MY TRANSMISSION REPAIR 8hp90

[cole3986]

I don't know about others but from talking to curt these transmissions are having problems,,as I stated in the post earlier I believ I caused mine

You think you caused it by doing a pull on street or in sport mode? No way (if that was the case I would be on 6th A8).

There are a few quick A8's that have not had any issues, Omega (has run 8.9s), Summit (just ran a 8.9). Then there is me, it is only part of the drive train that I have not killed I is the A8. This is just to name a few.

Omega and I have the same Curt TCM tune as you.

For these reasons, I say why this happened to you is as clear as mud.

 

[Magnified]

Well then the next go to is Redline D6 ... Used by Coan and alot of others..I used it in my NAG 1

Redline is a good product.

 

[hellno]

You think you caused it by doing a pull on street or in sport mode? No way (if that was the case I would be on 6th A8).

There are a few quick A8's that have not had any issues, Omega (has run 8.9s), Summit (just ran a 8.9). Then there is me, it is only part of the drive train that I have not killed I is the A8. This is just to name a few.

Omega and I have the same Curt TCM tune as you.

For these reasons, I say why this happened to you is as clear as mud.

I logged in street mode only Cole , I was saying had I logged in sport or track mode I probably would not had this issue, before I went to ethanol and changed the rear diff I never had an issue but with the hard pulls in the interstate with the 2.65 pulley in street mode that’s the only explanation I have. , that being said I could be wrong it may possibly have a solenoid as the underlying issue , either way the E and D clutches are burnt and I have to fix it

 

[hellno]

And Cole if you have an idea as to why it happened please feel free to explain
I’m open to any helpful info

 

[cole3986]

I think this thread is great, very informative.

I will tell you what I know, up the line pressure and the A8 will shift so hard it can break the tires lose on shifts and kill the pass. Turn off torque management and the clutches will get burned. Have the transmission do a lazy shift (for whatever reason) on the strip (on a hit) and it will burn the clutches (over time).

So that we are all on the same page, torque management is a fancy way of saying the PCM pulls timing for a milli second or so during the shift so that the torque is reduced, greatly reducing the wear on the clutches.

It has NOT BEEN demonstrated that any of the aftermarket built A8 are any stronger than the factory unit.

Your data log can tell how quickly the shifts were (are) and that can provide insight on whether the shifts are taking too long, causing excessive heat and wear. If the shifts are slower than published, test the solenoids (if possible) or replace them (if available). IMO, get the A8 back together, crank up the line pressure and data log. If the shifts are still slow, the problem is in the command or solenoids.

I do not have your skill set to rebuild my own A8 so my solution was to purchase a very low mileage A8 to just replace mine when it starts screwing up. I am treating them as throw away because they can be purchased with low mileage under 3K (much cheaper than rebuilding them).

 

[hellno]

On my last two runs the torque management showed up in the logs after the 1-2 upshift also the 2-3 shift would shift at 7000 instead of 6500 but I do agree that solenoids could be a concern because all the zf units I rebuild get a new solenoid kit but with mine having such low mileage I wouldn’t think they’d be suspect but then again I’ve seen new parts bad time and time again , I was already planning on sourcing new ones

 

[cole3986]

On my last two runs the torque management showed up in the logs after the 1-2 upshift also the 2-3 shift would shift at 7000 instead of 6500 but I do agree that solenoids could be a concern because all the zf units I rebuild get a new solenoid kit but with mine having such low mileage I wouldn’t think they’d be suspect but then again I’ve seen new parts bad time and time again , I was already planning on sourcing new ones

One thing I forgot to mention is the speed the hellcat is accelerating becomes a factor, install a 3.09 or numerically higher gear and the computers have a hard keeping up (the acceleration in rpms through 1st gear) in a really quick hellcat. That is one of the reasons I run a 2.62.

I say this is as clear as mud is because there are so many factors at play here and the ones with really good data or information don't share.

BTW, the Speedcore Demon (twin turbo, carbon fiber panels) best is 8.66 or so, why isn't it quicker? I think the A8 is a source of headaches on that car. Just an observation, spit balling here

 

[Hpindy]

I'm really glad I don't have the power you guys make . my transmission should be fine .

Sent from my BBF100-2 using Tapatalk

 

[2fast4u]

Very informative, following to see outcome. Curious as to the gains of using Demon converter, just more stall, or other benefits as well?

 

[coolblue]

Incredibly good thread. Thanks @hellno. I'm an M6 but this stuff is so informative, interesting and useful. I did one 727 in high school out of an Imperial. All I can say is that thing looks massive internally by comparison. Did not even realize it alternated clutches between gears. I thought it was evenly distributed equally in all gears to increase surface area before you posted graph. Amazing it can even take that much abuse on a stock part. The steals are burnt but not that bad. I'd think they'd be smoked with launches and power like that. (Cole says they can take more. wow). Excellent thread and presentation.

 

[Markp]

Can the mods sticky this thread. I don't remember ever seeing a thread this in depth on the A8 even on the other forum.

 

[tkracing1]

Can the mods sticky this thread. I don't remember seeing ever seeing a thread this in depth on the A8 even on the other forum.

Done!

 

[Markp]

This is the alto clutch and steel modules that I will be replacing my factory ones with View attachment 7421

Hellno your a sneaky guy......I see that converter is giving us the finger.

 

[hellno]

Hellno your a sneaky guy......I see that converter is giving us the finger.

Lmao I was wondering how long but would take for someone to notice that

 

[Hpindy]

Lmao I was wondering how long but would take for someone to notice that

Mark doesn't miss stuff like that ....... Because that's what he would do !

Sent from my BBF100-2 using Tapatalk

 

[hellno]

Here’s a pic of the solenoid set up and identity of each solenoid there is a green solenoid on the valve body that is for park function only, I’m shipping the solenoids out today to my friend Noah at Ericsson industries to have the solenoids flow tested , this will be critical as I have found out the solenoids are NOT available separately, you would have to buy the Valvebody from Chrysler at a cost of around 2,000 I will know next week how they tested and of course I have my fingers crossed that they pass with flying colors

 

[motorhead]

One thing I forgot to mention is the speed the hellcat is accelerating becomes a factor, install a 3.09 or numerically higher gear and the computers have a hard keeping up (the acceleration in rpms through 1st gear) in a really quick hellcat. That is one of the reasons I run a 2.62.

I say this is as clear as mud is because there are so many factors at play here and the ones with really good data or information don't share.

BTW, the Speedcore Demon (twin turbo, carbon fiber panels) best is 8.66 or so, why isn't it quicker? I think the A8 is a source of headaches on that car. Just an observation, spit balling here

I covered this in another thread (think it was when Speedy caused his engine overrev) people fail to recognize that this a hydraulic pump and it's abilities and limitations are dictated by the physics of that system; including the acceleration rate. You can influence it's behavior with mechanical changes, but even then it is only within the limits of the electronics.

This is why folks are going to proven analogue slush boxes when the thresholds are exceeded.

 

[hellno]

I covered this in another thread (think it was when Speedy caused his engine overrev) people fail to recognize that this a hydraulic pump and it's abilities and limitations are dictated by the physics of that system; including the acceleration rate. You can influence it's behavior with mechanical changes, but even then it is only within the limits of the electronics.

This is why folks are going to proven analogue slush boxes when the thresholds are exceeded.

That wouldn’t explain how mike @ostdyno is spinning them up to 7500 rpm

 

[Marc W]

im adding the demon converter

Are you shopping for one or already have it?

 

[hellno]

Are you shopping for one or already have it?

I have one being shipped as we speak 👍😃