SOTP Vintage Series
Main Motorcycle: 99 Legend Sprint GT
Join Date: Jan 2008
Location: Cork Ireland
Have you checked the spring rate for the ZX10R shocks at Racetech's site? IIRC the ZX10 springs can be a bit light.
My 08 ZX6R shock is very good, officially a 9.7kg spring, but feels like it might just be ok for your rider & pillion weights. Tho' not with much luggage as well.
At a rough estimate, you probably want a rear spring in the range 11kg to 12kg - a little lower than RT's calculator will suggest, but adequate for our bikes & typical use imo.
So long as the shock is adjustable for rebound & compression you could fit a ZX shock with higher rate spring from Racetech (or others?) & if you don't go up more than about 1kg in rate the shock will likely have enough damping adjustment to get away without a revalve.
One thing I've now realised buying older shocks is that the springs can be significantly weakened by age/mileage. My older 01 ZX6R unit should have had a slightly stiffer spring than the 08, but the reality was opposite. I'm assuming the 01 must have weakened & likewise the 94 ZX9R unit before it.
For info, the 08 ZX6R shock is about the same length as stock, tho' top & bottom mount holes are M8 not M10, so need sorting.
If it's brake dive that's the issue with the front, Ricor Intiminators would be much better than a spring change imo. The difference is huge but they are still very compliant over bad bumps.
+1 on Tmod, he's excellent, but the old style basic damper rod forks (not cartridge, except on TBS) don't give him much to work with on our bikes.
98 Tbird tank/seat, Sprint fairing, ZX7R forks+Racetech Gold Valves, 08 ZX6R shock, short sw/arm, Alcon 6-pots, Ignitech+TPS, T'bike 3-1+Beowulf can, airbox/jet mods, tubeless wheel mod, lots :) per mile, 55mpg ave(imp)