https://www.zpost.com/forums/ Everything related to the engine/drivetrain and modifications en Sun, 19 Apr 2026 11:12:54 GMT vBulletin 60 https://www.zpost.com/forums/images/misc/rss.jpg https://www.zpost.com/forums/ https://www.zpost.com/forums/showthread.php?t=2236486&goto=newpost Tue, 07 Apr 2026 03:25:15 GMT I replaced the battery the same way I did 1 1/2 years ago. lights in the trunk came on and so I went to start it, everything when dark and now the whole car has no power. 2004 BMW Z4 3.0 I replaced the battery the same way I did 1 1/2 years ago. lights in the trunk came on and so I went to start it, everything when dark and now the whole car has no power.

2004 BMW Z4 3.0 ]]> Engine, Exhaust, Drivetrain Modifications klaussca https://www.zpost.com/forums/showthread.php?t=2236486 https://www.zpost.com/forums/showthread.php?t=2236253&goto=newpost Sun, 05 Apr 2026 16:32:29 GMT Good Morning!! Has anyone had any experience with a transmission rebuild from either Metric Mechanics or DiffsonLine?? Noticeable improvements in shifting?? Thanks, Ted. Good Morning!! Has anyone had any experience with a transmission rebuild from either Metric Mechanics or DiffsonLine?? Noticeable improvements in shifting?? Thanks, Ted. ]]> Engine, Exhaust, Drivetrain Modifications wyshyvanuk https://www.zpost.com/forums/showthread.php?t=2236253 https://www.zpost.com/forums/showthread.php?t=2235892&goto=newpost Thu, 02 Apr 2026 23:01:00 GMT Why don’t I like the Z4M transmission?? Let me count the ways: It’s not so much that, at high RPMs, the shift from 1st to 2nd is less than well “synchronized”. I’m retired….I have the time to wait the additional half second or so. But it seems that all of the shifts seem less than,... Why don’t I like the Z4M transmission?? Let me count the ways:

It’s not so much that, at high RPMs, the shift from 1st to 2nd is less than well “synchronized”. I’m retired….I have the time to wait the additional half second or so.

But it seems that all of the shifts seem less than, oh what’s the phrase, as smooth as mayonnaise.

I’ve had some previous experience with manual transmissions, an MGB and a Lotus Europa, but, honestly, whatever skills I once had have certainly evaporated. But kiss a billy goat’s ass if I can successfully match RPMs to allow a smooth shift from 1st to 2nd gear.

It brings a tear to my eye when I think of the strain I’m adding to the drive train, and I do not use the Sport Mode.

Full disclosure: the engine is supercharged to the 425-450 hp range, but the same issues prevailed prior to the modification. The clutch delay valve has been removed, in a vain attempt to have more control over the clutch action. Car has 49K miles, 6k of which are mine.

So, what to do to improve the shifting experience?? I really, really, enjoy the Z4M, and I’m willing to do whatever’s necessary. That would also include going to How-to-Shift-Your-Transmission School. Ideas that I’ve read about:

Replace the transmission “Bearing Set” (what everyone calls the transmission mounts). I’ve recently replaced the engine mounts and actually have new transmission mounts resting on a shelf in the garage. The mounts “looked” fine when I was underneath but I’d be happy to replace them.

Transmission fluid has been changed using LT-3 rather than the LT-2 listed on the transmission label. LT-3 is specified by RealOEM and my trusted parts manager. I do have LT-2, also resting in the garage. Didn’t experience much of a change after the change. Yes, I’ve seen the tsunami of recommendations for third party fluids, but I remain unconvinced. If I remember correctly, ZF lists a couple of acceptable fluids in their documentation.

I could replace the delay valve. Might mitigate the harsh transition between gears, or at least salve my conscience.

I don’t have much of an idea about the condition of the clutch facing, nor would I know what to look for without pulling it apart. I usually overcompensate for perceived problems, so if someone suggests replacing the clutch, I’m all in!!

I’ve also read glowing reports of the benefits of replacing the shifting mechanisms with after-market units. One supplier, whose name I forget, was particularly well considered.

I had thought of having the transmission “re-built” and “improved”, but the one company that I had seen recommended quoted me in the neighborhood of $5K Yes, that’s thousands with a “t”. The re-build did include REM treatment on the appropriate internals. Well, in for a penny, in for a pound. I’m kinda’ sure I haven’t damaged the transmission but who knows about those previous 43K miles.

Replace the shift lever with a shorter, heavier, variety. This sounds like a Band-aid to me, but I’m ready to listen.

Replace every piece of rubber in the rear suspension. I’m guessing that a loose rear suspension could result in a jerky shift feeling as the car transitions from accelerating to decelerating.

To shorten this post, I need advice!! Thanks for any help!!!

Ted ]]> Engine, Exhaust, Drivetrain Modifications wyshyvanuk https://www.zpost.com/forums/showthread.php?t=2235892