Control the motion of the sprung and unsprung masses and keep the tire in contact with the road.
An Ohlins TTX 25 MkII twin-tube hydraulic damper. Twin tube construction separates the compression and rebound circuits, which is what allows genuinely independent four-way adjustment.
Mounted indirect, from the bellcrank to the frame with the damper body on the frame, which decreases actuating and unsprung weight.
Maintained rather than replaced: rebuilt biennially with fluids replaced annually. CR26I's dampers were selected from CR22's dampers after being dyno'd, with axles chosen based on similarity.
Purchased Ohlins unit. From the cost report drawings and CAD: From the cost report drawings: AISI 4130 Steel (CR26I_DamperBCSpacer).
Fault Vault, 2026-04-12, CR26I, Operational Errors, Complete Failure. On a TTX25 MkI, the limiting valve cap screw sheared and failed to stop the valve loosening excessively. The damper then discharged fluid and pressure into the vehicle while it was being adjusted. The dampers had to be replaced and rebuilt. The MkII does not have this failure mode, because its containment device is a circlip rather than a cap screw. The recorded action was to rebuild the dampers and change these screws.
Move from TTX25 MkI to MkII. The MkII retains the limiting valve with a circlip instead of a cap screw, which removes the shear failure that let a MkI damper discharge fluid and pressure into the vehicle during adjustment.
Overall length 200 mm, stroke 57 mm, weight 394 g without spring. Four-way adjustable: low speed compression and rebound in 25 discrete clicks of 1/6 turn each; high speed compression and rebound over 4.25 turns. From the cost report drawings and CAD: Weighed mass: 3247.7 g (7.160 lb), 3297.6 g (7.270 lb) (recorded as: Dampers). Dimensions called out on the cost report drawings. These are the figures printed on the drawing, not a labelled specification; open the drawing itself for what each one refers to. CR26I_DamperBCSpacer (mm): 9.5, 8.7, 7.9, 4.8 Source: Subteam weight books: CR25/Initial Documents/Weight Breakdown CR25.xlsx | Cost report drawings: CR26i/Suspension/Competition/Cost Report Drawings/Suspension and Shocks/Shock Assembly/CR26I_DamperBCSpacer.pdf Quantity per car, as costed: 4
Nothing in CrimsonStorage covers these yet.