STICKY GEAR SELECTION

[Southernboy]

I have gathered that the "sticky gear selection" syndrome is fairly common on the Z3 as it ages. Most common seems to be getting the 3rd gear position into it's slot. Mine is in the same category... I have been to see a gearbox specialist, who will be doing the restoration to correct the cause.... I have asked if I may take pics of the process and the remedial work required to restore proper gear selection function. I'll be doing this in the next 3 weeks whilst the gearbox is out to replace the clutch. I'll post the full details here for future reference of those who would like to know more or even do the job as a DIY project. The cost I have been quoted is £.40.00. That obviously excludes gearbox removal and re-fitting since I will have it out anyhow.

[siwilson]

Head over to the US boards and search for "Shift pin service" it's not s hard job for a man of your calibre

[Southernboy]

From what I have been told, the specific item is a spring, ball and piston - inside the gearbox - it is what tends to get gunked up. Getting to it requires opening the gearbox somewhere and removing the items... the guy I'll be using says he "hones" the ball to re-surface it as well as cleaning and honing the piston and it's shaft. I figured it would be something which would simply require a good cleaning and would be accessible from outside the gearbox - ie the shifter lever / bushes, but apparently that isn't the cause. Anyhow, I'll get the pics and do a write-up so it'll be clear enough for others to follow.

[gIzzE]

I was about to order the kit as mine was really bad, and would sit under 5th when it was in neutral.

However, I put in a quart of Redline D4 ATF and the other 1/3 quart of MTL and within a few miles it it was no longer sticking, plus it shifts so, so nicely now.
From cold it is actually a bit harder to get into gear, but within a mile it is perfect.

Very happy with the results.

[Southernboy]

... I'm booked in week after next for a new clutch... while the box is out, the fella will be "honing" my ball and cleaning out the sprung mechanism...
An interesting point he made whilst I was chatting to him with regard to gearbox oils. He said that once you had drained the ATF / OEM fluid and replaced it with a non ATF oil, you couldn't later change your mind and drain the oil (synthetic or otherwise) and replace it with ATF again. I was going to ask him to explain the statement, but he got onto another subject, and I missed the opportunity. I will make a note to ask him again when I see him in around 12 days time. His credentials are excellent and is an ex BMW race mechanic out of the DTM series... but an interesting comment nonetheless... anyone else come across this info ?

[Del]

I sometimes wonder whether some US sources tend to suggest "overkill" cures for some of these niggles e.g. shift pins, super expensive water pumps, rear shock absorber reinforcement plates and DISA valve reinforced parts. I've seen many posts on this site where a simple gearbox oil change has cured all sorts of niggles.

I don't know the technical/chemistry behind mixing gearbox fluids, but Mobil say it is OK to mix their synthetic ATF with conventional transmission fluid.

[gIzzE]

He said that once you had drained the ATF / OEM fluid and replaced it with a non ATF oil, you couldn't later change your mind and drain the oil (synthetic or otherwise) and replace it with ATF again.

I think that is generally correct, however, Redline have said that their MTL can be mixed, I wouldn't just do it with any fluid though.