*HOW TO* Modify and fit a "quick shift" linkage to smaller engines.
Quick shift gear linkage guide:
This is a guide for modifying and fitting an aftermarket quick shift gear linkage arm, designed for a GTE/GSi Nova to a 1.2/1.3/1.4 box (F10 )
*Firstly the usual disclaimer: This requires sacrificing your old linkage arm so I can’t be held responsible for you cocking it up, or anything like your arm/leg/head/life for that matter!
You’ll simply need:
- Hacksaw – Metal file – a vice – a heavy hammer – your old linkage arm – a suitable piece of tubing – and the other tools for removing/ refitting the linkage; this will be described in the Haynes manual so refer to that in conjunction with this.
The Theory; Why it’s a better idea to buy and modify one rather than try and modify your original one from scratch:
The gear linkage arm serves to transfer motion from the long rod that the gear stick connects to (remote control rod), to the gear selector/actuating arm on the gearbox. There are two main motions involved. First, the rotation of the selector arm which we are less concerned with in this case. Second the pushing and pulling of the selector arm. This engages/disengages the gears and it is this motion that we want to make shorter for us at the gear stick end:
Dig 1:
With reference to the diagram above depicting the new aftermarket linkage arm; The linkage arm moves about a pivot E. To make shifts faster, movement at A needs to be less and the resultant movement at B more. There are two ways to achieve this. Either shorten distance C or lengthen distance D.
You could shorten distance C on your original linkage arm as some have suggested in the past. However, this will have to be very accurately re-welded to avoid having to set the linkage up as a compromise rather than in the orientation as intended by the manufacturer. The linkage actuating rod would also be operating at a different angle and more force would be going into the linkage both resulting in more stress on the area, which you want to be reliable when you’re throwing it forward through the gears.
This is why the new linkage is much more substantial, to the point where holes could be drilled for those especially conscious of weight (though not recommended). It also takes the route of lengthening distance D which avoids the problems of shortening distance C. However, this creates another problem that is more easily solved:
WHAT TO DO:
- There are four problems that need to be addressed:
1) Increasing the range of motion of the universal joint:
In lengthening distance D, the linkage arm now operates the gear selector arm with a greater amount of movement. Therefore the universal joint that connects the two needs to be given a greater range of motion. This is done by simply filing away the two nylon motion limiting tabs seen below in dig.2:
Dig.2
Test the motion to ensure the universal joint can now accommodate the movement of the new linkage arm when it is offered up to its location.
2) The Pivot: If you are having a problem fitting your aftermarket linkage arm you’ll find the pivot hole much larger than the original.
Dig.3
(NB: READ BOTH A AND B BEFORE YOU CUT ANYTHING AS YOU NEED TO MEASURE THE OLD LINKAGE FOR YOUR SPACERS BEFORE YOU DESTROY IT!)
A) The way I overcame this is to sacrifice the pivot shaft AND bush of the old linkage as it fills the new pivot hole perfectly. This is a simple matter of cutting it out of the old linkage arm. Leaving a slightly imperfect surface behind is a good idea to ensure that it is a snug fit in the new linkage arm, yet not so snug that you damage the bush when you tap it in. This may take a bit of trial and error.
B) You now need to make and add some spacers to ensure that the new linkage arm sits at the correct height on the old pivot shaft. Measure the distances (A and B) between the top and bottom of the old pivot shaft and old linkage arm:
Dig.4
Clearly the aim is to get the new linkage to sit at the same height on the pivot as the old one. To make the spacers I used some old carbon fibre handlebars from a bicycle but you can use any piece of suitable tubing:
Digs.5+6+7:
3) Next we need to put a suitable bend in the new linkage arm near the ball joint that connects to the remote control rod. This can be done on a vice with a large hammer, hammering though a block of wood to protect your linkage arm.
The picture below shows both old and new linkage arms as they would be positioned in the car as if looking along a horizontal plane (crouching) from the front of the car:
Dig.8
Simply “manipulate” the linkage until the new ball of the ball joint (circled blue) matches the orientation of the old one (circled and represented by red).
4) Increasing range of motion of the linkage arm:
Finally and most simply we need to increase the range of motion of the linkage arm itself by cutting off a prominent corner. Otherwise the linkage arm will not rotate enough to fully engage 2nd and you will ruin your gearbox (as I nearly did). Simply remove the material in green below:
Dig.9
Now test to ensure it can move freely when located in the engine bay. i.e it can now rotate clockwise where the material you have removed was previously impeding this.
You may also like to apply some corrosion protection (paint) to the cut area you have now exposed (and the part where the plate meets the pivot shaft, as this commonly corrodes due to the weld)
And there you have it: FINISHED (almost); simply fit and adjust your new linkage assembly as in the Haynes manual and go test the mutha!
Copyright: beavy69 2006
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Originally Posted by denten91
