Triumph TR6 Servo and Repair Kit

Triumph TR6 Servo and Repair Kit
All servo repair kits include the following; seal & plate assembly, dust cover, dust cover retainer and filters. The major repair kit also includes the bayonet type non-return valve and O Ring seal. None of the repair kits include the main diaphragm seal.Construction and design of the servo fitted to the TR6 has changed since production commenced. There are two areas that will need to be observed if the correct repair kits are obtained and used. These items are the servo air inlet non-return valve attachment and the push rod seal between the servo and the brake master cylinder. The servo air non-return valve can be either a bayonet fitting sealed with an ‘O’ ring or a push-in type valve with a serrated sided seal area that fits into a grommet in the servo. The other change that is not so easy to see is the seal between the brake master cylinder and the push rod that it acts on in the servo. The easy identification for this is whether the seal is supported in a metal disc or it is a cup shape with groove grooves in it. The latter is also identifiable by a series of parallel knurls on the shank of the push rod.
The servo serviced by 12446 is quite rare and to make matters worse it was not allocated to any particular chassis numbers. The difference between the two types of servo is internal so the servo must be dismantled to ascertain which one of the two is fitted. If the master cylinder is removed from the servo, the outside face of the seal and plate assembly will be visible through the aperture to facilitate easy identification. The actual difference is that the master cylinder end of the valve push rod and the servo requiring kit 12446 has a 3/8 diameter and parallel knurled rod. Those requiring 18G8951A are diamond knurled and are 5/16 diameter. The correct seal for the 3/8 pushrod has 6 radially moulded ribs to identify it. (See illustrations A and B)
The servo unit may be fitted with metric threaded studs to attach the brake master cylinder. When installing a new servo ensure new nuts of the correct type are obtained with the servo to save difficulty when installing because of not having the correct fasteners.