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TR4 front suspension Trunnion 3 caster type Left Hand using a conical seal. If the pin only is required, this is available separately. Order parts number 101539

For a bush kit order 101557K. The pin through the trunnion is available separately, order part number 101539 and we have large stocks of good second hand trunnions with pins fitted 133839SH. These trunnions have the top machined to accept the conical seal which was introduced during late TR4 production (roughly when 3º caster was introduced) and continued right through to the last TR6.

Fitting Tips

The swivel joint between the vertical link and lower trunnion on TR2-4 front suspension is a critical safety area and should be examined with care periodically when servicing and in detail when the suspension is being worked on. To determine if the joint is acceptable, the following tips will help. 
  1. When dismantled, clean the components thoroughly and visually inspect. If there is physical damage of any sort, replace the components.
  2. The trunnion has a hardened steel pin that the lower wishbones swivel on. If this is corroded it will need to be replaced. Order part number 101539. These reproduction parts (and when they are supplied assembled into trunnions) are usually supplied without drillings for split pins to secure castellated nuts so self-locking nuts need to be used and will need to be ordered too. The part number is NV607141.
  3. Minimal rust pitting on the vertical link thread is acceptable as this will, once cleaned, in fact hold grease and not affect operation, excessive corrosion will mean the vertical link will need to be discarded.
  4. To check if the relationship between the trunnion and the vertical link is within serviceable limits, screw the two together to their operating engagement without the seal and measure the 'wobble' at the top of the vertical link. Up to 3mm is acceptable. More important is to establish if there is any vertical play. This can be established by inserting a screwdriver between the trunnion and the vertical link and levering the two apart. Any movement is unacceptable.   
  5. New parts are available, vertical link 201803 and various trunnions. 101557 flat top 0°, 101557X conical top 0°, 133838 RH 3° and 133839 LH 3°. All are available second hand (same part numbers with the suffix SH) which can be useful for selective fitting. Given that reproductions are invariably made as copies of original parts and not to original drawings, it is not surprising that fit varies with various parts from different manufactures, even if the supplier is the same outfit. It follows then that selective fit is important. Two new parts may not fit together at all, and what seems like a worn trunnion may be a perfect fit on a new vertical link.
  6. We are aware of a negative camber vertical link on the market. We do not approve of this product as it ignores some basic facts about the suspension. The relationship between the camber of the wheel and the king pin inclination is a fixed dimension, specified by cleverer people at Triumph than us. The negative camber vertical link changes this which cannot be good for the suspension geometry. Also, it would be unwise to only use one, so the cost of two would need to be borne.  In addition, the negative camber vertical link does not allow any adjustment to cater for variances on a 60-year-old car. We prefer to use our camber adjustment kit RTR3112K which allows you to retain your original vertical links and set the camber to standard or negative as you wish. Early cars will need other components too as the kit is intended to be used in conjunction with 3° trunnions. This kit also introduces another improvement in the shape of a change to the virtual swing axle dimension, allowing the car to roll into the ground rather than out of it, an additional improvement to road holding and braking efficiency. Not surprisingly, the upper fulcrum adjusting kit forms part of our integrated suspension packages, the most common are RTR3105PK for TR2-3B and RTR3147PK for TR4. More information is available if this is a subject you are interested in, an information sheet is downloadable HERE.

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