MY TRANSMISSION REPAIR 8hp90

[hellno]

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...

I can get it Monday because I have a kit ordered and should be in

 

[jgilj]

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

Thanks Jay now I have a headache 😂

 

[Speedy!]

So everything I posted is based on stock trans calibration. Tuners can custom tune it how ever they like. Mike likes Sport and that's how he taught me. Curt likes Track and nothing wrong with that either.

 

[hellno]

Everyone posting info on this thread will be helpful to the community as a whole

 

[zhc]

Sport is obviously Sport.

Not really... The labeling is generic to be useful across the multiple platforms that the ZF 8HP is used in and doesn't necessarily translate to the modes you see in any one particular platform like ours. Sport != Sport.

 

[Speedy!]

Good to know ZHC.

 

[zhc]

I had the pleasure of talking w Marc0779 while at Clay City last weekend. He apparently has made more Hellcat/Demon/Redeyes runs than most. He was explaining to me that he made a real effort to keep the rpms down on his engine at all times other than the actual run itself. Burnouts at 4 - 4500 rpm and putting it in neutral during shutdown. He explained to me that he'd made 700 runs running his car that way.
To each his own, but none of us are fighting our big ol' tanks at the finish line to the point of being too busy to push the shifter up a click.

I had the opportunity to listen to several cars in the other lane downshifting after the finish line and it really sounds hard on the engine from the outside.

IMO, in the end do what you're comfortable with but maybe try it once and form your own opinion.

What Marc0779 does is essentially what I do as well. It certainly feels like the strain on my engine is way less when I coast in neutral after a pass versus having it hang in gear waiting for the upshift to bring RPMs back down. Also, as my car got faster with quarter mile traps over 155 mph, I feel the transition from WOT to coasting in neutral easier to manage versus transitioning from WOT to engine brake at the very top of 5th gear, again at 155+... This practice also very likely saved me from a bad wreck when I had an oil filter seal blow out on me at 130 mph on the track. As soon as I noticed a cloud of smoke behind me, I was able to come off the throttle and into neutral before things got sketch when my right side front and rear tires became coated in oil. Now, had I left it in gear... imagine what could have happened instead.

 

[Speedy!]

@zhc do you have any advice for us amateurs trying to figure this stuff out? I can go setup a trans data log setup and spend a day cracking the code but appreciate any help speeding up that process.

 

[zhc]

@zhc do you have any advice for us amateurs trying to figure this stuff out? I can go setup a trans data log setup and spend a day cracking the code but appreciate any help speeding up that process.

Building a good foundation to work from helps a lot. Depending on how deep you want to go, studying up on any technical material you can on clutch to clutch automatic transmissions helps a lot.

Now, if you're just wondering what Normal, Perf, Sport, and Max mode tables are used for, the answer is it depends on a lot of factors. In the post you linked, Steven actually tries to explain this in one of his replies.

Generally though, Sport in HPT = Track mode but can also be used by other modes depending on the situation.

 

[Speedy!]

Sounds like @hellno and I need a conference call and looks like a day data logging the trans is in my future.

 

[hellno]

In my pics of the solenoids there’s a solenoid marked sys that’s the system pressure solenoid I’m going to ask Noah at Ericsson if they ever tried adjusting them to raise overall line pressure like we do in some Gm 4l70 and some of the 5r55e fords

 

[FFBOS]

I've had a 900rwhp setup for quite a while. I know my TCM tune is set it track for trans and it shifts a lot harder/faster, etc. I've "accidentally" left the car is sport for trans for a highway pull and I put the trans in limp mode. One of the "implausible torque" codes. I just don't think it likes being hit with the extra power there. I always triple check now like launching a space shuttle.

As far as going through the traps.....this season I started flipping the car into Neutral at the end of the run. Calms down a lot faster in my opinion. The only thing you have to be sure of is that your foot is off the gas prior lol.

This is a fantastic thread.

I have 21,000 on my 8HP90 with a LOT of WOT street passes, but only a dozen or so hard track passes. I was debating changing the fluid in the next 5k-10k, but I'm up in the air about it.

 

[hellno]

What’s your set up and 1/4 mile time at the track @FFBOS?

 

[FFBOS]

What’s your set up and 1/4 mile time at the track @FFBOS?

2.4 upper only. Best so far 9.75@142.5. That was shifting lower and with less timing. I have a revision I didn’t get a chance to try along with bigger tires now too.

 

[hellno]

Are you eth

2.4 upper only. Best so far 9.75@142.5. That was shifting lower and with less timing. I have a revision I didn’t get a chance to try along with bigger tires now too.

are you ethanol ? Don’t you have nitrous also ?

 

[FFBOS]

Pump e85. Have a nitrous tune to try at a 75 shot to start. Never got the car dialed in on blower only this year which was my main goal. I got a couple hundred rpm more in the shifts and a couple degrees of timing waiting to try. Goal with the car is a 9.5 blower only on this setup. If I can get a good 60’ I think l’ll get close. Then l’ll focus on spray. I had a hard time with the 305 tire last year so I got 315s now.

 

[hellno]

I’m sure you’ll

Pump e85. Have a nitrous tune to try at a 75 shot to start. Never got the car dialed in on blower only this year which was my main goal. I got a couple hundred rpm more in the shifts and a couple degrees of timing waiting to try. Goal with the car is a 9.5 blower only on this setup. If I can get a good 60’ I think l’ll get close. Then l’ll focus on spray. I had a hard time with the 305 tire last year so I got 315s now.

I’m sure you will get it and with the 315 you will hook good

 

[hellno]

@FFBOS DO YOU TUNE IT YOURSELF?

 

[FFBOS]

@FFBOS DO YOU TUNE IT YOURSELF?

No. Tim Barth. In these last couple years though I’ve learned a lot about the car though, especially on the datalog side of things. Something everyone should know the basics on at this level.

 

[coolblue]

@zhc and @FFBOS. So your saying at the end of a run at 140+ to 155+ The cars have enough braking on just the Brembo's to safely haul it down on most tracks unless there's something unusual with a really short shut off area on some tracks. Because if that's the case I would def have to say that would be easier on the tranny, motor and bearings esp. IMO. Meaning, I dk why that wouldn't be more of a known 'normal use' deal for guys drag racing with the auto.