[PeterPure]

Originally Posted by harkes

Weird you get slip in the lower gears - traditionally slip would occur in higher gears where the trans is loaded over longer time. The trans will experience the "same" torque in all gears - that of the engine. Only the torque to the wheels change with the gears.

@Darkiedm4 told me the other day that he has put 570lbft through the ZF8HP45

I ran 50k km with st2 turbo running 650 nm daily and 775nm peak for sprints. No issues. Stock flash just jb4.

[Gio72]

Originally Posted by Polo08816

Any idea if a ZF 8HP50 is an easier swap/conversion? It should be similar in physical dimensions to the ZF 8HP45.

The point is not if it is an easy conversion, but how much for it! I think it should cost a lot of money...

Originally Posted by Darkiedm4

I ran 50k km with st2 turbo running 650 nm daily and 775nm peak for sprints. No issues. Stock flash just jb4.

Do you use it on track or for long pull on mountain roads? Or just for some short pulls (2nd-3rd-4th-5th gear and stop)?

[lazycat]

Hi, My ZF 8hp45 is slipping at 5th and 6th. Logs show that even after gear change, rpm rises immediately and car does not accelerate much.

Is there any way I can swap in a torque converter that is stronger? Or buy aftermarket clutches?

[hardparker]

I'd have to open one up to see what interchanges with the higher torque models, how thin we could go with the clutch steels and how much could be taken off of the pistons. But, I could potentially build up clutch packs with increased clutch count and closer tolerances.

I've been wanting to crack into the ZF 8HP anyhow, since it's so ubiquitous. I'll start looking for a spare 8HP45 AWD transmission to develop on. If anybody comes across one for cheap, let me know. Anything under $1000, with transfer case still attached, is a good price.

[maxio]

Originally Posted by ShlemonboostedM

No need for it .. Bms 435i holding 539whp and 450lbft on stock tranny .. So unless you trying to go above that I don't think it's necessary ..

Hi there! I'm new around f30post, just got my 335i installed with JB4 Map 1 and enjoying the power so far, but lusting for more.

Saw your whp and lbft numbers, can you share what mods one would need to get to that level please?

[GTBrandon]

Originally Posted by maxio

Hi there! I'm new around f30post, just got my 335i installed with JB4 Map 1 and enjoying the power so far, but lusting for more.

Saw your whp and lbft numbers, can you share what mods one would need to get to that level please?

Downpipe, chargepipe, and a flash tune.

Then you can start messing with meth, ethanol, and turbo upgrades.

Lots of threads on flash tunes, most popular being BM3

[insanecoder]

Originally Posted by lazycat

Hi, My ZF 8hp45 is slipping at 5th and 6th. Logs show that even after gear change, rpm rises immediately and car does not accelerate much.

Is there any way I can swap in a torque converter that is stronger? Or buy aftermarket clutches?

Sure, torque converter, clutchpacks, shafts etc can be upgraded

[harkes]

Who has experienced this? Is the consensus that this is a gearbox safety feature and that the solution (smart thing for longevity) is to run a lower boost target in 6th?

hardparker Polo08816 Darkiedm4 obriennathaniel

[hardparker]

We'd have to see what clutch sets are engaged in sixth and see if it's a physical limitation. In that case, it may be prudent. Otherwise, I suspect it's a value hiding in the DME somewhere that can be flashed out. Either way, I say edit it to some unattainable value, once found, and lets see what breaks! Then, more clutches!

[PeterPure]

See the technical specs:
https://www.motor.com/newsletters/20...8HP_Tranny.pdf

In 6th gear clutches C, D, E are engaged which is said to put more stress on the unit hence bmw limits torque in the ppk for 335 to 400nm in 6th gear (while other gears are 450nm).

If there is some torque limiter in the dme why nobody found it after 5 years of being able to flash these? Then again i have not seen of any zf8 speeds blowing up yet...

[afranke]

At least one good thing about the AH3 is we get the GA8P70H (8HP70), so it's max is 700nm (a 250nm increase). Even with that, I can still feel the torque limiter when I hit 6th.

[hardparker]

Originally Posted by Darkiedm4

See the technical specs:
https://www.motor.com/newsletters/20...8HP_Tranny.pdf

In 6th gear clutches C, D, E are engaged which is said to put more stress on the unit hence bmw limits torque in the ppk for 335 to 400nm in 6th gear (while other gears are 450nm).

If there is some torque limiter in the dme why nobody found it after 5 years of being able to flash these? Then again i have not seen of any zf8 speeds blowing up yet...

I'd suspect D is the culprit, that followed by E. Wouldn't matter, since you'd want to upgrade the whole kit anyhow. Lazycat was slipping 5th and 6th. My guess is that D is common to both. I don't have the rebuild manual yet, but I'm sure it'll illustrate such.

Originally Posted by afranke

At least one good thing about the AH3 is we get the GA8P70H (8HP70), so it's max is 700nm (a 250nm increase). Even with that, I can still feel the torque limiter when I hit 6th.

That and the fact that Alto already makes a complete PowerPack upgrade with an extra clutch for each pack. Dunno why they've skipped over the much more common 8HP45 so far. There are plenty of powerful cars rocking one.

Long story short, get to breaking the 8HP45 and I'll whip up a solution for us. I've done similar in the past:

http://legacygt.com/forums/showpost....&postcount=129

http://legacygt.com/forums/showthrea...ts-210357.html

[Lancelot]

Originally Posted by FThirtyFive

JB4 lies to the DME about actual boost the car is running so the transmission doesn't know it should set itself up to hold higher power and torque. This is why you want to get a flash tune on the car so the transmission controller can see what's really going on and then use JB4 on top if you need it for anything. I was feeling what I think was slip as well with only JB4 on the car. With a BM3 flash now the car feels a lot better at full power and I have the JB4 for when I go with PI eventually. Right now its disabled just running BM3 on its own.

Exactly this, no reason to upgrade transmission, use a proper flash tune my JB4's been gone since then;

The ActiveHybrid uses a 8p70h transmission rated to 700Nm and i had the same issue with jb4

[harkes]

Originally Posted by Lancelot

Exactly this, no reason to upgrade transmission, use a proper flash tune my JB4's been gone since then;

The ActiveHybrid uses a 8p70h transmission rated to 700Nm and i had the same issue with jb4

Halim has promised me something to test for this issue so I'll keep you posted.

[harkes]

Originally Posted by Lancelot

Exactly this, no reason to upgrade transmission, use a proper flash tune my JB4's been gone since then;

The ActiveHybrid uses a 8p70h transmission rated to 700Nm and i had the same issue with jb4

Can you share a log from your current tune?

[Alpine3s]

I'm sorry if this is a dumb question, just trying to clarify. The 8HP45 handles 450nm of torque as input power from engine which is about ~340 TQ. JB4 Stage2 and some minor mods on 328i pushes 300 or more TQ to wheels, meaning, without drivetrain loss (15% or so) we'd be at that 340-350 "max" base engine TQ.

Are we theoretically exceeding the TQ specs on our trans?

I've read in other threads the 8HP45 has a 500nm limit, some others 450nm. I'm confused as I believe to have seen links for both.

The 340's with JB4, equipped with the same trans (anything with an inline 6 and turbo with the 8HP45), plus the JB4, it would almost venture into saying they are exceeding way beyond the TQ design of the unit.

What's the real story?

[afranke]

Originally Posted by Alpine3s

I'm sorry if this is a dumb question, just trying to clarify. The 8HP45 handles 450nm of torque as input power from engine which is about ~340 TQ. JB4 Stage2 and some minor mods on 328i pushes 300 or more TQ to wheels, meaning, without drivetrain loss (15% or so) we'd be at that 340-350 "max" base engine TQ.

Are we theoretically exceeding the TQ specs on our trans?

I've read in other threads the 8HP45 has a 500nm limit, some others 450nm. I'm confused as I believe to have seen links for both.

The 340's with JB4, equipped with the same trans (anything with an inline 6 and turbo with the 8HP45), plus the JB4, it would almost venture into saying they are exceeding way beyond the TQ design of the unit.

What's the real story?

You're conflating lb-ft and nm I think. The current 340i (stock) is 332 lb-ft, which is 450Nm. the 8HP45 is rated for 450NM "Engine Torque Capacity" and 550Nm "Input Torque Capacity" (700/760 on the 8HP70)

Page 8: https://www.motor.com/newsletters/20...8HP_Tranny.pdf

[valve float]

anyone gotta clue when xHP will have something for the 8HP45 ?

[Alpine3s]

Originally Posted by afranke

You're conflating lb-ft and nm I think. The current 340i (stock) is 332 lb-ft, which is 450Nm. the 8HP45 is rated for 450NM "Engine Torque Capacity" and 550Nm "Input Torque Capacity" (700/760 on the 8HP70)

Page 8: https://www.motor.com/newsletters/20...8HP_Tranny.pdf

Got it, thanks. Learn something new every day. Love these forums

[Romberg]

Anything new about this topic?

[harkes]

Originally Posted by Romberg

Anything new about this topic?

With xHP out and increased clutch pressure I think there is little need for any mechanical modifications. I am putting ~650 wheel Nm (760 crank Nm) through mine at the moment and has been doing so on and off the past 4 years without issues.

[bqik]

Originally Posted by harkes

With xHP out and increased clutch pressure I think there is little need for any mechanical modifications. I am putting ~650 wheel Nm (760 crank Nm) through mine at the moment and has been doing so on and off the past 4 years without issues.

do you really need that high torque?

wouldn't it be better 550Nm in the medium range?

for traction and engine/gearbox wear.

I am not criticizing just asking

thanks.