Subject: [TR] Fw: Transmission Temporary Locks In Neutral

From: "John Finlayson" <[email-masked]>
Date: Thu, 23 Aug 2012 21:28:52 -0700

On June 28, I posted the following message to the list. I received several
suggestions as to what the cause of the problem might be:
    - shift interlock in the top cover
    - clutch hydraulics
    - shift lever adjustment
    - clutch not releasing from the flywheel.

I think I have now ruled out most, if not all, of the above suggestions and am
appealing for any additional suggestions anyone might have.

I felt strongly that the shift interlock was the problem. I even ordered some
parts for it before taking it apart. When the parts didn't arrive, I removed
the top cover from the previous transmission I had in the TR4 and replaced the
top cover that I thought might be faulty on the current malfunctioning
transmission with the TR4 transmission top cover. After an hour of driving,
the problem came back. This seemed to rule out the shift interlock as the
problem as I had experienced no problems with the previous TR4 transmission in
several years of driving with it.

I checked the clutch hydraulics. They appeared to be within spec and the slave
maintained its position with the clutch pedal depressed.

I had used the TR4 shift lever on both the TR4 and TR6 top covers.

I removed the TR4 top cover and reinstalled the TR6 top cover. I installed the
TR6 shift lever and adjusted it as described it the TR6 Shop Manual.
Incidentally, the TR6 Shop Manual says to screw the locating pin in till it
touches the lever then back it off a half turn. The Haynes manual says, after
touching "screw the locating pin a further half turn.....".

On two recent occasions the temporary transmission jams occurred while the car
was stopped. While in neutral and stopped at a red light I couldn't shift out
of neutral into a forward gear. I finally had an opportunity to try reverse.
It went easily and cleanly into reverse. I shifted out of reverse but still
couldn't get it into a forward gear. I continued trying and finally got it
into first when the light changed. This was the first time I had tried to
shift into reverse when the forward gears were jammed. I was surprised at how
easily it went into reverse. The second occurrence was a repeat of the first.

There was no grinding of gears at any time during these incidents or any of
the previous incidents.

So I now know that these temporary jams are confined to the forward gears
only.

I don`t see how it could be the clutch if I can get into reverse while not
being able to get into a forward gear but I don`t know enough to rule it out.

I`m thinking it`s something in the transmission related to the forward gears
that occasionally jams. Given that this is an intermittent problem, I`m not
sure I`ll even recognize it when I see it. When I had the covers off the two
transmissions, the TR6 transmission was tighter and with less end float that
the previous TR4 transmission.

Any insights into what the problem might be would be greatly appreciated.

John Finlayson

----- Original Message -----
From: John Finlayson
To: [email-masked]
Sent: Thursday, June 28, 2012 8:19 PM
Subject: Transmission Temporary Locks In Neutral

I have a '62 TR4 in which I have installed a TR6 transmission with A type
overdrive.

Very intermittently after shifting out of a gear I will find that I can't get
out of neutral into the gear I am intending to shift into, or to any forward
gear including the one I just came out of. This can occur when the car is
stopped or in motion.

I can be at a traffic light waiting in neutral for the light to change. When
the light changes I find I can't engage any forward gear. After trying
repeatedly to select a gear and engaging and disengaging the clutch I have so
far eventually been able to get the transmission "unlocked" and shifted into a
gear. The same applies when the car is in motion and when I am either up or
down shifting.

I don't recall overdrive ever being engaged when this occurs although it's
possible it may have been on some occasions.

There is no grinding of gears when this occurs. The shifter doesn't get even
close to selecting a gear. When I try to select a gear, I can freely move the
shifter laterally in neutral but not up or down to select any forward gear.The
shift lever feels like it is physically blocked from moving up or down....I
have not yet tried to select reverse when this occurs, just haven't thought to
try reverse.

These are infrequent events and have occurred since since the transmission was
installed a year or so ago. Their frequency and the effort required to get a
gear has increased recently, however. It happened three times on a ~30 mile
drive I took last week....twice while stopped at lights and once while gearing
down from 4th to 3rd while on the highway. I wasn't successful in getting it
into gear till after I had stopped.

Any suggestions on what the problem is would be greatly appreciated.

John Finlayson

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