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Modification Modification
Car: Ford | Fiesta | CX (Mk3) | All Derivatives | Hatchback

Puma Gear Linkage Conversion

The Mk4/DX was launched with a linkage travel reduction of around 20% comapred to the Mk3, and when the Puma came along this was cut to approx 50% which makes a big difference to the driving experience. The same linkage also went on to be fitted to the Mk5 Zetec-S Fiesta. I have successfully retrofitted the Puma linkage to two Mk3 Fiesta's and this article will explain how.

The Puma linkage has a left-handed stabiliser bar where the Mk3 has right hand (IMG 3022) but I have found that this does not have any implications for fitment into a Mk3. The Puma linkage has been redesigned to improve NVH and location during engine movement; I've had a few occasions during hard driving in a Mk3 where it has been hard to select or engage a gear and this is down to the semi-rigid mounting of the gear lever. The Puma linkage has freedom of fore/aft movement within a rubber isolator.

BC vs iB5 Gearbox

I don't whole heartedly recommend a Puma gear linkage on the BC gearbox. While fitment is entirely possible I've found from experience that down changes, especially in to third, can be too swift for the BC Synchros resulting in a slight crunch. The Standard Mk5 linkage is a safer bet. The BC gearbox also does not have internal Neutral Return Springs – it is located within the gear linkage. The iB5 does and because of this the Puma linkage is without a spring. If you wish to fit the Linkage to the BC 'box then follow my guide at the bottom of this article.

information

Synchromesh

Synchromesh are additional cogs on the end of a drive gear which help match input (engine) speed with the output (wheel) speed. During the gear change process the Synchros will engage just before the drive gears, and due to their wide teeth spacing they can match more quickly with another synchro which is rotating at a different speed. The Synchros in the BC family gearbox were improved with the first Ib5, and this is noticeable in shift quality. Further revisions took place right through to the Ib5 in the Mk6 ST150. Synchros determine shift quality and are also one of the factors in determining how quickly the gears engage.

"The standard synchro mechanism that comes fitted to most vehicles can be improved by modifying the existing synchro ring or fitting an aftermarket one that has larger radial grooves. This lets the gearbox fluid flow more quickly out of the sandwich situation we've mentioned above. "

Purchasing

The linkage can be bought second-hand and taken from any Puma, or Mk5 ZS Fiesta. I fit new ones to ensure that the bushes and linkage are in perfect condition, price is around £125 from Ford which sounds expensive, but is cheap compared with after-market alternatives!

Fitting

Remove the Centre console & rear mounting bracket if fitted to gain access to the top side of the Mk3 Gear Linkage (IMG 3018) . The linkage is bolted through the bottom of the exhaust tunnel, and secured by 4 M8 nuts on top of a reinforcement plate, remove these 4 nuts along with the reinforcement plate and rubber gaitor. Next, under the car, slacken the 13mm pinch nut on the linkage rod, and the 19mm bolt securing the stabiliser rod. If you have a Catalytic Convertor Equipped vehicle you will need to remove the front Exhaust heat shields. The linkage can now be dropped down from under the car.

The Puma gear lever is positioned slightly further back than the Mk3 linkage (IMG 3108). Go back inside the car and notice that the gear lever mounting holes (4 of) are elongated holes approximately 15mm long, and between the rear pair there are two hexagonal cut outs (applicable to Automatic) . Starting from one of the rear pair of mounting holes cut a line from the rear most edge across to the rear edge of the first hexagonal hole, then across to the rear edge of the next hexagonal hole, and across to the rear edge of the next mounting hole. Now cut forward from the rear mounting holes to join up to the gear lever aperture. Removing this metal will have the effect of extending the gear lever aperture backwards by approximately 10mm thus providing clearance for the Puma linkage.

Now bolt up the Puma linkage to the gearbox (note that if it is a brand new linkage they come with a locking pin which keeps them in 4th gear) and push it up inside the car.

Mounting the gear linkage requires 2 pairs of M8 x 30 nuts, bolts and washers. Get a feel for where the mounting bracket sits under the car, then go back inside the car and you will notice there is a stamped 12mm recess either side of the exhaust tunnel and these are the exact places to drill with a 10mm bit. Apply grease to the exposed metal and bolt up the linkage making sure that the mounting bracket/bush sits half way along the slider (IMG 3124).

Next, extend the original linkage cover plate forwards by the same amount that was removed from the exhaust tunnel, so we can cover the larger aperture and use the original front mounting holes to fasten the plate. The plate is necessary for 2 reasons: 1) It provides an anchorage point for the rubber dust gaitor and 2) it fits snugly over the gear linkage foam to provide a barrier to the elements. I welded 1mm steel plate to the front edge of the plate and drilled 2 holes that line up with the original mounting holes on the exhaust tunnel (IMG 3110). Finally drill 2 new holes in the exhaust tunnel behind the gear lever aperture using the plate as a guide. Seal the bottom of the plate with Silicone sealant and bolt or rivet in to place.

IMG 3114 shows the complete installation minus the dust gaitor and centre console. Note the extended plate and O/S mounting bolt head near the carpet. IMG3120 shows the installation from underneath the car, minus heat shields. Note that some slight heat shield tweaking is required to clear the rods

Fiesta Si Restoration and 2.0 Conversion3022
Fiesta Si Restoration and 2.0 Conversion3018
Fiesta Si Restoration and 2.0 Conversion3108
Fiesta Si Restoration and 2.0 Conversion3110
Fiesta Si Restoration and 2.0 Conversion3124
Fiesta Si Restoration and 2.0 Conversion3114
Fiesta Si Restoration and 2.0 Conversion3120
© Mark Stewart, Thursday 1st April 2010
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