Gearbox Guide - Page 4

Last Updated on November 04 2024

How to reduce the play and friction in a front wheel drive gear linkage.

I devised this solution in 2004 after I'd fitted a B&M short shifter #45096 bought from summitracing.com. I was still concerned about 'play' in the gear lever mechanism. After closer examination, the two universal joint connections in the gear linkage were identified as the source of the movement. So I set about re-working the joints. Read on...
What you need to do is replace the pairs of plastic top hat bushes in the universal joints, with ball raced bearings bought from rswww.com. Using lengths of 8mm diameter steel bar, tapped with M8x1.25 threads on the ends to hold the bits together, the modification can be made in a couple of hours, and makes a world of difference to the gear change. The photo's below show what's involved.

Summary

There should be no play whatsoever in the gear linkage. Not even any side to side play when you rest your hand on the gear lever. A very worthwhile modification, and it only costs around £20 including the cost of the 1" M8 die and the four bearings. The gear change is now much smoother too, due to reduction in friction from using bearings on the joints instead of plastic bushes.

Step by step guide

Using a 10mm drill, remove the head from the pin on the Fiesta gear linkage Using a 10mm drill, remove the head from the pin on the Fiesta gear linkage.
Gently drift the pin out of the linkage using a hammer and a suitable punch Gently drift the pin out of the linkage using a hammer and a suitable punch.
Remove the top hat bushes, and check out the wear on the pin Remove the top hat bushes, and check out the wear on the pin.
Clean the UJ and press the bearings in to the housing Clean the UJ and press the bearings in to the housing.
Tap 1cm of thread on to the end of the steel bar, before cutting it to length Tap 1cm of thread on to the end of the steel bar, before cutting it to length.
Feed the bar through the universal joint to determine the length of the bar, and cut to size Feed the bar through the universal joint to determine the length of the bar, and cut to size.
Tap the other end of the bar, and double check that it is the right length etc Tap the other end of the bar, and double check that it is the right length etc.
Refit the two sections of the linkage together, and tighten the nyloc nuts Refit the two sections of the linkage together, and tighten the nyloc nuts.
Repeat for the other half of the linkage. Push the bearings in to the selector shaft. Repeat for the other half of the linkage. Push the bearings in to the selector shaft.
The reassembled linkage, with both sections now housing bearings The reassembled linkage, with both sections now housing bearings.
The reassembled linkage, with both sections now housing bearings The reassembled linkage, with both sections now housing bearings.
The linkage reinstalled on the gearbox The linkage reinstalled on the gearbox
The linkage reinstalled on the gearbox The linkage reinstalled on the gearbox
Finally to reduce the noise in the car, you should fit the B&M shifter using these rubber insulators (cylinder mounts). It makes a huge difference. The shifter assembly bolts directly to the floor, which means firstly when the engine and gearbox rock, the linkage is put under a lot of strain, and secondly all the vibration from the engine is transmitted along the linkage in to the floor of the car which makes the car extremely noisey and unpleasant to drive. These cylinder mounts definitely do the trick by isolating the noise created by the solid mounting of the gear linkage.

Parts required

25cm of 8mm diameter steel bar (preferably stainless steel).
Four M8 stainless steel Nyloc nuts

Supplier - rswww.com
540-299 Radial ball bearings (4 required), flanged 8 x 12mm, order 2 packets
237-1966 Cylinder mount (4 off), 20mm x 15mm, M6 x 18mm, order 1 packet
183-2965 M8 x 1.25 Die (for cutting the threads on the 8mm shaft)