Changing the 6 speed saddle bush

[Andy135]

Last night I changed the saddle bush in the 6 speed gearbox from the standard nylon to the sintered brass version (here). The gearbox has only done 5k miles, but occasionally I found the change from 2nd to 3rd was easier to miss than it should be, so the quick shift was taken off and given a good clean and the new saddle bush went in at the same time.

From this:

 

To this:

After a static test I still have all six forward gears plus reverse. Yet to test drive it, but will post back my findings when I do.

The nylon bush itself is shaped to clip round the selector shaft - easy to fit but like wrestling with a greased pig to remove. I found that by rotating it 90 degrees I could get the flat of a screwdriver across both legs of the clip and ease it off past the selector shaft. Then a long handled artery clamp was used to gently lift it out. The brass one was fitted onto the forks of the quick shifter before the shifter/bush assembly was lowered onto the selector shaft.

If anyone else is thinking of doing the same, I found that the most time consuming part was winding back the white nylon handbrake adjuster knobs in order to remove the tunnel cover - with limited fingertip access it takes longer than it should unless you have access to a ramp.

[John Vine]

Very interesting.  Thanks for posting.

The brass one was fitted onto the forks of the quick shifter before the shifter/bush assembly was lowered onto the selector shaft.

The Burton link you provided says:

"Made with elongated ears which must be crimped when fitted."

Did you crimp yours?  If not, I guess there's a risk that the saddle could become dislodged?

Also, if you haven't already done it, this would be a good time to consider a gaiter around the Quickshift to keep road crud and water out.  For details, see this Guide.

JV

[Andy135]

No, I didn't crimp the bush onto the selector shaft. It didn't seem prudent to crimp the sintered brass, fearing a fracture. A test fit of the bush on the shaft showed that it had a snug fit as standard and it can't slip out of alignment once it's correctly in place.

In fact, I suspect that the recommendation for crimping is more to do with ease of installation than operation, but if the bush is fitted to the gear lever forks first, instead of being installed on the shaft first, there's no real need for crimping, as all that it would achieve is to hold the bush in position on the shaft more tightly, ready to receive the gear lever forks.

Anyway, if I've made an error and have to take it apart again to crimp the ears I'll post up again for rotten tomatoes to be thrown and to help anyone else avoid the curse of thinking he/she knows better than the manufacturer ;-)

[Andy135]

Well, after a brief road test this morning here are my observations on the brass saddle bush.

1. The gear change feels a little coarser from cold. I found I needed to be more precise with my placement of the gear lever up and across the gate. This could be due to the bush being brand new - perhaps with a few hundred gear changes under its belt it may loosen up a little.

2. When warm it feels much more smooth. This is probably more to do with the gearbox and gearbox oil rather than the saddle bush itself, but given the more direct feel of the brass over the nylon the brass accentuates the inherent feeling of the box more than the nylon did.

3. This was a short suburban test run involving a run to the petrol station for a top up and a quick stop to grab a coffee. Lots of stop-go traffic and fairly low revs. Need to stretch the legs of the gearbox on a longer, quicker blat before forming a definitive conclusion but early impressions are favourable. The box feels more direct, but requires more precision when cold.

[John Vine]

Thanks for the feedback. 

I'm left wondering whether an uncrimped saddle could still move up and down a little on the selector shaft?  The gear-lever fork describes an arc as you move it forward and back, so presumably wouldn't hold the saddle down all the time.  If that's the case, could it affect the quality of the change?

JV

[Andy135]

Possibly it could. However the bush is actually a snug, almost tight, fit in the forks, so introducing further tightness by crimping the bush around the selector shaft would imply the introduction of greater stiffness to the change. As it stands the action of the change felt good once warm, so I'm inclined to reserve judgment for now and run it as is for a few more miles.

[Geoff Brown]

Unusual for the bush to fail so early? Pre assembly lubrication at build vital.

Ten years/24,200 miles on my six speeder & gear change still as good as day one. 

 

[Andy135]

#7, the nylon bush didn't fail - this was principally a case of upgradeitis, spurred on by a couple of missed 2nd-3rd changes that got me wondering if a brass bush might help. Time will tell.

[7 wonders of the world]

The brass bushes should have the lower edges lightly squeezed to keep them in place on the selector shaft, crimped is a poor choice of phrase - hence your reluctant to do it