Banshee365

Some of you have been following my thread over here on my adventures with what started at one $800 LS400 purchased from a salvage yard. Long story short that car was hit, and nearly every piece of it except the body was transplanted to a really rough condition LS400 bought for $500 that had a good straight body with decent paint. It had 3 wheels in the junkyard (that's where it was going when if I didn't buy it) and now it has a really nice interior, great mechanics (almost... wait for it) and it shined up good enough for a really nice daily driver. The $800 LS400 was my second one. I've maintained and repaired a 96 LS400 for my mother since 2002 so I came into this with an already fairly large experience level with this car. I have never touched a UCF10, UCF11, or UCF21.

Yesterday afternoon the trans become unable to hold enough pressure to stay engaged. The drivetrain is out of the first LS400 that was destroyed. It was advertised as "May have a transmission problem." I was fresh off a successful overhaul/learning experience on another '96 LS400 so I knew worst case scenario exactly what money I would be spending to overhaul this car trans. I bought the car, brought it home, found the strainer slightly plugged, cleaned it, and test drove it around with good results. A thousand or so miles after the strainer clogged again. I noticed a whirring noise like a power steering pump starving for fluid, except it was the trans pump starving for fluid. I wanted to give this trans a shot so I bought a new strainer and replaced it. That was about 2,000 miles ago. The white car was running and driving great until it was hit. The new car I just finished building has had about 1,000 miles put on it in the last week or two. I've been piling the miles on to give it a good testing to see if anything pops up. I had all but forgot about the trans issues I had previously.

Then yesterday afternoon when exiting an off ramp the car shuttered under throttle and the RPM's increased as the trans started slipping. I made it about 1/2 mile down the road as I was thinking though my head the best solution. I used it's last leg to pull into a parking lot and park it. An hour later I towed it home with my truck. After the car cools for 30 mins or so you can put it into gear and it will move somewhat normally. Once the fluid starts to get at all hot it won't engage AT ALL. I used this opportunity to back it into my garage instead of working on it outside. Last night I had the trans out in about 2 hours. I tried to turn my frustration into motivation.

So here is what this thread is about. I have experience overhauling this transmission now so I feel comfortable in documenting some things along the way as I go and post them in this thread. I don't expect anyone to use the info I give as motivation to attempt this themselves. This is probably the most difficult thing to do on any car if you don't want to count properly done body work and weird things like that. An automatic transmission is a slush box full of hundreds of parts and if one part is installed incorrectly or left out you may make it a block or two before it's dead again. For that reason I'm not going to make this a DIY transmission overhaul tutorial. If you want to attempt this yourself I can answer questions and such but I want to make this more as an information thing than a DIY. I think it's beneficial to the community to provide info like this that you don't see much on other boards to help in understanding how your car works and what goes on behind the scenes. When members post in the future about transmission problems we may be able to revert to images and info in this thread to show in photographic form what could be going on that is causing their problem instead of trying to imagine in their head how the thing works. Also, if I were to make it a DIY it would take me weeks to put together and it would be dozens of pages. There are an enormous amount of steps and attention to detail to complete this job correctly. But I have learned some things from overhauling one of these before so as I come along interesting things I'll post it.

Before I get to posting photos and starting this process let's talk a little about a 95-97 LS400 automatic transmission. The 1995-1997 LS400 uses what is called an A340E transmission. It is a 3-speed with overdrive (4 speed.) It is electronically controller by solenoids in the valve body rather than mechanically like the old days. Except for the throttle cable. It still has a cable connected at the throttle body butterfly shaft that goes to a valve on the valve body. The rest is electronically controlled. In 3rd gear the output shaft spins at the same speed as the engine and in overdrive there is a 0.71 ratio that turns the output shaft faster than the engine hence the term overdrive. The A340E is of the A model transmissions built by Aisin-Warner, now known as Aisin Seiki. Aisin is owned by the Toyota corporation. The A model transmission is tremendously popular and used in many many many vehicles including some non-Toyota vehicles. The 90-94 LS400 uses an A341E which has a different 1st/rev gear and the 98-00 use an A650E which is a 5-speed. That's the last of any other transmission besides an A340E that I will mention in this thread from here on out. The A340 series of transmissions is a pretty heavy duty unit. It's more than adequate for a full size luxury sedan and can hold 1,000+HP with a couple mods. The A340 lines of transmissions is seen, other than the LS400, in the T100, Tacoma, 4runner, Supra, Sequoia, Tundra and obviously the GS400 and SC400. Later iterations were used for the LS430 and the LS460 still has an A model transmission. They're been around a long times and millions and millions have been built. The Supra community has pretty much found how to make these handle the monster horsepower and torque they are getting out of the 2JZ's over the years and the units hold up pretty good for popping wheelies down the 1/4 mile on big fat slicks. One thing that we will talk about later on that is one weakness for power levels like some Supra's can put out is the overdrive. The overdrive direct clutch on these units has 2 friction plates and 3 steel plates. They can't handle a 1,000 hp shift. Those guys do their runs with 1st-3rd gears only.

Lastly I'll go into what has happened to mine and what I expect to find. Automatic transmissions operate on pressure, known in the industry as 'line pressure.' The torque converter that is bolted to the engine is keyed into a gerotor gearset on a crescent style pump. It picks up fluid from the pan, through a strainer, and supplies pressure and volume for lubrication to the unit to operate. The unit is full of different clutch packs, gears, sprags, springs, seals, shafts, bands, pistons, clips, blah blah blah. Each component has a pathway that it gets it's fluid and pressure from. The magic is done in the valve body. The valve body is the brains of the operation and actually looks like a brain when you open it. I will show that. The valve body tells the fluid where to go and how much of it needs to go and when. The solenoids are fastened into the valve body and do most of this control while dozen's of calibrated pistons on springs divert the fluid to different places from there. The bottom like is that you must have pressure to operate. There are pistons that engage clutch packs at certain times. Those pistons are head back by springs. The piston must have a certain amount of pressure behind it to engage the clutch packs. No pressure, no engagement. Pressure can be lost by many reasons. The clutch packs are alternating steel and clutch material plates. Some have 6-7 of each like 1st and 2nd gear. Some of these packs are 3-4 inches thick. As the frictions and steels are smashed together some friction material is shed. This is engineered to be picked up by the magnets in the pan. The real problems arise when seals get old and start to leak internally. This is why changing fluid is important. ATF contains enzymes that keep rubber seals plyable. They will fail at SOME POINT regardless but a maintained transmission may last as long as anyone wants to drive the car. These enzymes deteriorate over time and then rubber can start to break down. If ONE important seal starts to leak your trans starts losing pressure. When you lose pressure the clutch packs begin to engage slowly and eventually partially. When they engage slowly they slip. You won't feel this as the driver at first. The more slip, the more material is shed and the thinner the friction plates get. Also, the more slip the more heat. And any trans expert will tell you the #1 killer/enemy of automatic transmissions is heat. Eventually the friction plates become too thin to where the piston cannot travel far enough to full engage. This is where your clutches start to slip. When they start slipping it's game over in the near future. With constant slipping even more material is shed and the heat increases in a hurry. This creates burnt fluid. I've had two of these fail in the same way. Never any slipping but the strainers become clogged with clutch material until the pump cannot suck enough fluid to provide pressure to the unit to operate. It's my experience that when a strainer clogs once you're end solution is an overhaul or replacement. Anything else kicks the can down the road, and every time you kick it the can stops closer and closer until you can't kick it anymore. I'm starting to wonder if age is the main culprit to the problems I've seen, I'm not the only one that has experienced trans problems on these cars. I look through ad's all the time and many say 'new transmission' or 'rebuilt transmission last year.' Until the past 5-10 years or so you really didn't hear of transmission problems with these cars. For a long time it was bragged that Lexus never sold a transmission over the counter for the LS400 over it's production run. I'm starting to wonder if the friction plates sitting in ATF for 20 years are just starting to break down. My trans quit working because it lost pressure. But it lost pressure because the strainer became clogged with clutch material. On one of these old friction plates in a clutch drum that got hot you can scrap the remaining clutch material off with your fingernail. Most of that is heat but I'm guessing it has started to partially break down over the years and years of normal heat and use. I mainly think that failing rubber seals is the main culprit causing the pressure to drop, clutches to slip, heat to develop and it's all downhill from there.

I expect to find one or two clutch drums with totally smoked friction and steel plates. The last one got so hot that the steel plates had blue marks all over them and the snap ring lost it's temper to where you could just spin it around with your finger. Crazy. These things can get hot so fast. I have a master overhaul kit and a rebuilt torque converter coming. That is what is required to do this properly. The master overhaul kit will have every single piece of rubber in the unit plus new friction and steel plates. Every piece of the unit has to be disassembled and cleaned like crazy clean. Then with new seals and such installed the unit is reassembled with new frictions and steels. There are also bushings in the rear of the case, overdrive support, and pump housing that must be checked for clearance and scoring. Any scoring anywhere in this trans is bad news and makes that part a paper weight. I have two other units sitting around so I should have enough good hard parts to complete this overhaul without calling the dealer and bending over. The master overhaul kit is overwhelming when you first open it. I will take photos of it when it comes in. It comes in a box the same size as large pizza box and is stuffed full of o-rings, steels, plates and all sorts of other junk. You use most of it by much of it is overlap for other models. There will be many seals and gaskets that don't even fit your particular unit. I'll also need a case of Toyota T-IV and a new strainer to finish the job. The transmission fluid is cooled by the engine radiator. There are metal lines leaving the trans the connect to rubber hose that connects to the bottom of the radiator. This is common among automatic transmission vehicles. This means that my radiator is contaminated. It used to be that transmission shops would add a filter on the return line of the transmission cooler/radiator to catch any metal that the old unit shed into it. Then they started making flush machines so good that would use and agitated flush to remove the metal from the radiator. I don't want to do either of those so my solution that is 100% best in my opinion is to replace the radiator. I've ordered a Denso (OE for Toyota/Lexus) radiator from RockAuto for $63.79. For that price you're stupid if you don't replace it. I'll clean the lines with brake clean and anything the fluid touches will be brand new or squeaky clean. If you hook up a new transmission to a radiator that had a failed transmission hooked to it your new unit will fail prematurely, like fast.

That's about it I suppose. Sorry to be long winded but this is a hugely complicated piece of equipment and I want to be thorough.

Banshee365

The evening that the unit failed I removed it from the car. This involves removing the exhaust from the front of the cats to the connection prior to where the pipe Y's into the mufflers. You must also disconnect the driveshaft. I don't mess with the adjustment at the center carrier bearing so I just disconnect the drive shaft at the rear end and transmission as well as unbolt the carrier bearing. This allows the shaft to be removed from the trans and pushed out of the way. Then I just put a transmission sized piece of plywood on my floor jack and bring it down that way. I know where they balance so it's pretty stable. I can't recommend it though. :P

Prior to dropping the trans I drained the fluid. It was full of small metallic particles. Typical of a failed trans. I've currently got the trans on it's side with the valve body out of it. Nothing too out of the ordinary so far except one thing. There is a wiring harness in the transmission that connects to the solenoids and also has a temperate sensor on it. They are regular Toyota style wiring connectors. The connectors were so brittle to the point of when I even touched the release tab it snapped off. Much like the fuel injector connectors when doing a starter. The harness is junk. I was going to head to a junk yard to pull one but to my surprise Toyota still has them available for $28. So brand new it is. The connectors were so brittle because of heat. I've taken apart units with 100k more miles and they didn't break like this.

That's not cool candy-apple paint. That's ATF full of metal from carnage.
This is the inlet to the strainer. It bolts to the valve body and sits in the fluid. The debris is clutch material. This is the main reason why the trans doesn't work right now. If this were cleaned and reinstalled it may drive perfectly for another few hundred miles. Then it won't...

nthach

Are you planning on just a stock-level overhaul or going with upgraded parts for power? I also know Chrysler also used a variant of the A340E in the old Jeep Cherokee.

I've always been curious about tearing down a transmission and putting it back together, even though I tore apart a Mazda tranny in my parent's backyard a while ago.

Banshee365

I meant to mention the Cherokee but it was late and I suppose I left that out. That is correct though.

I'm doing a stock overhaul. Stock springs and valving. And yes, gear heads like us are alway's interested in moving to the next level in difficulty. I am able to do this without many special tools other than some snap ring pliers and such. There are some special tools that would make it easier but it's possible without them, at least on this unit. It's very interesting to me to see each and every part and put together an autopsy of what happened inside the unit for it to fail.

Banshee365

I didn't take many photos after I removed the pump as it get's very very very oily and dirty from there and I don't want to clean my ands every single time to take a photo. I will take more on the reassembly as the disassembly is just the reverse of that. I've got the unit down to the bare case and have it washed up for the most part. I've got to finish completely drying it and cleaning with some q-tips until it's perfectly clean. My main concern on damaged parts was the pump itself. I've taken it apart and it looks pretty good. No noticeable scoring and the rotors are not contacting the crescent at all. You'll see a photo of one of my improvisations to a special piece of equipment for trans work, the spring compressor. Shops have a special spring compressor tool that is foot pedal controlled to depress the return springs to allow removal of the snap rings on the pistons units. I use threaded rod, some washers, a piece of wood with a hole in it, a proper size PVC pipe coupler and some little wrenches to compress the spring. There is one piston that does not have a hole in the middle of it. That one is a little more tricky to do without the proper tool but it's possible. With the return spring compressed you're able to get some snap ring pliers inside the PVC coupler and past the wrenches to pop it out. Then just back off on the nuts and take the contraption apart. It's sort of a redneck setup but it works fine for as much as I do this.

Here are some photos with a little description along with them:

This is the bottom of the trans with the valve body removed. The linkage towards the bottom of the image is the parking paw linkage. The mechanism is under the L-bracket. I'll take some more detailed photos of that on assembly so you can see how your park mechanism works. The 3 pistons at the top right are accumulator pistons. There is also one at the top left and there is a check valve ball and spring with retainer poking out at the bottom left.
The pump is pressed out by inserting two bolts into two holes like this. The bolt bottoms out and presses the pump out of the case.
Alternate back and forth on the two bolts and the pump should pop out rather easy after the bolts are all removed of course.
All of this comes out after the pump is removed. I just remove the component, flip it over and start stacking on the old torque converter for organization. Pictured here is the torque converter, pump, direct clutch and OD planetary gearset.
Here is the OD support that supports the shafts of the transmission halfway through the unit. The clutch packs shown are the OD brake pack. The OD support is secured by two bolts from the bottom seen in the first image.
This is my contraption for compressing springs. A little backwoods engineering but it works. You can see the snap ring popped lose at the bottom.
This is the majority of the parts out of the case. The silver pistons at the back are installed at the very rear of the case and they are the pistons for first and second gear.
This is the tower of parts from the OD support rearward. As mentioned earlier this is a good way to keep organization of your bearings, races, spacers and such.
This is the back of the pump. There are quite a few 10mm head bolts that hold the pump together.
This is the pump split apart. There are dots on the out and inner gears and that orientation must be kept during reassembly. The dots are down in this image. You need to look for scoring anywhere on the inside of the pump. Luckily this one is clean.
This is the pump with the gearset removed. Again, look for scoring. You shouldn't be able to feel any with your fingernail. Here you can see the crescent between the inner and outer gears hence the name crescent pump.

dicer

Wow I'm glad you didn't have all that first write up delete on you, I have had that happen when typing up a long story, Its not fun loosing everything typed.
So how many miles on this transmission? Must be another one size fits all transmission fluid unit. You know Valvoline max life.
I haven't worked on one of those yet, at least its not like a 700R4, I much prefer the older GM, FoMoCo, and Mopar transmissions, the older stuff was built better, not so much pressed and welded sheet metal stuff, and some had torque converters that were bolted together, yeah the good old days. Have you found what was making the metal?

Banshee365

The trans has 167k or so on it. I've owned it since 164k. I'm unsure of what type of fluid was used. I can't speak for the fluid compatibility. That's a bit over my head. It's my understanding that the T4 is important as the electronic controls on the trans except the fluid to work a certain way at certain temps. It's not a crazy exotic fluid I don't think, like VW/Audi DSG fluid for instance. Non-the-less I use the Toyota stuff, period. I used the OE fluid since 2002 on the last trans I overhauled. It still failed. Most of the material clogging the strainer is coming from the forward clutch in my opinion. I'll show you in the next post. There are 3 scorched clutch packs so far. Bummer.

Banshee365

The First/Reverse Brake and Second Brake packs are burnt up pretty bad and show signs of heat. You can tell there was heat when you see blueing. The Forward Clutch drum is also completely smoked. It's weird for the First/Reverse Brake pack to be burnt because it is only engaged in reverse and when the gear selector is placed in 'L.' The Second Brake is used in 2nd, 3rd, and OD (4th.) The Forward Clutch is what I've seen alway's bad on these as it is used in every gear except Park, Reverse, and Neutral. There is really no friction material left on the friction plates. The steels in that drum are blue and burnt up. The clearance between the pressure plate and snap ring is supposed to be .027-.039". I estimate the clearance to be about .125". It simply ain't gonna work like that. The clutch got so hot that the friction material easily scrapes off with a pick or even your fingernail. Most of this heat is from partial engagement. Just like a manual transmission, the clutch only wears when it is slipping. On a manual transmission it's better to let the clutch out quickly but smoothly rather than rev high and slowly let it out. Huge difference in wear. In a good trans the clutches don't slip much as the piston slams the tight clearance up and the frictions and steels lock together. When the pressure decreases from internal leaks and fat clearances. The wear becomes exponential from there.

This is the First/Rev and Second Brake clutch packs. Scorched. They are located at the rear of the trans.
This is the clearance of the Forward Clutch. It is supposed to be between .027-.039" or between 6 sheets of paper and 9 sheets of paper. We are looking at a bit more than that wouldn't ya say?
Here is the Forward Clutch pack laid out. Smokiinnnnnnnn'. There is hardly any friction material left on the friction plates.
Close up of the Forward Clutch discs. Here you can see the semi-metallic compound of the friction material which is what gave my fluid the metallic'y look to it.
This is the snap ring that holds the Forward Clutch pack in the drum. The gap at the opening should be much larger than this. This is because the snap ring lost some of it's temper/memory from the excessive heat. This snap ring is junk. The last one of these I did the snap ring was so lose that you could just spin it in the groove with your fingernail.
The friction material on the Forward Clutch discs scrapes off very easy with a pick or even your fingernail, what's left of it that is.

dicer

And normally these transmissions will last over 300,000 easy. For all the people that think you can use what ever fluid you want, I think this is a case of the wrong fluid attacking the material and helping it break down. None of us know for sure what kind of fluid was put in our transmissions unless we have owned the car since new. And even then it can depend on where you take it for service. Most transmission shops will used the one size fits all fluid because it is to their advantage, the cost is dirt cheap and if they luck out in 2 or 3 years the car comes back for a transmission rebuild. And great photo's Banshee.

Banshee365

While I wait on parts I'm cleaning the valve body. I will not make any mods or repairs to the valve body. The cleaning does wonder though. As I'm taking it apart I feel extra friction from crime and old fluid. The only thing I'm replacing in the valve body is the rubber ***** and the divider plate gaskets. You have to boil the divider plate that separates the two halves in water and scrap the old gasket off as it is bonded from the factory. It's a huge PITA but has to be done. I'm only working on the lower half presently. You can see the complexity of it and how it even looks like a brain inside.

This is the lower half of the valve body stripped and after cleaning. I just use soapy water and some water pressure. It's aluminum so it will not rust. Don't use purple power or anything as it will etch the aluminum. Lot's of passageways.... And this is only a 4 speed. The new F-150 has a 10 speed... Imagine what that looks like inside...
This is the other side of it. The valving and solenoids are stripped. The 3 larger ports to the top right are what the strainer bolts to.
This is the valving from the lower half before cleaning. The inside of these parts have black residue as there isn't a constant flow of ATF in some spots to keep it clean. Lot's of springs, valves, and keepers. Pretty much every keeper is a different size and must be put back in the proper spot.
This is the pile of bolts that hold the valve body halves together, the solenoids, detent spring that gives your shifter the notches, a ball check valve and another fluid strainer assembly.

timmy0tool

iTrader: (7)

holy moly! that's some dedication right here, it's like you jumped into brain surgery!!! you must have some system to keep things in order. sorry it's TL;DR.

nthach

Damn, those clutch plates are cooked! How did the Torrington bearings and bushings that support the clutch drums and shafts look?

Not to start a debate about fluid, I've used MaxLife with success in my past LS400, and there's people(mostly BITOG and others) who report good luck with MaxLife - but Toyota T-IV/WS are much more widespread in use compared to say ZF/Mercedes/Subaru spec fluids, but it's a one-size-fits-all and the friction coefficient of "universal" fluids might not be right for transmission that it's speced for. I think what will do a transmission under is an oil change shop who buys drums of plain old Dexron III/Mercon and use additives to modify the fluid.

Chrysler had a huge problem with their FWD trannies - they specified their fluid was to be used, but Dexron II/III could be used as well. Soon, trannies in K-Cars and minivans started to drop like flies, and Mopar made it a point that ATF+3/4 was the only fluid to be used in those.

Banshee365

The bearings and bushings look pretty good. The pump pushing that rides on the converter has a slight score and visual wear so I'm going to replace it. The rest look pretty good.

Superfast1

Banshee365, I'm amazed by your vast knowledge on these LS400's. My hat is off to you. Anyway, I have a question in regards to the tranny. The tranny in my 97 LS400 recently slipped while driving at low speed. I've figured it out it was due to the Solenoid E so I've replaced it w/ a new OEM solenoid. During the first few hundred miles, I've noticed there was a delay in shifting from 1st into 2nd gear for a few minutes in the morning when car was cold. Once warmed up, it's shifting fine. I've figured this is normal as the internal components of the solenoid need time to break in & I think I'm right on this as the tranny is no longer exhibiting this condition. The real question I have for you is in the morning, what cause the car to clunk (not every time) when I put the car in reverse & forward to back out of my driveway & drive away, respectively? Is it due to the high idle at cold start or the new solenoid still need time to open up to allow the fluid goes where it's supposed to go? Please advise.
Thanks,
John

Banshee365

Did you have a P0770 code to cause you to replace that solenoid or did you just test each manually or something? How much of a delay is there shifting from 1st to 2nd? In many cars this is normal when cold. It's by design that way to keep the revs high to aid in a quicker warmup of the engine. I don't recall if the LS400 does that for some reason. A solenoid shouldn't need any sort of break-in period. I haven't heard of that, but that is not saying that is not true. But, you say the trans no longer delay's its shift from 1st to 2nd now? Weird. This trans clunked into gear as well, both forward and reverse. I've noticed many of them do that. It is obviously sometimes more pronounced cold as the idle is higher but it still did it warm as well. It didn't chirp the tires or anything but it did sort of thunk into gear. This can also be caused by a separated rear trans mount and possibly even bad diff bushings. When I get this trans reinstalled in the car after the overhaul I will make note on this thread if the clunk into gear is still there or gone. I wonder if the huge clearances in the clutch drums and brake clutches were causing it to engage harshly.