[kbstuff27]

Hey all,
(Context 2015 3351x drive)

I just went through replacing my clutch with a spec stage 3+ and new steel SMFW. I got it back and the synchros in all gears were slow to let me into gear. I thought maybe this was a break in deal and it would get better…nope. I’m a little over 1000 miles into it and returned it to the shop that did the work. They have been a great shop with a solid reputation for working on performance BMWs.

I have no idea why the transmission would act like this because I had zero issues before the clutch change (will be upgrading turbo soon).

Anyone have any idea? I read that the clutch could have been dragging, but the synchros stayed the same and initially the delay was the same in all gears, now it seems like 5/6 are almost normal possibly because lower rpm when syncing?? but putting it in first from a stop takes the longest to sync. All gears are affected.

I don’t know a lot about this so trying to figure it out before I consider a new transmission and have that not be the problem. I did change the fluid back to redline (what I was using before the clutch swap) with no improvement (about 400 miles).

[AmuroRay]

Air in the clutch line or in or CDV?

[thejeremyman9]

You can usually do a simple test if the clutch is dragging by parking on level ground, clutch in, car in 1st gear and rev up to higher RPM and see if the car tries to move

[kbstuff27]

Originally Posted by thejeremyman9

You can usually do a simple test if the clutch is dragging by parking on level ground, clutch in, car in 1st gear and rev up to higher RPM and see if the car tries to move

I read about this also, the car is back at the shop now and they are working with Spec to try and figure it out. I am really lost on how all synchros would start acting this way, been trying to learn enough so I can think through it all. Thanks for the info.

[E36M3]

Part of the issue is fundamental to changing over to a SMFW setup with a clutch disc that has a spring hub versus the stock one that didn’t. Your synchros are working to slow down the mass of the clutch disc (they act as a brake to match speed of the next gear to allow it to mesh). Your new disc is heavier than your stock disc and is a reason you are experiencing this.

[zinner]

How does it shift if you rev match?

[kbstuff27]

Originally Posted by E36M3

Part of the issue is fundamental to changing over to a SMFW setup with a clutch disc that has a spring hub versus the stock one that didn’t. Your synchros are working to slow down the mass of the clutch disc (they act as a brake to match speed of the next gear to allow it to mesh). Your new disc is heavier than your stock disc and is a reason you are experiencing this.

This makes way too much sense, wow. I was trying to learn about how it all works together and did not put these together. Can’t thank you enough.