Back in 2015 AMD Magazine featured an all new rear suspension lowering system for all Twin Cam Softail Harley-Davidson motorcycles from 1999.
Called 'Slamtail', it is designed and manufactured in Australia. The brainchild of ex-Formula 1 senior suspension design engineer Ken Rutherford (who numbers the Benetton F1 team among his impressive credentials), Rutherford says that on returning to Australia after his F1 career "an old friend and mentor asked me what I was going to do and mentioned that the Harley-Davidson Softail suspension design offered an opportunity for me and my skill set, and suggested I have a good look at it and see if I could enhance it."
Well, the results were an internationally respected alternative to the conventional "airbag" type kits in which 'Hydraulic Rams' were used. Slamtail reused Harley's OEM spring and shock units, rather than scrapping them, therefore offering better value than some other systems, with the original ride quality retained and no change to damping and spring rates.
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| Vice-mounted spring compressor assembly for 'Slamtail' fitment, or any work required on the M-8 Softail mono shock assembly |
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| 'Slamtail' mono shock ram shown at lowest height |
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| Softail shown at maximum lowered height - the mechanical limit on the replacement polyurethane bump-stop |
With the eventual demise and replacement of the Twin Cam chassis/engine combo in MY 2017, Harley has engineered a new mono shock rear suspension platform with the M-8 Softail. In response, Slamtail has developed a new rear suspension lowering system for the M-8 mono shock Softail range for wide and standard frames.
With the system fully raised, the ride quality and suspension travel is the same as the OEM original, and the system re-uses the OEM Showa shock unit, replacing the OEM coil spring with a bespoke high-stress steel tapered wire coil spring with a progressive rate. The Slamtail-equipped bike can be ridden at any height whilst still retaining the stock ride comfort.
The new system lowers the ride from stock height to an absolute minimum, with supplied polyurethane bump-stop installed. An additional 10 mm of preload adjustment is available for specific rider/pillion demands.
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| ST5 'Slamtail' mono shock assembly |
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| Side stand mounting clevis for lowered suspension |
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| Power unit installed behind transmission |
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| ST5 mono shock system handlebar-mounted key-fob |
Among the changes in ownership and riding experience expectations that have matured in the past few years, the trend is for rider 'creature comforts', and the new 'Slamtail' mono shock Softail upgrade is 'right there' with advanced features such as ride height control via key-fob or cylinder head mounted on-board toggle switch.
The standard kit includes the hydraulic power unit, mono shock hydraulic ram, on-board toggle switch, two remote control key-fobs, new polyurethane bump-stop (to replace the OEM bump-stop) and a ‘C’ spanner for manual static coil spring preload adjustment.
A new side stand mounting clevis is also included in the standard 'Slamtail' kit, for use with any aftermarket lowered M-8 Softail (including all air systems). It replaces the OEM side stand clevis, and allows the bike to be safely lowered without falling over.
Optional kit extras include handlebar-mounted key-fob bracket and dummy preload adjuster knob to replace the original preload adjuster knob, filling the hole left in the RHS side cover left by the adjuster knob.
SLAMTAIL SUSPENSION
www.slamtail.com