Actual wrenching progress on our former ASA stock car project has been slow.
Honestly there’s a LOT of research to do before we break out the socket set and the welder, so most of our effort toward the car has been in the conversation and study department.
So, for our transmission: Which w…
Do eet. Let us go on the journey with you.
Sounds awesome honestly.
I was just thinking about this the other day wondering if it was still around. Glad to see it getting some love again.
In.
(Okay, I knew this was coming and edited the piece but just wanted to join in.)
I like the idea, everyone knows what this looks like with a 4 speed. I think this is really innovative for this application. It also made me think about this trans for a circle track application, we race vintage which has basically no rules. This could be an option...
Yeah I'm not really seeing much downside here. this seems to scratch a lot of itches that are practical as well as editorial.
I just kind of got the idea while driving home from UTCC and putting my Tundra in tow mode, which gives you some manual control over thr automatic's shifting. "Hey, sequentials are stupid expensive, but what's wrong with a good automatic with a manual valve body?" I thought. "Ooh, those 8HPs that are in the Supra are awesome. I wonder if they're available from boneyards and hackable?"
Literally googled for info while I was sitting in a rest area on I-75 in Tennessee and found that a) 8HPs are cheap and b) SLG exists. So thanks Tennessee DOT for making your highway men's rooms both comfortable and WiFi enabled.
In reply to JG Pasterjak :
Seeing as you've already raced one car with an automatic (F500) I see know reason not to do it again. Automatics have come a long way since the Powerglide.
I'm interested in how well this project goes, mostly because Seems Legit Garage has the right background to do something cool.
Very interesting!
I'm all about manual transmissions, but I think you have made a good case for this. I say go for it. I'm looking forward to following along.
I like that. It's an interesting combo. I would have never thought to do something like that.
I have the exact same ASA Chassis and am building it with a 67 mustang shell and a vintage boss 302. Funny I have had the same thoughts about using an automatic but did not have any idea what direction to go. I wonder if these Seems Legit Garage guys could make me an adapter to fit this trans to my boss 302? Heck I am a machinist so maybe I can just make my own. There is a ZF 8HP70 for sale locally out of a ram 1500. Not really at the transmission part of the project yet though but am going to keep this idea open for the future and try to learn more. Maybe I will call the Seems Legit” Garage guys and inquire. Wonder how it would work though as the thought of down shifting 3 or 4 gears for each corner seems kind of crazy. Maybe just leave it in automatic mode, use big brakes and let the trans and computer match the gear to the speed and rpm coming out of the corners. That could be cool if it could be done smoothly and having a wide spread of ratios to deal with fast and slow corner exits would make having the exact right ratio in the QC rear less critical. I am certainly going to try and find out more. This kind of thing certain is working the GT2 Porsche.
In reply to robert777 :
Just imagine all the pops and crackles with each of those downshifts! These transmissions can Crack off QUICK downshifts. Just pull the paddle!
My buddy's running this exact trans in his Ecotec Miata endurance car, and he loves it. He initially did the swap using the converter, but is getting rid of it for next season, says it's a 40lb reduction
Some more noodling and comments elsewhere have me thinking about two other possible hurdles, although I'm sure they can be overcome at some point.
1) Height: The dogboxes these cars usually run are vertically compact, connected to small bellhousings with tiny flywheels on engines with shallow dry sump pans so they can sit very low in the chassis. The 8HP looks to the eye like it has a bit of draft angle, so that may require raising the engine a bit to get everything in there vertically.
2) The crossover headers these things typically use are designed to go around those tiny transmissions and collect in the area that would typically be the passenger seat. A larger transmission, connected to a higher engine, could cause exhaust issues.
Like I said I think both of these are overcomable and certainly not dealbreakers, but particularly the exhaust situation does mean that you might not be able to use the off-the-shelf $400 headers that you'd typically use in this application.
Peabody said:My buddy's running this exact trans in his Ecotec Miata endurance car, and he loves it. He initially did the swap using the converter, but is getting rid of it for next season, says it's a 40lb reduction
What do you mean here? Like putting a clutch in front of it and running it like an old B&M hydrostick? If it is that sounds awesome. Two of my favorite car noises are late models when they rev with the clutch in (those little clutches let them spool super fast) and when they hit the chip at the top of the straight. This gives back the fast rev.
How does weight compare?
Is there any directness of feel missing? I read and absorbed the part about midcorner adjustments, but i couldn't help reading it and wondering "are you saying it's 'as precise' because you can't say it's quite the same?"
Yes, i have possibly irrational issues around the automatic idea, but this is really sounding like it has answers for them.
Also curious about how the 8HP (and other new automatics) manage this. Is it just a tight converter or keeping it locked when it's not pulling away from a stop or shifting?
Color me curious.
Jesse Ransom said:How does weight compare?
Is there any directness of feel missing? I read and absorbed the part about midcorner adjustments, but i couldn't help reading it and wondering "are you saying it's 'as precise' because you can't say it's quite the same?"
Yes, i have possibly irrational issues around the automatic idea, but this is really sounding like it has answers for them.
Also curious about how the 8HP (and other new automatics) manage this. Is it just a tight converter or keeping it locked when it's not pulling away from a stop or shifting?
Color me curious.
I'm sure the SLG guys can provide more insight into what's actually happening inside the transmission, but I can tell you from a driver's perspective, once the trans is in a particular gear, it feels very much like a direct drive between the engine and the wheels. My guess is that the converter is locked up in almost all situations except starts and stops and shifts. One of the design parameters of the trans was super high efficiency for both fuel economy and performance, so i wouldn't be surprised ot hear that there's minimal slippage going on anywhere in the system.
This transmission has been used in most Chrysler RWD based vehicle architecture products for the last 10 years. The lighter duty 8HP 45/50 behind say the Pentastar 3.6L V6, the 8HP 70/75 behind the 3.0L Eco Diesel & 5.7/6.4L Hemi V8 and the 8HP 90/95 behind the Hellcat. From my personally experience this is a great transmission. Nice wide gear ratio band with 6th being direct 1:1 and both 7th and 8th being over drive ratios.
More detailed info can be found here;
https://en.wikipedia.org/wiki/ZF_8HP_transmission
It does has a couple odd things about it. First is the OE factory plastic pan with the integral filter. The aftermarket has a fixed this with deeper / high capacity metal pans with more easily serviceable filters, like this one;
Second is that the fluid change procedure which is also rather unique to say the least. There is no filler tube or dip stick. Fluid temperature has to be between 90-120F and the engine must be running or you will not get the last 1-1/2 quarts of fluid into the transmission. That and its fairly disconcerting when you find yourself laying on a creep under say a 5000 lb SUV that is up on say a QuickJacks with the engine running, while you are attempting to pump in the last of the ATF fluid and at the same time trying to not burn you arms on the exhaust piping. BTW, you will need the help of a buddy for this or if you are really lucky, a remote start fob.
https://atracom.blob.core.windows.net/webinars/chrysler/845re_introduction.pdf
https://www.youtube.com/watch?v=kXKhZievmSI
Also the fluid is fully synthetic ATF Dexon VI so you don't need to buy only the crazy expensive stuff from the dealership. Make sure you also have a fluid cooler loop plumbed in with this transmission installation.
I have the 8HP75-LCV in my 2500 ram and I love it, I wonder about a smaller package for racing like this given the gear ratios and flappy paddles you can make it a video game shifting, would be neat.
way cheaper than a sequential or a DCT
but can I shift a ZF 8 speed at 8-9k RPM???
In reply to JG Pasterjak :
Thanks for the clarification!
I wouldn't call these definitive values by any means (sources include wikipedia and cjponyparts, so get out the accompanying grains of salt), but it does look to be nearly double the weight of a manual, if you don't feel too apples/oranges about ~95lbs for a T-5, ~115 for a T-56, and ~192 for an 8HP.
Not sure it matters in something like your ASA car, but it does give one pause when thinking about small, light cars with more moderate power... But I'm intrigued by the possibility of autocrossing without ever really being in the wrong gear.
Much like engine weights, comparing transmission weights is tougher than expected, due to the relative lack of information availalbe detailing what is or isn't inclued. I believe that MT weights typically exclude the flywheel and clutch, and may or may not include fluid and/or bellhousing. Similarly, automatic transmission weights don't typically say whether they're wet or dry, nor whether that includes the converter or not.
That being said, even if not as much as the internet weights indicate, it will still be heavier. However, that probably isn't going to make 'the difference' in most amateur motorsport applications.
I've been on the hunt for affordable and available 'true performance' automated transmission solutions for a while now, and like the sound of the 8HP. It's basically what I have long believed all automatic transmissions should have been since the advent of torque converter clutches and electronic controls. The cost of adapting it, if adapters are even available for the desired engine, on top of the cost of the transmission itself, the harness, and the controller is a bit steep though. Hopefully there will be more options like this for more transmissions in the future, that will cut costs by not requiring complete transmission swaps.
I'll definitely be interested to see how this turns out.
Jesse Ransom said:In reply to JG Pasterjak :
Thanks for the clarification!
I wouldn't call these definitive values by any means (sources include wikipedia and cjponyparts, so get out the accompanying grains of salt), but it does look to be nearly double the weight of a manual, if you don't feel too apples/oranges about ~95lbs for a T-5, ~115 for a T-56, and ~192 for an 8HP.
Not sure it matters in something like your ASA car, but it does give one pause when thinking about small, light cars with more moderate power... But I'm intrigued by the possibility of autocrossing without ever really being in the wrong gear.
I think this is a car that probably weighs in under 2500lbs to begin with, so I'm not sure a little extra weight down low and in the middle of the chassis is a huge penalty. It still may need ballast to make it into most classes it'll be eligible for. Maybe now I get to save some money on ballast.
Peabody said:My buddy's running this exact trans in his Ecotec Miata endurance car, and he loves it. He initially did the swap using the converter, but is getting rid of it for next season, says it's a 40lb reduction
More info needed. What's he using for adapters? How's he controlling it?
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