Gearbox rebuild problem --- what I found
Turbo Mini Forums

What did I do wrong????

I just finished rebuilding my gearbox, it will shift beautifully into 1st, 3rd, and 4th…but not into 2nd. It feels like a hard stop. I have taken out the detent plug but that did nothing… Could I have put the interlock plunger in wrong?

Edited by Mikes1098 on 30th Jun, 2008.

Do you have a photo of it from the top (looking down on the mainshaft) ???

Schrödinger's cat - so which one am I ???

There is a cross section of the first and second gear assembly in the Haynes manual, it shows the interlock plunger inline with a “cutaway tooth”….can it only go on in one orientation? I simply lined up the baulk ring grooves and put the interlock in after is was assembled…

Edited by Mikes1098 on 28th Jun, 2008.

Can you do it manually, i.e pushing it over with a screw driver?

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

I can not move it with a screw driver either….

Upon further investigation, I noted that there are 4 teeth cut out…3 line up with the baulk ring and 1 seems to be in the general location of where the interlock was. The last cut-out tooth does not seem to have the entire tooth removed, just one side. The cut-out is on the right side to let the selector side toward the 2nd gear.

My guess is that I did not line this up properly.... can anyone confirm that you do have to line this up???



Either way, I think I am hosed and the main shaft has to come back out…

Edited by Mikes1098 on 28th Jun, 2008.

Hmmm, 3 synchro box, years since I worked on one of those so I won't be much help.
Don't know what the fourth cutout is but surely if it was wrong, the three for the baulk ring would also be wrong?
The fact it slides in the 1st direction OK (where there is no baulk ring) does suggest something is misaligned with respect to the 2nd gear baulk ring.
Another possibility, did the selector fork/rod go back right, from memory, they are all held together with bolts and locknuts on that type of box.

Schrödinger's cat - so which one am I ???

Here is what I found…hopefully this will help prevent someone from making the same mistake. From what I understand this can only be screwed up on a 3 synchro gearbox… the 4 synchro can be installed in any direction.

Once, I got the 1st/2nd hub off the main shaft, I was able to confirm that the interlock plunger was not lined up with the 4th missing tooth.


Here is a picture of just the outer hub, and what I am calling the 4th missing tooth.


This is how I reassembled it.


This picture shows what the interlock plunger looks when the outer hub is shifted toward second. It is clear that if the missing tooth is not lined up properly it won’t shift into second.


It shifts perfectly into all gears now! Hopefully, this will save someone from making the same mistake…time to go drink some beer

Great! I hope I dont need it (ie. work on a 3sync one again ) :)

many thanks!
i just made same mistake putting together 3 scyh gearbox today.
your photos are helpful! hope to sort it tomorrow.