Selector Fork 3/4

[rideaway]

Hello everyone,

I’m rebuilding my 4-speed gearbox on my Elan S4 and the Burton’s new selector fork is not positioned correctly. The third gear is not engaged properly and will not hold in place..
Have you ever had this problem?
Would I have ordered the fake parts ( SELECTOR FORK 3RD/4TH: 2000E BULLET & TYPE 3 GEARBOX GB2E512 )


Thank you for your help

Best Regards

Stéphane

[rgh0]

Make sure the screw that secures the fork on the shaft is located in the hole in the shaft which locks the fork in the correct position.

[rgh0]

I have used the Burton selectors in the past and they have been OK. There may be some other problem with the assembly of the syno hubs if the fork is properly located on the shaft

cheers
Rohan

[rideaway]

Of course the screw is positioned correctly.
With the old fork, even worn, no problem the position is correct.

[promotor]

Hello everyone,

I’m rebuilding my 4-speed gearbox on my Elan S4 and the Burton’s new selector fork is not positioned correctly. The third gear is not engaged properly and will not hold in place..
Have you ever had this problem?
Would I have ordered the fake parts ( SELECTOR FORK 3RD/4TH: 2000E BULLET & TYPE 3 GEARBOX GB2E512 )


Thank you for your help

Best Regards

Stéphane

Stephane,

The offset of the fork doesn't look unusual - how does it compare to the original? That's the easiest of checks to do.

Throwing an idea out here, just in case it helps :

Could it be that the outer sleeve can't pass over the third gear dogs as the synchro ring is tight on the gear cone and the dogs on both gear and synchro ring are not aligned - it could be "blocking" if it is stuck. Before you select 3rd gear make sure the synchro ring is loose on the gear and try to select the gear.

Or perhaps the fork is too long on the selector shaft and the tube that goes over 3rd/4th selector shaft is stopping it going into gear?

[joe7]

Not sure about this but here's what I think. It looks like you may have the outer slider on backwards. I looked at a NOS later 3/4 hub and the side that is toward 3rd gear appears to not have as much "slope" as the 4th gear side and the groove for the shift fork is slightly offset toward 3rd gear. On yours, the side toward 3rd gear appears to have more "slope" (which IF it is incorrect) then the shift fork is off center. Another shot at my description, the distance from the inside of the rear of the shift fork groove to the outer side of the hub is shorter on the 3rd gear side compared to the same measured distance on the 4th gear side. Maybe the problem?

[rideaway]

Hello,
Thank you for your suggestions.

After finishing reassembling the gearbox at the end of a hard day's work, I didn't have the courage to investigate the fork problem in depth.
In fact, the problem was that the fork arms were not perpendicular to the selector bar. A slightly different angle and the position of the sliding ring was wrong. By carefully twisting it, I brought the angle back to 90° and everything was back to normal. Given the small amount of force applied to straighten the fork, I don't think its integrity is at risk.
The gear selection is now correct, and the position of the sliding rings is good.

One more question:
- is core plug on the propshaft a common source of leakage and should be secured before the propshaft is reassembled ?

Best Regards

Stéphane

[2cams70]

Before the days when replica selector fork were available I've had the originals successfully reconditioned by bronze welding and re-machining. The core plug at the back of the yoke is usually trouble free (provided the yoke is original). If the the propshaft has over extended and the gearbox mainshaft has made contact with the plug from the inside you may have trouble. Check for witness marks of contact on the inside.