[Stall]

Originally Posted by adrianv

Well, I lot of this is speculation, but I can make some observations:


BMW would not recommend using the transmission this way unless there was significant headroom in the torque handling of the transmission. Automotive OEMs are extremely risk averse when it comes to the actuarial analysis of their warranty cost and exposure.

.

This. As is the case with most manufacturers in the current decade. The bean counters always win.

[xHoon]

Originally Posted by PhilAnthony

Not going to lie... I have a 2013 335IX F30 with ZF8 and after installing ER dp and JB4 -- I was running maps 1,2, 5, and 7 with 100 octane and even some E20 to see how it responded. I was loving hthe beta map 5 that was release for the Fseries..

Until about 2 months ago, I had no problems. Then on a cold morning, I went full throttle on Map 2 (with dp, same setup dynoed at ~360whp and 450wtq) I ran into some slippage in the transmission. It would NOT catch gears from 1-2, 2-3, even 3-4 at heavy throttle shifting at its major torque making rpms (like 3500-5500)... I was stunned because I had not read one single complaint. The car would accelerate like a rocket but when shifting it would throw you forward because it was like hitting the breaks. It took very long to shift into the next gear and the momentum was broken. It was not normal and it was very much a fucking bad shift. I was so mad.

I was fairly certain that the tranny was overbuilt but once it started to slip I kept trying to turn off the JB4 and engine to see if it was a computer error. NO check engine light came on and NO shadow codes or tuner codes when read with BT Scan Tool. The transmission wasn't warning me or the computer about this.

I was due for an upcoming oil change so I removed the dp and the JB4.... told the service about the problem amongst other things. The water pump would turn on and continue to run after long drives and the oil gauge would note that oil was low (damn N55s suck up oil) and the car would also run a bit hot. I continued to feel the slip (maybe doing it too much .. like a bad scab on the elbow that you can't stop picking at). I feel that the clutch packs are toast and I would love to see the tranny fluid.

Not sure what BMW will be able to do for me since there is no check engine light. I am hoping they check fluid and other things. The good thing is after I would turn off the JB4, it would NOT slip anymore.

After noticing that the slip only occurred with the JB4, I figured it was most definitely due to the torque and stress on the tranny. I read someone's post on a thread I started about this problem and he said something along the line of "I like to think that the problem already existed and was exacerbated by the mods" ... so maybe the transmission was faulty from the start and it was made more blatant with the tune and dp.

I dropped my car off today actually. Got a loaner car for now. It is all stock and codes deleted (tuner codes like O2 sensor, blowoff valve jammed close, MAF problems). I hope they find it to be something simple like low transmission fluid or something (i am no mechanic lol). I think I remember seeing some fluid that had leaked from underneath and left its mark on the removable undercarriage that covers the tranny and turbo/cat. Maybe something blew?

Will update you on what happens. It will be hard to diagnose the problem if they cannot reproduce it (no more JB4).

EDIT: from adrianv's post ... I may have done a good amount of launches using the brake and accelerator with the jb4 active ... could the torque converter be "worn out" or "bad" from these launches?? I cannot recall how often I would do them because I only had the tune on for about 5 weeks and I have had it off for about 3 weeks.

Thanks.

The 335ix is awd right? Maybe that why it slip, since awd won't lose traction like the rwd do, all the torque is acting on the transmission, I assume rwd won't have that problem unless you running on slick tyres.

[PhilAnthony]

Got it back last night. Service rep said it was fine and he didn't find any codes in the transmission's ecu ... they did the oil change and some other updates and replaced some small part that had been recalled.

Service rep reset EGS in the transmission...stating that it was probably from sharing the keys and having the transmission trying to adapt to 2 different driving personalities.

I installed JB4 this morning and am running map 5 .... I do not have the dp installed yet but I can feel the same hesitation in shifting ... just not as bad because I am not making the same power without the dp installed.

It seems like it is on the verge of slipping as of now and any power increase will cause the tranny to not engage correctly like I had felt with dp. I am not sure what to do at this point. I want the dp on but maybe I will just run map 1.

How do I tell if its torque converter? I would like to think that the transmission fluid has some metal shavings settled on the bottom. Sucks that service only checked the computer.. Oh well..

[adrianv]

Originally Posted by PhilAnthony

How do I tell if its torque converter? I would like to think that the transmission fluid has some metal shavings settled on the bottom. Sucks that service only checked the computer.. Oh well..

You can do a torque converter stall speed test:
Stand hard on the brake, floor the gas for three seconds and see what rpm your motor settles at. (just like our "launch control")

My wife's 328xi stalls this way at around 3200rpm. I think the ZF8 in the 328 is the same one as the 235, but my 235 is still floating in the pacific, so I can't tell you if it is the same yet.

[SJL]

Hearsay the unmodified 8-speed ZF gearbox (8HP45Z) should not exceed 600nm on crank .

Seems quite reasonable .

[kanucks]

Hey guys, is the ZF8HP a planetary (torque converter) or single clutch AT? I am wondering because I just upgraded from a 2007 Honda FG2 which was MT and this is my first AT in 8-9 years... Thanks in advance and sorry for reviving an old thread.

And while on the topic, it seems like the ZF8HP on the F22 faces a stall issue when tuned with GSR. They've detuned it to around 330wtq (or about 376 ft/lbs at the crank), but obviously the 6-speed MT does not have this limitation as much. This seems to make sense, since the ZF80HP45 for the diesel engine is rated at 500n x m even though it's the same transmission as the gasoline version.

Converting 500 n/m to ft/lb is roughly 369 ft/lbs of torque, which corroborates with GSR detuning the ECU Flash map to have less torque. Same with Enzo Performance's Stage 2 tune for the F22 (228i on AT) which limits the crank torque to 343 ft/lbs.
https://enzoperformance.com/product/...u-calibration/

"But the options on the ZF8HP go beyond software programming. Different internal clutch packs can be used depending on a manufacturer's specific torque requirements. The transmission has a range of 221 lb-ft to a massive 738 lb-ft, but most applications land between 330 and 550 lb-ft."
http://www.popularmechanics.com/cars...peed-15855273/

"PLEASE NOTE: For those N20/N26 auto cars, there is a current torque limit at or about 350 wtq. Typically cars with DP and 93 can exceed this on our Stage 2 tune. We are working to find the limit within the code but have yet to identify how the torque limit is implemented. We recommend N20/N26 auto customers who run on 93 to stick with Stage 1 until we have resolution of the torque limit. There is no such limit on manual cars."
http://www.2addicts.com/forums/showthread.php?t=1128708

https://en.wikipedia.org/wiki/ZF_8HP_transmission#BMW

[EEBreh]

Originally Posted by Greenkirby21

yup I believe you are correct. According to real-oem, the M235i manual and auto are the same model # as the F30 335i.

Manual max is 470 nm
Auto max is 450 nm

Interesting. We have the same manual transmission that the 1M has and that puts out ~500NM of torque when it overboosts.

[moldcad]

I think it's simply impossible that the max torque for M235i ZF8 is just 450 Nm, which is what the factory specs for the max engine output is. There just must be some safety margin - and I suspect that just like BMW underrate their specs (reason being insurance rates in Germany are based on those figures, NOT the engine displacement), ZF might as well underrate theirs (possible reason being easier refusal of warranty claims from the "tuners").

Just take a look at Dinan's own dyno charts, comparing their DINANTRONICS output with stock; they show stock torque much, much higher than the 450 Nm BMW claims - actually 514 Nm (interestingly - hp not so much higher):

[quenotte]

Originally Posted by Greenkirby21

yup I believe you are correct. According to real-oem, the M235i manual and auto are the same model # as the F30 335i.

Manual max is 470 nm
Auto max is 450 nm

Full bullshit. I don't know how you read this on realoem...

Auto and manual gearbox are both rated at 450Nm max given their designation.

Auto gearbox are specific for N55 with 450Nm output, that is to say, Mx35i and N55 x40i (640i,740i,...). They should be reinforced compared to 400Nm N55 output ones (F series x35i).

Those gearboxes are not the same as F30 335i ones.

Period.

[walnuttea]

Out of curiosity, was this ever looked into further? A general consensus on transmission "longevity" after modding?

[bryan_G01]

Been over 450 lbs tq Wheel, not crank numbers as Dinan shows for over a year and i beat the shit out of the car.

No issues at all on awd xdrive, 23,000 miles. Tuned since day 1.

[Dylan86]

FWIW, the DSG's in the VW's are rated at 350nm, but there's thousand of guys over 400wtq (myself included) that have never seen destruction on the particular DSG from the TQ alone. The breakage usually comes with heavy wheel hop or abusive launching. Same would go for the ZF8, I wouldn't worry a bit about it...

[XutvJet]

Originally Posted by walnuttea

Out of curiosity, was this ever looked into further? A general consensus on transmission "longevity" after modding?

No one knows for certain the amount of torque needed to break the 8AT (many different types of failure can occur) but you can be assured that if you add more power than stock, it will DEFINITELY reduce longevity. The more power you add, the greater the longevity is reduced. Power results in heat and the greater the power, the greater the heat. The primary killer in planetary automatics is heat. Adding an extra 80-100wtq in 4th gear (typical dyno gear) is significant plus those gains are much much greater in the lower gears thanks to torque multiplication. I wouldn't be surprised if 100wtq would reduce 8AT longevity by 20-40%.

6MTs aren't immune either. Clutches become the primary weak link and I'm always amused when people act surprised when their clutch goes out after 40-60K miles and they had been running an extra 100wtq+ for a long period of time and drove it hard.

[bryan_G01]

Originally Posted by XutvJet

No one knows for certain the amount of torque needed to break the 8AT (many different types of failure can occur) but you can be assured that if you add more power than stock, it will DEFINITELY reduce longevity. The more power you add, the greater the longevity is reduced. Power results in heat and the greater the power, the greater the heat. The primary killer in planetary automatics is heat. Adding an extra 80-100wtq in 4th gear (typical dyno gear) is significant plus those gains are much much greater in the lower gears thanks to torque multiplication. I wouldn't be surprised if 100wtq would reduce 8AT longevity by 20-40%.

6MTs aren't immune either. Clutches become the primary weak link and I'm always amused when people act surprised when their clutch goes out after 40-60K miles and they had been running an extra 100wtq+ for a long period of time and drove it hard.

Dyno gear in a 8 speed is 5th, not 4th.

[amw896]

wheres luminous to chine in? Hes been running absurd amounts of power on his lol

[XutvJet]

Originally Posted by bryan_f22

Dyno gear in a 8 speed is 5th, not 4th.

It really depends on the shop when it comes to which gear is used. Some shops prefer to use the shorter gear to keep excessive load down. Others like taller gears to evaluate how load impacts knock, drivability, etc. It doesn't really much matter either. Dynoing in 5th will show only a 1-2% difference in the numbers compared to 4th. The point is pushing 20-30%+ more torque than stock will certainly impact the reliability/longevity of the 8AT or any transmission for that matter. Beating on your modded 8AT pushing a lot more power than stock for 1 year and 10,000 miles doesn't matter much here. Do the same for 3+ years and see how well that 8AT is holding up. My guess is it will be having slip issues.

[wjjkoevoets]

Originally Posted by amw896

wheres luminous to chine in? Hes been running absurd amounts of power on his lol

Yes, luminous has one hell of a ride! Don't forger about Darkie either, he was pushing over 700 NM on his ZF8 as well and didn't have any transmission issues either.

Should we really be worried about this transmission at all when throwing on a (heavy) tune?

Us Northern Europeans can just stop by a ZF service center for "regular" (every 60k miles) maintenance and transmission revision if necessary (for me, it's only a 50 miles or 150 miles if I'm feeling like doing a roadtrip to Germany). I'm not sure if they also have service centers in the US. The way I see it, is I'd just go to a nearby ZF service center and have them go over the basics (new oil, clean, replace some minor stuff and whatnot). That should keep it in decent shape with or without a tune.

Should it start giving issues at any point, I'd take it directly to one of ZF's centers and not the dealer. The dealer usually can't fix it and have to rely on ZF anyways.

That's just my take, feel free to correct me if I am horribly mistaken

[Boosted Autos]

The new M240i is quoted as making 500NM from factory, does it have the same 8HP450 transmission?

That might be a good indicator?

[AlexM240i]

Originally Posted by Boosted Autos

The new M240i is quoted as making 500NM from factory, does it have the same 8HP450 transmission?

That might be a good indicator?

Same question. Suscribing....

[Arrow29]

Originally Posted by Boosted Autos

The new M240i is quoted as making 500NM from factory, does it have the same 8HP450 transmission?

That might be a good indicator?

I remember reading somewhere that from 2014, ZF started producing the 2nd gen of their 8HP transmission, which updated the 8HP450 to the 8HP500.

[Boosted Autos]

Originally Posted by Arrow29

I remember reading somewhere that from 2014, ZF started producing the 2nd gen of their 8HP transmission, which updated the 8HP450 to the 8HP500.

Not sure but BMW say that the M235i has an 8HP450 in it, not 500 :S

Amazing we can't get a straight answer on this one. Are there any Dinan/BMS reps on here who would know?

[Polo08816]

Originally Posted by XutvJet

No one knows for certain the amount of torque needed to break the 8AT (many different types of failure can occur) but you can be assured that if you add more power than stock, it will DEFINITELY reduce longevity. The more power you add, the greater the longevity is reduced. Power results in heat and the greater the power, the greater the heat. The primary killer in planetary automatics is heat. Adding an extra 80-100wtq in 4th gear (typical dyno gear) is significant plus those gains are much much greater in the lower gears thanks to torque multiplication. I wouldn't be surprised if 100wtq would reduce 8AT longevity by 20-40%.

6MTs aren't immune either. Clutches become the primary weak link and I'm always amused when people act surprised when their clutch goes out after 40-60K miles and they had been running an extra 100wtq+ for a long period of time and drove it hard.

+1.

There's this uninformed mentality that if someone running X amount of HP and TQ hasn't blown their transmission yet, then the transmission is fine holding that torque.

The problem is that specific user's use case may be different from someone else's. For example, if that user is just doing 10-20 second WOT pulls, then there may not be enough heat generated to cause damage to the transmission. However, the if you were to driving the car at 10/10ths at the track for 10-20 mins, it's feasible that this specific use case would exceed the heat capacity for the transmission and cause catastrophic damage and/or reduce the longevity of the transmission.

This is why BMW and ZF appear to "underrate" the transmission.

Personally, I do a lot of HPDEs so I won't be doing significant powertrain mods.