Racetech rear spring swap - questions

[zixaq]

So I stupidly thought this would be a straightforward swap. Silly me.

I just discovered that the recommended springs from RT are 0.25" shorter than the OEM spring, so I need some kind of collar/bushing/spacer/whatever to make up a half inch of space. Has anyone done this recently that has a source for something appropriate to use for that spacer? I'm nervous cobbling something together given the forces from that spring.

FYI:
SK SPRING 7.0 x 2.25" 16.1kg SESP 702250900

Stock spring is 7.25" according to an old thread on this forum.

 

[FinalImpact]

Did you call RT and ask if they have something?

Some old notes from R1 shock install... Not that it helps you but ya, you need filler or you'll never get the proper preload. Edit; lets not say never. Did you try it? You might just install it and check the bike and bike + rider sag with your gear on. You'll need a helper to run the tape measure but it can be done alone...

2008 FZ6 Rear Shock:
Eye to eye: 300 mm (11.82")
Travel: 50mm (1.97")
Setting #1 light: 175.2mm (6.90")
Setting #7 firm: 165.8mm (6.53")
Installed length MANUAL SAYS: 172.0 mm (6.77 in), doesn't say what setting tho, suspect #3.

Range of preload: 9.4mm (0.37")
Coil OD: 77.6mm (3.055")
Coil Dia: 11.76mm (0.463")
Spring free length 185.0 mm (7.28")
Spring rate K1: 12.99 kgf/mm (727.45 lb/in), 127.40 N/mm


Perhaps go to McMastercarr.com and look for washer or make one from SS or Aluminum sheet?

 

[zixaq]

Haven't been able to get ahold of RT yet, will update when I find a solution. I'm going to have to put this off until at least Friday. No time to get to the garage until then.

The spring came with a slip of paper with a web address for instructions, but of course it's to a page that doesn't exist.

 

[FinalImpact]

Hindsite says it may be ok as it may have the same installed height force. Im just saying even tho they are different free lengths, that may not be a show stopper.

However, had your spring rate Gone UP vs down, I'd guess odds would be more in your favor. Id install and see. You might be fine...

One last thing; something I learned while playing is that shocks have top out springs and internal elastimer (spelling) bumpers. Meaning if you measure the installed height (spring end to spring end) while on the shock, the shock will be longer as the external spring is compressing internal springs/bumpers. So, if you measure the spring perches of the shock with spring off, without a load, the perch to perch distance will be shorter... Ask how I know!

Just be careful if you're swapping the spring yourself. They can unleash some serious Whoop @ss and be leathal. Be safe...

 

[zixaq]

I just got off the phone with Mike at RaceTech. According to him, the stock FZ6 spring comes with some excessive preload built in, and a straight swap with no spacer, even dropping .25", should give between 2mm-10mm preload adjustment.

I guess I'll try it this weekend and see how it works. 6 hours of garage time, gotta make sure I get everything right.

[I forgot to ask Mike (calling back shortly), but is there any chance going from 12 kg/mm to 16 kg/mm on the spring is going to damage my shock?
update: RT Mike says I should really revalve the shock, but is of the opinion that the spring swap will still be an improvement without. I'll give it a go.

 

[zixaq]

Finally got ahold of a spring compressor and got the thing swapped out yesterday. Wasn't paying enough attention during reassembly and the preload adjuster landed on "3" instead of "1". When I got the shock back on the bike sag was right around 30 mm, so it's within reason without mucking with a spacer.

Can't wait to get it on the road and try it out, but the sky is raining buckets and I figured a rain ride with a brand new rear tire was probably asking for trouble. Suspension definitely felt better on the way home from the garage, although rain + new tire meant I couldn't get too aggressive.