Installing a not-exactly-stock shock

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  • See here for notes on installing a GSXR shock.

Disclaimer: For anyone debating about doing the GSXR or similar piggyback shock mod - Don't do it, unless you have a LOT of time or free access to a machine shop to do the requisite grinding and cutting to make it fit. You're much better off using the time to find a shock with a remote reservoir.

This article will demonstrate some of the modifications necessary to install a Fox shock with a piggyback reservoir design (the oil reservoir is attached to the top of the shock). Fewer mods will likely be necessary if you can get a Fox with a remote reservoir like this one, which was used on a race EX250 from the early 90's. It was built for either the 250 or the EX500.

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This piggyback shock is a Fox TC-R from a '99 GSXR750. Right picture shows both shocks. OEM is the wimpy-looking one.

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The owner sent it to Aftershocks for an oil change, a spring that fit his weight, a nitrogen recharge, and to have the seals checked. Then it was time to make it fit. The following modifications were made before the Dremel came out:

  • The upper mounting bolt from the Ninja did not fit through the new upper mounting hole of the Fox shock. Both upper mounting holes were measured at 1" with the sleeves out, so the upper mounting sleeve from the 250 shock was moved into the Fox shock upper mounting hole.
  • The lower mount bolt hole on the Fox Shock was too small in diameter, but was easily drilled out to fit the 250 lower mount bolt.
  • The lower mount of the Fox Shock (U shaped part, aka the clevis, not the bolt hole) was 1/16" narrower than the 250 lower mount U piece. A little grinding took care of the problem. For such mounting issues, grind before bending. You can take some off the shock linkage, the clevis, or both. 1/16th of an inch isn't much when you consider being able to take from 4 surfaces.

Now comes the actual fitment. Because this shock has a mounted reservoir, the extra bracket that mounts from the upper shock mount to the battery box had to be removed. Before photos:

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And after:

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The fuse box bracket on the right side also had to be cut away a little for the right side of the reservoir to clear. Other normal things to do for this type of shock to work are pod filters and cutting away part of the battery box. With a little creativity and elbow grease you should be able to make your bike handle much better.

Unfortunately, after the shock was installed a small crack was found that allowed oil to leak out and wouldn't hold the proper pressure.

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The only thing to do was to send it back to Aftershocks to have a line added and make the reservoir remote, since Fox no longer makes shocks for street bikes.

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The reservoir creates another small installation problem. You have to find a decent place to put it, which isn't too hard, as there are several good candidates. This one ended up under the tank, above the air filter pods.

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For this install, another owner put the reservoir where the tool kit used to go and put the tool kit back by the brake lights. You'll have to take pretty much everything off the right side (rear brake reservoir and fuse box) in order to get it routed correctly, but it should fit well. Put a piece of clear plastic tubing around the SS line to prevent it from abrading anything.

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Sometimes a little extra fabrication is called for. This Fox twin clicker was supposedly from a '95 GSXR 750. The owner found that it had some clearance problems. The upper shoulder of the shock was too wide and hit the Ninja's shock mount, preventing the upper mounting holes from lining up. It was determined that too much metal would have to be removed from the frame mount area, so some of the top of the shock had to be ground away.

You may have to remove a lot of material. The key is to remove a little bit and then check the fit. You don't want to remove any more than necessary, and leave plenty of meat around the remote reservoir fitting. Taking bits out of the frame may work for some shocks.

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