MY TRANSMISSION REPAIR 8hp90

[hellno]

I think I might have a couple of more tenths on my set up but I’m pretty sure I’m about to hit the wall on it if I haven’t already I know with the weight reduction I can squeeze a little out of it but a high 9.3 may be it

 

[zhc]

What is the fastest hellcat meaning modded but no nitrous factory super charger and drivetrains pulleys and fuel can be any set up driveshaft mod is ok 3.09 or 2.62 A8 no demon supercharger all stock motor internals no cam upgrades , I’m just curious

uncrnps Sumit I think has this with his 8.98.

 

[Marc W]

I think I might have a couple of more tenths on my set up but I’m pretty sure I’m about to hit the wall on it if I haven’t already I know with the weight reduction I can squeeze a little out of it but a high 9.3 may be it

The tenths start getting exponentially harder to find the faster you go. The difference between for example a 9.5 and a 9.0 is like a mountain. Here’s a picture of my car on the track against a Demon who ran a 10.03 at 132 mph on this run. I ran 9.31 at 146 mph. Not much of a race. 😝

 

[Marc W]

uncrnps Sumit I think has this with his 8.98.

Yep! I’m embarrassed at having forgot that. At least I got the common denominator correct. You! 😂

 

[hellno]

Yea a few tenths looks like a beat down at the track

 

[hellno]

I’ve considered adding the 2.5 to my collection of pulleys

 

[Mean Cat]

I pull the shifter over to the left as I go through the traps. Then I can downshift myself at a reasonable speed or let it downshift itself.

Good info Jim , I'm gonna try it next time out.

 

[Mean Cat]

I’ve considered adding the 2.5 to my collection of pulleys

Smaller is better in this case !

 

[Mean Cat]

Hey hellno , since we mostly race our HC's - when do you think would be a good time mileage wise to change the trans. fluid & filter ?....surely b4 the OM recommends ?

 

[hellno]

Hey hellno , since we mostly race our HC's - when do you think would be a good time mileage wise to change the trans. fluid & filter ?....surely b4 the OM recommends ?

As hard as we drive ours I personally would change mine every 20,000 with the factory recommendation fluid I talked to alto and they suggested using the oem fluids but I pulled my pan and other then the burnt smell the fluid and the pan was very clean I’m right at 20,000 miles so I’d at least do it every 60,000 factory may say lifetime but when I went to the zf Seminar they recommended 60,000 miles

 

[Mean Cat]

As hard as we drive ours I personally would change mine every 20,000 with the factory recommendation fluid I talked to alto and they suggested using the oem fluids but I pulled my pan and other then the burnt smell the fluid and the pan was very clean I’m right at 20,000 miles so I’d at least do it every 60,000 factory may say lifetime but when I went to the zf Seminar they recommended 60,000 miles

I've a little over 6k miles on mine , I was thinking 20 > 25k miles might be a good time ?....I already have the filter kit with gasket & bolts & 10 qtrs. of oem fluid , I hope it doesn't go bad b4 I use it , lol.

Should I do a complete trans. fluid change encluding torq conveter or just the pan fluid & filter ?

 

[hellno]

At that mileage just the regular fluid change will be fine

 

[Mean Cat]

At that mileage just the regular fluid change will be fine

Thanks for your input & suggestions !

 

[fubar569]

I may have missed it...I got the part number for the fluid but what's the part number for the filter kit for these? 18+ if that matters any...

Mind = blown though. Never been this deep in an A8 before...

 

[Speedy!]

Couple misconceptions here I need to mention. Track does NOT shift harder than Sport. The opposite is true actually in most cases from what I can tell. Mike taught me that a while back as well when I used to use Track myself. It's complicated, but I found a thread discussing it on the HPTuner forum for anyone that wants to read. it has to do with driving patters, G Forces, and algorithms used to determine which table, or a blend of tables, to use for shift pressures.

https://forum.hptuners.com/showthread.php?69843-A8-hellcat-labeling

The real meat is in post #9

I've looked through all the shift pressure settings in a 2019 factory Redeye and 2016 factory Hellcat tune. There actually is no pressure setting labeled "TRACK" but there is Normal, Perf, Sport, and Max. Max from best I can tell is a base table of some kind and not actually a maximum since Perf and Sport actually have settings higher than what's in Max.

Surprisingly settings in Normal are HIGHER in the 2016 Hellcat tune than they are in the 2019 Redeye tune. Maybe due to the difference in the torque converter or maybe the extra grunt had them soften the shifts a bit?? This led me to check a 2018 Hellcat factory tune and everything matches the 2016 Hellcat tune EXCEPT Normal. The differences are all over the place so seems even the factory isn't sure what they want. Comparing the Hellcat tune to the Redeye tune Perf and Sport settings they're again kinda all over the place. The big difference is nearly all the settings for "on coming ramp" which the software defines as "oncoming clutch pressure ramp rate". The Redeye oncoming clutch pressure ramp rate settings are MUCH higher values in most cases. I'm not sure if higher = more pressure or if it's a time based value where higher = longer time?? @hellno any idea what that is doing? It's in the "Shift Pressures" "Upshift" table so I ass|u|me it's pressure.

There's not a ton of difference between Sport and Perf but in "most" areas Sport has a higher shift pressure defined. I "ass|u|me" Perf or a derivative is used in Track. Sport is obviously Sport. Here's a screen shot of a few gears showing Normal, Perf, Sport for the 2-3 (top) and 3-4 (bottom) shift so you guys can see. The pressures are different in each gear, but this is a good example. This is from a 2019 Redeye factory tune:

Note it's odd that Sport stops at 516 ft/lb turbine torque where Normal and Perf have a higher setting. Not a big deal, just weird. Sport will use the last row settings for anything over 516.

 

[fubar569]

Speedy....I didn't need this big of a headache tonight. Too much info to digest.

 

[Speedy!]

I've spent a few hours the past couple days digging through this stuff.

 

[fubar569]

What I know about the 8HP90:

I need to swap my fluid & filter in the spring for piece of mind.

Curt tuned mine. He said to use track. TBH I don't notice a difference between sport and track. I just don't ever use street if I'm beating on it.

Also...looks like I'll need beer for this project.

 

[hellno]

I’d like to know how to put just a little more in it

 

[hellno]

Couple misconceptions here I need to mention. Track does NOT shift harder than Sport. The opposite is true actually in most cases from what I can tell. Mike taught me that a while back as well when I used to use Track myself. It's complicated, but I found a thread discussing it on the HPTuner forum for anyone that wants to read. it has to do with driving patters, G Forces, and algorithms used to determine which table, or a blend of tables, to use for shift pressures.

https://forum.hptuners.com/showthread.php?69843-A8-hellcat-labeling

The real meat is in post #9

I've looked through all the shift pressure settings in a 2019 factory Redeye and 2016 factory Hellcat tune. There actually is no pressure setting labeled "TRACK" but there is Normal, Perf, Sport, and Max. Max from best I can tell is a base table of some kind and not actually a maximum since Perf and Sport actually have settings higher than what's in Max.

Surprisingly settings in Normal are HIGHER in the 2016 Hellcat tune than they are in the 2019 Redeye tune. Maybe due to the difference in the torque converter or maybe the extra grunt had them soften the shifts a bit?? This led me to check a 2018 Hellcat factory tune and everything matches the 2016 Hellcat tune EXCEPT Normal. The differences are all over the place so seems even the factory isn't sure what they want. Comparing the Hellcat tune to the Redeye tune Perf and Sport settings they're again kinda all over the place. The big difference is nearly all the settings for "on coming ramp" which the software defines as "oncoming clutch pressure ramp rate". The Redeye oncoming clutch pressure ramp rate settings are MUCH higher values in most cases. I'm not sure if higher = more pressure or if it's a time based value where higher = longer time?? @hellno any idea what that is doing? It's in the "Shift Pressures" "Upshift" table so I ass|u|me it's pressure.

There's not a ton of difference between Sport and Perf but in "most" areas Sport has a higher shift pressure defined. I "ass|u|me" Perf or a derivative is used in Track. Sport is obviously Sport. Here's a screen shot of a few gears showing Normal, Perf, Sport for the 2-3 (top) and 3-4 (bottom) shift so you guys can see. The pressures are different in each gear, but this is a good example. This is from a 2019 Redeye factory tune:

Note it's odd that Sport stops at 516 ft/lb turbine torque where Normal and Perf have a higher setting. Not a big deal, just weird. Sport will use the last row settings for anything over 516.

View attachment 7663

Great stuff @Speedy 👍