2.0   Maintenance & Repair

2.1   General

Essential for reference & basic information for operation & maintenance is the owner's manual for the car. These manuals show up often on eBay, & are also included in the CD sold by the Heritage Motor Centre (listed below under Workshop Manuals).

• Haynes Triumph Gt6 & Vitesse Owners' Workshop Manual, Haynes Publications, ISBN 0856966126
• Triumph GT6, 1966 to 1973 (CD-ROM), Heritage Motor Centre, purchase online
• Haynes Restoration Manual for Triumph Spitfire, GT6, Vitesse and Herald, Haynes Publications, ISBN 1859608671
• Triumph Service & Repair Handbook, Clymer publications (First edition, up to 1974 printing, has more information specific to the GT6 than the Third edition printed in 1976.)
• Triumph GT6, Vitesse, Autobooks Ltd., ISBN 085147389X
• The Complete Official Triumph GT6, GT6+, & GT6 MkIII, Robert Bentley, ISBN 0837601207, (contains the factory driver's handbooks & factory workshop manual)
• Stromberg CD Carburettors Owners Workshop Manual, Haynes Publications, ISBN 0856963003

A free service at 1,000 miles from the Triumph dealer was included with the purchase of the car.
The service included many of the items above, plus the following:

2.1.4.1    List of Triumph GT-6 part numbers and interchangeable parts
2.1.4.2    Triumph part number system for fasteners

2.2   Engine

Tools needed: Socket or wrench to remove valve cover bolts Large flat-bladed screwdriver Open-ended wrench for locknut 0.010" (0.25 mm) feeler gauge.

Valve clearances are to be adjusted to 0.010" (0.25 mm) for the stock camshaft.

Aftermarket & performance camshafts usually require different clearances, & sometimes must be adjusted when the engine is hot, so if the camshaft is not original, the camshaft supplier's specifications should be consulted.

Valves & cylinders in the GT-6 are numbered with #1 being at the front of the car. Turning the engine 'clockwise' is as viewed standing in front of & looking toward the car.

With the engine cold, chock the wheels, set the handbrake, put the gearbox in neutral, & confirm that the ignition is off & the key is removed. Remove the spark plugs & rocker cover, & turn the engine clockwise by turning the engine fan.

When the #10 & #12 valves open (are completely down), the #1 & #3 valves will be closed (completely up).

Insert a 0.010" (0.25 mm) feeler gauge between the top of the #1 valve & the rocker above it. The blade of the gauge should drag just slightly. If clearance needs to be adjusted, loosen the locknut around the adjustment screw at the back of the rocker arm, & turn the adjustment screw until the correct clearance is obtained. Hold the adjustment screw in position, & tighten the locknut (this may affect the clearance, so check the clearance again after the locknut is tightened). Repeat to set the clearance on #3.

Turning the engine clockwise, set the clearance on the remaining valves in the following order:

When the #	10 & 12	valves are open, adjust the #	1 & 3	valves
"	2 & 5	"	8 & 11	"
"	7 & 9	"	4 & 6	"
"	1 & 3	"	10 & 12	"
"	8 & 11	"	2 & 5	"
"	4 & 6	"	7 & 9	"

Another way to remember this sequence: When the 1st valve is down adjust the last valve, when the 2nd valve is down adjust the 2nd to the last valve, when the 3rd valve is down adjust the 3rd from the last valve, etc.

When done: Replace the valve cover. Examine & replace spark plugs; remove the wheel chocks

2.3   Carburettors & fuel system

Opinions will vary & performance can be tweaked with dashpot oil selection, but Dexron-II Automatic Transmission Fluid is an easily-available modern oil that will do for most applications.

2.4   Transmission, driveshaft, & rear axle

2.5   Brakes

Tandem brake systems (GT6+ & Mk3) incorporate the brake PDWA (Pressure Differential Warning Actuator), attached to the scuttle in the engine compartment near the master cylinder. If pressure loss is sensed in either of the two lines, a shuttle in the PDWA moves from its central position, closing an attached electrical contact, & activating the BRAKE light on the dashboard.

Sometimes after a brake fluid leak or bleeding, the PDWA's internal shuttle will remain on one side, causing the BRAKE light to stay on. Below is the procedure to re-centralize the PDWA from the GT-6+ Driver's Handbook:

• Fit a rubber tube to the brake bleed screw at the opposite end of the car to that which has just been bled (or had the leak which activated the PDWA)
• Open the bleed screw
• Switch on the ignition (do not start engine). The BRAKE light will glow, but the OIL light will extinguish.
• Exert a steady pressure on the brake pedal until the brake light dims & the oil light glows. (A click should be felt on the pedal as the PDWA shuttle returns to its mid-position.)
• Tighten the bleed screw.
• NOTE: If the pedal has been pushed too hard, the shuttle will move to the other side of the valve, thus requiring the procedure to be repeated on a brake at the opposite end of the car.

If all else fails, the PDWA can be removed, its internal electrical switch withdrawn, & the shuttle manually re-centralised through the opening by pushing the shuttle with a soft instrument. After re-installation of the PDWA, the brakes must be bled.

If rebuilding the PDWA, the correct O-rings material & dimensions are

• EPR EPDM Size 008 5/16OD x 3/16ID x 1/16W

Lube only with brake grease or silicone grease. --Peter Kennison

2.6   Suspension

2.7   Electrical

A hard-to-find variant wiring diagram for late Mk3's with seat belt lights, etc. is here:
mk3-wiring-variant.gif

UK & US values for automotive fuses differ:

2.8   Chassis & Body

Manufacturers such as PaintScratch (http://www.paintscratch.com) & PPG (http://www.ppgcarpaint.com) supply paints to match the original Triumph colors for touch-up or complete re-spray. Matches may not be perfect, due to variations in batches when originally applied, variations in batches at the paint manufacturer, fading, etc.

Be sure to check the paint code on the car's commission plate to be sure it matches the Triumph paint code listed before ordering a manufacturer's equivalent listed.

The nature of the construction of separate body tub & frame makes many accidents & instances of rust less likely to result in a totalled vehicle. However, this construction means that care must be taken in keeping the body straight when it is attached to the frame. There is a risk that the body may distort when mounted to the frame and cause problems with gaps at the door and bonnet, even to the extent of being unable to open or close them without damage.

As the cars become older & acquire a longer history of repairs, it may be more difficult keeping the body tub square with itself, & then not changing that alignment when the body tub is bolted to the frame. Slight distortions of the frame which otherwise are not critical may also contribute to this problem.

The solution is to approach the mounting of the body tub to the frame as the factory did with the Spitfires: Using spacers (if needed) at the body mounting points along with the bushings.

There is a rubber pad at each body mounting point. Over and above this, the factory used washers and spacers to even out the gaps at any given point. There is no hard and fast rule on this, the cars differed widely. People will tell you specific combinations noted when they took their car apart; I've never found two cars with the same combination. The thinner washers, up to roughly 1/4" thickness, have a slot allowing them to be slid into place with the bolt already installed loosely. In extreme cases, packers up to 3/4" thick have been observed; these are usually simple packers with a hole through the centre and no slot. Packing pieces are usually an aluminium alloy, though steel ones have also been noted in the smaller thicknesses. Never be tempted to use multiple rubber pads to take up gaps at these points. As the body mounting bolts are tightened, the pads compress. Extra pads give increased scope for compression, so a perfectly aligned shell can be pulled into a distorted form as the bolts are tightened. - thanks to Bill Davies of Rarebits4classics