Bucket Racer/Crasher
These arrived which has prompted the fascination with spring rates and stuff. R6 shocks with damping adjustments that actually work. They are just slightly shorter than the stock shock. Compared to the similar vintage GSXR shock they are in another league. The shock with seperate compression adjusters is an '06-'07 model and the other is a 2012 model.
After placing the order in the USA I had 2 replies to an enquiry here in NZ. One shock was $100 plus freight which I think is a bargain.
No8 Wire Extraordinaire
If you are lucky there will be enough thread on that clevis for a spacer to make up the difference. Then a bit more to race it up a bit from conservative Road setting. My YZF750SP got +5mm as per YEC handbook.
Don't you look at my accountant.
He's the only one I've got.
Bucket Racer/Crasher
I've been working away on fitting new springs to the R6 shocks. The first bit was checking the rate of standard shock compression versus wheel travel. I've measured a few springs. I also dragged a couple of springs out of a bin and have been cutting bits off and shortening them using heat and compression. I think I have figured a way to shorten springs in a controlled manner and will test the method next time at my mate Kev's place. If it works I'm going to cut down one of the Blitz 220mm long 7kg/mm springs to fit the R6 shock. Over the last couple of days I've made an adaptor for the top of the shock for the Blitz springs and a whole new piece for the bottom.
All this work and measuring has led me to believe that if nothing else I need to reduce the preload on the stock shocks. Currently the shocks can be compressed initially but as soon as the rate gets to the working range of the linkage it hardens up excessively. A lower preload will let it move into the working range before the spring compression gets too much. The standard shocks have about 10mm preload and being 8kg/mm springs the shocks have 80kg preload. This would require 30kg on the rear of the bike just to overcome the preload. The bike alone only has 40kg on the rear and with Cricket it's a total of 80kg. Minus the 30kg need to just overcome preload we have 50kg to compress the shock. This equates to 130kg on the shock which should compress it about 16mm. It'll be less as the spring rate will be increasing. I really need to measure the spring rate through the full stroke but the rear should sag about 40mm. It actually moves less than that so the math is wrong or the spring rate increases more.
Low personal B.M.E.P.
The team of production car racers from Timaru who were very successful over many years used to lower a car by leaving it full of sandbags while the engine was blueprinted. As much as 1 1/2 in lower with no marks or cuts on the springs.
Sit a concrete block on a spring for a week and see how much it shortens it.
Bucket Racer/Crasher
I'll try that, but probably with end caps and a threaded rod through the middle to clamp it up.
Low personal B.M.E.P.
It's got to be loaded past it's yield point. IE collapsed with a weight on it.Originally Posted by speedpro
Bucket Racer/Crasher
New spring on shock, shock in bike, new short dog ones fitted. It feels ok just bouncing on it. Still need to map progression and if there’s nothing too horrible happening I’ll finish the dog bones
No8 Wire Extraordinaire
Needs slotting and GreenLinKTM on the side
Don't you look at my accountant.
He's the only one I've got.
Bucket Racer/Crasher
Both excellent suggestions. I'm going to rough out another pair of links to use with the other R6 shock and then finish all 4 at the same time.
Bucket Racer/Crasher
Not too bad a difference. Good enough to give it a go.
Bucket Racer/Crasher
I have 2 pairs of dogbones and have made a start on taking off a bit of weight. No science involved, just cutting a bit off using the mill. I made a jig to allow each dogbone to be bolted down in exactly the same position each time. If, once I've finished, I decide I could take a bit more off it'll be a simple matter of bolting each one back on the jig and mowing a bit more off.
Bucket Racer/Crasher
The 8mm cutter I'm using is supposedly 70HRC. It mows through mild steel of course and when I milled a flat in a piece of round tool steel it just made nice chips and didn't seem to notice.
Bucket Racer/Crasher
One R6 shock fitted to the FZR/MB bike and this kit ready for my turbo twin bike.
The dogbones are slightly thinner than standard dogbones so 1.4mm washers are needed on each bolt to make sure that the dogbones are clamped tight to the bearing bushes. The top shock mount is only 30mm wide versus the original FZR shock being 40mm wide, so I made 5mm tapered washers to fit against the shock top mount(16mm OD) out to 25mm OD to spread the load on the inside of the chassis mount.
I'm going to try the stock R6 spring but I'll make an effort to reduce the preload by hopefully compressing the spring a bit. Using the spring compressors wasn't giving me any confidence so I'm going to have to come up with something really solid to do it.
Forum whore
What spring compressor are you using? I got a set of DRC compressors from bits4bikes. $36. While made for twin shocks, the springs I was compressing are off a GS1100G (ie heavy) and they handled that with no problems
it's not a bad thing till you throw a KLR into the mix.
those cheap ass bitches can do anything with ductape.
(PostalDave on ADVrider)
Bucket Racer/Crasher
The spring compressor is a cheap one from TM. I had to modify it a bit to fit the R6 shock. I can compress the spring more than enough to fit & remove it but compressing it to the yield point is another matter. I compressed the spring about 30mm. Being a 9kg/mm spring that's at least 270kg. I've discussed it with mate Kevin. We agree that the spring needs to be captive when compressing this much. It can be done by fitting the spring inside a tube and then compressing the spring with a piston in the tube, pushed by a hydraulic press. All very time consuming for doubtful results. Not wanting to spend the time fabricating all the bits I've decided to simply heat one end coil and compress it a bit using the same process I used when I shortened the 7kg/mm spring after I cut it. I only want to shorten the spring about 8mm so it's only a slight adjustment.
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