GPM Racing 4140 Medium Carbon Steel+Aluminum 7075 Shock Absorber Shaft Core Kit for Traxxas 1/6 4WD XRT 8S-78086-4 (XRTDP)

Precision shaft cores for XRT 8S applications

This shaft core kit is engineered as an aftermarket replacement for the TRAXXAS XRT 8S platform and fits GPM shock assemblies. Shafts are CNC-oriented 4140 medium carbon steel where strength is required, paired with 7075 aluminium components in specified locations; increasing the shaft diameter from 5.0mm to 7.0mm reduces bending moments and improves runout under load while maintaining shock body compatibility.

The set is configured for use in either front or rear damper positions and is compatible with both GPM shock absorbers and original factory shock absorbers for the listed model. The sealing system utilises an oil seal rather than an O-ring to reduce friction on piston travel and to provide more consistent oil retention during sustained operation.

During replacement, verify piston and seal face dimensions and tolerances, assess shaft straightness and smooth sliding within the shock body before final assembly, and preserve your selected oil weight and valving to retain intended damping characteristics. This upgrade primarily enhances durability and alignment precision rather than altering valving behaviour.

Packing includes

• Shock absorber shaft core – 2pcs
• shim – 2pcs

Original Name / Part No:

7762+7863

Compatible Models

• TRAXXAS-1/6 4WD XRT 8S-78086-4

Recommended where precision shaft straightness and improved seal reliability are required; confirm fitment and clearances in your shock bodies before final installation.

How does increasing shaft diameter improve durability?

A larger diameter raises the section modulus, reducing bending under lateral loads and lowering the risk of permanent deformation in high-stress runs.

Why choose 4140 and 7075 for this application?

4140 offers fatigue resistance and toughness for the shaft, while 7075 aluminium provides lightweight rigidity where required; the combination balances strength and weight for improved service life.

Does the oil seal change maintenance routines?

Oil seals reduce lateral leakage and improve piston feel, but inspect seals for wear during service and replace seals or shims according to observed clearance and condition. Write Product Review Please sign in your account before you can write any review. Sign In Close

Made to order: GPM Racing parts are shipped to us from GPM’s factory, so please allow around 14 days for dispatch.