Control Systems
a) 928S4. '87 MY onwards, manual and auto. Including GT (manual) and GTS (manual and auto).
They employ two accelerator cables, one from the pedal to control linkage assembly on the LH side of inlet manifold and another from this linkage around the back of the inlet manifold and under the manifold to the throttle linkage. On this cable the inner cable does a 90-degree turn via a nylon wheel with a semi-sealed ball bearing in the centre that can get notchy. It is 'greasable' if removed and the dust cap also removed, but the main culprits for a heavy accelerator pedal action are the two accelerator cables themselves. They simply wear out.
What a difference it makes when they are replaced as the accelerator will now perform as new, making the engine (appear) more responsive and much more pleasant to drive. The cable assembly from pedal to linkage assembly starts with a '927'-part number (for RH drive parts) and the other cable has a '928'- part number as it suits both left and right hand drive vehicles.
b) That is all very well if it’s a 5 speed, because that’s all there is but if it’s an automatic, the kickdown cable from where it takes up on the engine, all the way along the torque tube and onto and into the Auto Trans can also cause grief at times.
Remember, like the accelerator cables used on the 928 from '78 to '86 MY, the design and part numbers were changed quite a few times, through improvements or massive design changes. For example the 928S '86 MY Australian model, which for us was the last of the original shape car but with the new 5 litre, 4 cam, 32 valve engine. Due to the design of the inlet manifold etc. the control linkage is at the front of the engine, which means only one accelerator cable. Naturally this cable only fits this MY but also there are different cruise control and kickdown cables just for this model.
I recently had in the workshop a '86 MY with a heavy and notchy accelerator action and it was in this case caused by the kickdown cable. The only problem was of course accessibility. Luckily I had to remove the auto trans. Anyway because of an oil leak from the front pump area. This allowed the torque tube to be moved enough to fit and secure the new kickdown assembly in place and I mean assembly because it’s in its own metal conduit that secures to the top of the torque tube. On the sides of the torque tube are the auto trans cooling pipes and auto selector cable as well, all held in their respective clips and clamps.
In the end changing this cable made a huge difference not just to the accelerator action but also gear selection because the old cable was sticking causing a delay in the kickdown operation. The owner told me the vehicle now feels more responsive even quicker. Perception is reality. Remember we are only talking cables here. This applies to all 928 models in varying degrees.
Buchanan Automotive
Unit 2/2 Paton Pl, Balgowlah NSW, 2093
(02) 9948 2651
|
