Gearbox Oil Capacities:
Gearbox non overdrive - 1.13 Litres
Gearbox with overdrive - 2 Litres
Certain simple inspection routines can be carried out to ascertain what type of (or level) of repair may be required to your gearbox. The primary requirement of anything mechanical is of course the correct amount of a suitable lubricant. TR gearboxes are less robust in certain bearing areas which means lubrication is all important.
1. New or unusual noises from the gearbox may mean the failure of an internal component has occurred. The favourite is a knock or rattle in first, second and third gears; this usually indicates the failure of the countershaft (layshaft) bearings.
2. Drain the gearbox oil into a clean container and look at the oil and what may have come out with it.
a. If oil has moderate brassy look this is normal.
b. Pieces of brass denote broken synchro rings or bushes.
c. If the oil contains grey coloured lumps, remove the gearbox top cover and look for obvious damage to gears. The grey sludge invariably indicates the countershaft (layshaft); countershaft gear and bearings have collapsed.
The fitment of a magnetic drain plug will guarantee a heart attack every time you remove it! It will also enable you to assess the amount of ferrous sludge in your gearbox. The overdrive unit should have a magnetic washer inside the large brass drain plug.
3. While inspecting inside the gearbox with the top cover removed, check the end float of 2nd. gear; If 2nd gear play exceeds 0.020”, suspect its thrust washer has broken. This can eventually destroy the gear and mainshaft if not attended to.
4. After reinstalling a gearbox and refilling it with the correct quantity and grade of oil, test-drive the car before refitting tunnel or trim.
There is nothing more depressing than having to disassemble the interior of the car to re-attach the reversing lights wiring that you forgot and now the reversing lights do not work.
5. A useful tip to aid with installing a gearbox on a 6 cylinder car is with the gearbox flush with the engine backplate, and hanging off the 3 5/16” studs at the top, to ensure the 2 dowel (or place) bolts are fitted prior to fitting or tightening any of the others. These are 2 bolts (3/8" UNF) which fit opposite each other at approx. 2 o'clock and 7 o'clock. Their purpose is to align the engine to the gearbox on 6 cylinder cars and such is their fit, they may require driving into place. Misalignment of the gearbox and engine may produce any one of a number of clutch problems which are dealt with in some detail in the clutch section, so careful installation of these bolts is paramount, before going on to look for other 'erratic' clutch cures.
6. If you’ve got a 4 synchro gearbox and would like a higher 1st gear (giving a closer-ratio gearbox), the time to change is when rectifying the failed layshaft, which will probably have damaged the existing laygear in addition. Simply substitute UKC662 laygear and 152803 1st gear (from the post-73 TR6 gearbox) for the existing pair. You could even go the whole way and fit that close ratio gear set you always dreamed of but never had an excuse for before. (RR1512 fits all synchro gearboxes).
7. Don’t forget! A standard gearbox requires 1.13 litres and an overdrive type 2 litres of oil.