This is the Powerglide with a failsafe solid bronze alloy bushing instead of a regular roller bearing. No other differences excist between the regular Powerglide and the Powerglide Steady Roll tappets. Full bearing contact provides more stability, longer life and quieter operation due to the tighter tolerances this bushing design allows. The major drawback of a worn needle bearing roller is they will eventually break, spilling steel needles throughout your engine. This is no longer an issue. Even when the Steady Roll bronze bushing wears out the design is failsafe. Like the other Jims Powerglide™ tappets this Steady Roll version will give you a superior hydraulic function when compared with OEM style equipment, a billet steel body with hand-honed hydraulic unitcavity and an oil fed axle. To get full power, you must have zero valve lash and eliminate collapsing of the hydraulic unit as is found in the OEM unit, also called 'the shock absorber syndrome'. Failing to keep the valve open the full amount results in power loss. The Jims Powerglide tappets come as close to a solid tappet as possible, but are still able to compensate for heat expansion. They will even work well with solid style camshafts. Fits as an oversized replacement for 18538-99C. Note: Standard O.D. is .8420"
Fits: > 99-17 (NU) Twin Cam; 17-24 M8 (Excl. 23-24 CVO with 121" engine); 00-22 (NU) XL Sportster; 08-12 (NU) XR1200; 00-10 (NU) Buell XB
