4th Gear Problems

Hello,

I have just had my 1969 mkIII Riley Elf fully restored and Coopered. We put the original gearbox back in only to discover it doesn’t like 4th gear. It keeps popping out, especially when you speed up too quickly. Can anyone enlighten me on the problem. The other gears are great. Can you advise whether I should buy a new gearbox or just get the 4th gear replaced or repaired. Also how much does a job like this cost? Many thanks Al.

It’s unlikely to be a problem with the gear but rather the gear selection, possibly the synchro hub..

Assuming you can remove the engine and remove the 'box, then likely cost to recondition could range from about £200 to £400+