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Undocumented 2nd Clutch Sequence for AISIN A131L
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June 28, 2007, 5:45 PM
This clutch sequence applies only to the AISIN A131L Transmission for Toyota's built for Consumers in the United States. *** Further investigation is requested for conformation of the anomaly. ***

I have been working on this A131L transmission for about seven months now and have finally found (what I believe to be) all proper clutch plate sequences for it.

The problem : 2nd clutch brake preforms poorly due to improper clutch plate sequences documented in Official Toyota repair manuals.

Sources with incorrect data: Toyota Repair Manuals RM269U, RM332U, possibly others...

Transmission Serial info (usually stamped into the front side of the transmission): AISIN 91 21 10

I can only assume, from the Toyota repair manuals, that this info translates...

Manufacturer: AISIN (Obviously), Year of Production: 91 = 1991,
Month/Day of production: 21 = 2/1 = Feb. 1st., and Serial #: 10

The Toyota repair manuals show clutch plate diagrams for both the A131L and A132L.

see... RM269U, Page AX-59 and RM332U, Page AX-58

The documented 2nd Clutch Brake sequences are as follows...

A131L: Plate ?> Disc ?> Plate ?> Disc ?> Plate ?> Disc ?> Flange

A132L: Plate ?> Plate ?> Disc ?> Plate ?> Plate ?> Disc ?> Flange

The Undocumented 2nd Clutch Brake Sequence goes as follows....

A131L: Plate ?> Plate ?> Disc ?> Plate ?> Disc ?> Plate ?> Flange

This previously (based on available repair manuals) undocumented sequence is similar to the A132L setup, in regards to Number of Discs AKA ?Frictions? and double plating. I tried each configuration in the repair manuals, but the undocumented one seems to work best in the AISIN A131L.

I've read that AISIN may have used Plates in place of Flanges when compared to the identical model manufactured by Toyota. This may have been done to reduce production costs.

Has anyone else noticed any undocumented or unusual sequences?


July 4, 2007, 5:56 PM#1
Thanks for the heads up on this. I've worked on the A131L 3-speed (Toyota Corolla) before, but unfortunantly not to the level you have undertaken - so I've not seen this unusual sequence. Very interesting - could be very possible, given that even the transmission subassemblies are potentially assembled at different stages - could be something that fell off QC, a mid-assembly change, or like you mentioned something to reduce production costs.



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