virago xv535 replace rear shocks? Advice needed - Page 3

 seabreeze wrote:

 I am tempted towards changing the length and stiffness a little

Go for it. You will learn something.

 and of course on the other hand there is the issue is that the

Well, the engineers who designed the motorcycle and the engineers who
designed the shocks are two different groups of people who never met each
other.

Yamaha is famous for using commitees who aren't on speaking terms with each
other designing whole motorcycles.

And the final decision goes to the marketers and the bean counters.

If they can save $1.00 per shock absorber, that's heaven to them, they will
fit the cheaper shock regardless of performance, especially on commuter and
cruiser models where the customer is unlikely to know the difference.

Japanese motorcycles were once famous for their load carrying capacity. The
Japanese rider would try to take three or more people for a ride on his
motorcycle at the same time in the 1970's.

American magazine writers complained about the incredible rigidity of the
springs and, about 1982, the Japanese surprised us by building motorcycles
with softer springs!

The whole suspension picture was turned on its head. Suddenly, we had the
softer springs that most solo riders really needed, and the racers needed
*stiffer* springs!

Gawd only knows what is on your XV535, but Koni, who has been building the
same 7610-series shock for 40 years, appears to think you need two incredible
235 pound per inch springs!

http://www.ikonsuspension.com/content/shock_absorber_details.shtml

Let's see 235 X 2 springs X 3.5 inches of travel = 1645 pounds!

My gawd, what do they think Americans are going to carry on a motorcycle if
it takes 1645 pounds to bottom out the rear shocks?

If the rider is carrying a passenger and the static load on the rear wheel is
400 pounds, it will take 4.11 g's force to bottom the springs. Discounting
the mechanical advantage of the swingarm and the slight angle that the shock
is at, from the vertical, of course.

In my mind, a rear suspension that bottomed out (hit the rubber snubbers,
that is) after a load of 2.5 g's is applied would be just fine.

Looks to me like 142 pound/inch springs would be more like it.

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