setup Penske shock for a different bike

[02redhawk]

Hoping for a bit of information on a shock upgrade for my track bike.

I have a Penske 8987 triple that I'd like to use on my Gen2 SV650. It was originally set for a GSXR 600 with a 6” long Hyperco spring. The spring was marked 650 – 648. As I'm 175 lbs w/o gear it looks like I need to do a spring swap and change the valving. The length looks OK for an SV as it's eye to eye length is set to about 335mm (adjustable).

For spring it looks like I need a 500 lbs spring. I'm assuming all I have to do is move the upper spring collar from 6” to 7” from the lower collar, get a 7” Hyperco 500 lb spring and have the shock valve shimmed for my weight. Am I correct?

Thanks for your help.

[TheIglu]

Is the geometry/linkage the same on the GSXR as the SV?

[02redhawk]

I don't know about the GSXR geometry.

I thought the point when replacing a shock to keep the geometry of the bike as close to original as practical. I haven't changed the linkage of the SV. The new shock length is essentially the same as the original shock. Why do you ask?

[-Dutch-]

That sounds like an awful lot of work. Send it to me and forget about the headache.

[Rada]

Call PK at GMD...

[02redhawk]

Call PK at GMD...

I did today but got voicemail. I suspect they're pretty busy getting customer stuff ready for the season. I'll be trying again tomorrow. In the mean time I figured I'd ask for some that have gone this path before.

[marshdrummer]

You can call Penske also. they can tell you the original differences. I say original since the LRRS guys like there rear ends jacked up...(insert awesome comment here)

[Rada]

Stiff too

[TheIglu]

I don't know about the GSXR geometry.

I thought the point when replacing a shock to keep the geometry of the bike as close to original as practical. I haven't changed the linkage of the SV. The new shock length is essentially the same as the original shock. Why do you ask?

Because if the geometry is different in how it exerts force on the shock, then you may be in for a really bad time trying to get it to work. Things like progressive linkage vs non-progressive, length of lever for swingarm, etc. Any of those differences would make quite a difference in an SV shock to a GSXR shock.

So, while you wait for a call back from GMD, read what GMD wrote here:

http://www.nestreetriders.com/forum/...hock-Swap-Myth

[Tunertype]

Because if the geometry is different in how it exerts force on the shock, then you may be in for a really bad time trying to get it to work. Things like progressive linkage vs non-progressive, length of lever for swingarm, etc. Any of those differences would make quite a difference in an SV shock to a GSXR shock.

So, while you wait for a call back from GMD, read what GMD wrote here:

http://www.nestreetriders.com/forum/...hock-Swap-Myth

A shock is a very simple spring and damper. As long as the spring rate, length, and damping characteristics are good for the SV it will work. He said he was getting it resprung, revalved, and it is set to the right length. The linkage will affect the force the shock sees so a 500lb spring on one bike may be too stiff and on another it would be too weak based on the force curve, but a 500lb spring on an SV is a 500lb spring no matter what brand/model shock you have.

The post does bring up a good point though. If you pay $400 for a used aftermarket shock that needs to be resprung and revalved to match you, why not simply buy a brand new shock that is already in the right specs? it will end up costing the same. Also goes to the value of a used bike with an aftermarket shock. If it's not set for your weight(or close enough that it can be adjusted to work), it doesn't really add much value to the bike because of the expense of having to set it up.

[02redhawk]

Thanks for all your responses. I met with pk this afternoon and left the shock for a new spring and revalve. As for the going the reconfig route, I figured the shock body can be setup for many different bikes. Different springs and valving for sure but as long as I was looking at a config that had a similar length and stroke I should be fine. A good point was made about geometry but again I wasnt changing linkage, length or stroke so it seemed worth a shot.

Finally, I kept missing deals on the used Penske doubles and new ones were above $800. A new Jri was a bit more. I'll be into the triple including having it setup for me around $750 before I sell the other spring. Seems llike it should work out ok.

[stanga5o]

I'm a little late in replying but here goes. I got a 8983 (double) last year, which is pretty much the same shock as the 8987, but without the high speed compression circuit. I have an '06 SV and I weigh about 165-170. My shock was set up with 335mm length and 500# spring. I'm not sure what valving was used, but it was set up for an SV. The 335mm length raised the rear end, which improves the geometry over stock (330mm, I think). For racing, 340mm is common. If you're coming from a stock shock you are going to love the Penske!

[02redhawk]

Thanks for the replys. I'm looking forward to the improvement.