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[remmie]

This week the rear shock absorber of my Zero SR 2014 failed. First signs were a very pogostick like ride when riding two-up. Later the shock bottomed out at speed bumps at after that the shock bottomed out at just about every bump.
When I got home (riding a bit more cautious) the shock even bottomed when i would sit on the seat and released my weight on the seat by standing up. If i would bounce in the seat the whole bike would jump like a pogo stick. No dampening at all

From different posts on this forum the quality of the rear shock was described "mediocre" at best and now i can only add to that. I've ridden the SR for 3 years now and racked up 24.000 km (15.000 miles) and other than a few tires and a set of front brake pads it hasn't let me down, until this week.

In order not to replace it with the crappy stock shock i decided to replace it with a Wilbers shock (typenr : 640-1143-00)

https://www.wilbers-shop.de/Motorrad/Zero-Motorcycles/Zero-S-Z1-M5/Federbein-Typ-640-Road.html?manufacturer=amu5e4136ae98d5a8327b54d6aadf5d7&year=2014&catname=794e4df955161fa07d826ad45c552708

Delivery is stated on the website to be 14 days so plenty of time to see if the old shock is easy to remove. It turns out it is not too difficult if you have some basic mechanical skills.

* I first put the bike on a stand under the metal pan which protects the onboard charger. If you lift the bike high enough so that the rear tire is just touching the ground (almost all weight of of it) it wil be easier to lift
* next  step is to remove the seat by unbolting the 2 bolts at the rear of the seat and lifting the seat up.
* next step is to remove the tank plastics by removing 3 screws on either sides on the inside of "radiator shroud" side of the tank (font) these are 6 philips screws. Then 2 screws inside the "frunk" after youve taken out the "frunk bag" these 2 screws are near the helmet lock. Finally remove the 2 screws on the rear of the tank plastics (1 on each side). The entire tank plastics then can be lifted upwards and set aside.
* 3rd step is to remove the aluminium Y-bracket to which the rear of the tank plastics is screwed. This is done by removing 2 bolts (4 mm hex) at the end of the 2 "fingers" of the Y-bracket and the 2x 10mm locknuts at the other end of the Y-bracket. (see picture)
* to set the Y-bracket aside you need to unscrew the fuse holder which is bolted to the Y-bracket. (2x 3mm hex bolts) (see picture)
* now you have to remove the plastic shield above the controller. It is only screwed at the rear with a single philips screw.
* the shield can be removed by sliding and rotating the shield around the multi pole connector of the controller (no need to disconnect any connectors!)
* now you can see the top bolt which holds the shock to the frame. It is just a 17mm locknut and there is some room to manoeuvre (see picture). It is somewhat tight so take care you don't knock the bike of the stand
* now remove the rear wheel and belt guard by unbolting 4x 3mm hex bolts (2 on either side)
* also unbolt the locknut at the bottom of the shock. This may also take some force so again be careful not to knock the bike of the stand. (see picture)
* the bolt going through the shock can easily be pulled out if you lower or raise the stand on which the bike is standing so that the weight of the swingarm is exactly supported by the stand (this takes the load of of the shock and the bolts come out very easily) (see picture in second post)
* retrieve the bushings which go into the shock mounting and refit them to the bolt and also the locknut so you know the correct order in which to refit the bushings to the shock later.
* do the same with the top bolt and also retrieve the bushings while manoeuvring the shock away from the bike.
* now you will have the (broken) shock. (see picture)

refitting should be a matter of doing it all in reverse. As I will have to wait 2 whole weeks waiting for the new shock I will report the refitting in a later post.

attached are some pictures of the process.

Also some measurements of the shock

* distance between the mounting points 280 mm
* hole diameter of the mounting point 12 mm
* spring diameter 60 mm
* spring rate 710 lbs/inch

[remmie]

more pictures

[BrianTRice@gmail.com]

This is great! I've been looking for a detailed report on a replacement shock!

Do I have your permission to adapt the text and use the images on zeromanual.com?

[remmie]

Yes, off course 

some steps are already described in your excellent manual so that would only require a reference (seat off, tank plastic off)

One thing I forgot to mention that the shock was out within half an hour, including all steps described above. So it's quite easy if you have some mechanical skills.

[remmie]

And I found the culprit (I think)

In the first picture you can see that the flat seal on the sliding piston is not exactly how it should be 

And also the oil is not really the color that oil normally has. It's a deep grey (anthracite) instead of the light yellow light brown it should be.

Ah well, still only about 10 more days waiting for the new shock, I may try to source a new seal but it's not really rubber, it's sort of plastic like. Some quick searching led nowhere but that could be the search term in Google is the wrong one.
The measurement is 1mm thick, 4.2 mm high and the inside diameter is 25 mm i presume which is the outer diameter of the piston (couldn't measure the iside diameter because the ring is broken)

If anybody has any idea where to get such a rear shock piston seal, please let me know.

I've tried putting in some small o-rings (25x1.5mm), 3 next to each other but that doesn't work. As soon as i push the piston in the housing of the shock, one of the o-rings pops out of the groove.

[remmie]

Here some pictures of the Wilbers rear shock next to the original fast ace shock. and the shock mounted on the bike.

Quite a difference. The spring diameter is much larger but it does fit nicely. also no external reservoir.

Refitting the shock was quite easy. I didn't even had to take the tank plastics of. Just removing the plastic controller shield and pivoting it out of the way was sufficient to reach the top bolt holding the shock to the frame. So that reduces the amount of work to change the shock considerably.

I did a short ride yesterday and the ride is buttersmooth. much less bouncy than the fastace shock was just before it failed. but that makes sense. The fastace probably degraded slowly to the point of failure.

anyway, enjoy the pictures

[NEW2elec]

Great job and write up!  Aftermarket brake and spring upgrades plus the low(er) cost of 13,14 Zeros make them a great option for those looking to get into electric without the big hit of a new bike.