Tech Tips

Failure of Electrical Grounding Circuits
Horn Button & Pressure Oil Switch
 Triumph TR6 

If the oil pressure light, brake failure light and horn
 fail to function with the ignition key in the "on" posi-
 tion, the electrical grounding circuit for these items
 should be strongly suspected. (This defect may also
 occur only with the side-lights or head-lights ener-
 gized.) 

All of the above circuits share the same grounding
 connection which can be found in the in the wiring
 harness in area of the left hand front grill/ apron. 

Identifying wire insulation colour is black. There is a
 Lucas sleeve-style gang connector that shares an in-
 corning ground wire with the head-lamp, side-lamp,
 and circuits from the horn button and oil pressure
 switch ground. Corrosion of the sleeve connections 

results in a high electrical resistance and inability of
 the current to pass to ground. 

Correction is through replacement of the sleeve con-
 nector and cleaning up of the Lucas"bullet" style nip-
 ples. 

Eye-Bolt Seizure In   Chassis Tube
Rear Leaf Springs
 Triumph TR2, 3, 3A, 3B & 4 

When undertaking a   "body off" restoration on the
 above models, , it is prudent to ensure that the rear
 spring" eye-bolt" that goes through the chassis tube is
 both completely free and generously coated with an
 anti-seize compound. 

The head of the "eye-bolt" has in internal drilling that
 is threaded for insertion of a bolt withdrawal tool.
 However, severe seizure conditions require Oxy-
 Acetylene equipment to assist removal. 

Seizure of this "eye-bolt" in the chassis and/ or spring
 eye will not allow replacement of the rear leaf spring
 on TR2, 3, 3A or 3B due to insufficient room between
 the threaded section of the bolt and the underbody
 sill/rocker panel for the spring to clear. (On TR4
 models there is just enough room to clear the bolt and
 replacement can be effected. However, replacement is
 much easier if the "eye-bolt" is free in the chassis). 

Poor Performance & Hard Starting
Low HT Ignition / Coil Spark Voltage
 All Models With Ballast Ignition Systems 

Many enthusiasts in the search for better engine
 performance install a Lucas model 101B "Sports"
 coil. However, on a ballasted ignition system such
 as fitted to later Triumph models, it is imperative
 that the original coil be substituted only with one
 that is compatible with the ballast circuit voltage
 of 6Volts. These coils are generally stamped with
 6V on the coil base and will state on the label, "use
 only with ballasted systems". The Lucas "Sports"
 coil is designed for non-ballasted 12V systems and
 perform poorly at the ballasted circuit voltages of
 6V -7V. 

When replacing   coils ensure that the correct polari-
 ty is observed and be cautioned to pre-1965 mod-
 els having battery polarity reversal. (IE: positive
 ground vehicle circuit changed to negative
 ground). 

Carb Mixture Adjustement
All S.U. & Stromberg Carbs
 All Triumph Models 

Before any attempt is made to adjust the mixture
 on either S.U. or Stromberg carbs, it is of the ut-
 most importance that there be fresh fuel in the tank
 and throughout the fuel delivery system. Adjust-
 ing fuel mixtures following winter or long term
 storage can be an exercise in futility due to the loss
 of "higher-end" fuel aromatics resulting in poor
 combustion/fuel burn characteristics. 

It goes without saying that the ignition system and
 timing must be in good order, engine at operating
 temperature, no leaks in the induction system and
 carbs correctly balanced before attempting mixture
 adjustments. 

Electrical   Fires/Short Circuits
Accessory Wiring 

All Models 

Whenever connecting   an electrical accessory, al-
 ways install an "in-line" fuse as close as possible to
the live connect point. Avoid over-fusing.