Aisin Warner AW55-50SN and AW55-51SN Transmissions
Japanese Aisin Seiki – American Borg–Warner
The Aisin Warner AW55-50SN and AW55-51SN automatic gearboxes are used in a wide array of motor vehicles on the roads today and gauging by the amount of complaints they should never have been manufactured or at least they should have been replaced by a better gearbox. That’s how the story goes in any event. Truth of the matter is that these gearboxes are plentiful and because of their popularity they would reflect as having a high failure rate but the true test is how many have been manufactured versus failure rate.
General motors have also used the Aisin Warner AW55 series under their naming code AF33 which is identical, also a trans axle designed to drive the front wheels. Whatever naming convention is used, AF23/33-5, FA57, SU1 or RE5F22A the reliability of these gearboxes has been more often than not taken a beating from car owners because of solenoid failure and usually expensive repair. Many auto technicians do not like computerised gearboxes and will refer the owner to a specialised repair center. Although the internet is full of DIYers completing successful repairs on the valve body it is ill advised to dive into the electronics or mechanical aspects of these gearboxes unless one has a full understanding of their inner workings and has the specialised tools. It is generally accepted that certain malfunctions can leave one stranded but the more cautious of us will be aware that a faulty gearbox can be dangerous.
I came across this little nugget during the course of the week whilst looking for common problems with these gearboxes which just makes one think how many other gems we miss by not doing a proper search: The AF33 Is A Common Transmission That All Shop Owners Should Learn About. GM technical training on the AF33-5 is listed on the site.
Tech Files: AW55-50SN
AW55-50SN/AW55-51SN (from our friends in Russia, the ATSG service manual)
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Oh yes, why are Volvo resale prices so cheap? Is your Volvo hard-shifting?