Transmission

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airforce1 said:
As someone who needed a transmission rebuild at 93K, I would highly recommend a tranny flush regardless of whether it is a sealed system. My tranny rebuilder has seen many AB60s having given up the ghost due to inadequate ATF levels or burn ups.
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Is the AB60 the code for the 8 speed?
 
If I was to guess, I the tech's comments are probably more of a fuse analogy. The transmission may be acting as the fuse because it can slip. However that fuse could also be axle shafts or t-case, etc. It's just whatever is the weakest point at the time and the tech is saying that is transmission. I'm not agreeing or disagreeing with this position, just that this is how I interpret the comment.

FWIW I never thought that the 6 speed in my GX460, which is same as the pre 8 speed cruiser 6 speed, at least when I looked up the codes, shifted that great. It was better in some ways but not night and day. I don't think it had anything to do with the physical side, it was tuning and shift point related. The main thing I notice is that it would downshift and hold better (less throttle). Likely tuning for the smaller/lower output 4.6.

If I could fix anything with the 8 speed It would be the laggy 1/2 shift where it feels like the flashpoint on the TC is too high.
 
bronc076 said:
What are you disagreeing with? If the truck is in gear, the engine is producing power, and the wheels are not spinning, the transmission is the only option to eliminate the rotation the engine is producing unless something else breaks. This occurs through the torque converter heating the fluid, or internal clutch packs slipping. Torque converter is designed to provide slippage sitting at a stop light, accelerating through the gears, towing, and other normal driving scenarios. However if one were to pump significant power into the transmission without wheel spin for a long period of time, something has to give. Sometimes it's an axle, sometimes it's a U-joint, sometimes it's broken gears. But typically, it's the automatic transmission converting RPM into heat.

The fact that the LC200CG is having trouble in higher gears while driving now leads me to believe a fluid flush would probably help.

What are the sounds it is making, and does it make it in all gears? Is is a high pitched sounds and in say 6th or 7th gear RPM increases with the sound? Or does it happen when the converter locks? There are a variety of things that could be wrong, but as others have stated, I would start with a fluid and filter change. It's frustrating that these do not have a dipstick, that is a handy tool to smell and view the fluid.
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It's a medium pitch light metal grinding noise, mostly in 5,6,7,8. Yes the sound increases and gets more grindy with RPM. As bad as the grinding is that's why they are saying it might be a waste of time to confirm confirm what we already know.
 
I’m on board with a transmission making noises being too far gone for a fluid change to help significantly.

Im not sure of the power flow of the 8spd but if a sprag let go a trans can start making some strange sounds.
 
 
bloc said:
I’m on board with a transmission making noises being too far gone for a fluid change to help significantly.

Im not sure of the power flow of the 8spd but if a sprag let go a trans can start making some strange sounds.
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Thank you. I'm the annoying shopkeeper that always goes for a transmission fluid change first, but in this case it is making a lot of noise.
 
The only one-way clutch/sprag is used for 1-2 shift, not 5-8. So who knows what’s up..

edit: he also explains how this thing can be so light even as an 8spd. Basically it is a 2 speed transmission driving a 4spd. Interesting stuff.
 
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So update: replacement transmission is here. Technician is ready to put it in tomorrow. Truck is driving perfectly. No noise. We're going to look at the fluid closely when we go to drop the old transmission. If it's clean clean we're thinking of putting fresh fluid in, maybe a couple times to flush it, and then sell the transmission I just bought. Maybe it got angry driving hard in 1 and 2 then the computer or 3,4,5,6,7,8 were having trouble finding their place???
 
LC200JG said:
So update: replacement transmission is here. Technician is ready to put it in tomorrow. Truck is driving perfectly. No noise. We're going to look at the fluid closely when we go to drop the old transmission. If it's clean clean we're thinking of putting fresh fluid in, maybe a couple times to flush it, and then sell the transmission I just bought. Maybe it got angry driving hard in 1 and 2 then the computer or 3,4,5,6,7,8 were having trouble finding their place???
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Thanks for the update

How many labor hours for the transmission replacement? How much cost?
 
LC200JG said:
If my guy says he can do it in one day I guess maybe 12 hours labor $1200 or so plus like $4000 for the transmission.
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I would do a close inspection of your entire driveline. I am still hesitant to see a transmission fail. A comprehensive 13-16 quart fluid exchange will tell you a lot. Could even drop the pan in this case.

This sounds more and more like an intermediary that is failing or was misaligned. Any issues getting out of 4Lo? Any issues unlocking center diff? How do all of those function?

Mechanical failure doesn’t just magically disappear. Could you have had a rock lodged in the driveline?
 
04UZJ100 said:
I would do a close inspection of your entire driveline. I am still hesitant to see a transmission fail. A comprehensive 13-16 quart fluid exchange will tell you a lot. Could even drop the pan in this case.

This sounds more and more like an intermediary that is failing or was misaligned. Any issues getting out of 4Lo? Any issues unlocking center diff? How do all of those function?

Mechanical failure doesn’t just magically disappear. Could you have had a rock lodged in the driveline?
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4L , lockers, engage/disengage fine. Never had an issue. Who knows? Could a rock lodged in the driveline cause noise, slippage, etc?
 
linuxgod said:
FYI this is general info for you @LC200JG. Not sure how much will help but I figure it can't hurt. Most/all of this is based on the 6-speed, but I believe it applies to the 8-speed as well. I'm going to post this info, then I'll comment in a second reply

There are two temp sensors for the A/T. One is in exiting the torque converter (when the temps are the hottest) and the second is somewhere on the return and/or in or around the pan. I'm going to refer to these as the TC and pan temps, though I'd have to go look at the transmission diagrams to figure out exactly where in the path they lie.

Fluid from the transmission is pumped through the cooling system (exiting the torque converter, through the external cooler, then into the radiator cooler, before being returned to the transmission pan) by the engine. High RPMs will pump fluid faster. More on this later.

The LC transmission will generally run in the 180-195F range under normal operations. 195F is the normal engine operating temp, and because A/T fluid goes through the radiator second that ensures it's always at least at 195F when you're driving once warmed up. You could add a dozen external coolers before the radiator and they would do nothing for you so long as the oil temp coming out of the radiator is ~195F. The only things you could do to further reduce A/T temp are (a) reroute the lines to skip the radiator (which might leave you running "dangerously" cold in the winter), or (b) run in a lower gear (or 4L vs 4H) in order to get RPMs up and pump more fluid through the cooler faster.

Anyway, you'll sit around 180-185F in both the pan and the TC if you put the vehicle in park and leave it running for hours. That's no load on the transmission of course. If you drive for a bit you'll see the pan normally runs around 195F. The TC will get hotter anytime the TC is not locked, though how much hotter depends on the gear, speed, ambient temps, and general transmission load. In most cases normal driving will put it temporarily around maybe 210F at peak, but it'll cool back down into the ~195F range after a couple minutes if your TC locks up. If you climb a mountain pass and the truck downshifts into 2nd or 3rd (on the 6 speed... probably ~4th in the 8 speed) you might see it get into the 230-240F range during your climb. Most people don't see that unless they're towing though.

The A/T temp light in the dashboard comes on at 305F and goes off at ~270F, IIRC. Or maybe it's 275F. Anyway my perception from those numbers is that Toyota believes anything under 270F is not a big deal, since the manual pretty much says the fluid is lifetime for normal driving (not towing, not heavy offroad), but if the A/T light ever comes on you do need to change the fluid. To them 270-305F is the questionable range... if you got to 305F then the A/T will do things like force your transmission into a lower gear to lock the TC and force fluid through the system faster (higher RPMs!) until you get down to 270F. (Note that anything over 240F concerns me for any length of time, but I'm not a Toyota engineer and they probably do know best).
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There is another way to run cooler A/T temp with aftermarket or stock transmission coolers. The 6 speed XMSN has a thermostat that you can bypass. Not sure if it is on the 8 spd XMSN. Per FSM, you have to bypass it with a pin when changing out the transmission fluid. The thermostat won't let fluid go to the external cooler until it reached 180 to 195F. Not sure why Toyota picked that as the operating temp. My A/T temps have been staying between 140 to 165F in normal driving conditions on my 2013 LX after I bypassed the thermostat and installed aftermarket cooler. I did the same on my supercharged 4Runner (4 spd) and GX (5 spd) years ago with similar results. The 4 spd and 5 spd did not have a thermostat control (so no need to bypass). Both transmissions have over 200k on them.

Aftermarket XMSN install

Thermostat bypass on 6 speed transmission
 
runnerxa said:
There is another way to run cooler A/T temp with aftermarket or stock transmission coolers. The 6 speed XMSN has a thermostat that you can bypass. Not sure if it is on the 8 spd XMSN. Per FSM, you have to bypass it with a pin when changing out the transmission fluid. The thermostat won't let fluid go to the external cooler until it reached 180 to 195F. Not sure why Toyota picked that as the operating temp. My A/T temps have been staying between 140 to 165F in normal driving conditions on my 2013 LX after I bypassed the thermostat and installed aftermarket cooler. I did the same on my supercharged 4Runner (4 spd) and GX (5 spd) years ago with similar results. The 4 spd and 5 spd did not have a thermostat control (so no need to bypass). Both transmissions have over 200k on them.

Aftermarket XMSN install

Thermostat bypass on 6 speed transmission
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I suspect Toyota selected the 180-195F range because colder fluid is less viscous. Whether they did this for performance reasons, reduced transmission wear, or EPA MPG benefits is TBD. I also suspect ATF WS, which is a synthetic oil, is designed to operate at higher temps without breaking down like older non-synthetic Dexron III/Dexron IV/T-IV/etc fluids, so normal operation at 195F with short bursts into the 210-220F range and no big deal.

TBH I would be concerned about accelerated transmission wear if I was running at 140F all the time instead of 190F. Or possibly colder here in Chicago in the winter when we have days where the daytime high might barely reach 0F. Additional cooling that helps reduce temps when under hard acceleration and mountain climbs to keep the transmission always below, say, 210F would seem helpful though I'm not sure I'd want to always bypass that thermostat. But WTF do I know?

Incidentally one thing I noticed after re-gearing is that my transmission *and* my engine oil temps run 10-15F hotter. I *assume* that's due to additional drivetrain drag from significantly shorter gearing. But in my case I'm not sure that a tertiary (or larger secondary) transmission cooler would matter since both engine oil and transmission oil seem to run at the same temp (about 210-212F, vs 196-199F previously).
 
linuxgod said:
I suspect Toyota selected the 180-195F range because colder fluid is less viscous. Whether they did this for performance reasons, reduced transmission wear, or EPA MPG benefits is TBD. I also suspect ATF WS, which is a synthetic oil, is designed to operate at higher temps without breaking down like older non-synthetic Dexron III/Dexron IV/T-IV/etc fluids, so normal operation at 195F with short bursts into the 210-220F range and no big deal.

TBH I would be concerned about accelerated transmission wear if I was running at 140F all the time instead of 190F. Or possibly colder here in Chicago in the winter when we have days where the daytime high might barely reach 0F. Additional cooling that helps reduce temps when under hard acceleration and mountain climbs to keep the transmission always below, say, 210F would seem helpful though I'm not sure I'd want to always bypass that thermostat. But WTF do I know?

Incidentally one thing I noticed after re-gearing is that my transmission *and* my engine oil temps run 10-15F hotter. I *assume* that's due to additional drivetrain drag from significantly shorter gearing. But in my case I'm not sure that a tertiary (or larger secondary) transmission cooler would matter since both engine oil and transmission oil seem to run at the same temp (about 210-212F, vs 196-199F previously).
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Okay changing fluids in all of my diffs and the transmission. Thank you! Crazy update. Transmission is driving perfectly. I can not get it to mess up. $4000 replacement sitting here on my floor. Dropped the pan and filter. No chunks of metal besides normal shavings after 120,000 miles of use.
 
The slipping you said you originally experienced on your drive home... did you drive right to the mechanic or did you drive home and then to the mechanic the next day? I'm wondering if whatever slipping you were experiencing was something possibly electronic (transmission ECU misreading a hot sensor) that got confused and needed a "reboot"?
 
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