Wednesday, October 19, 2016

Junkyard shock swap

October 2015 - I remember when I first saw the Hornet's shock the only thing I could think of was to find a way to source another one, because of how much rusty and knackered it looked. With these bikes now more than 10 years old (last incarnation of the carbed version being the 05-06 model), there was very little chance I could find a descent shock second hand. 

So err ... well I don't' recall exactly how it started but I had a spare BMW R1100S shock hanging around (since I swapped it for a great Nitron), and when laid side by side the Hornet's and the BMW's looked suddenly rather similar. So I started playing with idea I could certainly attempt a shock swap.

I had read on several forums that no other shock could really go between the Hornet's frame and swingarm. And this is something I was ready to believe. Because, not only is the space rather tight on the frame side for a shock to slide in, but the rear suspension is a basic direct frame-to-swingarm system. No fancy Pro-Link linkage, no dog bone, just a bare shock between these two. And this has an impact on the shock type to use.

But then if you take a look at BMW's paralever suspension, you will be faced with the same kind of system. It's "just" a single sided swingarm mated to the back of the frame with a shock in-between. So if the sizes look the same and the mounts look the same too, then there's no reason not to try the swap.

The first thing I did was to present the shock to the bike. One thing to notice immediately is that the lower mount is actually larger and would require some custom spacers.

On the top side, the BMW's shock requires more room to fit in. It touches the expansion bottle, but nothing to really worry about. More concerning was the shock's body touching the frame at the swingarm's lowest position. A bit of metal (but really not much) had to be ground here and there to give the shock a little more room at the top.

One of the key issues was that the BMW's shock comes with a preload adjuster and its protruding knob. There was no way the right side panel would fit again, so the knob, complete with the stem, had to go.

One other issue was that the remaining of the preload adjuster, the parts that could not be removed form the shock, was in the way of the main starter relay. The latter had to be relocated.

50 spacers later (I had to order 50 at once ...), we have the shock properly attached to the swingarm by reusing the shock's internal spacers and needle bearings.

So now, there's actually an alternative to the Hornet's shock.

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