Any trans experts out there for the A340E?
06-09-16, 10:20 PM
#1
Instructor
Thread Starter
Any trans experts out there for the A340E?
Hey all. I'm in the middle of an overhaul of a '96 LS400's A340E. The car was shedding material from somewhere and clogging the strainer. The clutches have looked great so far, even having the printed numbers still visible. Until I got to the forward clutch pack. I could tell right away without even removing the snap ring yet that they were rough. The area had a film of black goo more-so than the others. the steels have some bluing spots and the frictions are toasty looking. I also noticed a MUCH larger clearance between the top plate and snap ring than the other clutch packs.
The trans had about 230k on it. Are the forward clutches the first to go bad or burn in these transmissions? Or, should I be looking for a valve body issue related to the forward clutch circuit? The pump looks perfect and I'm obviously replacing all of the piston seals.
I would greatly appreciate any input on the A340E forward clutches and if there are typical problems with them. I feel like this post would be better suited in a performance car section like the SC300/400 or especially a Supra forum but being that it's out of an LS400 I thought maybe someone around here had experience inside the A340E.
The trans had about 230k on it. Are the forward clutches the first to go bad or burn in these transmissions? Or, should I be looking for a valve body issue related to the forward clutch circuit? The pump looks perfect and I'm obviously replacing all of the piston seals.
I would greatly appreciate any input on the A340E forward clutches and if there are typical problems with them. I feel like this post would be better suited in a performance car section like the SC300/400 or especially a Supra forum but being that it's out of an LS400 I thought maybe someone around here had experience inside the A340E.
06-10-16, 10:28 AM
#2
So far I have not been inside one yet, but have done other brands. Usually the cause of clutch slipping is a loss of pressure at some point that feeds its piston. That is most likely always a seal ring some place, and could be caused by the ring itself going bad, and if its an iron ring they can have porosity and just break, or just plane get worn out and that is mostly caused by dirty fluid and lack of maintenance. It could also be things like valve body gaskets leaking, cracks in the transmission case, cracks in the valve body, cracks in the piston, the piston check ball leaking, other in circuit (hydraulic circuit that is) check ***** not sealing, worn thrust washers/bearings allowing drums to move enough to disengage the seal ring with sealing point. Use of wrong transmission fluid that allows excessive slippage or attacks the friction materials.
I suppose I missed something but all are things to consider.
The first thing that would have been nice to do is check the pressures before digging into it, can usually tell a big story whats going on.
And you should do that when you get it back in. You can jack the rear wheels off the ground to run it through the gears and check the pressures.
I suppose I missed something but all are things to consider.
The first thing that would have been nice to do is check the pressures before digging into it, can usually tell a big story whats going on.
And you should do that when you get it back in. You can jack the rear wheels off the ground to run it through the gears and check the pressures.
Last edited by dicer; 06-10-16 at 10:33 AM.
06-10-16, 02:16 PM
#3
Instructor
Thread Starter
So far I have not been inside one yet, but have done other brands. Usually the cause of clutch slipping is a loss of pressure at some point that feeds its piston. That is most likely always a seal ring some place, and could be caused by the ring itself going bad, and if its an iron ring they can have porosity and just break, or just plane get worn out and that is mostly caused by dirty fluid and lack of maintenance. It could also be things like valve body gaskets leaking, cracks in the transmission case, cracks in the valve body, cracks in the piston, the piston check ball leaking, other in circuit (hydraulic circuit that is) check ***** not sealing, worn thrust washers/bearings allowing drums to move enough to disengage the seal ring with sealing point. Use of wrong transmission fluid that allows excessive slippage or attacks the friction materials.
I suppose I missed something but all are things to consider.
The first thing that would have been nice to do is check the pressures before digging into it, can usually tell a big story whats going on.
And you should do that when you get it back in. You can jack the rear wheels off the ground to run it through the gears and check the pressures.
I suppose I missed something but all are things to consider.
The first thing that would have been nice to do is check the pressures before digging into it, can usually tell a big story whats going on.
And you should do that when you get it back in. You can jack the rear wheels off the ground to run it through the gears and check the pressures.
06-10-16, 07:29 PM
#4
Instructor
Thread Starter
Pictures are worth a thousand words. So here are a couple I took of the pack thickness difference between new and old. The pack on the right has a straight bar laying across it showing the gap between the top of the new pack and top of the old one. The old pack without the flange measures .795" and the new one .888". It's a pretty considerable difference. Check out the bluing off the bottom plate and the darkening of the 2nd from the bottom plate. Both plates are wiped clean.
06-10-16, 08:20 PM
#5
Since these transmissions are so durable, and of course nothing is perfect, still with lack of knowing for sure what the cause is my first blame would be mixing in the wrong transmission fluid. If someone uses dexron that has a lot of make it slip in it and the transmission shift schedule is programmed to do a slip its going to slip way more than its supposed to and slippage causes heat. Its one of the reasons there was special ford and Gm transmission fluids in the old days. The ford type F was actually the better fluid, I spent some time around a transmission shop in my younger days and they would put type F in a GM transmission, I thought it was not a very nice thing to do, I don't know how many returns they had. I was told the clutches wouldn't slip as much and the transmission lasted longer. BM transmissions had their own fluid and the way I understand it, it was based on the ford type F fluid, that had way less slipim in it than type A or dexron.
06-10-16, 08:29 PM
#6
Instructor
Thread Starter
The car has been been in the family since 72k miles. Prior to that the first owner maintained it at the dealer. I've been the only hands to touch the car since. I did a transmission service or two with T-IV. This trans had about 230k or so when I pulled it. I just finished reassembly of the forward clutch pack. The clearance seems great now BUT the snap ring may have lost some temper with the high heat from the clutch pack at some point. It is very very lose and can spin in the groove with hardly noticeable pressure from your pinky finger. I swapped it with the OD clutch pack snap ring as it's the same one and will need to find a new one before installing the OD direct clutch assembly. It's little things like this that can cause heaps of problems I bet.
06-10-16, 09:34 PM
#7
Instructor
Thread Starter
dicer, while you're here and have some AT experience. The forward clutch is a lot tighter but the clearance with the original flange plate is still high on the clearance by 0.013". The spec is 0.028"-0.039" and mine is sitting at 0.052" with the new clutch pack. I can get a new flange that's thicker to put it at 0.036" but they are over $40 IF they're even available. Is that something worth putting in spec or does that seem close enough? I've already closed the clearance by 0.093" but i still need another 0.013" to be at what the book likes. My flange disk could be worn slightly from the burn clutch pack but it measured right at it's spec of 0.126". The new flange would be 0.142".
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06-10-16, 10:45 PM
#8
Are you talking about the pressure plate that the snap ring holds in? And calling it a flange plate?
I think you can also get the steel plates of different sizes. In the catalog for Asian find the trans then scroll to plates, they show different sizes. And they wouldn't cost what the pressure plate would.
I say they spec that clearance for a reason, there is so little movement allowed for the piston that excess clearance could pop the seals out, so that clearance is important. I'd rather be under it a bit than over, but then temperature expansion can cause wear if its too far under. And in the end spending for the part is cheaper than having a shop do the work your doing, they would add twice the cost of that part if they were buying it for the job.
Here is a place to down load a parts book.
http://www.transtar1.com/catalogs
Okay I just checked my Lexus transmission manual for the nomenclature thing, they do have flange on the mind. And in a 700R4 4L60 manual they call it Backing plate. I'm still calling them what they do. Oh checked ATSG Ford manual they call it a pressure plate. YES
I think you can also get the steel plates of different sizes. In the catalog for Asian find the trans then scroll to plates, they show different sizes. And they wouldn't cost what the pressure plate would.
I say they spec that clearance for a reason, there is so little movement allowed for the piston that excess clearance could pop the seals out, so that clearance is important. I'd rather be under it a bit than over, but then temperature expansion can cause wear if its too far under. And in the end spending for the part is cheaper than having a shop do the work your doing, they would add twice the cost of that part if they were buying it for the job.
Here is a place to down load a parts book.
http://www.transtar1.com/catalogs
Okay I just checked my Lexus transmission manual for the nomenclature thing, they do have flange on the mind. And in a 700R4 4L60 manual they call it Backing plate. I'm still calling them what they do. Oh checked ATSG Ford manual they call it a pressure plate. YES
Last edited by dicer; 06-11-16 at 10:36 AM. Reason: Edit to change an S to a T. An is to an it.
06-11-16, 06:24 PM
#9
Instructor
Thread Starter
Yea, I was just trying to stick with the nomenclature that Toyota uses if you were to look up any book info. It's just like different manufacturers calling the engine computers different things like ECM, PCM, ECU, etc...
I'd rather not try to tighten the gap with extra thickness over 7 plates. I would rather stick with what the manual says and use different thickness pressure plates. I already have brand new Raybestos steels in there anyway. I called my parts sources today and they said to call back monday with the specs on pressure plates that I need and they'll look around the shop. They've torn down tons of A340's over the years and he said they have lots of parts laying around and will probably what I need for a very cheap price. I have to order a band from them anyway so they could just throw the new pressure plates in with the band as well last he new snap ring to replace my lose one. It would sure beat $45 and $72 for the pressure plates I need.
The forward clutch clearance is 19 thousandths fat and I also found the OD direct clutch pack to be about 6 thousandths too tight. That pressure plate is the $72 one from Toyota. The one in the trans is one of the thicker ones listed in the manual so the new clutch pack must be a bit too tight for it. The direct clutch is dead nuts in the middle of spec which is nice.
I'd rather not try to tighten the gap with extra thickness over 7 plates. I would rather stick with what the manual says and use different thickness pressure plates. I already have brand new Raybestos steels in there anyway. I called my parts sources today and they said to call back monday with the specs on pressure plates that I need and they'll look around the shop. They've torn down tons of A340's over the years and he said they have lots of parts laying around and will probably what I need for a very cheap price. I have to order a band from them anyway so they could just throw the new pressure plates in with the band as well last he new snap ring to replace my lose one. It would sure beat $45 and $72 for the pressure plates I need.
The forward clutch clearance is 19 thousandths fat and I also found the OD direct clutch pack to be about 6 thousandths too tight. That pressure plate is the $72 one from Toyota. The one in the trans is one of the thicker ones listed in the manual so the new clutch pack must be a bit too tight for it. The direct clutch is dead nuts in the middle of spec which is nice.
06-11-16, 07:43 PM
#10
What I was talking about is the steel plates can sometimes be got at different thicknesses and that is a perfectly okay way to adjust the dimensions and will not hurt a thing. Yeah better if that place has the used part you need. Believe me if it was a shop doing it they would do what ever the cheapest way they could find, and charge you big for the resolution.
06-11-16, 09:09 PM
#11
Instructor
Thread Starter
If it were a shop doing it they would probably look at how much 19 thou is on their mic and say "ahhhhh it's fine." Especially for the OD direct pack that's 6 thou tight. I want to do everything right that I can so this overhaul lasts a while.
06-20-16, 02:14 PM
#12
Instructor
Thread Starter
Hey dicer, i'm in the middle of reassembly and have a clearance issue in the 1st/reverse brake that I'm wondering if I should spend the money to tighten up. The 1st/reverse brake clearance is spec'd at .028"-.038". Mine is at .051". I can get a thicker pressure plate from Toyota but the cheapest price I can find is around $50. Would you think 12-thousanths is enough to warrant spending the $50 to tighten up or is that going to work out fine in the long run. It's technically out of spec so part of me wants to spend the extra money and do it right but when I look at 12 thou on my mic it looks like nothing. It's 3 pieces of paper thick.
06-20-16, 03:51 PM
#13
Yeah but again the specs are for a reason. It will probably work like that, as it would if the friction material was worn off. It just doesn't give much extra room for friction material wear, it will be like you already have .012 of wear.
Again to have the work done the cost is upward to $2000, or so. Whats $50.? You can spend that on a steak dinner and flush it down the toilet the next day.
Again to have the work done the cost is upward to $2000, or so. Whats $50.? You can spend that on a steak dinner and flush it down the toilet the next day.
06-22-16, 10:44 PM
#14
Instructor
Thread Starter
Well, I agree so I ordered a 1st/reverse pressure plate from Toyota. There are 21 left in the US and that's it. I had to order the thickest one for the match to put the clearance in spec. I'm tired of waiting on parts to finish this thing! As soon as I get one step more into reassembly I'm ending up having to order parts. The only main pack that I haven't been able to check was the OD brake clutch clearance as it's the last installed. Hopefully that will be in spec.