Info: Leading Cause of Transmission Failure at Elevated Power Levels.
05-15-10, 03:33 AM
#1
Info: Leading Cause of Transmission Failure at Elevated Power Levels.
Ok, I've been spending the past year or so doing some extensive research into these Toyota A650E 5 speed automatic transmissions. Mine kept on breaking and I got seriously fed up. I haven't really seen any serious research into this transmission, so I decided to take the initiative.
The leading cause of transmission failure on a higher power car is due to the failure of the intermediate sprag, or what most people refer to as the infamous 3rd gear sprag. Once this part goes out, the car will no longer have a 3rd gear.
I've worked closely with a custom sprag manufacturer and after many many revisions, we have come up with an industrial grade ultra heavy duty sprag clutch. It has a one piece billet cage instead of the more common OEM style double cage freewheel type.
Here are some photos of the stock sprag VS other builders sprags VS my new solution.
It's late 5:30AM and I haven't slept yet lol. I was up all night measuring, spec'ing, and testing. I'll have more to write up here in the following days.
Keep in mind, these transmission parts are tested on my personal car. It can rev to 8000rpm, but I usually shift it at around 7600-7700rpm. The car runs 25-35psi of boost under testing. I literally test the parts until failure to find the weakest link in the transmission.
Here is where the problematic part is located.
The problem arises when the sprag cage deforms, collapses, or shatters into pieces.
Another shot of the stock sprag damaged. Once the cage fails, the sprag elements/teeth will fall out.
The stock sprag is weak and small. It has 16 elements and a total cage height of 14mm.
Two failed stock sprags side by side. As you can see, the failure is similar in which the cage is damaged.
Here is a picture of the PFS upgraded "race" sprag clutch. Same problem, the sprag cage failed catastrophically in this instance.
The inner cage blew apart and everything went into pieces.
This is an upgraded heavy duty sprag clutch that I spec'd out and had custom manufactured for me. They used a heavy duty sprag cage, but it still failed under extreme stress. I shift at close to 8000rpm on my auto trans and running around 30psi on the engine. When the sprag cage fails, the teeth will seize and get burned up/ground down by the excessive friction. The upgraded cage did not shatter, but it still deformed under the excessive stress. Under these situations, the sprag has a "roll over" where the teeth on the sprag all flip around to the wrong direction.
Close up of the sprag element damage and roll over.
Close up of worn out/burned up elements.
Close up of the PFS race sprag. Same damage as the stock sprag clutch.
The PFS race sprag has 20 elements with a 22mm cage height.
I originally had my trans upgraded by them and it failed at around 450rwhp.
A second shot of the PFS race sprag.
A shot of the OEM Toyota sprag 14mm cage height VS my Version 1 upgraded sprag with heavy duty cage. They both failed. The v1 sprag has a 16mm cage height.
In this photo. The stock sprag is in the very front, v1 sprag is behind it, and the v2 sprag are the two in the back.
Another angle.
A shot of all the parts side by side. I had my version 2 sprags custom built to my specifications. There are two versions, one is the 16mm and the other is the 22mm double height unit. The v2 sprag is an extremely heavy duty clutch with a solid one-piece cage. It is leaps and bounds stronger than the OEM style double cage freewheel design.
A photo of the v2 single height VS double height.
Another angle.
More info to come in the following days as I do further testing.
The leading cause of transmission failure on a higher power car is due to the failure of the intermediate sprag, or what most people refer to as the infamous 3rd gear sprag. Once this part goes out, the car will no longer have a 3rd gear.
I've worked closely with a custom sprag manufacturer and after many many revisions, we have come up with an industrial grade ultra heavy duty sprag clutch. It has a one piece billet cage instead of the more common OEM style double cage freewheel type.
Here are some photos of the stock sprag VS other builders sprags VS my new solution.
It's late 5:30AM and I haven't slept yet lol. I was up all night measuring, spec'ing, and testing. I'll have more to write up here in the following days.
Keep in mind, these transmission parts are tested on my personal car. It can rev to 8000rpm, but I usually shift it at around 7600-7700rpm. The car runs 25-35psi of boost under testing. I literally test the parts until failure to find the weakest link in the transmission.
Here is where the problematic part is located.
The problem arises when the sprag cage deforms, collapses, or shatters into pieces.
Another shot of the stock sprag damaged. Once the cage fails, the sprag elements/teeth will fall out.
The stock sprag is weak and small. It has 16 elements and a total cage height of 14mm.
Two failed stock sprags side by side. As you can see, the failure is similar in which the cage is damaged.
Here is a picture of the PFS upgraded "race" sprag clutch. Same problem, the sprag cage failed catastrophically in this instance.
The inner cage blew apart and everything went into pieces.
This is an upgraded heavy duty sprag clutch that I spec'd out and had custom manufactured for me. They used a heavy duty sprag cage, but it still failed under extreme stress. I shift at close to 8000rpm on my auto trans and running around 30psi on the engine. When the sprag cage fails, the teeth will seize and get burned up/ground down by the excessive friction. The upgraded cage did not shatter, but it still deformed under the excessive stress. Under these situations, the sprag has a "roll over" where the teeth on the sprag all flip around to the wrong direction.
Close up of the sprag element damage and roll over.
Close up of worn out/burned up elements.
Close up of the PFS race sprag. Same damage as the stock sprag clutch.
The PFS race sprag has 20 elements with a 22mm cage height.
I originally had my trans upgraded by them and it failed at around 450rwhp.
A second shot of the PFS race sprag.
A shot of the OEM Toyota sprag 14mm cage height VS my Version 1 upgraded sprag with heavy duty cage. They both failed. The v1 sprag has a 16mm cage height.
In this photo. The stock sprag is in the very front, v1 sprag is behind it, and the v2 sprag are the two in the back.
Another angle.
A shot of all the parts side by side. I had my version 2 sprags custom built to my specifications. There are two versions, one is the 16mm and the other is the 22mm double height unit. The v2 sprag is an extremely heavy duty clutch with a solid one-piece cage. It is leaps and bounds stronger than the OEM style double cage freewheel design.
A photo of the v2 single height VS double height.
Another angle.
More info to come in the following days as I do further testing.
Last edited by JeffTsai; 05-15-10 at 03:53 AM.
05-15-10, 03:59 AM
#2
Very impresive research Jeff. Man this really show you got to pay to play! Lets hope your v2 will last under pressure.
So did the double height sprang required a new houseing to fit into the OEM trans considering it is near 2x bigger than OEM or was this a plug n play design?
So did the double height sprang required a new houseing to fit into the OEM trans considering it is near 2x bigger than OEM or was this a plug n play design?
05-15-10, 04:04 AM
#3
Very impresive research Jeff. Man this really show you got to pay to play! Lets hope your v2 will last under pressure.
So did the double height sprang required a new houseing to fit into the OEM trans considering it is near 2x bigger than OEM or was this a plug n play design?
So did the double height sprang required a new houseing to fit into the OEM trans considering it is near 2x bigger than OEM or was this a plug n play design?
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05-15-10, 11:26 AM
#8
So our tranny can only handle 325 or so WHP?
wiki:
A650E
5 Speed Automatic Transmission
Applications:
1998-2005 Lexus GS 300 (2nd Generation)
1998-2000 Lexus GS 400
1998-2000 Lexus LS 400
2001-2005 Lexus GS 430
2001-2005 Lexus IS 300 (1st Generation)
2001-2003 Lexus LS 430
2001-2005 Lexus SC 430
Gear Ratios: 1st 3.357 2nd 2.180 3rd 1.424 4th 1.000 5th 0.753 Rev 3.266
Max Power Rating: 325 wheel horse power.
So the question is, even after the upgrade from version one then onto version two, where were the failure point@ and what power level? Also, could it be possible that there is another weak point on each end of the mast that can cause a vibration to make the sprag not operate properly? What is the difference with having a shorter bearing vs longer bearing elements or more elements, would that change the integrity of the casing?
I don't know anything about mechanical stuff, but just wanted to pose these question just in case it's being too focused. I'm just one of those kids that like to look and ask silly questions
wiki:
A650E
5 Speed Automatic Transmission
Applications:
1998-2005 Lexus GS 300 (2nd Generation)
1998-2000 Lexus GS 400
1998-2000 Lexus LS 400
2001-2005 Lexus GS 430
2001-2005 Lexus IS 300 (1st Generation)
2001-2003 Lexus LS 430
2001-2005 Lexus SC 430
Gear Ratios: 1st 3.357 2nd 2.180 3rd 1.424 4th 1.000 5th 0.753 Rev 3.266
Max Power Rating: 325 wheel horse power.
So the question is, even after the upgrade from version one then onto version two, where were the failure point@ and what power level? Also, could it be possible that there is another weak point on each end of the mast that can cause a vibration to make the sprag not operate properly? What is the difference with having a shorter bearing vs longer bearing elements or more elements, would that change the integrity of the casing?
I don't know anything about mechanical stuff, but just wanted to pose these question just in case it's being too focused. I'm just one of those kids that like to look and ask silly questions
Last edited by sam430; 05-15-10 at 12:10 PM.
05-15-10, 12:45 PM
#9
So the question is, even after the upgrade from version one then onto version two, where were the failure point@ and what power level? Also, could it be possible that there is another weak point on each end of the mast that can cause a vibration to make the sprag not operate properly? What is the difference with having a shorter bearing vs longer bearing elements or more elements, would that change the integrity of the casing?
I don't know anything about mechanical stuff, but just wanted to pose these question just in case it's being too focused. I'm just one of those kids that like to look and ask silly questions
I don't know anything about mechanical stuff, but just wanted to pose these question just in case it's being too focused. I'm just one of those kids that like to look and ask silly questions
07-11-10, 11:47 AM
#13
Lexus Champion
Jeff, fantastic work, great contribution!!!
Is this an adaptation of a racing type sprag developed for a powerglide or turbohydramatic?
This opens the door to all the 1998-2004+ vehicles that otherwise are on the edge at 350rwhp (or lower depending on torque production). I may have to build a V8 turbosystem yet!
Is this an adaptation of a racing type sprag developed for a powerglide or turbohydramatic?
This opens the door to all the 1998-2004+ vehicles that otherwise are on the edge at 350rwhp (or lower depending on torque production). I may have to build a V8 turbosystem yet!
07-11-10, 12:29 PM
#15
Jeff I am not much of a transmission guy and I only know the basre basics. Do you think this sprag can be adapted to the A340 series 4-speed transmissions? Also, it appears that the main problem with the A340 series is tha second gear sprag rolls when shifting under high torque loads and there goes the transmission. I appreciate your comments.
Ryan
Ryan