anyone else grind 2nd gear in their Z4M?

[07ImolaRot]

I keep grinding 2nd gear with REALLY quick shifts at high RPM. On 3 separate occasions with the clutch pedal smashed against the floor I grinded 2nd gear VERY badly at like 6-8k RPM with a super quick shift... I couldn't even get into second gear which is very frustrating ! I am using fresh Pentosin FFL-4. For what it is worth car has 62k and brand new Lemforder engine and trans bushings. I do not think those matter... I just think the syncrhos are the issue... It is almost impossible to do a drag race because I keep getting locked out of 2nd gear. CDV was removed and system was flushed with Pentosin DOT 4 LV. Should I try MTF-LT2 instead of FFL-4?

Edit: A lot of old threads on this subject but seems like a definitive solution was never found? Any new insight on this?

[grannyknot]

Mine does that occasionally when the trans hasn't fully warmed up.
What you are describing are badly worn syncrhos, your only options are swap in a another transmission or find a specialty shop that can tear down your unit, very hard to find parts for these transmissions.
Metric Mechanic overhauls them and maybe Lang.

[maupineda]

Mine has done it too when trying to do a super fast shift, in two occasions, after that I have learnt not abuse it, if you just reduce the pace, no problem. I mean, is not like you need to wait or do a granny move, just don’t flash it through. You can be quick, just not lighting quick.

In this sense, the M3 G420 is better as I have seen those guys can smash it and no problem

My car is at 82000 km, so is not mileage, and my tranny overall is super tight and crisp.

I also don’t have the notchiness issue many get with second gear. My car runs on atf, but will change to Royal purple synchromax

[07ImolaRot]

Originally Posted by grannyknot

Mine does that occasionally when the trans hasn't fully warmed up.
What you are describing are badly worn syncrhos, your only options are swap in a another transmission or find a specialty shop that can tear down your unit, very hard to find parts for these transmissions.
Metric Mechanic overhauls them and maybe Lang.

Is it really worn out synchros though? seems like a lot of people have this issue... the tranny is otherwise just fine !

Originally Posted by maupineda

Mine has done it too when trying to do a super fast shift, in two occasions, after that I have learnt not abuse it, if you just reduce the pace, no problem. I mean, is not like you need to wait or do a granny move, just don’t flash it through. You can be quick, just not lighting quick.

In this sense, the M3 G420 is better as I have seen those guys can smash it and no problem

My car is at 82000 km, so is not mileage, and my tranny overall is super tight and crisp.

I also don’t have the notchiness issue many get with second gear. My car runs on atf, but will change to Royal purple synchromax

Maybe I will switch to RP. I have a 6spd E46 M3 with a UCC SSK and I smash it into second gear lightning fast without any issues. I personally feel like the Z4M trans is not as good as the E46M

[pungo]

I've noticed the denied 2nd gear shift several times, usually only when shifting fast at higher RPMs and this was with less than 10k miles on the clock. Not sure what's happening, but it's inconsistent where sometimes is goes right in and sometimes the shifter just stops moving toward second. Been rowing gears for over 50 years and have rebuilt many manual transmissions so have a good understanding on their mechanical operation; therefore I can only guess there's some quirk with the 2nd gear syncro/shift/system on these

I've just learned to live with it and shift a little slower with a little less RPM and it works fine, after all, it's a sports car not a drag car

[chickdr]

It has happened to me as well. My car has 21k miles. It has done it since I bought it in the exact situations the OP stated. Quick shifts at high rpm's. The transmission is not the Z4M's best component. It doesn't like to be rushed. No solution has been found from what I have read.

[07ImolaRot]

Originally Posted by pungo

I've noticed the denied 2nd gear shift several times, usually only when shifting fast at higher RPMs and this was with less than 10k miles on the clock. Not sure what's happening, but it's inconsistent where sometimes is goes right in and sometimes the shifter just stops moving toward second. Been rowing gears for over 50 years and have rebuilt many manual transmissions so have a good understanding on their mechanical operation; therefore I can only guess there's some quirk with the 2nd gear syncro/shift/system on these

I've just learned to live with it and shift a little slower with a little less RPM and it works fine, after all, it's a sports car not a drag car

Originally Posted by chickdr

It has happened to me as well. My car has 21k miles. It has done it since I bought it in the exact situations the OP stated. Quick shifts at high rpm's. The transmission is not the Z4M's best component. It doesn't like to be rushed. No solution has been found from what I have read.

What a bummer... I know it is not a drag racing car but hey what If I want to go drag racing one weekend? I'll get beat by a civic Si that has a better suited tranny

[maupineda]

Just don’t try to be Ayrton Senna. You can still be quick. Or drag with your Civic :P

[zed_fan]

Granny shifting, not double clutching like you should.

[Lucky1]

Come on, isn't this a known issue and a design "feature" of the transmission? I read about this over ten years ago when I was thinking of buying the car and it almost scared me off.

You just can't shift lightning quick from 1st gear to 2nd gear in this car, especially after WOT. Gets worse the higher in RPM in 1st you shift from. You have to take some time, add an artificial delay into your shifting if you need to. In other words you have to drive around it.

I had read previously that royal purple gearbox fluid was found to help but I went the redline D4 route and actually it made the problem worse and I'll tell you why It actually made the shifter faster, more direct and enjoyable. Now I can physically shift the gear lever so damn fast I need to drive in sport mode all the time just to have the engine keep up revs wise BUT I get too cocky and excited with the fast shifts and forget to take it easy on the 1st to 2nd shift and grind more frequently as I get "lost in the moment" thanks to the rapidity of this box with the changed fluid.

Sadly don't have this problem in my 128i ehich also becomes a fantastic shifter after changing to Redline. It does exist in my Carrera 991.1 with OEM fluid but its much less frequently triggered there. I know some people think it sucks to need to this on an ///M car but its never kept me personally from enjoying the car.

[07ImolaRot]

I read in one of the other threads that having warmed up transmission fluid helps as well as pushing shift lever to the left as you go from 1st to 2nd...

Needless to say, tonight I was coming back from a 50 mile highway drive and everything was warmed up properly. I exited the freeway and came to a stop at a red light. Once it turned green I went WOT all the way to about 7k and was super focused on how I was about to shift... I slammed the clutch pedal to the floor, pulled the lever down and to the left lightning quick and with brutal force.... not only did I grind 2nd once again, my force popped the shift knob completely off the lever and I had to pop it into neural without the knob and pull over to put it all back together....

So ladies and gents, I have been defeated and give up. I will drive my German Engineered motorsport car like a Prius from now on. I have learned my lesson !

[2one3E90]

double clutch the upshift the . I do it when i daily drive.

[pungo]

Originally Posted by 07ImolaRot

I read in one of the other threads that having warmed up transmission fluid helps as well as pushing shift lever to the left as you go from 1st to 2nd...

Needless to say, tonight I was coming back from a 50 mile highway drive and everything was warmed up properly. I exited the freeway and came to a stop at a red light. Once it turned green I went WOT all the way to about 7k and was super focused on how I was about to shift... I slammed the clutch pedal to the floor, pulled the lever down and to the left lightning quick and with brutal force.... not only did I grind 2nd once again, my force popped the shift knob completely off the lever and I had to pop it into neural without the knob and pull over to put it all back together....

So ladies and gents, I have been defeated and give up. I will drive my German Engineered motorsport car like a Prius from now on. I have learned my lesson !

Shifting "lightning quick and with brutal force" is abusing the synco system and not doing the trans any good (poor soft brass synco). With this trans, some finesse goes a long way for smooth 1>2 shifting. I've learned to use the proper finesse to grab 2nd gear with authority and no grinding, but would never attempt it with "lightning quick and with brutal force

[Steeler]

In my non M with the GS6-37 box I have not experienced the 2nd gear grind. I do not rev out to the S54 limits of course.
I do "use" my car aggressively though.

Also equipped with very stiff mounts on engine and box as well as a chassis mounted shifter.

[maupineda]

the Non-M revs to 7k, I have never had this issue at 7k, the only two times I saw a refused 2nd gear, was changing at redline, so the M is more prone to this due to the higher rational speeds.

[3798j]

Found it interesting that Redline Oils recommends their D6ATF for the Z4 3.0si but for the Z4M it's their D4ATF. Both models list the same ZF S6-37BZ as the transmission.
As was already suggested, I'd double-clutch that 1 to 2 shift and I'd use a two step shift lever motion...1st to neutral/neutral to 2nd. Even with that momentary pause, with practice it can be done surprisingly quick. Back in the day, many transmissions needed to be "babied" like this.

[cbpip]

Tried the Redline ATF products, syncrhos did act very well with it. Was explained here on the forum that the syncrhos needed more time to slow down using the Redline. Too thin.
Went with Ford ATF fluid that others are using and corrected the issues. Big following in other groups as well with manuals.
Ford Fluid XT-M5-QS Full Synthetic Manual Transmission Fluid
https://www.amazon.com/gp/aw/d/B000NUES82?psc=1&ref=ppx_pop_mob_b_asin_title

Been using it half of the season and no issues so far.

[07ImolaRot]

Originally Posted by cbpip

Tried the Redline ATF products, syncrhos did act very well with it. Was explained here on the forum that the syncrhos needed more time to slow down using the Redline. Too thin.
Went with Ford ATF fluid that others are using and corrected the issues. Big following in other groups as well with manuals.
Ford Fluid XT-M5-QS Full Synthetic Manual Transmission Fluid
https://www.amazon.com/gp/aw/d/B000N...b_b_asin_title

Been using it half of the season and no issues so far.

So you can shift into 2nd gear at higher RPM really quickly with this fluid ?

[Coi]

I had an issue with grinding into 2nd on fast, high rpm shifts but it would be cured if I was making a right turn. Would happen on even slower shifts sometimes with left turns. I would also get locked out of 3rd sometimes on quick left turns. Those symptoms made it seem more like some kind of shifter or transmission alignment issue rather than purely a synchro issue. I think my motor mounts were quite tired and the suspension mounts probably are too. I do have a UUC ssk installed.

I recently had my motor mounts replaced (after the bracket and studs for the right one catastrophically failed, but that's another story) and the occasional grinding I would get before has disappeared. I did get the Bimmerworld Group N style mounts which are much stiffer than stock. I can shift pretty quickly from 1st to 2nd now with no issue. Tbf I haven't tried slamming the it from 1st to 2nd at high rpm without letting the revs drop but despite my aggressive driving I don't feel the need to even try that. I'll be changing the trans mounts to aftermarket soon.

I also very recently swapped the fluid to Redline MTL 75W80. I don't know if the fluid before was original or not because my car was mostly dealer serviced but at least one of the previous owners was requesting extra services including "low-mileage" oil changes so maybe they had it done. (I'll change it again next time I do the oil in case it was original.) I chose the MTL because it's the same weight as the OEM LT-2 fluid (75W80) and GL-4 like the OEM fluid. At first it seemed very similar to stock with maybe slightly lower shifting effort, but that may be in my head. The effort is quite a bit higher when cold and decreases as it gets up to temp.

I know a lot of people on this forum seem to run much thinner fluids without trouble, especially if they drive their car in cold climates, but I didn't want to try that. Most ATFs and the Royal Purple Synchromax (RPSM) don't publish a gear oil viscosity rating but their data sheets indicate they're quite a bit thinner than 75W80 gear oil. For reference, the RPSM is very close to Redline D4 in specs. Not sure why anyone would recommend those when the manufacturer lists a specific viscosity and type of fluid though.

The Ford XT-M5-QS "Unicorn tears" is actually 75W90, so thicker than stock. May be a good choice for a track car. I know Miatas demand 75W90 GL-4 (I think GL-5 is incompatible due to the brass composition of the synchros or something but don't quote me on that). Redline makes a GL-5 75W90 manual trans fluid and it's way, way thicker than their MTF 75W80 based on the data sheet.

[cbpip]

Originally Posted by 07ImolaRot

So you can shift into 2nd gear at higher RPM really quickly with this fluid ?

Trans seems to like the Ford fluid. Autocross and very spirited driving . Autocross, winding out first to second shifts without issue. Also running Vibra-tech motor mounts, Rouge Engineering trans mounts and Garagistic short shifter. So the drive train has minimal shifting. All of the mods were done prior to any fluid switches so the difference between stock , Redline and Ford ATF fluids were a noticeable difference. Ford wins.

[wdb]

I have Vibra Technics motor mounts, Auto Solutions shifter, RP Sychromax fluid. I don't have any complaints about second gear balkiness anymore but I also don't slam shift my car. The former owner had Redline ATF in there, the stuff Redline recommends. I did not like that stuff.

[maupineda]

I have redline ATF too since the PO used that. Will change to RP. I have the same SSK and mounts and I have had 2nd gear rejected. So all I have left is try another fluid.