[Geighty7]

Hey guys,

Please help weigh in here-

I wanted to explain what’s going on with my 6MT. For some reason, at WOT when I bang 3rd to 4th, I’m getting a major lockout. It’s happened twice now and sort of concerning me. At first I thought it was user error, but it happened again last night.

I’m doing hard pulls on freeway and at the top of my powerband in 3rd, I drop into 4th and dump the clutch. As soon as I dump, I’m getting a MAJOR lockout and grind. My engine over-revs (likely due to rev match) but I’m stuck in gear and my rear wheels stop spinning. When this happens I have to pop into neutral and downshift to 3rd or put it back in gear and I’m fine.

It’s scary af going that fast and having it happen.

The reason I don’t think it’s user error is because I’m banging 1-2-3 WAY harder than I do at high speed 3-4. It’s almost like my synchro is messed up there? When I’m driving around normally, there’s 0 issue and it’s smooth.

I replicated it again after with a lot more gentleness and it glides in if I slip the clutch more, but I don’t want to do that or granny shift.

FYI- my CDV is gone and my clutch stop is in, but it’s only helped and never hindered.

Does anyone have an inclening of what this could be? Tempted to take it into dealership, but I don’t want them to take apart my tranny really.

Also- any permenant damage that could be happening during these instances?

-Car drives fine as of now.

[ednir98]

I'm not sure but I will say this, put your CDV back in and remove your clutch stop if you decide to bring it to the dealer for this... if you care about your warranty.

[Dave07997S]

Originally Posted by Geighty7

Hey guys,

Please help weigh in here-

I wanted to explain what’s going on with my 6MT. For some reason, at WOT when I bang 3rd to 4th, I’m getting a major lockout. It’s happened twice now and sort of concerning me. At first I thought it was user error, but it happened again last night.

I’m doing hard pulls on freeway and at the top of my powerband in 3rd, I drop into 4th and dump the clutch. As soon as I dump, I’m getting a MAJOR lockout and grind. My engine over-revs (likely due to rev match) but I’m stuck in gear and my rear wheels stop spinning. When this happens I have to pop into neutral and downshift to 3rd or put it back in gear and I’m fine.

It’s scary af going that fast and having it happen.

The reason I don’t think it’s user error is because I’m banging 1-2-3 WAY harder than I do at high speed 3-4. It’s almost like my synchro is messed up there? When I’m driving around normally, there’s 0 issue and it’s smooth.

I replicated it again after with a lot more gentleness and it glides in if I slip the clutch more, but I don’t want to do that or granny shift.

FYI- my CDV is gone and my clutch stop is in, but it’s only helped and never hindered.

Does anyone have an inclening of what this could be? Tempted to take it into dealership, but I don’t want them to take apart my tranny really.

Also- any permenant damage that could be happening during these instances?

-Car drives fine as of now.

As someone else said, put the CDV in and have it looked at.

[Wheelwright]

Looks like your synchro is toast, I had my manual transmission replaced twice because of that, because BMW doesn't replace/rebuild synchros. There is no other permanent fix (don't let them smoothtalk you otherwise, or blame "driver error"), and the grind will only get worse over time.

[ednir98]

Originally Posted by Wheelwright

I had my manual transmission replaced twice because of that

Do you know if they were defective transmisions or is it a poorly designed part?

[Geighty7]

Originally Posted by Wheelwright

Looks like your synchro is toast, I had my manual transmission replaced twice because of that, because BMW doesn't replace/rebuild synchros. There is no other permanent fix (don't let them smoothtalk you otherwise, or blame "driver error"), and the grind will only get worse over time.

Ya it’s looking like a synchro issue as it’s only in that gear. I don’t have my CDV anymore so I might be F’d. I hope it’s not expensive, or that they will still cover it and it’s defective without the synchro.

[BroDoze]

I'd go buy a CDV (probably $1 part) and reinstall it. You don't want to buy a new 6MT+labor out of pocket.

I'll just say it, it's things like this that reinforce BMW has pretty much abandoned the 6MT. If they were continuing development on it, the whole box would have been continued to be upgraded/beefed up (synchros and all) for what these S58s are putting out.
I had a lot of grinding in my 135i and shifting headaches and it's one of many reasons I went ZF8 this time. Not to derail the thread.

[ednir98]

Originally Posted by BroDoze

I'd go buy a CDV (probably $1 part) and reinstall it.

If you go to the dealer for it don't give them your VIN just in case. You don't want that purchase tied to your BMW account. Sounds paranoid but better to be on the safe side.

[Geighty7]

My SA is pretty cool. I may just be honest and see what happens.

[BroDoze]

Just order it from one of the eleventy-billion online BMW parts stores.

[ednir98]

Originally Posted by Geighty7

My SA is pretty cool. I may just be honest and see what happens.

[reallymarkedup]

Originally Posted by BroDoze

I'll just say it, it's things like this that reinforce BMW has pretty much abandoned the 6MT.

We know nothing about the history of OPs particular transmission, their driving, what if any other mods they've made, their skill level, etc etc etc. You can't just make a massive blind jump from "one person has a problem" to "well obviously BMW has jumped the shark".

[BradMX5]

Mazda has crazy failures with the transmission in the ND Miata. Doesn’t mean they’ve abandoned it. Just took them 5 revisions to “fix” it.

[Geighty7]

Originally Posted by reallymarkedup

We know nothing about the history of OPs particular transmission, their driving, what if any other mods they've made, their skill level, etc etc etc. You can't just make a massive blind jump from "one person has a problem" to "well obviously BMW has jumped the shark".

15 years experienced 6MT trans never faced this issue that wasn’t user error. Usually baby my car but do some fun pulls here and there. No trans or engine mods besides listed.

[reallymarkedup]

Originally Posted by Geighty7

15 years experienced 6MT trans never faced this issue that wasn’t user error. Usually baby my car but do some fun pulls here and there. No trans or engine mods besides listed.

That comment wasn't meant to be directed at you or your driving ability. It could be summed up as "one example is not indicative of BMW as a whole" and it's a bit baffling when people jump to conclusions like that.

[Tag]

Originally Posted by Geighty7

My SA is pretty cool. I may just be honest and see what happens.

Doesn't matter how cool your SA is, if this gets escalated, they will look for any reason to decline repair. Better be safe than...

[minn19]

I’m curious how they’d know the CDV was gone, I doubt they’d even look there. They don’t seem to troubleshoot anymore, they just replace things. Also curious as to how you’d put it back in correctly.

After having F80 manual before and now with my G87 (plus driving many other MT BMWs), IMO they don’t like to be shifted fast. BMW has pretty much given up on MT development for probably over a decade now. Unfortunately BMW makes you choose the ZF8 if you really want to use the full potential of the S58. The G87 especially doesn't like it, I don’t remember this much rev hang in my F80. It’s one of the few disappointments of the car.

[ednir98]

Originally Posted by minn19

I’m curious how they’d know the CDV was gone, I doubt they’d even look there.

Is it even worth the risk? They could easily blame the lack of a CDV then you're out of pocket what, $15k for a new transmission?

[minn19]

Originally Posted by ednir98

Is it even worth the risk? They could easily blame the lack of a CDV then you're out of pocket what, $15k for a new transmission?

Trust me, I hear you. After watching videos how it’s removed, I’m legit curious if it can be put back in correctly. And if you don’t, what kind of problems you have then. It’s one of the main reasons I haven’t done it yet. Maybe it’s as easy as the removal, I honestly don’t know.

[ednir98]

minn19 I've never removed or reinstalled one but hopefully the latter is not difficult.

[dienstag]

Originally Posted by Geighty7

Hey guys,

Please help weigh in here-

I wanted to explain what’s going on with my 6MT. For some reason, at WOT when I bang 3rd to 4th, I’m getting a major lockout. It’s happened twice now and sort of concerning me. At first I thought it was user error, but it happened again last night.

I’m doing hard pulls on freeway and at the top of my powerband in 3rd, I drop into 4th and dump the clutch. As soon as I dump, I’m getting a MAJOR lockout and grind. My engine over-revs (likely due to rev match) but I’m stuck in gear and my rear wheels stop spinning. When this happens I have to pop into neutral and downshift to 3rd or put it back in gear and I’m fine.

It’s scary af going that fast and having it happen.

The reason I don’t think it’s user error is because I’m banging 1-2-3 WAY harder than I do at high speed 3-4. It’s almost like my synchro is messed up there? When I’m driving around normally, there’s 0 issue and it’s smooth.

I replicated it again after with a lot more gentleness and it glides in if I slip the clutch more, but I don’t want to do that or granny shift.

FYI- my CDV is gone and my clutch stop is in, but it’s only helped and never hindered.

Does anyone have an inclening of what this could be? Tempted to take it into dealership, but I don’t want them to take apart my tranny really.

Also- any permenant damage that could be happening during these instances?

-Car drives fine as of now.

If your are sure your car over-rev'd, AFAIK there is no other cause than a misshift. Rev match will not over-rev your engine, and certainly not if it thinks you're upshifting. And you couldn't over-rev it with the throttle due to rev limiter. I am not a BMW guru so maybe there's something I'm missing, but I cannot see how this car can be over-rev'd other than mechanically by picking the wrong ratio.

[aerobod]

The CDV refit should be straightforward, but it isn’t a pair of parts sold separately from a complete slave cylinder.