Z4M gearbox
- Thread starter exdos
- Start date
I found mine could be a bit awkward at times so I changed the shift knob for a weightier ZHP version first purely through forum recommendations (here and zpost) but tbh it only really seemed to make a difference at higher speeds when you are 'rowing' through the gears. Aside from that though i much prefer the tactile element so it's staying put.
After that I changed the gearbox oil for Royal Purple Synchromax and had the clutch bled at the same time. This totally transformed the shift. It was a pleasure to use at any speed in any gear and removed the occasionally rattle noise you get when declutching at low speed. It really was a night and day difference. The brakes also seemed sharper but seeing as they share the same reservoir I figured that was normal.
But, and there's always a but! It has gradually worsened over time to the point where I now wonder if the clutch system has taken on air, so ill bleed the system again and go from there. If the bleeding solves the issue and it returns to its super smooth self then I may just get the slave cylinder changed (or perhaps something else if others feel there's a more likely cause)
As for the mounts helping, I can see they would under real load or when in faster turns so its something I'm considering, funnily enough though, I find gear engagement is easier when going through turns and only ever run into the blocked shift when tootling about. As a general rule I've found the z4m to be a car that needs to be driven quickly for it to all come together so as and when I get tugged by the boys in blue I've got my get out of jail excuse all lined up!
After that I changed the gearbox oil for Royal Purple Synchromax and had the clutch bled at the same time. This totally transformed the shift. It was a pleasure to use at any speed in any gear and removed the occasionally rattle noise you get when declutching at low speed. It really was a night and day difference. The brakes also seemed sharper but seeing as they share the same reservoir I figured that was normal.
But, and there's always a but! It has gradually worsened over time to the point where I now wonder if the clutch system has taken on air, so ill bleed the system again and go from there. If the bleeding solves the issue and it returns to its super smooth self then I may just get the slave cylinder changed (or perhaps something else if others feel there's a more likely cause)
As for the mounts helping, I can see they would under real load or when in faster turns so its something I'm considering, funnily enough though, I find gear engagement is easier when going through turns and only ever run into the blocked shift when tootling about. As a general rule I've found the z4m to be a car that needs to be driven quickly for it to all come together so as and when I get tugged by the boys in blue I've got my get out of jail excuse all lined up!
mad4slalom
Senior member
i am with you on that one exdos, mine is crashy on anything other than perfect tarmac !
pilchardthecat
Active member
exdos said:pilchardthecat said:Mine is a daily hack, so this could be another garage-queen ailment
The problem of having a few cars is that you can only drive one at a time. I treat my Z3MC and Z4MC like racehorses: they're very well looked after and want for nothing but when they're allowed out they're asked to gallop. 8) BTW I've received the honeycomb for the MAF mod today.
I have more than one vehicle, but the Z makes a great commuting hack - fast, fun, comfy, and i'd rather drive one empty seat to work than 3 or 4
Looking forward to your datalogging
BMWZ4MC said:I've been baulked on the occasional second-third upchange at maximum attack I suspect due to trying to change faster than the synchromesh can permit, but I've almost never had the problem you describe on downchanges even over many hundreds of track miles. I suspect the reason why my downchanges are reliable is because I always double declutch as well as rev-matching (even on the road). This obviates the need for the synchromesh to spin up and is most of use when entering a gear at over 7,000 rpm during aggressive downshifts into corners. I started double declutching in my first car (an ancient Fiesta) because the synchro was poor and the downchanges would frequently baulk (I used to drive it in the same way I drive my ///M). Try double declutching when entering a lower gear at very high revs and you should find that the change is much smoother than with a traditional downchange.
The other thought I had is that your Mk I Exdos clutch stop may be preventing your clutch from fully disengaging - maybe this needs a tweak?
I've only had the problem you describe when downchanging when I've failed to coordinate hand and feet when tired at the end of a trackday.
Interestingly, the cast metal gear selector fork for third gear in my Audi TT suffered a fatigue fracture during a maximum rpm upshift leaving me with only third gear and no neutral. This made for an interesting drive to the garage
Bingo! I"ve no C>VD delete or fancy tranny moiunts etc and the the ZF shifts fine exept when I cock it up.
This is a different problem though. The stiffness of first-to-second or even neutral-to-first changes is common and often questioned on here by new owners. The baulking you've experienced during high transmission load and perhaps high body shell torsion gear changes I suspect to be an entirely separate issue.
Yesterday, was the first time that I'd driven my Z4MC since returning from The Ring a week ago, and I paid particular attention to the gear-shifting, and I had no problem whatsoever with it. The gearbox was happy to allow access to any gear with or without heel & toe rev matching on downshifts. I simply couldn't repeat the problem I'd experienced on track.
Before I went out, I checked that I'd got sufficient clearance to completely disengage the clutch with my clutch stop mod, which I had, so I've ruled that out as a potential cause of the problem. I'm considering changing the gearbox oil to either Royal Purple Synchromax or Amsoil MTF, can anyone recommend these or any other gear oils to try?
Before I went out, I checked that I'd got sufficient clearance to completely disengage the clutch with my clutch stop mod, which I had, so I've ruled that out as a potential cause of the problem. I'm considering changing the gearbox oil to either Royal Purple Synchromax or Amsoil MTF, can anyone recommend these or any other gear oils to try?
mad4slalom
Senior member
my point exactly, the thing i find is that when i take the time to think about rhe action of shifting then it is fine , maybe when flying inti a hairy corner at the ring at the limit then you are also thinking about a host of other issues, brakes , apex ,other cars etc etc,plus like you say the soft mounts may be the causes of the problem. I had amsoil mtf in my 3mr, with good results so put it in the 4mc as soon as i got it, but also did the cdv delete at the same time so dont know which had most effect. going back to my post re the sport button, i can see from the graph that bit has no effect on how much the throttle opens but is it not a bit quicker just because you are on the revs quicker, mine just feels so different, without the feeling of being bogged down because the revs have dropped so quickly, also, when i blip the throttle with sport on , it seems to respond quicker or is it just that it is the equivalent of giving it a bigger blip, ? dont know either way but it feels better to drive fast to me with it on.
I fitted the Vibra-Technics "road" Engine Mounts yesterday. It took me 2 hours in all to do the job and it was easier than I anticipated. Whilst I was at it, I also removed the clutch delay valve completely.
I went for a test drive earlier and I have to give this mod a big I did this mod as an attempt to improve the gear shifting but what I noticed most was the general effect that the engine mounts have had on the car's suspension and handling. I've already got the ACS Racing suspension and H&R ARBs but with the Vibra-Technics mounts, the suspension feels as though it's just been upgraded some more! The feel now is that the whole mass of the car is "as one" which makes the front suspension now feel like it has coilovers with linear springs. Because the engine doesn't move in the horizontal plane with the V-T mounts, when you turn, the engine stays put, so the car turns sharper than it does when centrifugal force pushes the engine mass to the outside, as it does with OEM engine mounts.
Before today, although I've considerably improved the handling of my Z4MC it hasn't felt quite as completely "together" as does my Z3MC (I feel as though I wear that car), and I often drive them back to back to compare. But now, I feel that the missing piece of the handling jigsaw is in place. 8)
As for gear shifting; the gear lever now feels connected to a stationery gearbox at all times, giving much better and more secure gearshifts. Time will tell whether this remains the case. I shall now change the gearbox oil in the hope of making the shift feel smoother.
As for the CDV delete; I can't say I really noticed much difference, because I never found the clutch to be a problem. Then again, I was probably most aware of the change in suspension dynamics with the engine mounts.
This is definitely a mod to recommend.
I went for a test drive earlier and I have to give this mod a big
I did this mod as an attempt to improve the gear shifting but what I noticed most was the general effect that the engine mounts have had on the car's suspension and handling. I've already got the ACS Racing suspension and H&R ARBs but with the Vibra-Technics mounts, the suspension feels as though it's just been upgraded some more! The feel now is that the whole mass of the car is "as one" which makes the front suspension now feel like it has coilovers with linear springs. Because the engine doesn't move in the horizontal plane with the V-T mounts, when you turn, the engine stays put, so the car turns sharper than it does when centrifugal force pushes the engine mass to the outside, as it does with OEM engine mounts. Before today, although I've considerably improved the handling of my Z4MC it hasn't felt quite as completely "together" as does my Z3MC (I feel as though I wear that car), and I often drive them back to back to compare. But now, I feel that the missing piece of the handling jigsaw is in place. 8)
As for gear shifting; the gear lever now feels connected to a stationery gearbox at all times, giving much better and more secure gearshifts. Time will tell whether this remains the case. I shall now change the gearbox oil in the hope of making the shift feel smoother.
As for the CDV delete; I can't say I really noticed much difference, because I never found the clutch to be a problem. Then again, I was probably most aware of the change in suspension dynamics with the engine mounts.
This is definitely a mod to recommend.
mad4slalom
Senior member
sounds like a must, where did you buy the mounts and how much, is the fit a fairly easy diy ? thanks
mad4slalom said:
See: http://www.vibra-technics.co.uk/bmw/z4/528/BMW360M/front_engine_mount_
This isn't the easiest of DIY jobs and you've got to be confident with your lifting method and working underneath the car, so it all depends on what jobs you've done before and the equipment you have as to how hard/easy you'd find it. Also you have to lift the engine off its engine mounts to do the job so you've got to be happy about that too. If you do your research before you start and plan the job, it's definitely DIY but not for a novice.
On this job, rather than lift the car onto axle stands, I ran the car on to two 16' long 10" x4" planks which are supported at various points along their lengths to form a ramp, so that when I lifted the engine, there was no possibility of lifting the car off axle stands.
exdos said:mad4slalom said:
See: http://www.vibra-technics.co.uk/bmw/z4/528/BMW360M/front_engine_mount_
This isn't the easiest of DIY jobs and you've got to be confident with your lifting method and working underneath the car, so it all depends on what jobs you've done before and the equipment you have as to how hard/easy you'd find it. Also you have to lift the engine off its engine mounts to do the job so you've got to be happy about that too. If you do your research before you start and plan the job, it's definitely DIY but not for a novice.
On this job, rather than lift the car onto axle stands, I ran the car on to two 16' long 10" x4" planks which are supported at various points along their lengths to form a ramp, so that when I lifted the engine, there was no possibility of lifting the car off axle stands.
this is definitely not a DIY job if your not confident on working on the car imo.... john is a seasoned veteren at home mods so it sounds kinda easier than it really is..... i found this one quite difficult.... the bolts are awkward to get to and take work to just undo.... lifting the motor is a brown trouser moment but, soo satisfying when you do DIY it.... The road version are a huge 4x stiffer than the stock mounts, they do not increase NVH at all, you wouldnt notice they are in their, but engine control is much better, you can feel the engine being held tight, infact vibrations are Cut down as the motor isnt thrashing and moving around....
the competition mounts are 8 x stiffer... i run these.... with my added power i wanted ultimate control and even these are pretty civilised but do offer increased NVH.... but imo nothing at all concerning and i now barely notice them....
the mounts can be rebuilt for 30 quid from now on as well!! they are a completely failsafe design meaning they will never seperate, EVER.... again for the z4m imo one of the best mods for the money, incredible difference.... VT use natural rubber too that doesnt alter characteristics during extreme Heat... they are even pretty to look at..... MUST HAVE imo....
my stock mounts which only had 10k on them were severely worn, severely.... to the point where the motor sits up higher..... im CERTAIN.. alot of the shifting issues on the z4m are coming from the motor shifting around so much on the stock engine mounts.... i noticed such an improvement i know love the gearbox action and changes....