[RichiJun]

Hello,

I have Hyundai i30 Diesel 2012. I had an issue with changing gears were too hard so clutch was replaced. Also gearbox oil is new. But now when i change gears first, reverse or 3rd, i see its not smooth and i need to be change with little force else it misses to change gear. My mechanic has no idea what can be reason of this issue.
Any hints what it can be ?

[BrendanP]

Hello Richijun,

If you had a new clutch fitted, did they check that the clutch slave cylinder is OK? If that is worn or leaking, it reduces the  amount of movement to disengage the clutch so it doesn't fully release and the gears are hard to engage because the input shaft is still turning. There is a rubber boot over the end of the cylinder, if you peel it back and it's wet inside then it's leaking. Slave cylinders are fairly cheap to replace. The other problem may be the damper valve attached to the clutch master cylinder. If that's faulty it can also reduce the available travel. Also, I hope there's no air in the hydraulic line and it's been bled properly.

As Brendan says, check these things first, my car has a low bite but all the hydraulics are fine with no leaks and no air, I suspect a faulty clutch release bearing as sometimes the gears can be difficult then suddenly they're fine, I also have a 1800rpm vibration, new clutch is on its way so we'll see what changes when I fit it.

[Lorian]

Manually bleed the slave cylinder - the procedure is written up on here somewhere
check the right grade of gearbox oil was used
Consider if the pressure reducing valve is faulty

(cheapest to most expensive)

For gearbox oil, I searched for a 75w85 but couldn't find anything suitable, I filled with Comma fully synthetic 75w90 and it's much smoother now, the vibration has also disappeared with a new 3 piece clutch, old clutch was fine, even the release bearing so I assume the pressure plate fingers were bent and/or didn't like heat. Bite point is marginally higher/better but completely acceptable, I have slight play on the master cylinder pushrod so fitting a new one then the car is completely sorted.