the sprag clutch, IF you de-clutch while shifting into or out of
overdrive, and be on the alert for any slipping, especially in first gear.
I may be able to locate some used parts here on the west coast of the US,
if you're desperate enough to pay shipping to Sweden. But, I imagine
you'll fare better with finding parts in the UK, where these overdrives
were used on many other cars. Another possibility is to scour the
junkyards, I understand that some 50s and 60s Volvos used the same OD unit.
Even though the gear ratios were sometimes different, I believe the sprag
clutch will interchange between all A-type overdrives.
Randall
On Monday, June 12, 2000 1:38 PM, Nyberg Peter [SMTP:Peter.Nyberg@lio.se]
wrote:
>
> Hi list,
> May 23, 1998 I bought a ' 62 TR4 which hadn't been on the road since '
74.
> The DPO had finnished step 1 in a total body off resto. i.e. body and
everything else detachable removed. There was plenty of rust, seized
> engine (work of the elements) and lots of missing parts (!?!). Some of
the parts that came with the car came from other cars. I had only seen
> TR4's on pictures so I didn't know what to look for.
> Anyway, May 23, 2000 the car passed the gov. imposed inspection with
flying
> colors. CO was 0.3 you're allowed 5.5 on a +30 year old car. Except for
> sand-
> blasting chassis & tub and fixing the frozen calipers, I've done
everything
> myself.
> It's definately not a concours winner - it's my first restoration and on
a
> limited
> budget. And have I learnt some !
> Now the reason I address the list - I can't get the O/D to work. When
> reversing there's
> a grinding noise in the box and when going forward the rev counter (and
> engine) rev
> quicker than the wheels (no, no clutch slip - it's transmission slip).
The
> solenoid is OK,
> I've tried several lift heights on the operating valve and yes, there's
oil
> under pressure
> when loosening the plug. However I measured the diameter of the valve
(the
> rod that
> lifts the ball) and the diameter of the ball - they are both 1/4 ". The
> illustration in
> the workshop manual shows a ball seat and a ball that seems to be bigger
> than the seat.
> Anybody know the correct size of the ball?
> At the moment the valve, ball, plunger and spring is removed and that
> grinding noise
> when in reverse is gone. The rev counter, engine speed and car speed is
> syncronized.
> Sorry about this long message. If I ever come back I keep the next one
> shorter.
> Cheers,
> Peter Nyberg
> Linkoping, Sweden
> CT 17307 LO
>
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