Sorry to bomb the list, but I don't seem to be able to reach Alan Myers
directly. You out there Alan ?
Just to be sure my memory was correct, I crawled into the garage rafters and
measured two different transmission housings, before correcting Brians'
post. Measuring on an angle, from the bellhousing edge to the rear edge of
the housing (where either the OD or tailshaft housing would attach), I got
16" on the non-synchro box, and 16 3/4" on the synchro box. (The measurement
is slightly different at different places around the transmission, but I
measured the same place on both of them.)
I've currently got the early OD trans from my TR3 spread across the bench,
but I'll take a measurement when I get it put back together (hopefully
Is your 30" measurement taken parallel to the drive axis, or literally from
the edge of the bellhousing to the edge of the flange ?
My understanding is that the input shaft was shortened for the TR6, around
1970, and the pilot bearing was moved from the end of the crankshaft into
the flywheel to match. Supposedly you can tell the difference because the
later TR6 transmissions will sit flat when rested on the bellhousing face,
while the earlier ones (and all TR2/3/4) will not (because the input shaft
sticks out past the surface of the bellhousing). I've been told you should
not use the short input shaft without dealing with the pilot bearing issue.
ISTR hearing that the late box can be used on TR2-early 6 by using the later
flywheel with it, but I'm not certain. It's possible the flywheel had to be
drilled. TR2-4A would presumably also have to use the early starter, since
the TR6 starter engages from the front instead of from the rear like later
TR3-4A. Or, the TR6 starter can be used, but you may need to mill the
starter mounting surface on the block to get the correct engagement.
How thick is your bellhousing flange ? I haven't looked in a long time, but
ISTR the flange on the synchro-1st box (which I believe came from a 64 TR4)
is thicker. I've also got a friend's 70 or 71 TR6 engine and OD
transmission in my garage, I'll take a look at it.
> -----Original Message-----
> From: firstname.lastname@example.org
> [mailto:email@example.com]On Behalf Of Alan Myers
> Sent: Tuesday, December 28, 1999 1:40 AM
> To: Bill Brewer
> Cc: Fred Thomas; firstname.lastname@example.org
> Subject: Re: trans. mounts & gearboxes & OD's
> Bill & Fred,
> This is odd. I never heard of a diff. in length of the gearboxes from
> TR3 to TR4.
> It so happens I have my orig. TR4 non-OD gearbox (in need of rebuild,
> mostly 1st gear synchro, drives like a 3 ;-) conveniently laying in my
> garage alongside a freshly rebuilt OD gearbox. Went out with a tape
> measure a few min. ago & can report that both measure 30" from the
> bellhousing to the drive shaft flange. Wish I had a TR3
> gearbox handy to
> give you a full comparison! Maybe someone else can check theirs or you
> can use this to check against yours.
> If yours is somehow a half inch longer, I am sure you could
> ovalize the
> rear mounting holes, but I would be a bit concerned about the
> driveshaft. Maybe you just got a bad set of engine mounts. I think
> Revington TR offers urethane mounts.
> While we're on the subject, one diff. between the gearboxes
> (besides the
> OD) is a much beefier flange on the bellhousing of the rebuilt unit.
> >From this plus odd locations of the OD cutout switches on
> the top cover,
> I am guessing this is actually a much later unit, maybe 4A,
> 250 or 6 (or
> Dolomite or ???). Anyone know about the change point for the heavier
> flange on the bellhousing? From markings on the packaging
> when I got the
> rebuilt unit (without the OD), I think it was overhauled in England.
> One thing that concens me about the rebuilt gearbox is that the input
> shaft "nose", where it fits up to the "spigot" bushing in the rear of
> the crankshaft. It's a full half inch shorter than the one on the old
> box! (machined length is about 3/4" on the newer one, compared to
> approx. 1-1/4" on the old). Looks to me like there won't be a lot
> (1/4-1/2"??) meshing between the input shaft and the
> crankshaft. Anyone
> have any comments or opinions? Should I be concerned?
> Dave Massey mentioned 5 speed conversions. Just noticed in the latest
> Grassroots Motorsports Mag that XKs Unlimited is now an "exclusive
> supplier" of complete conversion kits for most LBCs,
> including our TRs.
> Kits are priced from $1999. www.xks.com fyi
> Happy holidays!
> Alan Myers
> San Jose, Calif.
> '62 TR4 CT17602L (guaranteed Y3K compliant!)