Modern internal combustion engines are subject to a constant optimization process in terms of performance and production. This results in ever increasing demands on fasteners. Engine bolts must show high elastic resilience under load and have excellent ductility in order to ensure the necessary clamp load after tightening as well as in operation and a reduction of stress amplitude under dynamic loading.
The tightest strength tolerances are guaranteed by continuous development of materials and extensive experience in the production of high tensile fasteners.
In order to increase the dynamic load carrying capacity and to optimize thread quality, 4fastening engine bolts can be rolled after the heat treatment process if required. In addition, special surface coatings lead to constant coefficients of friction.
4fastening engine bolts are developed and produced to satisfy the multiple requirements in respect to, loading, environment, influences, and economic aspects
A combination of the most modern production engineering equipment and a powerful quality management system enable 4fastening to supply engine bolts which fulfill the highest demands of our customers, while of course meeting all national and international standards


In order to center the connecting rod cap on the connecting rod, our connecting rod bolts are either produced as ground bolds, cold headed reduced shank press fit bolts, flat rolled helix bolts, or bolts with annular rings.

In the case of cracked connecting rods centered via the crack surface, 4fastening connecting rods with long threads rolled after heat treatment are used.

If the crack structure of the connecting rod surface is very fine, the connecting rod bolts can be provided with an additional pre-centering capability. We have optimum production processes and possess the necessary knowhow for the calculation, design and testing of these highly dynamically loaded fasteners.


The quality of the machining of the bearing seating for the crankshaft and the service life of the bearing shells are both substantially influenced by our main bearing cap bolts.

The prime object of this bolted joint is a completely uniform clamp load, both for the machining of the bearings and during the subsequent assembly process. Our main bearing bolts can be provided with internal threads in the head for the additional function of fastening oil pumps and oil deflectors.


Our valve adjustment bolts represent the most important component of the total valve operation and must fulfill the highest demands in terms of dimensional specifications and wear resistance over a long service life.

Optimized production processes guarantee best quality and economy during the production of completely cold headed versions. For highly loaded engines, our valve adjustment bolts can be produced in a hollow drilled version.


High dynamic loads are securely transmitted with the shortest possible clamping lengths.


With weight optimized head shapes the largest bearing surfaces can be achieved.



Our cylinder head bolts with tight strength tolerances are assembled in modern combustion engines. The bearing surface geometry is specially laid out to suit the particular joint and if necessary optimized with assembled washers.

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