Evening all, hoping someone can help with some thoughts on what could be causing my gearshift issue.

So, brief history, 2004 S2000, currently at 103k miles. When we bought the car ~10 years ago at ~80k miles, when cold, 4th gear was always difficult to engage, you had to really pull on the shifter to get it into gear, but once you had engaged it, it was never any trouble after that. It also occasionally had a bit of a grind going into 2nd. But generally, gear shift was fine.

Fast forward to end of 2023 and started to get a bit of noise from the transmission at speed. Booked it in for secondary shaft bearings and the noise was gone.

However, the car wasn't used for some time, maybe 12-18 months and at some point after being repaired the gear shift suddenly got very stiff.

No obvious reason, but it is similar to the 4rh gear shift since for as long as we can remember, but now in most gears.

It is the same whether engine is running or not.

The only gear that shifts fine when cold is into 3rd, all other stake effort to engage. Shift does improve when warm but can still be notchy/tight. Shifter has been rebuild without improvement.

I would summarise each shift as below:

1st gear - very tight to engage and also difficult to disenage.
2nd - tight to engage but then slots in ok as you reduce pressure a touch, disengages no problem.

3rd gear - easy in, a bit more effort to disengage.

4th gear - take effort to engage, but disengages buttery smooth.

5th gear - ok going in, a little notchy ourlt.

6th gear - hard to engage, but disengages easy.

Reverse - hard to engage, notchy coming out.

This was all after warming the box up a little just driving around in a yard.

For anyone who knows these boxes well, what would you suggest could be the issue? Main selector shaft? Synchros?

It doesn't grind going into gear at all, it just takes lots of effort to get it into gear as if the gate or shift is being blocked somehow.

Appreciate anyone's thoughts on this!

 

Does it shift any easier if you double declutch between gears, or still feel the same?

 

Sounds to me like clutch is no longer fully disengaging. Classic clutch drag symptoms.

Maybe from grease drying and gelling up from disuse.

 

I've not tried this when driving.

The symptoms are the same whether engine is running or not, as it is the same with the engine off I thought that would rule out a clutch issue??

One thing I can say, regarding clutch, you can hear noise from the throw out bearing and you can hear that noise go away when the clutch is depressed, then come back as you started to engage again - so assumed that meant it wasn't dragging.

i'm all for investigating a clutch issue, if it is still indeed a likely culprit even though it doesn't shift nicely with the engine off.

Thanks!

 

I suppose you could try changing the transmission fluid. It prolly is not going to solve the problem, but it's a cheap try.

I use Royal Purple Synchromax. I like the feel of the shifts.

 

Shifter rebuild/regrease?

https://www.s2ki.com/forums/s2000-un...er-diy-772277/

 

It did have the fluid replaced when the secondary shaft bearings were replaced, but it wouldn't hurt to do it again to see if there is any change. Have previously used Honda MTF, but have also heard good things about the Royal Purple.

 

I did that Saturday in the hope it would help, but it didn't make any difference. In fairness the original parts were in good order, so was no surprise that it didn't improve.

 

+1 for Royal Purple fluid but if the clutch is original, it is definitely time for a new kit. Has the clutch system been bled recently? Old fluid can cause really strange issues.

 

Thanks, will definitely give it a try.

The clutch & hydraulics are original, and assuming the box is going to have to come off again, then I will replace the clutch - however, the shifting issue is the same whether engine is running or not.

Think I'm leaning towards full gearbox overhaul for this one, but will at least try the Royal Purple first.