Has anyone tried a 04-05 GSXR750 shock on a 1st gen? Based on the FAQ, the spring is 408lb which is reasonably close to Racetech's recommendation for my GF. But the length is 332.5mm, which is 4.5mm shorter than stock. Is there a solution to this? Slightly different dogbones perhaps?
deckard
You definitely DO NOT want to go shorter on the shock, unless you compensate with the dogbones (go shorter, IIRC, to raise the tail of the bike).
But it can be more complicated than that. What is the stroke length of the Gixxer shock? If it is significantly shorter than the OEM piece you could run into problems with it bottoming out.
I'd also be a tad apprehensive about going softer than stock with the spring. One of the reasons the 1st gens have a reputation for a rough ride is that the stock spring is too soft. Couple this with a rising-rate linkage and the static sag puts the spring into the range where it has way too little leverage- it acts like it's a lot stiffer than it actually is. So you end up with a rear end that's essentially underdamped and oversprung.
This is why all the suspension gurus advocate for a stiffer than stock spring, generally in the 600-650 pounds/inch range, compared to approximately 500 pounds/inch for the stock piece.
Not saying it can't or shouldn't be done, just that it may not be as simple as a parts swap-out.
But it can be more complicated than that. What is the stroke length of the Gixxer shock? If it is significantly shorter than the OEM piece you could run into problems with it bottoming out.
I'd also be a tad apprehensive about going softer than stock with the spring. One of the reasons the 1st gens have a reputation for a rough ride is that the stock spring is too soft. Couple this with a rising-rate linkage and the static sag puts the spring into the range where it has way too little leverage- it acts like it's a lot stiffer than it actually is. So you end up with a rear end that's essentially underdamped and oversprung.
This is why all the suspension gurus advocate for a stiffer than stock spring, generally in the 600-650 pounds/inch range, compared to approximately 500 pounds/inch for the stock piece.
Not saying it can't or shouldn't be done, just that it may not be as simple as a parts swap-out.
I initially did a spring rate calculation through racetech.com, and for a 130lb rider get 6.5kg/mm -> 363lb/in.
After reading your reply I've doublechecked against Penske, and they recommend 625lb/in.
Jesus, that is quite a discrepancy. Thanks for pointing it out, and I will have to sort through this before moving forward. I have an unused 2004 GSXR750 shock, and based on racetech, the spring rate at least would have been close.
After reading your reply I've doublechecked against Penske, and they recommend 625lb/in.
Jesus, that is quite a discrepancy. Thanks for pointing it out, and I will have to sort through this before moving forward. I have an unused 2004 GSXR750 shock, and based on racetech, the spring rate at least would have been close.
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