A343F(?) Shifting trouble shooting help (1 Viewer)

[BGMachine]

hey all,

I have a new to me '95 FZJ80 (the bluey-dadwagon thread) and it's glaring flaw is transmission trouble. here's the summary so far:

regardless of warm/cold transmission, these symptoms persist.
- takeoff from stop is difficult. if you stay less than ~20% throttle, vehicle can pull away from a stop but there is some slipping. greater than 20% causes a violent shudder.
- 1 to 2 shift is similar. light throttle, there is slipping but it can make the shift. +20% throttle, violent shudder+slip+brief gear grind.
- 2 to 3 & 3 to 4 shifts complete with no slip / shudder. if there is high throttle input, the shift can be on the hard side.

So Far, I've drained & refilled the fluid twice (5qrts each time). The fluid is getting better and the first fluid was on the opaque / darker side. I added LucasOil stop slip on the 1st change with not much of a difference. On the second change, I added LubeGard Instant Shudder fix. this took a bit of the edge off, but the symptoms remain.

The trans has 142,000mi on it and from what I can tell, the truck sat for a number of years. I did the vin decoder and it's a 07/1995.

before I give up and take the truck to the shop, I was debating dropping the pan and changing out the solenoids & filter. The thought being, that maybe the solenoid that controls 1-2 isn't building enough pressure and the clutches are slipping. maybe that solenoid is stuck from years of sitting?

Or maybe something is wrong with the torque converter?

Or the clutch pack is dying?

I don't really know. From what I can tell searching the internet, this may not be a solenoid issue. But I don't want to take it in and drop the trans if I can fix it at home.

I don't know if this line of thought makes sense. I've not had to diagnose automatic transmission issues before.

Or should I just take it to a shop and let them do it...

Any input is appreciated. Thanks!

 

[jonheld]

First thing I would do is lock the center diff and see if the symptoms persist. It could just be a stripped drive flange or some other "open" in the driveline.

 

[Marvelicious]

Dropping the pan and changing the filter is always a worthwhile step when diagnosing transmission issues. As nasty as it sounded like it was, you might find that the filter is just gummed up and restricting flow. I'm no auto transmission expert, but it certainly sounds to me like something that could indicate a lack of pressure. I have known people to solve what seemed to be major transmission issues with a filter change.

 

[reklund5]

Toyotas dont really have a "filter" like domestics do. its just a pickup screen. If it was clogged, it'd be with huge debris that would render the trans in need of a rebuild. You need to get some line pressure readings and see if it even is making enough pressure. If you manually shift to L-2-D does it work normally?

 

[Marvelicious]

Normally I'd totally agree, but I'm thinking of severely nasty atf that sat for a few years... Who knows what's happening there?

 

[BGMachine]

ok, here's an update. I cleaned the pan, cleaned the magnets, replaced the filter, and flushed 16qrts through it. No change to performance.

I called a couple shops in the area and A) they won't touch it; too old. and B) they believe that it's the 1st gear clutch pack.

I think I'll attempt to rebuild it on my own. it's already broken so I can't make it worse! haha

I found this kit that I think should be perfect.

A340E Transmission Master Rebuild Kit A340F A341E A343E A340 V4AW3 Stock HD HP Overhaul

Check out the deal on A340E Transmission Master Rebuild Kit A340F A341E A343E A340 V4AW3 Stock HD HP Overhaul at Oregon Performance Transmission

www.oregonperformancetransmission.com

 

[Kernal]

@BGMachine : I would check every other possibility before you drop and rebuild your low mileage A343F transmission.

IME additives of any type in this transmission can make slip/shudder worse including that specific "Shudder Fix" product. What type of transmission fluid is in the transmission now?

Did you drive the vehicle (on a loose surface like dirt, gravel, grass) with the CDL locked (transfer case in LO) to check if the symptoms still occur? If you've never done that be prepared for the engine to rev much higher in each gear, that is normal, and you should not drive more than ~35mph when the transfer case is in LO.

You might consider taking it to a Toyota Dealer and asking them to perform the factory service manual procedures to check line pressure and solenoids. Might cost a few hundred dollars but better than dropping a good transmission.

There is a known issue with the Valve Body in the early 95+ A343F transmissions models that can be fixed with a light rebuild of the Valve Body ie: you don't need to drop the transmission, just the pan and the Valve Body.

IME it shows up as a screech/slip/shudder in reverse, worse when cold and backing up an incline.

Read through this thread:

A343F reverse noise

It's a '95 FZJ80 with the A343F, 93,000 miles. Recent tranny flush a few months ago. What happens is when I put it into reverse and there's a load, such as trying to back up a hill or over something, the engine revs, the rig doesn't move and then a noise that sounds like metal grinding or...

forum.ih8mud.com

 

[Malleus]

Oh, go ahead and pull it. You'll never know what fun you can have until you do.

 

[Malleus]

You will need the shift pawl sleeve. It's not in the rebuild kit.

The seals are in the kit, but you can't replace them until you remove the shaft, which requires removing the sleeve. The FSM says you can use a chisel and reuse the sleeve and the pin, but I don't see how.

 

[Malleus]

You'll also need a way to compress the piston retainers. This is the Haggerty SnapPress. I have this one. It's the gold standard.

These are worse than useless:

You can make your own, but do not attempt to use your hydraulic 12-ton press. It'll work, but you'll end up buying new spring retainers for the effort. The springs don't take too much force to compress, but you need a tool that seats on the entire face at once.

 

[Malleus]

This tool is sold as an upgrade to the original Haggerty design (all the current Haggerty tools already incorporate this design change):

If you already have a press, you can use this to remove and install the spring retainers. If you make your own, it should look very much like this.

 

[Malleus]

There's also a floor mounted model:

but it takes up floor space...

 

[BGMachine]

There's also a floor mounted model:
View attachment 3506852
but it takes up floor space...

Thanks Malleus for all of the info! I'll have to save those links for later. I may get a junkyard trans as a temporary / permanent fix. I'm still exploring all possibilities.

@BGMachine : I would check every other possibility before you drop and rebuild your low mileage A343F transmission.

IME additives of any type in this transmission can make slip/shudder worse including that specific "Shudder Fix" product. What type of transmission fluid is in the transmission now?

Did you drive the vehicle (on a loose surface like dirt, gravel, grass) with the CDL locked (transfer case in LO) to check if the symptoms still occur? If you've never done that be prepared for the engine to rev much higher in each gear, that is normal, and you should not drive more than ~35mph when the transfer case is in LO.

You might consider taking it to a Toyota Dealer and asking them to perform the factory service manual procedures to check line pressure and solenoids. Might cost a few hundred dollars but better than dropping a good transmission.

There is a known issue with the Valve Body in the early 95+ A343F transmissions models that can be fixed with a light rebuild of the Valve Body ie: you don't need to drop the transmission, just the pan and the Valve Body.

IME it shows up as a screech/slip/shudder in reverse, worse when cold and backing up an incline.

Read through this thread:

A343F reverse noise

It's a '95 FZJ80 with the A343F, 93,000 miles. Recent tranny flush a few months ago. What happens is when I put it into reverse and there's a load, such as trying to back up a hill or over something, the engine revs, the rig doesn't move and then a noise that sounds like metal grinding or...

forum.ih8mud.com

Kernal, thanks for all of the input.

the current fluid is Napa Dex III with a splash of Lubegard ShudderFix.

I have not noticed the shudder in reverse. Even with aggressive throttle.

After talking with a couple transmission shops in the area (including Toyota), they did help me diagnose a bit. We believe that the clutch pack for 1st gear is burned up. This explains why taking off in 1st there is a violent shudder that feels like a clutch slipping and grabbing. Kind of like when a manual is about to slow speed stall.
Forward Clutch F2 seems to be the culprit. it's the only one that's engaged only in 1st gear. and since 2-4 shift more or less OK, and reverse drives ok, this makes sense to me.

In all honesty, based on my time and financial resources, I'll likely get a salvaged transmission with as low of miles as possible and refresh that one. I need to replace the rear main seal on the engine anyways so dropping the trans doesn't bug me too much.
And I can hold onto the original trans and rebuilt it later if I want to.