Rear Shock

From Unofficial Zero Manual
Revision as of 21:39, 31 March 2020 by BrianTRice (talk | contribs) (extract from manual)

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Zero motorcycle models use a single shock absorber rear suspension, joining the Swingarm to the Frame.


Rear Shock Mounting

On Gen2 models, the rear shock fastens to the Swingarm by an M10 bolt.

On SDS Platform models, the upper mount reaches the frame centertube ahead of the controller heatsink area so is difficult to access.

Rear Shock Specifications

Rear Shock Specifications
Years Brand Model Description Media Specs Models Travel Length
2013-2014 FastAce BDA58RC Piggy-back reservoir shock with adjustable spring preload, compression and rebound damping
2013 S Rear Shock FastAce BDA58RC
Spring Rate
550 ~ 805 lbs/in
Spring
Length 142mm, Diameter 57mm
Bottom bushing width
11/16"
Top bushing width
~1.25"
S/SR 6.35 in (161 mm) 10.25-10.5 in (260mm)
DS 7.03 in (179 mm)
BFA57RC
Part 22-06105-03
  • 319mm / 12.56" eye-eye
  • 17.9mm / .705" eye width (top & bottom)
  • 31.95mm / 1.258" bushing width (top & bottom)
Resevoir
offset angle ('clocking angle'): 242° CW / 118° CCW from 12 o'clock
offset width (shock centerline to far LH side of reservoir): @ 90mm / 3.60"
Spring Rate
475-585 lbs/in.
Spring
181mm / 7.125" length (on shock, no load, min. preload)
FX
2015-2020 Showa 40 mm piston, piggy-back reservoir shock with adjustable spring preload, compression and rebound damping S/SR 6.35 in (161 mm)
DS/DSR 7.03 in (179 mm)


Rear Shock Substitions

Substitutions
Years Models Worked? Description
2013-2014 S/SR Yes JRI Double-Adjustable Shocks per 2014 SR shock absorber replacement by Doug S with Harlan's help.
Yes (with machining) Wotefusi [1] 260mm Central Air Shock Absorber Universal Fit - fits when mounted upside down. Need to cut/grind down the bushing.
Yes (with machining) TDPRO 260mm 10.2 [2] Almost fits; the area on top of the spring is just slightly too large. You can take a grinder and shave away some of the top to make it fit. [3]
NO The Yamaha R3 has the same length rear shock, but the spring is too wide.
NO Fastace Rear Shock BDA-51AR/58-AR has a weaker spring, and is rotated 90 degrees. [4]
Mixed results - new orders may have all the kinks worked out. IKON 3610-ZERO-S Shock Absorber [5] - The spring is too wide at the top, and to be installed, the sping must be compressed. When Installation is complete, the spring is always compressed by at least a couple centimeters.
Mixed results - Get dimensions from Wilber's dealer before ordering - theirs is ~279mm Wilbers Shock absorber Type 640 Road Part. No.: 640-1143-00 [6] Wilbers claims the shock fits "2011-2013 S M5" (which does not exist). The M5 designation is buried in the VIN of the 2014 S; and may or may not be relevant. This shock could be mislabeled for the DS. Make sure to get full dimensions before ordering.
Yes - DO NOT BUY ZXTDR Rear Shock Absorber Suspension Sensa-Trac Load Adjusting for Dirt Pit Bike Motorcycle 1200LBS. [7] This shock phyisically fits, but underperforms. It feels like you're riding on a trampoline. You get what you pay for.


Rear Shock Adjustment

Notes
The Official Manual section on Rear Shock Adjustment illustrates how to measure preload and check sag.
Compression
The official manual's description here is adequate and this can be done readily by hand on the right side of the bike at the top of the shock.
Rebound
The adjustment knob is at the bottom of the shock facing rear, as described in the manual, and can be worked by hand or with a wrench with a careful reach into that area.
Spring Preload
The official manual illustrates the collar and procedure for spring preload adjustment, but does not recommend a specific tool, and there are clearance issues in that area for tools.
The adjuster sleeve diameter is 58mm (2.3").
A Stockton spanner wrench was found to be suitable for the job if modified as follows (per 2017 DSR Showa rear shock spanner wrench):
  • Grind the nose of the wrench to fit the notches.
  • Bend the wrench a couple of degrees to clear the Sevcon motor controller fins.
Obviously, a better solution is still worth seeking.
A small suspension wrench / ER collet spanner size 30/32 can be use even with the lack of clearance
Suspension wrench around the collar