Notes On Bolted Connections With Self Tapping Screws - AH00.00-P-0007-01SF

Model 415, 420, 447, 448, 470, 471, 636, 639 

Model 450.3/4, 451.3/4, 452.3/4, 453 

Model all (4xWD, CAR, Light transporter) 

General: 

Terms: 

"Self-forming" is the generic term and includes both "thread-rolling" and "thread-cutting". Only thread forming screws of the globally applicable "TAPTITE" standard are dealt with in the following.

Properties: 

Thread forming screws create a screw-in thread in prefabricated core holes, usually by means of beveled crests.

The screw-in threads that are created by thread-forming screws can accommodate screws with ISO metric threads (standard screws) without problems.

Self-tapping screws are automatically centered when they are first manually screwed in.

The screw-in thread has to be cleaned using compressed air; wear safety glasses while doing so.

Repairs and replacements: 

• The reuse of an existing or another used thread rolling screw is permissible if the screw is undamaged.
• A thread-rolling screw may be replaced with a new or used standard screw. The length of the standard screw must be three threads (tapping point) smaller than the length of the originally installed thread rolling screw.
• All models (GWs, light vans, cars) 

  It is permissible to fit a new thread-rolling screw into a screw-in thread that already exists.

• Model 450.3/4, 451.3/4, 452.3/4, 453 

  Screwing a new  thread forming screw into an existing  screw-in thread is not  permissible.

All models (GWs, light vans, cars) 

With safety-relevant components (e.g. front axle integral carrier), no standard screws/bolts may be used.

Only self-tapping screws may be installed here.