Well I'm thinking of just giving up on stock rear shock. Is there any compatible shocks i.e. R6? I know someone racing has changed it out, also springs for front?
Very informative. Thanks for the info! This makes me wanna just not bother with cheaping out on suspensions and I'll probably just get the Ohlins shock made for this bike. A little pricier option but still way less than a TTX shock for a 600 or 1000.I wish I would have seen this post awhile ago, I can offer some input here. There is only 1 OEM shock on the market (that I've found) that comes close to working with the R3, and here's the reason why...
Most bikes use a progressive link type rear suspension (there are dog bone links under the shock), and therefor, use a similarly soft shock spring (the OEM spring on an R6 shock is about 600 lb/in and works well for a racer around 225lbs or a street guy around 260 lbs, I ran a 550 lb spring on my R6 and I weigh 160). The progressive link allows the suspension to feel softer at the beginning of the stroke, but it gets stiffer and stiffer the more you compress it, so it can be soft at the start, and still support the rider at higher speeds, while cornering, and while braking by changing the leverage through the stroke. The R3 is one of only a few bikes that doesn't have a progressive link type rear suspension (the Ninja 650R is another one). This means the rear suspension is linear. A soft shock spring will feel plush and lower speeds, but as you go faster and compress the shock more, smaller bumps and throttle changes cause a large change in the rear and you blow through the stroke. A stiffer spring will feel rock hard when riding slow and hitting bumps, but when under heavier load while cornering, will sink into the middle of the stroke and work properly. But, the linear, linkless suspension has a much different mechanical advantage. The "super soft" stock spring on the R3 is around 700 lb, which would be rock hard on a lot of other bikes. I run a 1200 lb spring on my Penske shock. It feels very hard when sitting still, but works amazing when going fast, and the valving in the Penske must be very stiff to match the different mechanical advantage and the heavier spring.
This difference is why you can take a shock from a GSXR (about 317mm eye to eye length and I think the spring is around 500lb) and put it on a Ninja 250 (OEM length about 315mm) and have it work great, as they both use similar mechanical link systems and the small length change benefits the Ninja, but if you try to put a 317mm GSXR shock on an R3 you run into tons of problems. The R3's OEM shock is 275mm eye to eye, so it's very short, and the R3's stock spring is (estimate) 700 lb, so the GSXR's 500 lb spring is going to be even softer. The R6 is another one to consider, as the length is shorter, 291mm, but it has a stock spring of about 600lb, so again, it will be even softer than the stock R3 spring.
For those of you not as familiar with suspension valving, the valving inside the shock must be closely matched to the load on the shock (the rider weight pushing against the spring (at least within the adjustment range). This means you can't just take an R6 shock and change the spring out for a way stiffer one, or the valving will be too soft and be ineffective at damping the higher forces generated by the rider and the spring with the mechanical advantage of the R3s suspension setup.
By now, it's pretty common knowledge amongst racers that the R3 benefits from raising the rear by lengthening the shock, which increases the angle from the chain to the swingarm, and increases ground clearance. So a longer shock is a good thing, but there's a limit. For example, I run my shock at 287mm, 12mm longer than the stock shock.
So, what is the OEM shock that works for the R3? Well, looking back at that other bike with a linkless suspension, the Ninja 650. The 650 OEM shock is also very short, at 290mm, which is a good length to raise the R3 slightly. And the Ninja 650 is a heavier bike with a more powerful motor than the R3, so it would make sense that it may have a stiffer spring and valving. The Ninja 650's oem shock has a 970 lb spring, and valving to match, which again, is decent, especially for an upgrade for street riders. The downside to the 650 shock, is that it only has basic preload adjustment, like the R3, so it may be an upgrade, but it's a pretty limited upgrade, and it will only work well for 1 particular weight, since even though it has preload adjustment, ideally, the preload must be matched to the rebound damping. Still, it's a cheap upgrade. I have a 650 shock showing up in a day or 2 so I can put together a cheap mounting kit to use it with the R3. I think it might be a nice little budget street upgrade.
But, the bigger news, is that I still have wanted to find a budget racer solution, that's fully adjustable. So watch for a full post on this in my forum, but I finally finished and installed the first R6 shock conversion in a local rider's bike this past weekend. I took an OEM R6 shock, machined the mount to shorten the length from 291 to 287, to match what I use on my bike. Then machined some spacers and put together a mounting kit to mount it on the R3. I then shipped the shock off to Traxxion Dynamics to tear it down and rebuild it with new valving to match a stiffer spring (in this case, the rider weighs 160, like me, so it's built with a 1200 lb spring). The valving is also centered in the adjustment range, so it has plenty of adjustment for different rider weights and even a few different spring rates.
To mount the shock on the R3 requires a small modification to the bike. I will do a complete How to guide very soon, but basically, a small bracket in the subframe and part of the front of the battery box must be trimmed out to make room for the piggyback canister on the R6 shock.
The install was actually quite painless, and the results so far are excellent. The bike will be on track testing it out and working with my local suspension guy this coming weekend, so I'll have more results then, and will be offering this for sale in the next week or 2. A few extra machined parts were needed, so the cost is a little higher than the $360+ OEM R6 shock core that I initially was hoping for, but not by much.
Could you elaborate a little bit more on this? I'm interested.I am using a rear shock from a 03-05 r6 yamaha... had to modifiy the lower mounting point on the swingarm and notch out the airbox a little..The stock r6 spring is a little weak for my old fat and slow 195lbs but works much better the the stock shock and set me back less then 50 bucks for an almost new shock on Ebay..