AA80E overview

Very good explantation on why our transmission behaves the way it does.

 

Nice find! That's a great article.

When I first get going in the morning there's one particular right turn I make that I slow down for. The trans always makes an audible clunk but after that it warms up and is much better.

 

This article and post should almost be pinned given all teh chatter about "why is my transmission so clunky" discussions

 

Yeah this same article has been posted before in various posts, such as: https://www.clublexus.com/forums/is-...l#post11591907

Can be summed up as: "This is a 20-year-old transmission with compromises because it was the first of its kind". But it is nice to see WHAT those compromises are.

 

Short answer: It's cold and old.

 

^^ I use that line on my wife every night!

 

Saw this circling the FB groups. It is a great read.

 

Interesting that the transmission only has a 8-10 lb-ft of buffer below the max torque rating. What happens when people do mods and increase their torque rating above that? It wouldn't take much to surpass the torque rating .

 

There's also this

 

We could just ask the RRR guys to chime in. They've worked on a few supercharged 2UR-GSE/Aisin builds. Honestly, I find it hard to believe that the slow, ancient Aisin transmission can only handle 8-10 lb-ft over its stock output. That doesn't exactly scream reliability, and it's probably the only real advantage this transmission has. However, I do agree the Aisin is (almost) garbage compared to the ZF or other modern transmissions, and reliability is not even a valid excuse anymore; it just feels like Toyota's being greedy or lazy.

Check out his other articles on the 500. He may have a point about a couple of things, but it's pretty obvious he's got something against Lexus/Toyota. Sure, the car's old gen, but come on, he's even picking on the max power output and referencing a short list of SAE-certified engines. Something about that just doesn't sit right.

 

The rated torque limit is really just a number. It could mean that they only tested it to those torque settings or it can simply be a conservative number. These transmissions are essentially bulletproof, I don't think I have ever seen one fail.

 

I was going to point that out earlier. Beware of misinformation in the article.

Many of us modded with bolt-ons, are making more than 406 ft-lbs to the crank. Full bolt-ons are making much more up to 490 whp and around 422 wtq in the case of a few RCFs. Then there are supercharged 2UR that make upwards of 600+ whp and a lot more torque than N/A mods can allow. The transmission is extremely reliable and can hold much more torque than 406 ft-lbs while being reliable contrary to what the article claims.

 

Yeah, I have an extraordinarily hard time believing they made the design margin so tight. The engineering Lexus puts into these vehicles is the highest quality. Also, we've not heard of transmission failures over the many years this unit has been in service through multiple, different vehicles.

 

Yeah, you can tell writer has a bone to pick about the transmission. Everyone makes a good point about its reliability and that speaks volumes.

 

While there's a lot of technical info in the articles on that website most of them seem be 50% opinion piece and 50% tech review, with a bias against the IS500 for some reason.

Even if the 8-10ftlb buffer thing is true more than likely thats 8-10ftlb from the safety factor limit, meaning there's a safety margin built in. A google search shows typical safety factor for automotive is around 3, meaning they would build things to tolerate 3x the max torque output expected. Nobody is using a transmission in a vehicle that is 10ftlb's away from destruction.