[ZLRob]

The saga continues on the filter front.


Official dimensions from GM are as follows:


- 24291343 GM/ TF933 AC Delco (steel pan version) 14.2"L x 11.2"W x 1"H
- 24294355 GM/ TF937 AC Delco (aluminum pan version, likely Gen 2 valve body) 9.07"L x 6.66"W x 1.8"H


As I said, even if the filters are different, I really don't see how them being different heights would really affect anything if anything at all. Maybe someone else knows something I don't here. Feel free to chime in!

[ZLRob]

Back with some more news. I went into the fold and replaced my transmission pan today using the modified 2019+ aluminum pan with the 1LE standpipe modification... Here is what I found:


Gen 1 filter while does measure shorter dimensionally at the shortest point compared to the Gen 2 filter actually holds its own in the dimensional arena due to other dimensional changes between the pans which I will touch on below.


10L90E pan rail (this measurement is fixed between ALL generations as the case is the same for all of us) depth measurement to bottom of Gen 1 filter taken at the open mouth where it will take in fluid- 2.05" or 52.07mm. At this current time I cannot provide Gen 2 filter measurement as I obviously do not have this gen (redundant anyway as these dimensions are already in place by GM)


Gen 1 steel oil pan depth from outside of pan to mounting flange - 2.432" or 61.78mm. Gen 1 filter has a gap of .382" or 9.7028mm by plugging in the measurements I supplied above and subtracting 2.05" from 2.432".


Gen 2 aluminum pan depth from outside of pan to mounting flange - 2.6875" or 68.262mm using a Gen 1 filter gives a gap of .4425" or 11.239mm.

By using a Gen 1 transmission filter on a Gen 2 aluminum pan there is a .2551" (1/4") or 6.47954mm difference between both pan heights with Gen 2 being the taller pan and being the slightly taller filter. This is beneficial for this mod as the Gen 2 pan being slightly taller allows for more fluid to be in the pan over Gen 1 and should negate any issue of the Gen 1 filter sitting slightly higher in the pan than the Gen 2 filter does. This is subsequently beneficial to doing the 1LE standpipe trim mod I did in my previous posts of this thread, as based on these measurements I can say with confidence that YES the filter bottom will sit well beneath the standpipe, so starvation is a non issue during driving.

The fluid I initially pulled out of the pan and filter was approximately 5.2-5 .3 quarts. This is based upon a 203-212* F temperature fluid correction level and is accurate to 2017's (possibly 2018's). What I placed back into the system was 6 quarts initially just as a starting reference point and after a 5-10 minute drive cycling through all gears then draining fluid I pulled out 5 quarts exactly after reaching the appropriate fluid correction temperature. Based on everything here I am actually estimating that the retrofit is going to allow me to run .3 quarts less than the previous Gen 1 OE set up (this one is hard to say, however, based on the fact that I never pulled the filter off the second time around, as everything was obviously installed and back in place with the new service facilitated set up).


Draining fluid, adding it, and correcting level is now incredibly easy thanks to all of the modifications that I made to the pan. After using AMSoil blue cap fuel efficient ATF (ULV equivalent) I found that the transmission is still more than capable of regulating it's temperatures properly sitting between 198*F while doing steady state driving like highway and a high of 208*F in stop and go traffic AND to boot, the transmission has NEVER shifted into gears easier and shifted between 3-4 upshift/ 4-3 downshift as easy and as seamlessly as it does now. to add to this, shifting is confirmed quicker via data logging going from .7 seconds under certain circumstances all the way down to .3 seconds.


I know this is a long post but I hope this helps someone. I will add more to this as time progresses, but all in all, I would say that this was a very successful mod. Given that the Gen 1 filter now sits in a Gen 2 pan I can confidently say that there is no worries about magnet interference (ie magnets physically touching the filter based on their respective fixed locations and given the incredibly negligible ultimate height difference between the depth of the two filters sitting inside the actual pan the chances of any starvation under any situation is highly unlikely. All of this and the pan itself is now capable of shedding heat much quicker and more efficiently and effectively due to it's all aluminum construction.





Flushes or any services are now incredibly express due to this new handy drain plug being added. Look how pink the fluid is after the second drain!




For reference purposes, this is the measurement of the Gen 1 standpipe.

[Patriot Motorsports USA]

Originally Posted by ZLRob

The saga continues on the filter front.

Feel free to chime in!

Great thread and lots of useful information!!!

Have you compared or measured with the differences in the standpipe heights, the amount of fluid volume with the side drainplug removed from the case?

For the past three years with my ZLE, I have been using the side drainplug level as my mark with engine running, vehicle cycled through all gears and then idling in park while topping off. Temps are typically 100-140º when measured and with the Amsoil Signature Series ATL Blue Cap fluid. This is the ONLY fluid of the three high performance fluids that is backdated approved for DEXOS as well as CVT for extreme temperatures. The ULV and Multi-Use is not intended for racing use in an automatic.

[ZLRob]

Originally Posted by Patriot Motorsports USA

Great thread and lots of useful information!!!

Have you compared or measured with the differences in the standpipe heights, the amount of fluid volume with the side drainplug removed from the case?

For the past three years with my ZLE, I have been using the side drainplug level as my mark with engine running, vehicle cycled through all gears and then idling in park while topping off. Temps are typically 100-140º when measured and with the Amsoil Signature Series ATL Blue Cap fluid. This is the ONLY fluid of the three high performance fluids that is backdated approved for DEXOS as well as CVT for extreme temperatures. The ULV and Multi-Use is not intended for racing use in an automatic.

I never pulled the plug off primarily because I don't have the right size Allen to fit on it and I don't want to go through the trouble or purchasing one then trimming it down. I have just left it as is.


I figure as a progress update on all of this, I have run it quite a bit now and have gotten some good hard miles on it with more than plenty of hard pulls up to redline and have been pleasantly surprised by the results. No negative changes to report (or no slippage under load, no excessive heat build up on transmission and log confirmed considerably faster upshift times over previous efforts).


The thermostat on mine is set to open at 203, so quite higher than later models unfortunately, but they stabilize and go up to 208 usually at maximum in stock and go and taper down to around 198 under sustained driving.


From my understanding ULV was designed to handle the higher temperatures that this transmission puts out before thermal breakdown so I'm not too worried about temps over 200, especially since these temps are typical on the Gen 1 valve body equipped transmissions and all of them seem to live their lives just fine whether they are on the track or the road.

[Patriot Motorsports USA]

Do you or have you experienced harder shifts once your transmission is fully warmed up in the upper gears? I have a customer tracking a 2019 ZLE who has identified it to have the steel pan and I wonder if the difference between the 2019 to the 2020 updated A10s could have significant changes, which could be remedied by switching the valvebody & pan to the later model. Thoughts??

[ZLRob]

Originally Posted by Patriot Motorsports USA

Do you or have you experienced harder shifts once your transmission is fully warmed up in the upper gears? I have a customer tracking a 2019 ZLE who has identified it to have the steel pan and I wonder if the difference between the 2019 to the 2020 updated A10s could have significant changes, which could be remedied by switching the valvebody & pan to the later model. Thoughts??

This is going to sound odd, but I have indeed experienced harsher shifts once the transmission was warmed up. After leveling things out properly back when I had the steel pan most of that subsided, however, some of it still existed. After dealing with some odd issues with throttle closure under high RPM circumstances during datalogging, what I ultimately found that was messing with shift quality and general drivability out of all things was my Soler ported throttle body. Which confirmed by messing with the throttle error percentage settings in the engine diagnostic side of things under the engine diagnostic tab (P2101). The code was also not setting when throwing me into reduced engine power mode despite going back to stock settings from the initially set 25% up and down parameters, which was a super odd side effect. I swapped back to OEM purely for test purposes and I found was that not only did I regain drivability ten fold (seriously EVERYTHING softened up and got proper), but I gained power output which was confirmed via a few different instances on datalog, particularly with the fact I went lean and MAF output, so now I'm going to stick to the OEM and call it a day.


If your customer is having issues and has an aftermarket TB, and the transmission fluid level is correct or the fluid is even brand new, he may want to take a good look into replacing his TB for test purposes to see if that helps things out.


Outside of that, the difference from the switchover between Gen 1 and Gen 2 pans didn't show me any overly outstanding difference in shift quality. I also would strongly not advise switching to a Gen 2 valve body unless it has been revisioned to the performance of, or overhauled by Next Gen Drivetrain because they have been documented to have big underlying issues that if left as is can cause major long term issues to the transmission. Quite notably the CDF drum, the converter, and if left as is long enough, to the actual clutches.


After putting in some good work on this set up via general miles and hard driving and experiencing great results out of it, he may very well be a solid candidate for trying this mod out. It didn't take much time or money to do outside of the cost of transmission fluid and the cost for materials and labor to get them welded up once obtained.

[cdb95z28]

Excellent detailed info ZLRob! Thank you!

[CalgaryZL1]

Good results to every one wanting to service the Transmission with the trans pan mod. I was able to buy the car from brand new therefore being the only one to dump and fill so it gave me a very good reference point on fluid volume from the factory.

[Slurpee]

Originally Posted by ZLRob

Draining fluid, adding it, and correcting level is now incredibly easy thanks to all of the modifications that I made to the pan. After using AMSoil blue cap fuel efficient ATF (ULV equivalent) I found that the transmission is still more than capable of regulating it's temperatures properly sitting between 198*F while doing steady state driving like highway and a high of 208*F in stop and go traffic AND to boot, the transmission has NEVER shifted into gears easier and shifted between 3-4 upshift/ 4-3 downshift as easy and as seamlessly as it does now. to add to this, shifting is confirmed quicker via data logging going from .7 seconds under certain circumstances all the way down to .3 seconds.

After servicing my transmission fluid myself last time, I transitioned from my OE ZL1 aluminum pan to the ZL1 1LE pan. I experience intermittent very hard up shifting from 3-4. No issues with downshifting. You're saying going to AMSoil resolved this harsh up shifting?

I was considering going back to my OE pan because I did not have these events prior to swapping my pans. I drained my fluid at 175F

[Patriot Motorsports USA]

In my experience, only those using the ULV fluid are getting the intermittent harsh shifting. I think it has to do with the low viscosity designed for MPGs vs Performance as I have been using their Blue Cap Signature series fluid for the past two years with zero issues. The Amsoil ULV was not available in 2023 when I bought my car, so I have stayed with what I found to work and was suggested by Amsoil in Feb 2023. It is also what I use in all my customer's cars with zero issues.

[ZLRob]

Originally Posted by Slurpee

After servicing my transmission fluid myself last time, I transitioned from my OE ZL1 aluminum pan to the ZL1 1LE pan. I experience intermittent very hard up shifting from 3-4. No issues with downshifting. You're saying going to AMSoil resolved this harsh up shifting?

I was considering going back to my OE pan because I did not have these events prior to swapping my pans. I drained my fluid at 175F

Originally Posted by Patriot Motorsports USA

In my experience, only those using the ULV fluid are getting the intermittent harsh shifting. I think it has to do with the low viscosity designed for MPGs vs Performance as I have been using their Blue Cap Signature series fluid for the past two years with zero issues. The Amsoil ULV was not available in 2023 when I bought my car, so I have stayed with what I found to work and was suggested by Amsoil in Feb 2023. It is also what I use in all my customer's cars with zero issues.

I didn't even realize this had new comments in it. My apologies.


After some time running this mod I have found 3-4 upshift downshift is back to its usual behavior of intermittent harsh upshift or downshift. What I presume has happened here is that the transmission has finally fully adapted to its shift values and has fully restored its shift logic.


I believe the harsh shift is more of a characteristic of how close the gear ratio is between both gears more than anything else. While it is sort of sucky that it shifts the way it does, it is not something I am worried about at this point, especially given that I have a gen 1 valve body and my tranny is in good condition.


This is just one of those behavioral quirks from the transmission that owners of the A10 have to live with and there is no amount of tuning, or mechanical tinkering that will make it go away short of a full overhaul and redesign within those specific gears.

[Slurpee]

Originally Posted by ZLRob

I didn't even realize this had new comments in it. My apologies.


After some time running this mod I have found 3-4 upshift downshift is back to its usual behavior of intermittent harsh upshift or downshift. What I presume has happened here is that the transmission has finally fully adapted to its shift values and has fully restored its shift logic.


I believe the harsh shift is more of a characteristic of how close the gear ratio is between both gears more than anything else. While it is sort of sucky that it shifts the way it does, it is not something I am worried about at this point, especially given that I have a gen 1 valve body and my tranny is in good condition.


This is just one of those behavioral quirks from the transmission that owners of the A10 have to live with and there is no amount of tuning, or mechanical tinkering that will make it go away short of a full overhaul and redesign within those specific gears.

What does the hard shifting feel like for you? For me it almost feels like I’m hitting the rev limiter. Car just completely falls forward on itself and jolts. What’s interesting is that it never once happened at WGI when it was 95F ambient. I wonder if it’s fluid expansion related. Which is why I’m considering adding 1 to 1/2 cup of extra fluid

[ZLRob]

Originally Posted by Slurpee

What does the hard shifting feel like for you? For me it almost feels like I’m hitting the rev limiter. Car just completely falls forward on itself and jolts. What’s interesting is that it never once happened at WGI when it was 95F ambient. I wonder if it’s fluid expansion related. Which is why I’m considering adding 1 to 1/2 cup of extra fluid

It's just a hard shift. Like as soon as you shift down into 3rd gear or up into 4th it just feels like a jolt and it's done, very common on these transmissions but interestingly enough I noticed when I initially put in 6 quarts into it I noticed that it shifted all very softly. However, I also know that this transmission changes the way it performs over time so anything that's different it will adjust to and potentially perform poorly over (over a long term perspective). I can confirm that based on the way my old set up was overfilled and it absolutely hated it but performed well with it for a very long time despite that until the fluid started getting a little dirty. The change in shifting I felt was more likely than not a temporary false positive.

[ZLRob]

Also, if anyone needs a Gen 2 valve body filter, I got a spare one sitting on my toolbox that I'll sell you for $50