[TR] Wedge 5 speed gearbox issues

[Ann and Tim Buja]

Adrian wrote:
> My first question would be what is the colour of the oil in the
> gearbox? Has someone filled it with ep oil? or 20/50?
> This would give a sluggish gearchange.
>
> The oil to use in the Rover/TR7 5speed is auto trans fluid and
> should be red in colour and very thin. You can buy special
> oil but auto trans fluid works perfectly.
>
> Adrian TR4A CT64306 O
> Wales UK

The Triumph recommended oil fill for the Rover LT77 5 speed changed from 75W
gear lube in 1979 to Type F ATF in 1980 to Type G ATF in 1981.  Do not use
80W90 or higher Gear Oil, as this tends to break the fiber oil pump gear
teeth in cold weather.  Broken oil pump gear teeth are fatal to this
gearbox, which relies on forced oil lubrication to the tapered roller
bearings throughout the gearbox.  Don't forget that 75W Gear Oil is
approximately the same viscosity as 30W engine oil, since the viscosities
are measured at different temperatures.

The TR8 CCA folks, including myself, have had very good luck with GM
Synchromesh Transmission Fluid, which is a 75W gear oil compatible with
yellow metals found in manual transmissions..  This fluid significantly
improved the shift from 1st to 2nd, especially at cooler temperatures where
I just couldn't get past a balky 2nd gear synchro when using Type F ATF.
You'll need to purchase two quart bottles to refill the gearbox.  Look for
GM part numbers 12345349, 12345577, or 12377916 at your local GM dealer.
Pennzoil also sells a Synchromesh Fluid that meets these GM specs.  A Google
search on "GM Synchromesh Transmission Fluid" will give you lots of positive
comments on this gear oil.

As previously mentioned, the shifter mounting bushings tend to perish over
time, allowing the remote control housing to drop down and make gear
selection "difficult".  In extreme cases, the bottom of the remote control
housing will rub on the output flange.  You should not be able to raise or
lower the shifter vertically - if you can, it's time to replace the eight
bushings.

One more thing - never flat tow a vehicle with the LT77 five speed unless
the drive shaft is disconnected.  The countershaft drives the oil pump gears
and since the countershaft only turns when the engine is running, you'll
quickly ruin the gearbox due to lack of oil flow to the upper bearings.  I
think Triumph limited a flat tow to less than 25 miles at less than 25 mph.

Tim Buja - Rockford, IL - 80 TR8, 73 Stag, 72 TR6