Overdrive/Transmission Failure --> Replacement --> More Problems

Hey everyone, I'm hoping someone out there might be able to provide some insight into what might have gone wrong inside my transmission...

I have a 2001 3.4L 4x4 automatic with a A340F transmission. It has about 175,000 miles. Running on 33s and just finished re-gearing the diffs with a 4.88 ratio and air lockers. After completing the 500 mile break in and changing the diff oils I had to drive 6 hours with some good freeway time. Was cruising around 75 mph at about 2,750 RPM, intermittently. Only thing abnormal was a vibration between 65 and 75 mph. It wasn't terrible, and I assumed it was from the drive line spinning faster. It was going great and the new gears made the all the difference everyone on here said they would. Then just as I pulled into town it went downhill.

Going about 30 there was a clunk and the truck dropped out of gear, but not to neutral. There was significant resistance and slowed me down real quick. Then getting back on the gas it shifted hard back to 3rd. None of that felt natural or good. No CELs or trans warning lights. It kept doing that so I put it 2nd, and limped home. I had a temperature gun with me from the diff break in. So I pointed it at everything I could see under the truck. Diffs, transfer case, transmission, all normal.

Upon further investigation the next day, this is what I've found. Transmission fluid is about 50,000 miles old, normal level. Smells singed but definitely not burnt. Drives completely normally outside of 4th gear (OD). So I can drive around just fine in 1st, 2nd, or with the overdrive off button pressed. The same condition from the night before happened every time it tried to shift to 4th. Whether that be accelerating or coasting.

Every time it shifts to 4th theres a clunk and what feels like heavy engine braking. Except there's no throttle response until it shifts back down to 3rd which is accompanied by another harsh clunk. I tried using a scanner but it's not throwing any codes. I've spent a while combing through the forums to find answers, but still not sure. Read through the service manual for the A340, but most of that went right over my head. I got pretty good idea of how it works, but don't know what actually would've broken.

So here we are, hopefully someone can tell me what I'm up against here. As this is the first mechanical issue the truck has ever had I have to assume it's related to the diff project, but not sure how. Higher revs for an extended period of time? Vibrations? Coincidence? Do I or someone who knows what they're doing have a chance of fixing this, or is it time for a manual swap? Sounds cheap.

Thanks in advance!

 

OK, well I took it to a transmission shop and made some calls and it seems like it definitely shredded its overdrive planetary gear. Maybe caused by a bearing going out. Which is apparently common on these years. The question now is what to do next. I could find a cheaper donor transmission from a scrapyard ($1000-$1500), but is it worth all the trouble to know it has the same thing waiting to happen. As everything is pretty high mileage at this point. The local shops/dealership won't rebuild it, but can order a rebuilt one for around $5k. A price point which makes me seriously consider figuring out a manual swap. Any recommendations on where to either buy a quality rebuilt one or where I could send mine to? I've read good things about import performance transmissions and they seem to offer a fair price, but are all the way across the country from me so shipping would hurt. Thanks!

 

I'm doubtful dealerships rebuild anything like that any more.

Surprised a local shop won't rebuild it. Are you contacting actual transmission shops, or just general shops? For example, my independent would point me to a transmission specialty if I had a need.

Whose giving you that kind of price?

@gearcruncher any pointers for this fella?

 

There's two local automatic transmission shops, both told me they couldn't rebuild the A340, due to "a lack of available parts". Then said they could source the rebuilt one for that $5k. Which I agree seems excessive, especially when it matched with what the dealership told me. So hoping someone knows of a shop in the Montana/Idaho area that I could trust.

 

Maybe chat with these folks? https://spprecision.com/products/toyota-a340e-transmission-sale.html

 

Listed on Offerup in Los Angeles

 

Yeah I had talked to them. For whatever reason they only sell the a340e, and they didn't even have on of those in stock. I asked if they could rebuild mine if I shipped it in and they told me the same things the other shops did. Can't source the parts.

There's a few similar options to that one near to me. I'm just weighing if it's worth to gamble on one which I don't know its condition. Paying to have it installed and everything. There's one from an 04 tacoma nearby, but pretty sure I remember reading somewhere I need either an 01 or an 02.

 

If it was me, i would drop the pan and check for solids (chunks) on magnets, if its all clear, get a used torque converter from junkyard and send it, yeah its a lot of work and the price of a used torque converter ($100?) but your at zero right now. Another note an A340E can be converted to a A340F fairly easy, so last straw find a same year prerunner auto and convert it….food for thought. For an educated answer wait for gearcruncher.
R/
Andy

 

I was able to source my A340F for a 4x4 conversion for under $1k shipped...with 350k miles on it. So you can definitely find a low mileage one for under $1500

 

It's only easy if you also have an A340F to rip the output shaft out of, which I guess the OP has, so ya this seems like a feasible option

 

Nope, cut existing output shaft on prerunner box, drill 1/8 hole for oil passage in shaft to lube adapter bearing, swap spacer and tone ring, drill and tap 6 oclock mount hole….done.

 

Try Nick at Yota1 Performance. A few years back His pricing on a rebuilt A340F was $2,500. Don’t know about long term performance of his rebuild, but after 30,000 hard miles the rebuild on my truck is like new. He can also hook you up with everything you need for a MT swap if that’s the way you want to go.

 

Thanks for the tip, I called them and they were very helpful. Quoted me $2,700 to rebuild, much better than anything else I've heard. Closer by too, getting it shipped won't be as bad. I think I'm gonna go with that option because everything used I've found is higher mileage than what I've got, so will be curious to see if they have an explanation for what caused mine to go. I'll post an update once I'm up and running again.

 

I finally pulled the transmission yesterday. Lots of useful advice on these forums, so really wasn't too bad. Below is a photo of the pan, definitely some good chunks in there. I have a remanufactured one on the way from Yota1 which was $2650 with core refund. So far they've been great. What I'm curious about now is the potential issue of some of this shrapnel having gotten into the cooling system. I drove the truck close to 500 miles since this started so I would think there's a pretty good chance it did. I was planning on adding a trans cooler anyway, but I see most people recommend running it inline with the radiator. Can I get away with flushing it or do I want a new one? Seems excessive but would hate to contaminate the new transmission. Or is it okay to bypass the radiator? It seems like the main reason not to is for warm up in the winter, which I do want... Thanks!

 

A lot of 3rd gen 4Runner people will bypass the radiator in case it cracks and mixes with the coolant.

Since you are in this far, I highly recommend putting in a transmission cooler. There are a few threads on here that go through the process. I put in a Tru-cool LPD 4454 https://www.trucool.com/EN/Products/Tru-Cool-LPD.aspx

Also worth it to install a gauge, unless you can get that over OBDII on your truck. Here’s a post in my thread that mentions some of the stuff. https://www.tacomaworld.com/threads/tiffany-the-taco.374490/page-8#post-15903947

 

I'm intrigued by the first shop saying the can't "rebuild" your trans but offer to sell you a "rebuilt" one.... Sounds like parts are available...and people rebuild them.
Anyway, you're on your way. Good luck..

 

Yes, flush your lines and any coolers

 

Toyota Re-manufactured A340F transmissions are still available from any Toyota dealer. They are called re-manufactured but every part is NEW except for the housing. The only way to go IMO.

 

Thanks for all the tips. Definitely gonna add a cooler and a gauge. I like where you put yours, where the ECT switch is. Since mine can't get it from the OBD2 port. I'm having a hard time finding a Tru-Cool 4454 online, but will keep looking. I've seen others using Hayden models too and seem satisfied. I will try to flush the cooler in my radiator, there seem to be some products out there for that. Then maybe add an in-line filter right after it temporarily. It's cold where I am so I think I want keep it in line and hopefully not buy a new radiator.

I totally agree, and why didn't go back to them. I'd imagine it's easier and more profitable for them to replace rather than rebuild. So unfortunately with no good shops around had to ship it out, but still cheaper.


Anyone have any recommendations for ATF? I've read through a lot of opinions on here, but am in a bit of a unique situation as I'm starting dry. The transmission builder recommended Toyota WS, but then there's posts like this:
https://www.tacomaworld.com/threads...e-get-it-out-of-your-transmission-now.331521/
I believe Toyota recommends Toyota type-IV, but I believe my dipstick says DEX II or III. Is it best to go with one of these OEM options or are there better ones out there? What about additives, I see a lot of positive reviews for products like Lubeguard red but is that something I should even be worried about with a freshly remanufactured transmission? As always, thanks for any input!

 

I'd just run valvoline machine ATF like in the post linked above but I'd ask Yota1. You shouldn't need any additives.