What's the deal with ATF for CVT transmissions?

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In a nutshell, what is the biggest difference between "universal' ATF's like Maxlife & Amsoil, vs. the stuff that's used in CVT transmissions?
 
Quite simply because with a CVT fluid not only do you have to deal with all of the issues associated with a conventional ATF but in addition there are the metal/metal friction problems to address.
 
The two replies above are correct. I will add the following.

CVT's use a special chain that runs betweens two "pullies". Each pully can change its width, causing the ratio to change between the drive and driven pully. It needs a very special fluid to keep the chain from wearing out, and from binding in the pullies, and also to keep it from slipping.

Very different from a "shifting" automatic.
 
The two replies above are correct. I will add the following.

CVT's use a special chain that runs betweens two "pullies". Each pully can change its width, causing the ratio to change between the drive and driven pully. It needs a very special fluid to keep the chain from wearing out, and from binding in the pullies, and also to keep it from slipping.

Very different from a "shifting" automatic.
 
Some cvt's, like used in the Toyota Prius, make use of a planetary gear set to provide ratios. A drive chain is used to connect that to the conventional differential.

The Prius uses the same Toyota WS fluid as their conventional automatic transmission cars and trucks

I have some photos of a disassembled Prius cvt. How do I insert photos?
 
Originally Posted By: heyjayman
Some cvt's, like used in the Toyota Prius, make use of a planetary gear set to provide ratios. A drive chain is used to connect that to the conventional differential.

The Prius uses the same Toyota WS fluid as their conventional automatic transmission cars and trucks

I have some photos of a disassembled Prius cvt. How do I insert photos?

You have to host them. But anyway, are you rebuilding yet another failed Prius CVT? There's a shop around here that's starting to see CVT failures in Prius-es.
 
Originally Posted By: The Critic
You have to host them. But anyway, are you rebuilding yet another failed Prius CVT? There's a shop around here that's starting to see CVT failures in Prius-es.


CVT failures are very rare in Prius second generation (+2004) cars, and rare in first generation cars. There isn't a "snowmobile" system with sliding pulleys, the ratios are determined by the planetary gear set. The transfer chain appears stout, many awd and full time 4wd's use the same system with no trouble

I got the photos from the Oak Ridge National Lab. ORNL did a teardown - reverse engineering - of a 2004 Prius to determine how it worked.
 
Interestingly 'they' decided to label the Toroidals as IVT (Infinately Variable Transmissions) and not CVT (I don't know why). An interesting debate then ensued (and I think still goes on) as to which is the better system (Full Toroidal vs Half Toroidal). One of the problems was the sheer cost of a fluid that had the performance that was required in order to make it (Toroidal) work.

Oh, by the way unDummy and Tempest please be reassured that if you disagree with my opinion, I wouldn't dream of calling you out on such a trivial matter!
 
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Oh, by the way unDummy and Tempest please be reassured that if you disagree with my opinion, I wouldn't dream of calling you out on such a trivial matter!

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