This Haynes repair manual covers 1958-1973 Triumph Twin-Cylinder motorcycles, including:

• Triumph 3TA Twenty-One, 348cc 1957-1966
• Triumph T90, 1962-1968
• Triumph 5TA, 490cc 1958-1966
• Triumph T100A, 1959-1961
• Triumph T100SS, 1961-1970
• Triumph T100T, 1966-1970
• Triumph T100R, 1970-1973
• Triumph T100C, 1970-1973

Book Excerpt: 1958-1973 Triumph 350, 500 Twins Repair Manual ENGINE

EXAMINATION AND RENOVATION | GENERAL

1. With the engine completely stripped down, examination for wear can now take place. First clean all the parts thoroughly. It is always a good idea to have sheets of paper laid out on which the parts can dry without fear of them getting dirty again.
2. Examine all the castings for cracks or any other signs of damage, i.e. damage to any joining surface or bearing surface, and where alloy castings butt against each other.
3. Should any studs or threads need attention, now is the time. Care is necessary when removing or replacing them. Castings are sometimes weak at these points. Beware of shearing them off or overtightening which will cause more problems.
4. Where internal threads are stripped or badly worn, it is preferable to use a thread insert rather than tap oversize which weakens castings and sometimes does more harm than good. Most dealers can provide a thread reclaiming service by the use of a Helicoil insert, which is better than the original in aluminum castings.

MAIN BEARING AND OIL SEALS | EXAMINATION AND RENOVATION

1. When the main bearings have been removed, wash them in a petrol/paraffin mix and inspect for wear or pitted tracks. If there is any play in a ball race or if it runs roughly, then replacement is necessary. This also applies to roller bearings. Should the bearings be loose on their shafts or in their housings the use of Loctite Bearing Fix is recommended.
2. Oil seals must always be replaced when the engine is being rebuilt, even if no visible sign of wear is apparent.

CLUTCH

EXAMINING THE CLUTCH SHOCK ABSORBER ASSEMBLY

1. The shock absorber assembly is contained within the clutch inner drum and can be examined by unscrewing the three countersunk screws in the front cover plate. Remove the cover plate using a small screwdriver as a lever.
2. The shock absorber rubbers can be pried out of position commencing with the smaller rebound rubbers, to make the task easier. Avoid damage to the rubbers which may disintegrate in service if they are punctured or cracked. The center ?spider? will be left in position and need not be disturbed unless it is cracked or broken. It is held in position by the nut that retains the clutch assembly to the gearbox mainshaft.
3. Reassemble the shock absorber assembly by reversing the dismantling procedure. Insert the large drive rubbers first and follow up with the smaller rebound rubbers. Fitting will be made easier if the smaller rubbers are smeared with household liquid detergent so that they can be slid into position. It is advisable to keep the rubbers free from oil, even though they are made of a synthetic material.
4. Before the cover plate screws are replaced, smear their threads with a sealant such as Loctite and tighten them fully. It is permissible to caulk the heads in position with a center punch.

Even though this is a repair manual, you can also use it to assist you with a ground-up restoration project. A must-have book for the serious Triumph motorcycle collector and enthusiast. Subject: 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973 Triumph 350, 500 Twins service, maintenance, repair. ISBN-10: 085696137X | ISBN-13: 9780856961373 | Haynes 137