It could be a rebuild or a simple filter replacement.
2000 LX470 Transmission Failure
- Thread starter BLetty
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BullElk
SILVER Star
Was anything like this?
Malleus
Far west of Siegen
So, the overdrive system is actually two systems, one clutch set for the overdrive gearing (the O/D brake) and the overdrive planetary and clutch for all gears except overdrive. The overdrive brake surrounds the overdrive direct clutch, so they're both in the same spot, axially.
If you've lost O/D only, but have forward and reverse, the problem is likely loss of clutch material in the O/D brake set. This is the first set beneath the pump.
FWIW, turning the O/D off will only prevent actuation of the clutches. There's really nothing more to lose if they're already gone. Beyond filling the case with more crap, that is. And that's not an indication, in and of itself, that anything else is wrong. The horror stories about people who've lost their O/D planetary assemblies don't apply to you. At least not yet.
From a "man, I just want this thing to run again" perspective, it's the easiest fix, after the pump itself. From the perspective of doing the job correctly, you have to tear the entire unit down, clean everything, measure every function, and reassemble it. This is what transmission shops won't do. What you get is a "fix" for the failed component and reassembly (parts swap). You likely won't get a new torque converter. They also won't flush the cooler lines and transmission cooler (bottom tank on an 80 A343F). That leaves the majority of fluid in the system, which still has contaminants in it, and a case which hasn't been flushed, much less cleaned, so it also has crap in it. The fluid passages in the valve body and the valve spool clearances are beyond small. Anything at all will clog them. Each of the operator pistons in the clutch assemblies has a check ball in it that will freeze with no effort at all if it's dirty. That keeps the fluid pressure on it after it's released and increases clutch wear.
Anyone can rebuild these, but I'd be wary about anyone who says they can do it without a manual. Take a look for yourself, there's a copy in the Resources section. I don't know how anyone can keep all that in their head. Transmission shops should have a Sonnax, or similar, subscription, which gives them access to FSM-like documentation. This isn't as good as the Toyota manual, but it's the bare minimum, IMO. If the shop can't prove they have instructions, don't pay them for any work. The real problem is that these A3xx transmissions are used in lots of cars and trucks and they all look similar (and the procedures are mostly the same), but there are important differences that have to be accounted for in the repair.
If you do this yourself, be prepared, in addition to what you know you have to spend money on (overhaul kit, fluid, etc.), to be ready to install different top level steels in one or more clutch sets. Unlike the steels (which list for about $40), these run $80 or more, each.
You need to closely inspect the stack of each clutch set, after it's installed. The top "steel" is actually a thickness setting device for the stack. Each one of the four has eight (yes, eight) different thicknesses to account for the manufacturing variability in locating the snap ring grooves in the case, that set the relative location of each assembly, within the case, with respect to its ideal location. There is some empirical wisdom (rumor) that the assembly tooling that was used to select these thickness plates (Toyota calls them flanges) was getting worn by the end of the 2000 model year builds, and some of the cases may not have been assembled as tightly as they could have been. This would lead to axial variability of the clutch set within the brake/carrier assembly, which in turn would stress the (all too tiny) thrust bearings beyond their limit. My personal opinion is this is what leads to thrust bearing failure that the transmission repair shops identify as the cause of transmission failures in the A343F. But that's just my guess.
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Malleus
Far west of Siegen
Yeah, but losing a valve spool replacing a filter is a pretty major screw up. On the other hand, forgetting to put it back in after rebuilding the entire unit is a pretty major screw up, too.
I don't think Tundra trans is the same as the one in the LC. Please check before you pull it.
Finally came across a 2002 LC with 180K. Motor was locked up, but Pan, Filter and trans fluid were all clean, going to test all the servos this weekend. If it works out I'll probably do an upgraded valve body and call it good. Have been driving mine with out OD for a few months. Dropped the pan, cleaned it up and put a new filter in it, has been fine, except gas mileage lol.
