Triumph TR6 Reconditioned Exchange Gearboxes
Reconditioned exchange gearboxes have different specifications to match your vehicle. Whether you exchange your old gearbox for a reconditioned item, or attempt a rebuild or repair yourself, you must first establish the exact type of gearbox which you currently possess in your car. The gearbox number is always stamped on one of the lower corners of the bell housing: usually the lower left hand corner, adjacent to where the clutch operating cross shaft protrudes. Genuine Triumph TR6 gearboxes were numbered with CD, CC, or CF prefixes; these prefixes and the subsequent serial numbers bore little relationship to the commission (chassis) number of the car. To further compound the lottery of what might be fitted in your car, gearboxes from other Triumph sports and saloon models could be fitted directly or adapted to fit - and frequently were. The most commonly discovered anomaly on TR6’s is fitment of the overdrive gearbox from the Triumph ‘Large Car’ 2000/2.5 saloon range. Such fitment does however involve an amount of adaptation on the gearbox, chassis, and clutch. Original factory exchange reconditioned units were numbered with the prefix GR and a suffix of /7, and can be identified by these markings.
‘A’ type overdrive gearboxes were fitted between 1969 and 1972 with the overdrive operating on 2nd, 3rd and 4th gears. They are quickly identified by having a 2 bolt fitting solenoid and large brass sump plug on the overdrive.
‘J’ type units were fitted between 1973 and 1976 with overdrive on 3rd and 4th only. The overdrive has a screw-in type solenoid and finned sump (6 bolts).
Units returned for the exchange reconditioning scheme should as a matter of course be completely assembled, drained of oil and externally clean, with no obvious visual damage. In addition, they should be of identical type to that supplied. Please contact us to determine exactly what is required in return as an exchange old unit (i.e. less clutch operating ancillaries, adaptor plates etc - see also ‘Specification’). Note that non-TR6 old units will incur a surcharge.
NOTE: We can also offer a customer own unit reconditioning service. Particularly useful when we have no unit available off the shelf due to a lack of old core.
Specification - Reconditioned Exchange Gearboxes & Overdrives
Exchange reconditioned gearboxes are fitted with new bearings, seals, gaskets, synchro rings, countershaft and have matched internals. All units are fitted with the top cover/selectors but please check that this is compatible with the unit removed from the car (i.e. switches / wiring etc). You may need to swop over top covers. Please note that the gear lever, wiring, switches, clutch cross shaft, fork, release bearing carrier, adaptor plate (O/D) and rear extension housing (non O/D) are not supplied with our units - again you will need to transfer over from your old gearbox.
Exchange reconditioned gearbox and overdrive assemblies are as above supplied less overdrive solenoid, output flange and any mounting bracketry.
Special Note: ‘A’ type units
Depending upon availability, the type of overdrive annulus fitted may differ from original necessitating re-calibration of speedometer.
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. TR6 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 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 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 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 pre-73 car 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 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 TR6 gearboxes.)
7 A non-overdrive gearbox requires 1.13 litres, ‘A’ type units 2 litres and ‘J’ type units 1.5 litres of hypoid 90 gear oil (GGL190/0.5litre).
8 A J-type overdrive does not require a relay in it’s wiring system, so don’t try and fit one. The holding circuit is dealt with by the solenoid internals.