U660E C2 Clutch Air Test Question

cswanson

Newbie
Joined
May 5, 2008
Messages
21
Points
3
Make
Toyota
Model
Sienna
Year
2015
Miles
134000
Engine
2GR-FE
Rebuilding my wife's U660E. Failed to engage into 4th gear. One C2 steel had gotten blued. However, C2 clutch would never engage with air during dissassembly.

After rebuild, C2 clutch is now engaging, but does not hold pressure so it releases even under applied pressure.

I can hear the air leaking from the base, so I suspect the sealing rings are not sealing. However, I have new sealing rings and I overcoated with ATF to better the seal.

Question: Should I be expecting the C2 clutch to maintain engagement with applied air as I am getting from the C1 clutch?

I obtained a new C1/2 Drum assembly from Transtec and it doesn't even engage.

I am suspecting the cover plate that holds the drum assembly to be faulty, but I have no means to verify this.


U660E is a USA version from West Virginia
 

billr

wrench
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Mar 12, 2007
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I, too, would expect the clutches to act the same with air-check. Are you doing these air-checks with the VB off, no chance something in the VB is leaking? (I suspect the VB off is only way to do the checks, just asking to be sure...)
 

cswanson

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May 5, 2008
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Right. The test I am running is with the C1/C2 drum assembly fit onto the rear cover. So, the transmission is disassembled. So, no VB.

I am running the C2 clutch clearance test with air prior to installation from Toyota's service manual.

My guess is any clutch assembly should hold firm with applied pressure, but maybe this trans type is different?

I am going to try to force some UV dyed ATF through the C2 passage to attempt to follow where the fluid is escaping, but I am at a loss how to pin point why the clutch is not holding pressure.


One idea I also have is trying to apply air to the drum directly, but the are 6 feed ports of which 5 need to be plugged to properly test. The placement of the ports is inside a bore with a shift in the center. This makes direct testing of the drum challenging.

However, I think if I can certify the drum, then the rear cover will be the problem. This could also explain why the trans wouldn't shift into 4th.


The U660E from what I've learned doesn't exhibit this as a common fault. Although, I did have to replace the case bearing which is a common fault.

In fact, thinking cosmically, maybe the vibrations from the faulty case bearing (which carries the planet assemblies) distorted the aluminum shoulder that carries the C1/C2 drum assembly and also provides fluid pressure for the clutches. In other words the shoulder is out of round.

Just thinking cosmically of course.
 

billr

wrench
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As you can probably tell, I am not familiar with this type trans; can only offer general advice. We have a trans expert who usually checks posts in the early morning. Let's see if he joins in tomorrow. If not, I will summon him privately.
 

grcauto

wrench
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May 29, 2014
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48
The seals have a lip and go in one way only. The lip faces pressure.
 

bp042665

transmission guy
Joined
Nov 26, 2012
Messages
779
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28
Location
Iva South Carolina
it is easy to damage the seal's on this when assembly it. are you useing a book to go by i have had issue with the hub ring being wrong size
 

cswanson

Newbie
Joined
May 5, 2008
Messages
21
Points
3
I think the sealing rings have an orientation as pointed out by grcauto. The literature does not mention anything about seal ring orientation and I am using the Toyota U660E manual and the ATSG manual on the U660/760.

However, on the opposite side from the sealing ring's opening, there is a subtle mark that indicates one flat side from another. I positioned these toward the pressure side and with one more adjustment - which is totally noob - I am getting solid C2 activation.

The other issue was I had the air pressure too low. I'm using a tiny compressor with super coarse PSI gauges and raising the pressure a smidge brought continuous clutch activation.

Oddly, the C1/2 drum assembly I bought from Transtec doesn't activate at all, but my son pointed out the number of clutches and steels in the C2 clutch is two which is less than what is required which is 3. Thus, the part is probably not assembled correctly to begin with.

So, I am going to take the clearance measurements and proceed.

Thank you everybody for your help with this matter.
 
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