New spring recommondations for GSXR shock?

[DavieSV]

Hi all,

I've fitted a GSXR 750 k7 front end to my SV650 K5 and an Aprillia RSVR K5 rear Sachs shock.

I'm considering re-springing both ends.
Before I take the plunge, I would like to know if any of you had any thoughts on spring rates to suit.

I have put my details in Racetechs calculator that came up with the following spring rates.

Rider weight 198 lbs.
Bike weight 402 lbs.

Street:
Fork springs 0.918 kg/mm (51.4 il/in)
Shock spring 8.25 kg/mm (462 lb/in)

Racing:
Fork springs 0.968 kg/mm (54.2 il/in)
Shock spring 8.66 kg/mm (485 lb/in)

I sometimes have a quite aggresive street style of riding but I don't do a lot of track days (but want to)

I believe I have 1.0 kg/mm (56 lb/in) springs in the front and maybe 10 kg/mm (570 - 600 lb/in) of spring on the back (not sure about the back though.

So do I just run what I have?
or change the rear to say a 9 kg/mm (500 lb/in) to suit the stiff front end.
or dchange both ends to say 0.95 kg/mm (53 lb/in) fronts & 8.5 kg/mm (475 lb/in) rear?

And another thing, How good is the racetech calculator, is there any other calculators for spring rates?

[yorkie_chris]

Traxxion has a chart of total weight vs spring rate but it is not much different to any best guess. Penske has a good chart of rear spring rates.

Offhand I think chart recommends #525 for rear.

That springing seems a bit firm for you, but pretty balanced front and rear. If it is not giving you particular traction problems or breaking your back then I'd be tempted to play with the valving with springs as they are.

[zadar]

Those gsxr forks do have 1.0 springs.
If I was you I would use .90 or .925 in front and 475 on rear for street bike.
.95/500 for track.

[yorkie_chris]

And I would pay more attention to zadars info than my ramblings :)

[DavieSV]

Why do most people use kg/mm for front springs and lb/in for rear :confused:

so to confuse things more...

9.0 N/mm fronts
85.0 N/mm rear

I think I'm going to get me some of those.

It would be a shame to put the forks & shock on with out getting the springing right.

Then I just have to get me finger out so YC can set my valving up :D

[DavieSV]

Just been down to K-Tech to chat to them.

They recommend:
9.5 N/mm on front
80 N/mm on rear

:confused:

They didn't fill me with confidence though,
They said that the standard fork springs in the GSXR 750 k7's are 0.85 kg/mm, so if they carn't get that right do I trust them to get my spring rates right?

They have a rear spring in (ohlins) but no fronts.
They are due in at the end of this month so I have a little more time to choose the spring rates that are best for me.

And to top it off, my alternator belts on my truck snapped on the way back and I lost all brakes. :(
Very very scary

[DavieSV]

Also for reference..

Aprillia RSVR rear spring rate is 9.26 kg/mm (518 lb/in or 90.8 N/m)

[yorkie_chris]

What is spring ID? You can get any rate you want from faulkner springs, or hypercoils if it is 2 1/4".

[DavieSV]

Yes it is 2 1/4"

57mm ID X 160mm long

[DavieSV]

What is spring ID? You can get any rate you want from faulkner springs, or hypercoils if it is 2 1/4".

Well there's a saving of £50 straight away £30 from them V's £80 from K-Tech :D

Just need cheaper fork springs now :D

[yorkie_chris]

Cheapest fork springs are buying some bent GSXR forks that have right rate in and using them. You will not find cheap fork springs new!