Zf 8hp70 mated to sbc

[Vimes]

And it all came crashing down. Just realized while talking to my brother about possibly doing this transmission in his car that the adapter setup and standalone controller wouldn't be able to use torque management, and without torque management the engine would smoke the transmission by slamming more torque than it's rated to handle at it on the shift. Oh well, it was a nice idea while it lasted, but I'm going to have to rethink my drivetrain now.

[dap03]

And it all came crashing down. Just realized that the adapter setup and standalone controller wouldn't be able to use torque management, and without torque management the engine would smoke the transmission by slamming more torque than it's rated to handle at it on the shift. Oh well, it was a nice idea while it lasted, but I'm going to have to rethink my drivetrain now.

Are you saying that having a plc or something like that controlling the solenoids would make it destroy itself?

[Vimes]

Are you saying that having a plc or something like that controlling the solenoids would make it destroy itself?

No, wasn't even thinking about that. What I was going to use was a standalone controller that uses an RPM and TPS signal, but there's no way to use torque management since it's a one way path from the PCM to the TCM. What kills this for me is I was going to start with an LS3-based 427 that the builder said makes over 700TQ at the crank. And, once I had it up and running and had all the bugs worked out of the truck, I was playing with the idea of turbocharging it. The only way the 8HP90 is able to live behind the Hellcat engine is torque management. Without torque management, I'd kill it after just a few runs.

So far as what you're doing with direct solenoid control, so long as the engine you put in front of it doesn't make too much more than what the trans max input torque is, it'll be fine. In other words, torque management isn't something you'd need to worry about unless your engine is quite a bit stronger than the trans can handle.

[dap03]

Looks like cmcnitt was running a turbo LS. Seems like quite a stout trans for anything other than a purpose built race engine. He said it was making 740whp.

[dap03]

Can someone with more transmission knowledge chime in?

The tcc (torque converter clutch solenoid) controls the lock up right? Cmcnitt said that he has his only lock up in 8th gear. Is that the best way?



The way I'm looking at it, if the tcc has the same voltage as the other solenoids at max, I could program it to engage in a few different ways.

1) I could set a toggle switch to turn it on or off. You could be in any gear, turn the switch on, and you'd be locked up.

2) You could have it where you have to up shift from p-r-n-1st-1st lock-2nd-2nd lock-3rd-3rd lock and so on and so forth. I guess it would be sort of like 18 gears.

3) I could make it where the 8th gear is the only one that locks up or 7th and 8th. That mean those have an extra shift after each of those gears.

4) It could be variable so that there is a dial wired in where you control how much lock up it has. That's if the voltage is 0-5v or something like that.

5) It could be on a timer where it slips on its own after time. It snap on or gradually come on.

This is only if it's what I think it is and you can adjust the voltage to adjust the tcc solenoid.

Also if the LPS solenoid is similar maybe the harshness of shifts could be adjusted?

Most of this is speculation but if someone can verify this then I could make some of these as PLC's pretty quickly.

[Vimes]

I'm no expert, but I have programmed a few TCC lockups over the years, and have installed locking converters in vehicles that didn't come with them. If an actual transmission expert posts up and disagrees with any of my points, their advice would be more valid. With that disclaimer...

The torque converter is a nod to the IC engine's need to maintain a minimum RPM to stay running, and acts like a clutch for a manual transmission. The TCC lockup changes the torque converter from the equivalent of a clutch that slips like mad below 1000RPM into a solid connection between the engine and transmission. If the TCC were to stay locked until the car came to a stop, as in your Option #1 should the driver forget to disengage the TCC, the engine would die just as it would if you stopped a stick shift in gear without engaging the clutch. Ask anyone who ever wired a lockup transmission to a toggle switch in the early 1990s about what happened every time they forgot to flip the switch when they came off the interstate.

#2 would work fine so long as it didn't engage at any point when the gear vs speed was at a point where the engine can't maintain idle speed. The OEMs that I've programmed (and I am not a pro, I just program my own) don't engage the TCC before about 40MPH because it's not going to kill the engine if engaged at this speed. But there's no reason why it couldn't if you can program the correct speed for each gear so that the TCC isn't locked if the engine is below 1000RPM. Some of the lower speeds might have a harsh lockup though.

#3 is how a lot of cars are programmed. But, the newer the car, the more thought was put into how many gears can be locked just as #2. Only locking up in the top gears is simpler, but also means more heat generated and more fuel burned in the lower gears.

#4 Need to be careful with this one - it will depend upon what materials are used for the lockup clutch. GM switched from an on-off TCC lockup to a lockup that allows some slippage in order to allow the TCC lockup to occur more smoothly, which caused a problem if you installed a non-slip TCC torque converter into a car whose computer allowed for slippage. The TCC would burn out in a very short amount of time if this occurred. I think the TCC slip converters used carbon fiber in the TCC lining, but it's been a long time since I've had to think about that.

#5 would work so long as you paid attention to #4.

[dap03]

If you had the tcc locked up and then shifted from one gear to the next would it be clunky and harsh without the slippage?

[Vimes]

Didn't know on that so I did a little searching. Seems the OEMs go both ways on it. If the transmission is weaker, they'll unlock on the shift but if the trans is bulletproof they won't necessarily unlock the TCC on a shift. If doing this on an 8HP70 or stronger, it may not be necessary to unlock for a shift. On a rubber band trans like the 4L60E, you definitely want to unlock it because those things need all the help they can get to keep the bands from glazing.

[ULTM8Z]

How about a built 4L80 with a gear vendors behind it?

I know Its a little more low tech, but my TH700 with a GV is an absolute blast with 8 speeds.

4L80 is supposed to be a TH400 with an OD, and a GV is almost indestructible...

[Vimes]

For my project, it's the spread I was interested in, not just having 8 speeds. The wide spread essentially gives you the best of both worlds with drag racing performance with gears 1-4 and an econobox fuel efficiency with gears 5-8. This was what I loved the most about my 2016 Charger with a 5.7L and 8 speed, 13.2 seconds through the quarter and 28MPG cruising on the highway at 80MPH, and that was factory stock with no tune.

If you sit down with a gear calculator and look at the actual spreads, using an 8 speed with 3.55 rear gears is like using a 4L80E with 4.88s in first gear that becomes a 4L80E with 2.72s in 4th gear. Not those numbers exactly, of course, but that's close to what it works out to be. A 4L80E GV overdrive still has the almost the exact same spread as the 4L80E by itself, except 4th gear goes a bit further, so all a GV does is convert your 4L80E into a close-ratio transmission. You don't get the spread advantage with it. When I did the numbers between a 6L80E and an 8L90E, I was looking at 3.73s with the 6L and 3.42s with the 8L to get about the same 1st gear takeoff, with the main advantage being highway cruising with the 8 speed being some 500RPM lower.

I think I'm just going to go Gen5 takeout and get either an 8 or 10 speed trans to go with it, see how I like it once the bugs are worked out, then if I think it needs power go ahead and turbocharge it. Barring any problems at the shop I'm using I should have my truck in the shop for the new suspension and engine mounts by April 2021.

[dap03]

I just wanted a strong cheap tranny that could be dropped into whatever I wanted with a $100 controller. Sure the adapter plate could cost a bit but if you leave the hemi you can have an economical v8 with 8 speeds and lightening shifts running for less than $5k I'd assume. Like vimes was saying, in a heavy charger he was getting 28 mpg but in something lighter and more aero dynamic you could easily great 30 mpg.

Back to the set up. I think the way to go would be to have a rocker switch set up within right thumbs reach on the steering wheel to control the tcc solenoid. That way you could have lockup in any gear.

[ULTM8Z]

I just wanted a strong cheap tranny that could be dropped into whatever I wanted with a $100 controller. Sure the adapter plate could cost a bit but if you leave the hemi you can have an economical v8 with 8 speeds and lightening shifts running for less than $5k I'd assume. Like vimes was saying, in a heavy charger he was getting 28 mpg but in something lighter and more aero dynamic you could easily great 30 mpg.

Back to the set up. I think the way to go would be to have a rocker switch set up within right thumbs reach on the steering wheel to control the tcc solenoid. That way you could have lockup in any gear.

I'm getting ~30 mpg right now in "8th" gear. I'm doing about ~2100 rpm at 80 mph.

50 year old muscle car with 1990's EFI technology on top of a SBC with same basic design out of the 50's, and 1980's transmission technology getting 30 mpg on the highway and still making ~400 hp.... who'da thunk it?... lol...

I actually activated the highway mode fueling which got me a couple of more mpg (cruising at about 15.5 to 16:1 on the WB O2 after the ECM detects light throttle cruise for at least 10 seconds above 60 mph). I think GM never activated it from the factory due to the higher NOx emissions coming out of a leaner burn.

[dap03]

Those are pretty impressive numbers.

The gear vendors is still ~$3k. With an 8hp70 you can have the tranny for ~$800, adapted to an engine for ~$1000 and controlled for ~$200. But that $1000 can be to any engine. Gear Vendors has a lot of options but not for everything. I'd like this on something like a 1980s mercedes 300td. Not just a protouring car.

[Vimes]

Yes, the NoX was why GM never turned it on in the US. And let's not forget, that heavy Charger not only got 28MPG, it got 28MPG running 80ishMPH, and was able to run the quarter mile in 13.2 seconds, all on the stock tune. It wasn't having 8 gears that allowed it to do both, it was the spread between gears. The spread on a 4L80E is 3.30, a GV only increases it to 4.23 by converting the overdrive from .75 to .53. The 8HP, on the other hand, has a spread of 7.0 on the first gen models, and 7.8:1 on the 2nd gen models. That spread in the transmission is what makes it a good all-rounder. Don't get me wrong, the Gear Vendors makes a great unit and if I were building a drag racer I'd be all over one. It would turn a 4L80E into a close ratio 8 speed, and this would keep you within 1000RPM of the peak power band pretty much all the way down the track. A towing rig would be perfect for one as well although I think I'd rather have an 8 speed and a GV overdrive for that.

[ULTM8Z]

Holy crap those things are heavy...

http://www.new-cars.com/2016/dodge/specs/charger.html

Lightest one (probably the V6) is sitting at ~4000 lb? Yeah, you would need some decent gearing to get that moving.

Amazing how heavy these newer cars are getting... I know when I park next to one, the Camaro just looks so much smaller.

Last time I weighed my Camaro it came in at ~3400 lb. That was before the GV unit and aftermarket A/C, so my guess I'm probably around ~3500 now.

[dap03]

Found the OP on another site.

https://www.forabodiesonly.com/mopar....431245/page-3

He explains how the controller he uses works.

"I used a teensy controller and arduino. and some mosfets. I used oshpark to print the board. I'm no hardware engineer but it works. basically I hard wired the 5 clutch solenoids, the park solenoids, the lockup solenoid, and the pressure solenoid each to a mosfet. I used the pwm feature from the teensy to vary the current to each solenoid. crude but it allows me to put full pressure to the clutch packs which i think is partly why i get away with putting so much power through it.
I'm a software guy so i thought it would be fun but at this stage i just manually shift it with an up shift and down shift switch. I'm playing with full auto but have no desire to compete with commercial stuff.
one of the awesome features of this tranny is that any shift is simply release one clutch, engage another one. I actually engage the shift clutch before i release the other clutch, it makes for a FIRM shift [https://www] I lock up all of the clutches for a transbrake then release the 3 that give me the gear i want.
also, and it's pretty obvious in that video above, I use the lock up converter alot. the dyno pull was in 6th gear with locked converter."

[protour_chevelle]

HTG GCU would be my choice for transmission control with this gear box. guys are controlling it with great success.

[dap03]

That's also $1000+ for the controller and an extra ~$500 for paddles unfortunately. I'm sure its a great system but for someone who just wants a paddle shifted 8 speed and no auto mode or frills, an arduino or plc would be the cheaper option. The plc could run it for <$200 with just the paddles controlling it.

[protour_chevelle]

That's also $1000+ for the controller and an extra ~$500 for paddles unfortunately. I'm sure its a great system but for someone who just wants a paddle shifted 8 speed and no auto mode or frills, an arduino or plc would be the cheaper option. The plc could run it for <$200 with just the paddles controlling it.

To each their own. I have zero interest in always having to shift an automatic. Been there, done that. Over it. Heck if I could buy an auto feature for a stick I would haha.

[harleyc04]

I know this is an old thread but if anyone wants to know anything about installing an 8HP70/90 with the PCS controller, let me know. And yes you can have torque management regardless of which ecm you are running.