A343F Transmission Rebuild Dilemma

[Gerrha]

Today I started the installation process for the newly rebuilt components in my A343F transmission. This is for my 97 LC. I am currently on hold...

Following the FSM, right out of the gate at Step-4, you are instructed to install the rear planetary gear unit, the second brake drum, the output shaft, and the first & reverse brake pack. Once that is done, you are then instructed to measure the clearance of the first & reverse brake pack. The clearance is supposed to be 0.70-mm to 1.22-mm (0.0276" to 0.0480"). Well, mine came in at 1.65-mm (0.0650"). To allow adjustment of this clearance, Toyota offers a range of flanges with differing thickness. My flange is the #50 flange at 5-mm (0.1975"). So, in order to meet the specs, I need a thicker flange. The thickest flange they offer is 5.4-mm (0.2126"). If I use that flange, my clearance will be 1.27-mm (0.0499"), which is still outside of the spec by 0.05-mm (0.0019"). As I see it, I have only two options.

Option-1: Get the 5.4-mm flange and accept being slightly out of spec. My question with this option is, what issues could creep up with the transmission with a slightly too large of a gap in the first & reverse brake pack?

Option-2: This is a bit more radical. The plates in this pack are 1.8-mm (0.0710") thick. If I combined one of the plates alongside a 4.0-mm (0.1575") flange, that would give a total thickness of 5.8-mm (0.2283"). This would bring the gap to 0.87-mm (0.0342"), which is right in the middle of the spec. The question here is would there be any negative outcome from placing a plate directly next to the flange? I cannot think of any, but I am not a transmission expert.

Can anyone guide me here?

 

[Kernal]

@Gerrha : You could also send the question above to Wholesale Automatics in Australia, they know this transmission well and IIRC add an extra steel and friction plate to their Extreme Transmission (after machining for more room??).

Post up their remarks.

Ask Orto - Technical Questions and Answers

Orto is our resident technical automatic transmission expert.

automatictransmission.com.au

 

[Gerrha]

Thanks for the tip.

 

[alia176]

Today I started the installation process for the newly rebuilt components in my A343F transmission. This is for my 97 LC. I am currently on hold...

Following the FSM, right out of the gate at Step-4, you are instructed to install the rear planetary gear unit, the second brake drum, the output shaft, and the first & reverse brake pack. Once that is done, you are then instructed to measure the clearance of the first & reverse brake pack. The clearance is supposed to be 0.70-mm to 1.22-mm (0.0276" to 0.0480"). Well, mine came in at 1.65-mm (0.0650"). To allow adjustment of this clearance, Toyota offers a range of flanges with differing thickness. My flange is the #50 flange at 5-mm (0.1975"). So, in order to meet the specs, I need a thicker flange. The thickest flange they offer is 5.4-mm (0.2126"). If I use that flange, my clearance will be 1.27-mm (0.0499"), which is still outside of the spec by 0.05-mm (0.0019"). As I see it, I have only two options.

Option-1: Get the 5.4-mm flange and accept being slightly out of spec. My question with this option is, what issues could creep up with the transmission with a slightly too large of a gap in the first & reverse brake pack?

Option-2: This is a bit more radical. The plates in this pack are 1.8-mm (0.0710") thick. If I combined one of the plates alongside a 4.0-mm (0.1575") flange, that would give a total thickness of 5.8-mm (0.2283"). This would bring the gap to 0.87-mm (0.0342"), which is right in the middle of the spec. The question here is would there be any negative outcome from placing a plate directly next to the flange? I cannot think of any, but I am not a transmission expert.

Can anyone guide me here?

did you take the tranny apart and now reinstalling pieces as a DIY? If so, holy cow dude, that's badass!!!

 

[Gerrha]

did you take the tranny apart and now reinstalling pieces as a DIY? If so, holy cow dude, that's badass!!!

Yes, I did. I started with the transfer, rebuilding it for part-time 4WD and replacing every seal, bearing, snap ring and etc. along the way. Of course, I had Georg Esterer's excellent video series to nurse me through that. Now I am on the transmission with a full Transtar rebuild kit with steels and discs. I am also replacing every bearing, race, and snap ring in it plus all the valve body solenoids, sensors, and so on.

It is indeed a challenge. There is one semi-useful video series out there and whatever I do, I check and recheck. Keeping things organized is a must. The FSM and other guides are very challenging to digest. Also, I thought several snap rings in the transfer were real bad, but they were just child's play compared to several in the transmission. For two of them, I had to walk away for an hour, or I was going to destroy something. I am almost there now and just waiting for a new flange so I can complete my Option-2 above.

 

[alia176]

shoot dang man, I'm very impressed with your tenacity. I've done everything except the 343F and hope to do that someday as my bands are wearing down I'm sure. I hope you can find the time to reflect on this project and tell us about any special tools that made this project easier.

 

[Gerrha]

Thanks. I have made a half-dozen different odd items (it would be difficult to call them tools) to help here and there. The part of the project that has required the most of these odd helpers, were the piston return springs along with their ever-present snap ring. They are everywhere, easily damaged, and a real pain to take apart and put back.

 

[Malleus]

To answer your questions directly:
» 1. Your shift will lag (a very slight amount, probably not so much you'd notice) because the piston isn't on the clutch pack immediately.
» 2. I'd choose this option, personally, as long as there's no damage in the case, either the bottom of the bore or the snap ring groove above it.

Yes, you can alter the stack to make up the clearance. The only critical dimension is the spring engagement that the piston has to overcome. You have to keep two things in mind when measuring the opeating clearance:
1) how much piston movement is available, and
2) the stack height of the clutch/steel pack.

These two measurements, and the "gap" in the clutch operating window are all that are involved in the clutch engagement/disengagement. There has to be enough "reach" in the piston movement to collaspe the clutches against the steels, and there has to be enough "room" in the stack window to allow the spring retainer to move the piston away from the clutch pack so they don't drag against the steels.

 

[alia176]

this is fascinating info, thanks amigo!!

 

[Malleus]

I hav a couple of questions, before I let this go:

» Are you using Toyota clutches? When I rebuilt the last A343F I measured the clutch thicknesses in every pack and they were within 0.002-in of each other. I also had to replace several (most) of the steels and the new (Toyota) steels were within the limits of my micrometer to measure them against their nominal thicknesses.

» Is there any wear in the "bottom" (the rear inside face) of the transmission case?

Either, or both of these, would contribute to a larger than allowable measurement.

 

[Malleus]

this is fascinating info, thanks amigo!!

Rebuilding these units is far easier than American designs, and probably the easiest large ticket item to repair on the truck. There's really no way to screw it up, and, unlike an engine, you'll know long before you're done whether it's right or not, because you can test each individual gear, before installation in the truck.

The hardest part is lining up the two sets of clutches in the overdrive unit, before dropping it in the case, but that's mostly learning to hold your mouth right. There is a trick to it, that's not in the manual.

 

[alia176]

Rebuilding these units is far easier than American designs, and probably the easiest large ticket item to repair on the truck. There's really no way to screw it up, and, unlike an engine, you'll know long before you're done whether it's right or not, because you can test each individual gear, before installation in the truck.

The hardest part is lining up the two sets of clutches in the overdrive unit, before dropping it in the case, but that's mostly learning to hold your mouth right. There is a trick to it, that's not in the manual.

Do you have any writeups that I can look at and be in wonderment?

 

[Malleus]

Working on it...I'm generally too busy tearing things apart and puttign them back together to memorialize my work, but I have fairly good notes and photos. Somewhere.

 

[alia176]

Working on it...I'm generally too busy tearing things apart and puttign them back together to memorialize my work, but I have fairly good notes and photos. Somewhere.

sounds like you do this more often than any of us!! My tranny is doing great but someday I'd like to refresh it since the turbo is adding more strain on it now. Perhaps a winter project for me?

 

[Gerrha]

Thanks everyone. My new steel plates and clutches are from the Transtar kit. Since this pack consists of 7 steel plates and 7 clutches, a tiny thickness variation might easily explain why my gap came in a bit large. I still have all of them so I could make those measurements to check that. However, things are not quite so clear cut.

The FSM and various parts diagrams such as, EPCdata, are not always in agreement with each other or reality. This situation we are discussing here is a good example of that. On page AT-59 of the FSM, there is a nice drawing for this first & reverse brake pack. The problem is, the drawing does not match what was in my transmission. That drawing shows 8 plates and 7 discs/clutches in the Land Cruiser pack. Mine had 7 of each. I watched a decent video of an A343F rebuild and that transmission also had 7 of each. If you look at the EPCdata drawing, it shows 7 plates and 7 discs/clutches, which matches number-wise, but the order they show is not correct.

My Transtar kit had 7 plates and 7 discs/clutches, which agreed with what I removed, and so that is what I replaced in mine. But, when I discovered that the gap was a bit too much, I will add back 1 plate taken from my old plates. Doing that, I will get the gap right in the middle of where it should be. So, funny enough, when I am done, I will have 1 flange, 8 plates, and 7 discs/clutches, which matches the FSM...

The only remaining question is where to place it. My plan was to add that extra plate directly on top of the flange, creating a thicker flange. But oddly, the FSM shows that 8th plate going in at the top of the pack. In effect there are 2 plates back-to-back at the top. SO I will need to think about that.

 

[Malleus]

sounds like you do this more often than any of us!! My tranny is doing great but someday I'd like to refresh it since the turbo is adding more strain on it now. Perhaps a winter project for me?

A weekend project, if you have all the parts you need. And the two tools you can't do without (one can be a milk crate).

 

[Gerrha]

You asked about wear at the inside rear of the case. I did not see anything, but it seems an unlikely place for wear since nothing is turning there.

 

[Malleus]

Thanks everyone. My new steel plates and clutches are from the Transtar kit. Since this pack consists of 7 steel plates and 7 clutches, a tiny thickness variation might easily explain why my gap came in a bit large. I still have all of them so I could make those measurements to check that. However, things are not quite so clear cut.

The FSM and various parts diagrams such as, EPCdata, are not always in agreement with each other or reality. This situation we are discussing here is a good example of that. On page AT-59 of the FSM, there is a nice drawing for this first & reverse brake pack. The problem is, the drawing does not match what was in my transmission. That drawing shows 8 plates and 7 discs/clutches in the Land Cruiser pack. Mine had 7 of each. I watched a decent video of an A343F rebuild and that transmission also had 7 of each. If you look at the EPCdata drawing, it shows 7 plates and 7 discs/clutches, which matches number-wise, but the order they show is not correct.

My Transtar kit had 7 plates and 7 discs/clutches, which agreed with what I removed, and so that is what I replaced in mine. But, when I discovered that the gap was a bit too much, I will add back 1 plate taken from my old plates. Doing that, I will get the gap right in the middle of where it should be. So, funny enough, when I am done, I will have 1 flange, 8 plates, and 7 discs/clutches, which matches the FSM...

The only remaining question is where to place it. My plan was to add that extra plate directly on top of the flange, creating a thicker flange. But oddly, the FSM shows that 8th plate going in at the top of the pack. In effect there are 2 plates back-to-back at the top. SO I will need to think about that.

Which A343F manual are you using? There are two and they are both for Land Cruisers, but they are for the 80 and 100 series versions. The two transmissions are not the same.

 

[Malleus]

You asked about wear at the inside rear of the case. I did not see anything, but it seems an unlikely place for wear since nothing is turning there.

Wear trash collects in the rear first.

 

[Gerrha]

Rebuilding these units is far easier than American designs, and probably the easiest large ticket item to repair on the truck. There's really no way to screw it up, and, unlike an engine, you'll know long before you're done whether it's right or not, because you can test each individual gear, before installation in the truck.

The hardest part is lining up the two sets of clutches in the overdrive unit, before dropping it in the case, but that's mostly learning to hold your mouth right. There is a trick to it, that's not in the manual.

I thought the hardest part was that ?!?!?!%%@@ snap ring at the bottom on the Number 2 brake piston. I almost needed a bigger sledgehammer for that job.