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Murena gear shift linkage

Improvement of the gear shift linkage in Murena is a frequent subject for discussion among Murena owners. This article explains how the system works so that it can better be restored.

How the system works

The gearbox is mounted traversely to the left side of the engine. Shift control rod is in the top of the gearbox.

This picture is the diagram shown in the service manual for the Murena:

Gear shift linkage in Murena

The arm G sits on top of the gearbox and is connected to the rod inside the gearbox which puts the syncros in the gears. There are three selector forks in the gearbox: One for 1-2, one for 3-4 and one for 5-R. These selector forks are mounted on rods with lockout mechanisms in between so that only one rod can move out of the neutral stage at a time. The following picture shows the inside of a Citroen CX gearbox (identical to the Murena gearbox):

Citroen CX / Murena gearbox internals

In the picture, the part that is near to the photographer is the top of the gear box. Visible to the right is the differential housing. In the lower front of the picture, the opening for the clutch mechanism is visible.

The yellow arrows show how the selector forks move. They are controlled by the three little forks visible by the red arrow. The connecting rod from the outside is not present in the picture.

The connecting rod moves up and down from the neutral position. Moving it up (towareds the photographer in the picture), makes it operate the 1-2 gear selector fork. Leaving it in the neutral position leaves it connected to the 3-4 selector fork, and moving it down, connects it to the 5-R forks. There are two selector forks for 5 and R - in the picture, the 5'th gear is removed completely, and should sit on the top of the main and secondary shafts. The connecting rod (C in the diagram) is spring loaded to ensure that neutral is the middle (3-4) position.

The gear shift lever L pivots around a ball in the floor of the cockpit and is connected to a control rod B that goes under the car to the back of the engine compartment. This rod transmits the movements of the gear lever to the engine room. The rod is fixed to the gear lever at the bottom so that the gear levers movement from side to side rotates the rod B, as well as moves it from side to side opposite to the handle. The rod pivots arouns the joint I and is bent so that it goes clear of the chassis.

Gear shift linkage in Murena

The link A transmits the sidewards/rotational movement onto the link D and the L-shaped link E. This link is mounted on the side of the gearbox in a way so that it can rotate, meaning that the sidewards movement of the rod D is converted to an up/down movement of the rod F. F is then connected directly to the control rod going inside the gearbox.

This way, the sidewards movement of the gear shift rod is converted to the up/down movement of the selection rod inside the gearbox.

The other direction of movement (forward and back) forces the joint I forward and back in a similar way. The rod H is fixed to the chassis and can rotate. It is rotated by the longitudal movement of the gear stick. J converts this into a sidewards movement of K, which again converts to a rotation of the rod going inside the gearbox.

Typical wear and how to improve

Weak points in the system are:
  • The top-hat bush at the bottom of the gear stick connecting it to the main rod B. Wear in this bush will distort the transmission of the sidewards movement of the stick to the sidewards/rotational movement of the main rod quite severely. It has to be a tight fit. Wear in the bush will not affect the front/back movement as much.
  • The pivot point on the L-shaped link E becomes worn.
  • The joint I becomes worn.



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Page updated: 2006-06-08 19:14:31