lobuxracer

iTrader: (2)

I finally decided it was time to do something more dramatic than just send samples, so I dropped the pan and replaced the filter last night. In doing so, I drained a little over 5 quarts of ATF. Given the capacity is 11 quarts, that's a pretty substantial change.

I have not had much time to drive the car since completing this, but initial impressions are, nothing new is happening. Behavior is no different than what I have come to expect when the level is correct.

While I had the pan off, I cleaned everything. This includes the three magnets in the pan. They had quite a bit of iron stuck to them. The fluid I removed was not red, but also not black. It still had a reddish appearance when looking at the valvebody with the pan off. The task is not difficult, but I will say, it's a waste of time to use the drain plug. It's not designed to drain much. If you really want to remove some fluid and get a good refresh, you really need to drop the pan, replace the filter and gasket, and pour in about 5.5 US quarts of WS.

There are only 9 bolts on the pan. It's pretty easy all things considered.

ROYALISF

Quick question. I know to service the transmission the fluid needs to be cold but I'm going in for service tomorrow and wanted to have them check the fluid levels. Does it have to stay in order to fully cool or is normal operating temps fine?

Joker4096

iTrader: (2)

It has to sit there. I took mine last month in the morning around 10 and the temp was fine to check around 1.

lobuxracer

iTrader: (2)

That has not been my experience. Once the gearbox reaches full operating temperature, it takes all of 8 hours to cool. When I did this in the summer, it was 74 degrees in the morning in my garage. The car had been parked since 5 pm the previous day and it was 9 am when I did this. The gearbox was still 10 degrees above air temperature when I started the engine.

lobuxracer

iTrader: (2)

Interesting new note - the GSF has the Aisin AA80E in it. I did some poking around and found two very interesting things - first, the part number for the AA80E in the ISF is not the same part number as the GSF (and RCF) despite all major technical specs appearing to be the same. Second, TIS has a "fluid change" procedure in the FSM for the GSF. This does not exist for US models. Also, the level setting procedure is done at higher temperatures than the ISF. Still not normal operating temperatures, but their low temperature is the high temperature for the ISF, and their high temperature is high enough that even on a hot day in Phoenix, you could successfully set the level on the GSF. I don't think it would be possible on an ISF since the high temperature limit is only 114F for it.

Much of the rest of everything is the same, but I was really surprised to see a fluid change procedure in the manual.

Oh, and it boils down to drain the pan, reload, drain again, reload, level set and you're all good. Probably swaps about 70% of the fluid if done correctly.

lobuxracer

iTrader: (2)

After some digging, the difference between the ISF and GSF (RCF) AA80E gearboxes is the valve body. Not sure what they changed, but from my cursory look, the major guts are the same, but the valve bodies are different part numbers. It is really surprising how many Lexus vehicles use this gearbox with only small tweaks in the parts designations.

supersonic

iTrader: (2)

fascintating lobuxracer! thanks for that info. my stupid lexus dealership said that it was a closed system and couldnt check to see how the fluid level was in my tranny. although my car sits at 41k miles i know it must have been tracked with the previous owner. they didnt even tell me that they could plug it in to a computer to read the levels. SOBs. now i have to find a way to get it checked. even though it may be perfectly fine its always in the back of my head

lobuxracer

iTrader: (2)

Odds are it isn't fine. These gearboxes seem to be pretty finicky about fluid level. While you can't just plug in and read the fluid level, you certainly can adjust it, and you can do a lot of things to minimize the aging process. At the same time, with only 41k on your ride, it shouldn't be in really bad shape at all.

supersonic

iTrader: (2)

thank you for that. ill keep that in my mind then. anything particular i should look for though? shifting hard at WOT is one right? ROYALISF and I come from the same town and we both went to the same lexus dealership, they said to him they could check it by "plugging it in" for $175. he didnt do it, rightfully so. he is over 100k miles though

nks979

So mine is back to slipping under light acceleration in 1st gear, along with slight rpm jumps in higher gears every so often(~50rpm or so). Also has a slight jerk in 2-6 sometimes, can this be considered totally normal with the temp being 30-40 degrees every day or should I start looking into an extended warranty here? Got it topped off about 2k miles ago and it was acting fine then.

isfvss

Could someone (lobux) tell me the temperature in Celsius or Fahrenheit that the gearbox should be between when checking the level please. I had a quick look but couldn't find it cheers.

ZDCATC

95-108F, 35-42C. Small window, huh?

isfvss

Thanks for that, small window your not wrong, what would happen if you over filled it by a 1/2 to1 litre just for interest sake ?? and the same box as GS and LS 460

lobuxracer

iTrader: (2)

I've run 120cc over and did not have any issues. I did that by setting the level per the manual, then adding 120cc through the fill hole afterwards. I figured it would be a hedge against running low quickly. I am not sure it worked well to prevent issues. I recently dropped the pan and did a much more involved fluid swap and did not add any extra after setting the level, but IME, it seems there are symptoms of being low as soon as 10k km if you do not add any extra. When I dropped the pan to replace the filter and gasket, I needed 5.2 liters of ATF to bring the level into spec. That's about 50% of capacity, so it seemed like a pretty good compromise to me.

Because the temperature range is relatively small and the cooling period necessary to get it back below the top number is so long, I would recommend adding about a half liter of fluid before starting the engine to set the level. That way you'll be pretty likely to have enough excess that some will drain when you open the level setting plug.

redspencer

iTrader: (1)

Also something else to add is that the RC-F and GS-F Aisin 8-speed transmission incorporates what Lexus calls "G-AI Shift" or "G-Force Artificial Intelligence Shift Control" to keep the transmission in lower gears while cornering in order to minimize surprise upshifts (when in auto mode).

I'm not certain if any physical electronic components were added to the transmission to incorporate this feature or if the G-AI Shift technology is simply a programming tweak to the main ECU but that's another behavioral difference between the generations of Aisin 8-speed gearboxes.