I recently fitted a new clutch to my 03 STI. The clutch works beautifully but I've noticed a slightly notchier gearchange since fitting - especially 4th-5th-6th and back. With the gearbox out, I also changed the transmission fluid and put some low-friction stuff in made by Redline and recommended for the car. But I'm wondering if this may have something to do with it? Any advice appreciated.

 

It may be that the clutch is dragging slightly ie not disengaging completely. does the clutch start to bite very early? Make sure the pedal and release arm strokes are correct.
Quite a few on here have experienced problems with synchromesh performance after filling with full-synthetic gear fluid (me included!)

JohnD

 

stick some castrol driveline in it, i dont like that redline stuff.i also had problems with synchromesh and the redline oil made it worse

 

Cheers for the advice guys - I'll try draining the box and using some Driveline!

 

what redline oil did you use?

 

Hi Paul - it was a Redline fully synthetic 75W90 gearbox oil. I think the code was 75W-90NS GL5 but I'm not totally sure about that. Cheers

 

We've had good results with that, so I'm surprised it was worse than what it replaced. It's specifically designed for the subaru style box with the diff and hypoid in the same oil. The "NS" part means it has less or no friction modifiers that can cause problems with the baulk rings gripping the gears.

 

you might find that it goes away with use, emptying the gearbox for a while and filling it can make it a little notchy to start with. I changed the clutch on my MR2, when i got it running again, all the gears were notchy, but it went away soon after i started driving.