grind shifting from 1-2

[xlea135i6mt]

Recently I've been experiencing a slight grind with wot shifts from 1-2. Only happens when shifting quickly and at high rpm (6-6.5k), otherwise it seems to go into 2nd gear just fine. Anyone have any idea whats causing this? Bad synchro maybe? The car only has 17k miles.

[ShocknAwe]

Have you done a CDV delete yet?

[FactorX81]

I think most people find 1-2 shift pretty crappy. The gearbox just doesn't like being rushed for that shift in particular. Many people have done SSK, CDV delete, different fluid, etc. to get these kinds of issues resolved with varying degrees of success. Personally I have done CDV delete and while I notice a difference in clutch engagement it has not made the 1-2 shift any better for me. I just shift slower for that shift than the others. I don't do any kind of drag/stoplight racing so it doesn't bother me too much but its not a solution if you do.

[Grinchxvx]

1st to 2nd shift blows that's just how it is. when I'm driving hard I miss it sometimes even with CDV, fluid change, clutch stop, and ssk.

[Suds]

Yep,worn synchro, the 1st to 2nd shift is the hardest on the transmission, and then the CDV dosen't help engagement.
Shift 1-2 a bit slower and it will still last a long time without a rebuild.

[xlea135i6mt]

Originally Posted by ShocknAwe

Have you done a CDV delete yet?

Nope haven't done it yet, but definitely going to consider it now.

[xlea135i6mt]

The 1-2 shift hasn't ever felt great, but I never had the grinding while going into 2nd. Kind of why I think it might be an issue with the synchro. Is this something that might be covered under warranty?

[ShocknAwe]

Originally Posted by xlea135i6mt

Nope haven't done it yet, but definitely going to consider it now.

Very simple. I'd also add a clutch stop and fluid change since you're grinding. Can't comment on a SSK though I have heard both ways that it makes the shift smoother, and at the same time more notchy. Guess it depends on what kit you get. If you're grinding already you don't want it to be more notchy.

[Grinchxvx]

I have b&m short shifter and it's pretty notchy compared to stock but throws are so much shorter. 1st 2nd and reverse are the worst then 3-6 feel Amazing. I had uuc on my old m3 so I'm pretty used to notchy short throws though.

[Freon]

1 to 2 is the biggest gap to cover between gears. It's always going to be the slowest shift. 5 to 6 is super tight and can be made remarkably fast.

It's true with almost any gearbox, not just the 135i, since the 1-2 is typically the biggest change in ratio.

It still should not grind.

[Kgolf31]

Torque from the engine will cause the tranny to "twist", especially at WOT. This is a common issue in Z4Ms as well

Stiffer engine and tranny mounts will cure the issue.

[rsr552]

I found all the comments above true when I had my 135i but also when I had a K20 Civic Si.....the K20 Civic Si are also notorious for a 2nd gear grind as well and Stiffer motor mounts definately helped in that application.

[Suds]

Here is a video that gives you an idea of what is happening in the gears and how the synchro's are trying to mesh gears, after watching this you will be able to visualize that gear mesh takes time.

And yes I am a Mech Engr, so this shit gets me excited.