A91-MT 10k Mile Status Update

[WrenchMonkey]

4k+ on my 23 MT. No real complains. Very enjoyable car experience. Every now and then into 3rd from redline, the RPMs seem to float after the clutch pedal is released and at WOT for about 1 to 3 seconds before speed/rpm start to increase together. My first impression was a "heavy flywheel feeling" but later learned it might be a CDV related issue (this is my first
BMW).

• Better fuel milage than I expected.
• Center Display creaks now, in the colder weather (fixing soon).
• Jerky 1-2 on "less committed" shifts.
• Trunk/rear noise rattle fixed

9 Months and 3500 Miles into ownership.
I have the CDV deleted. Here are my findings (similar to most):

4. In colder temps (< 40F), I have noticed that, shifting into 3rd gear at lower speeds is difficult. I can feel the synchro's still locking me out. It is repeatable and is scary. The lockout goes away once the car has been driven for about 15 mins at 40-50mph. It might be that the trans fluid does not get warm enough or at least on par with the engine. At least this is my theory. Anyone else notice this?

I always wait till the rpms stabilize at around 600rpm. I've noticed there's 3 stages after a cold start. (1) high rpms 7-800+ (2) at high 600s, car gets noticeably quiet here and (3) low 600s normal idle. Using the JB4, transmission fluid temp stabilizes after that plus 2 min of driving (219-221⁰F). That being said, before this point, I too notice the gears engage much nicer if I change into gears higher than 2k rpm.

Hope this helps!

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[WrenchMonkey]

Happens during regular shifts at 25 mph ~ 30 mph at 2k or lower rpms. Interestingly, at higher speeds and more aggressive shifts, it goes away.

Same! Except I don't remember if this was the case in the summer also . I didnt drive it as much then.

 

[Stvee]

4. In colder temps (< 40F), I have noticed that, shifting into 3rd gear at lower speeds is difficult. I can feel the synchro's still locking me out. It is repeatable and is scary. The lockout goes away once the car has been driven for about 15 mins at 40-50mph. It might be that the trans fluid does not get warm enough or at least on par with the engine. At least this is my theory. Anyone else notice this?

That doesn't happen on mine at all. It's the only manual I've owned that shifts smoother when it's cold actually.

 

[Tacoma714]

I find third gear is the go gear in this car.



Skipping gears on the upshift shouldn't ever be an issue if your revs are up. If they're not up you're just going to enter a slow zone until the revs build (not ideal) or you downshift.

Skipping gears during downshifts is when you might encounter waterworks.



Dude.. I'm almost convinced. I'm going to see how much this will cost me to get done. Is a CDV delete easily reversible?

It's reversible, but once you do it you won't want to go back trust me. The CDV was made for people who don't know how to drive manual and beat on their clutches hard. Once I got it done the difference was noticeable and reminded of my past 6MT cars without the jerky 1-2.

 

[Tacoma714]

closing in at 8k miles, and still pretty damn happy, Have not had the clutch slip in a little while but I know if I replicate the conditions it will probably do it, luckily I am not really pinning it in 1st so I not a huge problem for me. I think CDV delete is next on the list for me. Still unsure if I will ever be unlocking and tuning this one, still debating the dinan piggyback.

Still unsure because of the cost of upgrading a clutch due to more power or unsure because you might not be keeping long term?

 

[BrettMRC]

I still have the CDV on mine, and will shortly be going down the hybrid turbo route.

Do we think CDV deletion is a good safeguard?

I don't track or drag the car, it's an occasional fast road toy...

 

[Tacoma714]

I still have the CDV on mine, and will shortly be going down the hybrid turbo route.

Do we think CDV deletion is a good safeguard?

I don't track or drag the car, it's an occasional fast road toy...

Hybrid turbo with no upgraded clutch?

 

[Spart]

Every now and then into 3rd from redline, the RPMs seem to float after the clutch pedal is released and at WOT for about 1 to 3 seconds before speed/rpm start to increase together. My first impression was a "heavy flywheel feeling" but later learned it might be a CDV related issue (this is my first
BMW).

[snip]

• Jerky 1-2 on "less committed" shifts.

Ditch the CDV as soon as possible.

 

[BrettMRC]

Hybrid turbo with no upgraded clutch?

Initially, yes.

 

[Tacoma714]

I

Initially, yes.

Per my local shop that works on A LOT of MKV Supras along with plenty of G8X's, going hybrid turbo and if you start pushing 550+HP, you'll probably need an upgraded clutch sooner than later. They recommended Spec as their preferred upgraded clutch which is the one I'm gonna go with. They've had issues with Clutchmasters and mentioned Spec has been in the BMW game and drifting for a long time with an excellent track record. The furthest I would go with the stock clutch is Femto BM3 unlock with a downpipe and E50. Anything after like hybrid turbo, upgraded fuel pumps, port injection or anything more would definitely require an upgraded clutch.

 

[Eddy90]

I always wait till the rpms stabilize at around 600rpm. I've noticed there's 3 stages after a cold start. (1) high rpms 7-800+ (2) at high 600s, car gets noticeably quiet here and (3) low 600s normal idle.

Very interesting find regarding the idle. I have not paid attention to it tbh. I usually let the car warm up to the (2) stage ... I can only guess its stage (2) because the idle does drop at least once.

Using the JB4, transmission fluid temp stabilizes after that plus 2 min of driving (219-221⁰F). That being said, before this point, I too notice the gears engage much nicer if I change into gears higher than 2k rpm. Hope this helps!

Bingo. I think we are describing the same thing. I had a feeling it was something to do with transmission temps and your findings line up with that.
Do you know what the temps are at idle at the (3) stages you just described? I think the transmission cooler might also make it harder to reach the right temps.
From my experience, it takes around 15-20 mins to reach a smooth feeling shift (and by that logic, a stable trans temp) when driving at <40F temps.

Same! Except I don't remember if this was the case in the summer also . I didnt drive it as much then.

No issues at all in the summer. I think the trans fluid heats up pretty quickly and it reaches stable temps in the first few minutes of idle.

 

[Eddy90]

That doesn't happen on mine at all. It's the only manual I've owned that shifts smoother when it's cold actually.

Your transmission fluid probably gets warm enough on its own, AND/OR you might be shifting at a >2k RPM unknowingly.
What temps are you typically seeing in your area?

 

[lucky phil]

When I leave my 40-45 F garage, its fine as well.
But it sits out for 6-8 hours in 30F while im at work. Driving driving back home from that - is when i notice it.

Happens during regular shifts at 25 mph ~ 30 mph at 2k or lower rpms. Interestingly, at higher speeds and more aggressive shifts, it goes away.

For now, I've been dodging 3rd, and shifting straight to 4th lol.

Cold shifting issues isn't uncommon in manual transmissions. I've had a few over the years that needed to be warmed up before shifting was ok. The Holden M21 wouldn't shift into second at all until it had 5 or 6 klm on it in cold weather. A lot of people just changed over to ATF to solve the issue. Yea I know, ATF in a manual trans but it seemed to have no detrimental affects on the trans.
The Tremec T56 wouldn't shift into reverse when cold unless you selected a fwd gear immediately before. So to select revers, select 4th and then straight into reverse. If you drive in cold weather all the time and the issue annoys you then a change to a thinner grade gear oil will help and won't create any issues for the trans.

Phil

 

[Eddy90]

Cold shifting issues isn't uncommon in manual transmissions. I've had a few over the years that needed to be warmed up before shifting was ok. The Holden M21 wouldn't shift into second at all until it had 5 or 6 klm on it in cold weather. A lot of people just changed over to ATF to solve the issue. Yea I know, ATF in a manual trans but it seemed to have no detrimental affects on the trans.
The Tremec T56 wouldn't shift into reverse when cold unless you selected a fwd gear immediately before. So to select revers, select 4th and then straight into reverse. If you drive in cold weather all the time and the issue annoys you then a change to a thinner grade gear oil will help and won't create any issues for the trans.

Phil

Thank you Phil, very insightful information.
I will chalk all the findings down to the transmission fluid just not reaching the right temps.

It is annoying, however, since I am able to identify the cause and have a potential workaround (I'll just skip 3rd or 4th) until the fluids all warm up, I should be Ok.
I also intend to store the car in the colder winter months (sub 30F), which starts in January anyways, so ill check in around April to see if the problem still persists

 

[MattPhantom]

Hi everyone, approaching 12k miles at around 700hp for the last 5k. Haven’t noticed any major issues except every now and then the transmission seems to go up or down a gear even when im not touching the shifter. It happens so quickly sometimes I barely notice. Should I be worried?

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