[AWM235i]

I have an M235i with ZF trans and recently added a racechip ultimate and wondering how much torque it can handle. I currently am on "B" setting and wanting a little more power and considering upping by 1-2 ticks on unit using 93 octane with drop in filter. I've read online that the transmission is rated to take basically stock tq, but not sure how conservative they are being.

[dt20011]

You should be ok, I'm over 450wtq and the tranny is solid.

[AWM235i]

Thats good to hear as it seems everyone has been running high power numbers on this forum. Thanks

[harkes]

Several people are running +500whp - have not heard of problems so far.

[alexc93]

The ZF8 is also used in the F-Type R and Range Rover Sport Supercharged, both well over 500hp, 500tq.

So I would imagine our cars (weighing much less) can definitely handle it.

You are likely to have other mechanical issues way before transmission..

[overcoil]

Doesn't the ZF website have maximum torque listed for the different 8 speeds?

http://www.zf.com/corporate/en_de/pr....shtml#tabs1-1

[Killramos]

Originally Posted by alexc93

The ZF8 is also used in the F-Type R and Range Rover Sport Supercharged, both well over 500hp, 500tq.

So I would imagine our cars (weighing much less) can definitely handle it.

You are likely to have other mechanical issues way before transmission..

There are many iterations of the ZF8 transmissions, I'm pretty sure we have one of the lowest rated versions.

The same transmission is in a dodge ram pickup truck, but very different rating.

Like saying the Allison transmission in a Silverado HD is the same as the one in an M1 Abrahms lol

It should be noted that ratings and actual capability before breaking are very different things.

[alexc93]

Originally Posted by Killramos

There are many iterations of the ZF8 transmissions, I'm pretty sure we have one of the lowest rated versions.

The same transmission is in a dodge ram pickup truck, but very different rating.

Like saying the Allison transmission in a Silverado HD is the same as the one in an M1 Abrahms lol

It should be noted that ratings and actual capability before breaking are very different things.

I understand there are different ratings, but it was stated by someone a while back that we had the same iteration as the F-Type R.

[Killramos]

Originally Posted by alexc93

I understand there are different ratings, but it was stated by someone a while back that we had the same iteration as the F-Type R.

I have never seen anything pointing to that. They use the 700 n.m version. Pretty sure we have the 450. Which is used by every other BMW of our cars size including the 1 series.

https://en.wikipedia.org/wiki/ZF_8HP...F_8HP_variants

BMW's only move up in the *50i size engines, SUV's and the 7 series from the evidence i have seen.

[dcpower]

In my experience there is certainly a perceivable difference in smoothness and drivability as power output increases. Our cars use the ZF 8HP45 as mentioned above. Having driven my partner's 428 xDrive extensively, the transmission is smooth and poised at all times. Recently, I've spent a couple weeks in a loaner 435 xDrive, and under heavy acceleration it certainly clunks into gear near redline. My car before it was recalled was an M235 xDrive running an ER Catless DP, BMS Intake, and JB4 Map 2. With this setup there were occasional rough shifts that warranted enough concern on my behalf to result in several trips to the dealer to confirm normal operation. I was told everything was running OK, but it is a far cry from the smooth experience as seen in the 428.

[Killramos]

Originally Posted by dcpower

In my experience there is certainly a perceivable difference in smoothness and drivability as power output increases. Our cars use the ZF 8HP45 as mentioned above. Having driven my partner's 428 xDrive extensively, the transmission is smooth and poised at all times. Recently, I've spent a couple weeks in a loaner 435 xDrive, and under heavy acceleration it certainly clunks into gear near redline. My car before it was recalled was an M235 xDrive running an ER Catless DP, BMS Intake, and JB4 Map 2. With this setup there were occasional rough shifts that warranted enough concern on my behalf to result in several trips to the dealer to confirm normal operation. I was told everything was running OK, but it is a far cry from the smooth experience as seen in the 428.

Stock its smooth enough, but we ( and likely the 435i ) have some different shift software that definitely alter the behavior of the transmission. Esp in sport mode.

I definitely can tell the difference in shifts between my M235i and my mums X1 xDrive28i.

[alexc93]

Originally Posted by Killramos

I have never seen anything pointing to that. They use the 700 n.m version. Pretty sure we have the 450. Which is used by every other BMW of our cars size including the 1 series.

https://en.wikipedia.org/wiki/ZF_8HP...F_8HP_variants

BMW's only move up in the *50i size engines, SUV's and the 7 series from the evidence i have seen.

I was just reiterating what I had read previously. Regardless, I still think our transmissions can well handle close to 500hp.

[dcpower]

Can handle it? Perhaps.
Personally I felt as I increased power Transmission shift quality degraded significantly. Such a shame this car was omitted a DCT or a 6-speed when configured with xDrive.

[SPJR]

I was curious about this too. From what I've read and like others here stated the 2 series as well as a lot of other BMW models run the ZF 8HP45 which is rated for 450NM of torque or 330 FT/LB. The Jaguar F-Type R on the other hand is running the ZF 8HP70 which is rated for 700NM or 516 FT/LB.

Same transmission different variant big difference.

I've also read of people running close to 700NM on their 8HP45. So who truly knows what they're capable of. Anyone know what the major differences are internally between the variants?

[ocN55]

Shouldn't the zf8 in the m235i be the same as the one found in the x6m? A car that has well over 500hp

[Killramos]

Originally Posted by ocN55

Shouldn't the zf8 in the m235i be the same as the one found in the x6m? A car that has well over 500hp

Only if you insist on ignoring all of the posts above you in this thread on this specific issue.

[ocN55]

Originally Posted by Killramos

Only if you insist on ignoring all of the posts above you in this thread on this specific issue.

I wasn't really declaring anything though. Merely asked a question.

But you got me, I didn't bother to read the whole thread in it's entirety

But having driven both the x6m and m235i, they feel the same to me truthfully. And I find it unwise for BMW to have 2 significantly different sport tuned ZF8s.

[Killramos]

Originally Posted by ocN55

I wasn't really declaring anything though. Merely asked a question.

But you got me, I didn't bother to read the whole thread in it's entirety

But having driven both the x6m and m235i, they feel the same to me truthfully. And I find it unwise for BMW to have 2 significantly different sport tuned ZF8s.

Actually they have 3 lol There is a 500 n.m version as well.

The transmissions are all the same, some of them just have a bit different engineering to them.

Its just bad engineering to shove a transmission that is way overbuilt just so you only have to keep 1 part on the shelf instead of 3. I guarantee the X5m version is not only bigger but heavier than the one in the 2. Should they increase the weight of the 2 ( or the 3, 4 and 5 for that matter) just to use the same part as a halo sport truck?

I am sure that transmission is also a fair chunk more expensive than the one in the 2. Would you like the msrp to be accordingly adjusted?

Also remember its not BMW's job to overbuild their cars just so you can tune them to near double torque and horsepower. Its their job to select parts that will allow their vehicles to run reliably stock for 100k+ km.

[kanucks]

It seems like the ZF8HP45 on the F22/23 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. This seems to make sense, since the ZF80HP45 for the diesel engine is rated at 500 n 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

[kanucks]

In other words, the ZF8HP45 should be able to handle 335whp and 335wtq or <380hp/tq at the crank without stressing it out beyond the manufacturer's specs. Anything beyond that and you're taking a risk, but I'm sure it'll still work (as many other members have dyno'ed 400+ wtq). However, you might sacrifice longevity and smoothness of shifts (i.e. slippage etc...), as well as warranty.

I think one of the main differentiators between the 2 series and the M2/3/4 would be the transmission and how much horsepower and torque it can handle. Obviously the N26 engine (N55) and F80 (S55) will have differences too, even though both are I6 3.0L engines, probably higher strength forged parts in the S55. And BMW probably strategically chose these parts in order to separate the M235i from the M3/4 sibling.

[PeterPure]

I have a f20 m135i with zf8hp45 trans. I ran pure stage1 turbo for 18k miles at 630nm max output. No issue. Now i have pure stage2 for 9k miles on the car which produces upto 700-750nm at 4500 rpm. Again no issue.

My german zf sources say this gearbox is good for 700nm. Ans its torque convertor for 650nm.

I have tuned only with jb4. No flash. Car still shifts smooth when not on the gas and shifts sporty brutal when going wot. Just the way i like it!

[terminator335i]

Originally Posted by AWM235i

I have an M235i with ZF trans and recently added a racechip ultimate and wondering how much torque it can handle. I currently am on "B" setting and wanting a little more power and considering upping by 1-2 ticks on unit using 93 octane with drop in filter. I've read online that the transmission is rated to take basically stock tq, but not sure how conservative they are being.

Bmw always underates everything. It never sets it at 450Nm torque if this was the "maximum" safety limit of the zf8 transmission. It will easily handle more torque and power to the engine as well for those who tune it. All the tuners (jb, racechip, afe scorcher, manhart, active autowerkes active 8 tuner, vr tuning box etc... All set their tunes to a safety value of around 40-70hp gains and torque gains of 100Nm. They can easily set their tunes to go beyond this and make it much more, but this will go outside the spectrum of the "safety" zone. I have an f30 335i and am running the racechip ultimate on setting +4 and have had absolutely no issues whatsoever. It drives very smooth on comfort (but feels more punchier than stock) and when you floor it on sports/sports+ it revs to redline and shifts so well. You certainly feel the torque and power difference.