MY TRANSMISSION REPAIR 8hp90

[Marc W]

I have one being shipped as we speak 👍😃

Ok good they aren’t easy to come by. I have a near new one that will be coming out in two weeks when I change to the T400.

 

[motorhead]

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

Spinning what?

 

[hellno]

Spinning what?

He told me they are shifting them as high as 7500 rpm

 

[motorhead]

He told me they are shifting them as high as 7500 rpm

Are we talking about engines or transmissions?

 

[hellno]

Transmissions

 

[motorhead]

Transmissions

So is the suggestion here that the pump can/cannot keep up with the demands of the hydraulic system and is therefore RPM dependant?

Because input speed and pump capacity aren't what I was addressing.

My point is there is a distinct possibility that the limitations of the electronics (TCM, sensors, and solenoids) could be causing failures in extreme applications. Line pressure and shift timing is managed by calculated torque models are determined by the TCM - how much fluid and fluid pressure to deliver and when is paramount. The ability for an electronic system to predict or respond is limited by the capability of the mechanical system it is commanding. If the hydraulic system doesn't want to cooperate there is not much the computer to do about it. This is where the TH400-based units come in - tossing out the electronics and any thresholds.

That being said the highest torque demands are at lower RPM input speeds, and if the engine is producing increased torque and accelerating at a higher rate there may be insufficient pressure or volume to support the demands.

Do the ZF8s have internal pressure transducers, or the provisions to add them?

I have pressure transducers on my GM transmissions, so I can log the commanded line pressure vs delivered line pressure vs calculated torque vs acceleration rate vs shift time delay vs input/output speed (slippage)... basically proving the fluid model.

Do your tuners offer this service? They should.

 

[hellno]

I’m not sure if curt has that service but I would imagine there a data pid for actual and commanded pressures whether or not it’s in the hp tuner I haven’t looked but in my shop scanner there is a lot of data including clutch fill times and counters etc

 

[Hpindy]

I think we need to fix the issues with the A8 vs going back in time to a band aid fix by replacing it an out dated TH400 . It has enough parasitic loss to chock an elephant.

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[cole3986]

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

IMO, he is not shifting that high, the A8 will not shift past 7,000 RPM. I like to see a data log with the shift points past 7,000 rpm.

BTW, when my cat decides not shift (for whatever reason) and it hits the rev limiter and bounces off it, bad things have happened to the blower on a big nitrous shot.

 

[cole3986]

I think we need to fix the issues with the A8 vs going back in time to a band aid fix by replacing it an out dated TH400 . It has enough parasitic loss to chock an elephant.

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A power glide (two speed transmission) has the least amount of parasitic losses, it may be better than the A8, only a few moving parts. However try going from a 4.71 1st gear to a 1.62. Not really an option unless crazy rear gear is used and the car spins 4,000 rpm at 50 mph.

 

[motorhead]

I think we need to fix the issues with the A8 vs going back in time to a band aid fix by replacing it an out dated TH400 . It has enough parasitic loss to chock an elephant.

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Disagree. Modern rollarization and new products from companies like ATI have fixed the legacy misconceptions. Plus, at these power levels you can "turn up the boost" to compensate.

 

[motorhead]

IMO, he is not shifting that high, the A8 will not shift past 7,000 RPM. I like to see a data log with the shift points past 7,000 rpm.

BTW, when my cat decides not shift (for whatever reason) and it hits the rev limiter and bounces off it, bad things have happened to the blower on a big nitrous shot.

This reinforces the possible limitations of the controlling electronics, and not necessarily the hydraulic pump converting power into motion; but both will eventually hit a wall without physical or program changes.

 

[Marc W]

I

I think we need to fix the issues with the A8 vs going back in time to a band aid fix by replacing it an out dated TH400 . It has enough parasitic loss to chock an elephant.

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l disagree with a full built race 400 being a bandaid. For the builds that exceed what the stock drive line will take, it addresses some huge problems. It starts with the differential. After going thru a half dozen of those, one might consider the 9” conversion. That will address the strength issue but adds a problem for the transmission. A 1200whp car needs a gear ratio below 3.00 to allow the A8 to keep up. That’s why you see most of the high hp cars going back to the 2.62. The 9” doesn’t have that available. Trying to manage the tcm and get it to reliably do what you want it to do when running a 3.25 to 3.40 gear is a challenge to put it mildly. For me personally.... I don’t have the capability to tcm tune at all (let alone constantly at the track) and I can’t have one of the few tuners who can do this at my disposal full time. Then there’s the cost of rebuilding/replacing one of these hp90’s. Mr. Hellno is able to do this. That is a pretty big consideration when you’re looking at $3k to $5k a pop every time you’re trans starts slipping if you can’t rebuild your own. More if it actually breaks. I’ll be swapping my A8 for a new 400 next month and will get some dyno results to see just how much hp one of the race built 400’s suck up.

 

[motorhead]

I

l disagree with a full built race 400 being a bandaid. For the builds that exceed what the stock drive line will take, it addresses some huge problems. The first one is the differential. After going thru a half dozen of those, one might consider the 9” conversion. That will address the strength issue but adds a problem for the transmission. A 1200whp car needs a gear ratio below 3.00 to allow the A8 to keep up. That’s why you see most of the high hp cars going back to the 2.62. The 9” doesn’t have that available. Trying to manage the tcm and get it to reliably do what you want it to do when running a 3.25 to 3.40 gear is a challenge to put it mildly. For me personally.... I don’t have the capability to tcm tune at all (let alone constantly at the track) and I can’t have one of the few tuners who can do this at my disposal full time. Then there’s the cost of rebuilding/replacing one of these hp90’s. Mr. Hellno is able to do this. That is a pretty big consideration when you’re looking at $3k to $5k a pop every time you’re trans starts slipping if you can’t rebuild your own. More if it actually breaks. I’ll be swapping my A8 for a new 400 next month and will get some dyno results to see just how much hp one of the race built 400’s suck up.

Lots of guys going 9s on bone stock 4L80Es with TransGo shift kits. Lots of TH400s backed by Gear Vendor OD units on Drag Week. You don't want to know what it cost to build the 4L70E in my TBSS to support the Procharger... disgusting.

The ZF8 is great, but either you want a race car or you don't. The development work that makes a 2000hp capable TH400 has been done.

 

[Hpindy]

That's why I said we need to fix the issues in the A8. If I was forced to go back to a older transmission I would take the 727 all day long . I guess my choice if forced to would be a Dana 60 with 3.54 gears and a 727 with a gear vendors. I guess the A8 is too new

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[hellno]

OK SOLENOIDS SHIPPED AND IM WAITING FOR A CALL BACK FROM SOUTHERN HOTROD ABOUT THE KOLEEN STEELS ,FROM WHAT IVE BEEN TOLD FROM ALTO USA IS THAT SOUTHERN HOTROD IS TAKING KOLEEN STEELS FROM 8HP70 AND THE HIGHPERFORMANCE FRICTIONS AS WELL ,ALTO TOLD ME THE STEELS AND FRICTIONS FROM AN 8HP70 ARE DIFFERENT THICKNESS SO APPARENTLY FROM WHAT I CAN GATHER IS THAT SOUTHERN HOT ROD IS BUILDING THEIR OWN KITS AND THE CLUTCH PACKS THRU SNAP RINGS AND IM SURE SOME TYPE OF MACHINING(CNC) THEY ARE SETTING THE CLEARANCES TO SPEC .WHILE I WAS ON THE PHONE WITH JUSTIN FROM ALTO HE TOLD ME THAT NEXT YEAR THEY ARE COMING OUT WITH A BETTER TYPE OF PERFORMANCE STEEL FOR THE HP90 IF I DONT HEAR BACK FROM SOUTHERN HOT ROD THEN IM GOINHG AHED AND REASSEMBLING MY TRANS AND SENDING IT DOWN THE TRACK ,ILL BE WILLING TO BET IT PERFORMS AS IT SHOULD BECAUSE THE GLAZED OVER STEELS AND CLUTCHES NO LONGER HAVE THE COEFFICIENTCY TO APLY PROPERLY ,I STILL HONESTLY STAND FIRM ON THE CAUSE OF MY FAILURE UNLESS NOAH AT ERICSON TELLS ME A SOLENOID IS NOT PERFORMING PROPERLY ILL KNOW THAT ANSWER MONDAY ,GOOD THING IS I FOUND OUT THAT HOLLYSPRINGS WILL OPEN THE RACE TRACK IF TEMPS ARE ABOVE 50 DEGREES ALL YEAR AROUND SO I WILL BE ABLE TO TEST IT WITHOUT WAITING TIL NEXT YEAR MAYBE,,ALSO AS A SIDE NOTE THE KOLEEN STEELS ARE ONLY INSTALLED IN THE C,D AND E CLUTCH PACKS

 

[hellno]

SOLENOID APPLICATION CHART ABOVE

 

[hellno]

NEWS FLASH!!! GUYS I HAVE JUST GOT OFF WITH ROY BAKER SENIOR TECHNICAL DIRECTOR FOR ALTO USA ,AND HE IS SENDING ME THE POWER PACKS FROM THE HP70 C,D AND E CLUTCH WITH EXTRA CLUTCHES AND STEELS TO INSTALL IN MY ASSEMBLY ,,,,,, HE ALSO TOLD ME HE HAS ALREADY DESIGNED POWER PACKS FOR THE HP90 THAT WILL GO INTO PRODUCTION VERY SOON ,,SO THERE YOU HAVE IT HOT OFF THE PRESS ILL BE GETTING THEM NEXT WEEK DAMN THIS THREAD IS FUN,HE TOLD ME THERE IS SOMEONE FROM SUN COAST THAT DID THIS AND ARE HAVING GREAT SUCCESS

 

[Hpindy]

NEWS FLASH!!! GUYS I HAVE JUST GOT OFF WITH ROY BAKER SENIOR TECHNICAL DIRECTOR FOR ALTO USA ,AND HE IS SENDING ME THE POWER PACKS FROM THE HP70 C,D AND E CLUTCH WITH EXTRA CLUTCHES AND STEELS TO INSTALL IN MY ASSEMBLY ,,,,,, HE ALSO TOLD ME HE HAS ALREADY DESIGNED POWER PACKS FOR THE HP90 THAT WILL GO INTO PRODUCTION VERY SOON ,,SO THERE YOU HAVE IT HOT OFF THE PRESS ILL BE GETTING THEM NEXT WEEK DAMN THIS THREAD IS FUN,HE TOLD ME THERE IS SOMEONE FROM SUN COAST THAT DID THIS AND ARE HAVING GREAT SUCCESS

Fantastic . I can wait to hear and see the new products and testing out come .

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[motorhead]

The machining and clutch packs/steels are usually the first step.