Webb Automatic Slack Adjusters (ASA) and Self-setting Automatic Slack adjusters (S-ASA) are identified by the part number which is marked on the cover plate.
After a long life in service or while still on the vehicle, it can be difficult to read the information on the cover plate. Therefore the following measurements can be taken to assist identification:
The cast housing has an identification mark, for Webb ASA this begins with T (eg T-32) and for Webb S-ASA this begins with S (eg S-43).
The cast housing can be straight or offset.
It can also be straight or inclined.
On Webb ASA the control arm angle can be checked.*
On both ASA and S-ASA the Anchor Point type will be Quick-Fit, Peg Bolt, or Anchor Pin (D).
The number of teeth on the worm wheel which mates with the camshaft can be counted (E).
The clevis bush internal diameter (ID) can be measured (F).
The distance from the center of the worm wheel to the center of the clevis hole can be checked (G).
With the above information any Webb slack adjuster can be identified. In addition it is always useful to know the vehicle application and which wheel end the adjuster is fitted to.
* For S-ASA this Is Not Applicable as the control arm will work from any position within the working arc of the control arm.