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TR Drivers Club
The National @ British Motor Museum 30th June, 1st& 2nd July, 2017

TR7 BONNET RELEASE PROBLEMS - SOLUTIONS STEP BY STEP.

Problem 1. Bonnet will not open and bonnet release cable will not fully pull to its normal release length about 25mm. The Bonnet release cable sheathing as been trapped with the removable Air intake chamber (Plenum) which fits to the bulkhead. This was most likely removed / refitted prior to bonnet been closed.

Solution 1 A good torch is required to shine on to the bonnet release assembly. This is to allow you to see the movable post slider on the bulkhead catch, which requires pushing towards the fixed anchor post. This is achieved by using a long narrow screwdriver inserted through the centre bonnet centre grill. Taking care not to damage the paintwork. Remember to release the trap cable from Air intake chamber before closing bonnet. For total peace of mind, fit a suitable sized P Clip holding the bonnet release cable clear of entrapment in the future.

Problem 2 Bonnet will not open again but the bonnet release will fully open to normal length. This most likely happens after refitting / adjustment of the bonnet to eliminate free movement of the bonnet / alignment. The end cap top edge had locked into the side slot of the bulkhead bonnet catch not allowing the plunger to spring up when the bonnet release handle is used.

Solution 2 This requires the gently removal of the centre rubber strip fitted to the lower windscreen bottom tray lip which forms a seal to the underside centre of the bonnet. You will see the tray lip as been lowered, from the centre cut out to allow access of a ring spanner. I have also noticed the lowered cut length is shorter on the early TR7 cars and is twice as long on the later cars allowing more rotation of the spanner. This is to gain limited access to the under side of the bonnet plunger fixing bolts 13mm, which hold the assembly to underside of the bonnet. You will require a 13mm ring spanner which as a angle shaft similar to the profile of the windscreen and the spanner may require bending slightly upwards to achieve correct profile. With use of a good torch plus trail and error you will locate the spanner onto the bolt head. Un-tighten the two 13mm bolts turning the spanner clockwise looking from above. This will release the tension / misalignment problem, locking the bonnet shut closed. To assist this slow process I recommend you fit a two / three cloth pegs as appropriate to keep the bonnet release cable fully open. The bonnet should be pulled gently upwards without any side ward movement to release the trapped plunger at intervals when releasing the two bolts to save completely releasing the two bolts. Members with early cars not worried by total originality can lengthen lowered lip for possible future troubles.

Proposed trouble free alignment process

On my TR7 the best solution in fixing this above problem was to leave the Clothes pegs holding the Bonnet release cable out and with the Bonnet plunger spring / end cap removed allowing better viewing of plunger entering the catch hole. This allowed me to see the required direction too move the bulkhead or catch plunger assemblies to give the best trouble free movement in the up / down direction without catching the n/s or o/s of the hole. After achieving this good alignment, refit the spring / end cap. The final adjustment is the plunger length will require adjustment to eliminate free movement of the bonnet and a good process is to start too long and gradually reduce the bonnet movement.

James Johnson.

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