[Saif2018]

XHP just dropped an update!

[Saif2018]

Drag race mode eliminates torque reduction altogether and increases clutch wear by 4X!

Staying in 2nd gear in stop and go traffic is nice. I've also noticed XHP have added several preset shift points (relaxed, relaxed+, sportive and sportive+) with the option to also store 3 different custom shift points.

[flipmode]

xHP really giving it all with the drag race mode. No timing drops or torque loss! This will be very hard on your clutches for sure lol. Check out this log I pulled on my 94 petrol tune. 2nd gear launch

https://datazap.me/u/johnnyb12/log-1...ata=3-16-20-26

[Bimmer_Bro]

Originally Posted by Saif2018

Drag race mode eliminates torque reduction altogether and increases clutch wear by 4X!

Staying in 2nd gear in stop and go traffic is nice. I've also noticed XHP have added several preset shift points (relaxed, relaxed+, sportive and sportive+) with the option to also store 3 different custom shift points.

I assume the drag race mode it's just to be flashed before the track and not DD?
I would be curious about these presets! Wonder if any of it can be changed on the fly or if you need to flash each time.

[Godzilx]

Seems very interesting. Will have to wait and see how other peoples' transmissions hold up before I try this. Seems like it would be great for the track- lots of power loss on shifts due to the torque reduction which they seem to have removed.

[Saif2018]

Originally Posted by Bimmer_Bro

I assume the drag race mode it's just to be flashed before the track and not DD?
I would be curious about these presets! Wonder if any of it can be changed on the fly or if you need to flash each time.

Switching presets would require a flash before they are active.

Drag race mode - this is what XHP says...

[Saif2018]

Originally Posted by flipmode

xHP really giving it all with the drag race mode. No timing drops or torque loss! This will be very hard on your clutches for sure lol. Check out this log I pulled on my 94 petrol tune. 2nd gear launch

https://datazap.me/u/johnnyb12/log-1...ata=3-16-20-26

clutches must be screaming in agony lol

[iqraceworks]

That looks like a cool feature....but those ZF 6HP21 transmissions are only rated at something like 250 ft/lbs of torque......most people are close to putting double that much torque through them or more.

Not sure I want to slam into each gear with no torque reduction between shifts on a transmission that's already being overloaded with more power than it's been designed for.

Thanks....but I'll take the fraction of a second in 1/4mile et reduction in trade for a transmission that (hopefully) isn't going to come apart on me

Seems like a good way to really tear things up......

[rismo]

I put a good bottle on the level of structural damages this will give to an 21.
Been in the position to conduct some thermal testing on such gearbox, this will kill them.

In average your gearbox hovers around 10-15 degrees behind your engine temp, the oil in the gearbox is not doing well when overheated (once), it should be replaced after such an event because it's becomes very fast very powerless in terms of keeping your gearbox lubricated.
When either your gearbox oil or your hardware is not (longer) in a good shape the wear of your gearbox will go through the roof compared to a gearbox in a good state.

A bit similar with tires, when they start to wear, traction will be suboptimum, more slip, more wear..

For those who are interested, there is equipment from ZF to read out all peak events measured during the life of the box. It will for example show each moment of overheated oil temps. Information not pushed to the ECU of the car. The gearbox overheated warning is to my measures triggered way beyond safe oil temps if you consider the oil vendor temp recommendations.

On the other hand, it will be damn fast :-)

[Saif2018]

Originally Posted by iqraceworks

That looks like a cool feature....but those ZF 6HP21 transmissions are only rated at something like 250 ft/lbs of torque......most people are close to putting double that much torque through them or more.

Not sure I want to slam into each gear with no torque reduction between shifts on a transmission that's already being overloaded with more power than it's been designed for.

Thanks....but I'll take the fraction of a second in 1/4mile et reduction in trade for a transmission that (hopefully) isn't going to come apart on me

Seems like a good way to really tear things up......

6hp21 is rated at 250lbft?

[iqraceworks]

Originally Posted by Saif2018

6hp21 is rated at 250lbft?

Sorry, I was wrong. ZF rates the 6HP21 at 332 ft/lbs. I bet most FBO N54's are making 500ft/lbs or more. Not sure I want to abuse the transmission any more than I have to with crazy hard shifts and no torque reduction.....sounds like a sure fire way to kill it in a hurry.

Especially just to gain a tenth in the 1/4 mile....

[spacey_n54]

Originally Posted by iqraceworks

Sorry, I was wrong. ZF rates the 6HP21 at 332 ft/lbs. I bet most FBO N54's are making 500ft/lbs or more. Not sure I want to abuse the transmission any more than I have to with crazy hard shifts and no torque reduction.....sounds like a sure fire way to kill it in a hurry.

Especially just to gain a tenth in the 1/4 mile....

For daily spirited driving, do you think it saves the trans at all to manually let up between shifts for a brief second? I notice if I'm in manual mode and let off throttle slightly on a 3-4 shift, it takes much longer for the shift to complete and it's ready for more throttle.

[iqraceworks]

Originally Posted by spacey_n54

For daily spirited driving, do you think it saves the trans at all to manually let up between shifts for a brief second? I notice if I'm in manual mode and let off throttle slightly on a 3-4 shift, it takes much longer for the shift to complete and it's ready for more throttle.

I'd be willing to be that the best thing to do it just let the transmission do its own thing when it shifts....it reduces torque from the motor for a split second during shifts, so that should help. I wouldn't bother trying to let off the gas between shifts....just drive it 😁

[spacey_n54]

Originally Posted by iqraceworks

I'd be willing to be that the best thing to do it just let the transmission do its own thing when it shifts....it reduces torque from the motor for a split second during shifts, so that should help. I wouldn't bother trying to let off the gas between shifts....just drive it 😁

Will do. I saw this update come in on XHP the other day, and I just finished installing a replacement 6AT in my car not too long ago. Never dismissed something so quickly 😂

[Saif2018]

Originally Posted by iqraceworks

Sorry, I was wrong. ZF rates the 6HP21 at 332 ft/lbs. I bet most FBO N54's are making 500ft/lbs or more. Not sure I want to abuse the transmission any more than I have to with crazy hard shifts and no torque reduction.....sounds like a sure fire way to kill it in a hurry.

Especially just to gain a tenth in the 1/4 mile....

Yeah, I'm in the same mindset, no way am I going to be going through 4 x clutch wear just to get the fastest drag times.

[Saif2018]

Originally Posted by spacey_n54

For daily spirited driving, do you think it saves the trans at all to manually let up between shifts for a brief second? I notice if I'm in manual mode and let off throttle slightly on a 3-4 shift, it takes much longer for the shift to complete and it's ready for more throttle.

That's completely unnecessary, and will just slow down the shift.

Doing this on a single clutch transmission like the SMG made it smoother, but on a torque converter trans it wouldn't benefit the trans in any significant way.

[Saif2018]

Originally Posted by spacey_n54

Will do. I saw this update come in on XHP the other day, and I just finished installing a replacement 6AT in my car not too long ago. Never dismissed something so quickly 😂

The move off from 2nd gear during traffic should be useful though, as well as the preset shift points and the ability to store custom shift maps.

[rjahl]

Originally Posted by Saif2018

That's completely unnecessary, and will just slow down the shift.

I think you guys are missing the real physics of a gear shift in an automatic gear box.

Firstly, torque reduction is nice when you have slow soft shifts taking 500-800 milliseconds to execute. The clutches are slipping for a really long time and generating a ton of heat. As you start speeding up the shift to 200-300 milliseconds, the inertia of the rotating masses starts to become a bigger factor than the power produced by the engine. Think about the engine, flywheel and torque converter spinning at 7000 rpm and the gear shift slowing at all down to 4500RPM in a quarter second.

If you have enough command in the clutches to make that shift, the stress on the rest of the drivetrain is brutal. I'd be more worried about output shafts, gears and driveshafts than wet clutches, they won't slip long enough to generate much heat.

My two cents

[iqraceworks]

Yeah good point. It they do say it's going to wear the clutches 4x faster......so something has got to be causing that extra wear. I wish they would give more details instead of being so vaige about it.

What do "drag setting" actually do? Boost line pressure even more? Get rid of all torque reduction? Other things that might be going on? Those ZF transmissions are pretty complicated as far as what they can do.

[Saif2018]

Originally Posted by rjahl

I think you guys are missing the real physics of a gear shift in an automatic gear box.

Firstly, torque reduction is nice when you have slow soft shifts taking 500-800 milliseconds to execute. The clutches are slipping for a really long time and generating a ton of heat. As you start speeding up the shift to 200-300 milliseconds, the inertia of the rotating masses starts to become a bigger factor than the power produced by the engine. Think about the engine, flywheel and torque converter spinning at 7000 rpm and the gear shift slowing at all down to 4500RPM in a quarter second.

If you have enough command in the clutches to make that shift, the stress on the rest of the drivetrain is brutal. I'd be more worried about output shafts, gears and driveshafts than wet clutches, they won't slip long enough to generate much heat.

My two cents

From what I understood, it's not just nice or necessary for slow trans, Some degree of torque reduction is a necessity in the ZF gearboxes even the latest 8 speed ones, and easing off the gas in a torque converter trans for upshift is completely unnecessary and doesn't save the trans. Removing TQ reduction altogether increases load on clutch pack several fold as stated by XHP.

Might be ok with a one off launch but multiple launches with 4 x clutch wear will no doubt fry them quickly but yeah other parts of the trans also likely to break as you stated.

[Saif2018]

Originally Posted by iqraceworks

Yeah good point. It they do say it's going to wear the clutches 4x faster......so something has got to be causing that extra wear. I wish they would give more details instead of being so vaige about it.

What do "drag setting" actually do? Boost line pressure even more? Get rid of all torque reduction? Other things that might be going on? Those ZF transmissions are pretty complicated as far as what they can do.

Gets rid of virtually all torque reduction, no timing pulls between shifts as a result. Look at the log posted

[iqraceworks]

Originally Posted by Saif2018

Gets rid of virtually all torque reduction, no timing pulls between shifts as a result. Look at the log posted

Yep...So is 4 times the wear on your transmission worth a tenth in the 1/4? Not for me. Give it 6 months of guys running that "drag" option...and let's see what happens. If there are no issues with people burning up transmissions..I will give it a try.