SV and Pirelli help

[Robert Taylor]

Okay I was thinking that just the second yo wrote that last piece...hmmm...what about running a higher spring rate with shortening the lenght [eye to eye] of the shock..and running slightly less sag? or would that still be in the sense of 'FUDGING IT' ???

No that wouldnt neccessarily work so well as youd be compromising the geometry setup, the SV genearlly likes to run tall when raced.

[JJ58]

Robert, I think you've hit the nail on the head!! I thought they were two seperate issues, but maybe they're one...that is the issue in changing tires and the rear issue that I'm having with the SV under hard acceleration.

....I've worked out that the progression isn't great in the rear.... Putting two and two together I think that the Pirelli's causing the rear to use a different part of the progressional stroke in the turn to the Dunlop....

...It was going to be my project to play with the rear ride hieght over the next two races to try and combat this issue, and also to try a get the best anti-aquat angle for the SV..... I've had the rear shock internally revalved numerously and have tried different spring rates front and rear to combat this issue......So you've saved me plenty of time telling me about the chances of getting into the dead progression area.......

I'll be looking forward to what you hear from Ohlins on this matter.

Just out of curiousity, would changing the "dog bones" in the rear linkage alter the progression? I think we may be able to do that under our rules.

[DEATH_INC.]

Yes, in theory if ya lower the shock back to the original height, then alter the ride height with the dogbones it'll keep the link in the same position and part of the progressive curve as stock...BUT the shorter dogbones will normally make the progressive curve a little more aggressive than stock....prolly worth a try though if ya can do it...and of course then you can bugger around with various combos of dogbone and shock length

[FROSTY:Me]

Over the last year its occurred to me that with our current F3 rules why arent we going back to a clean slate with our SV setups?
Im well aware I'm oversimplifying but why not simply measure up all the numbers from a (for example) K3 gsxr600 and build a front and rear suspension setup the same?

[Robert Taylor]

Robert, I think you've hit the nail on the head!! I thought they were two seperate issues, but maybe they're one...that is the issue in changing tires and the rear issue that I'm having with the SV under hard acceleration.

....I've worked out that the progression isn't great in the rear.... Putting two and two together I think that the Pirelli's causing the rear to use a different part of the progressional stroke in the turn to the Dunlop....

...It was going to be my project to play with the rear ride hieght over the next two races to try and combat this issue, and also to try a get the best anti-aquat angle for the SV..... I've had the rear shock internally revalved numerously and have tried different spring rates front and rear to combat this issue......So you've saved me plenty of time telling me about the chances of getting into the dead progression area.......

I'll be looking forward to what you hear from Ohlins on this matter.

Just out of curiousity, would changing the "dog bones" in the rear linkage alter the progression? I think we may be able to do that under our rules.

Yes, Death and Frosty also make some sense re this. I will make it my mission to speak to Ohlins this week re SV650 and GSXR600 linkage curves. If I can access a couple of bikes I may also do this myself, but that will take rather longer.

[JJ58]

Yeah, interesting...
....I'm keen on trying it out and giving some feedback. I'm pretty sensitive to changes on the bike so I'm sure we'll be able to get some good set up notes.

Yeah, Robert it'll be great if you could get some data on this from Ohlins and instruct on possible changes and I'll hunt out where I can get some shorter dogbones from..... I'll be away racing from Thursday and won't be back until 2nd week in July. I then have a race a week later that I get three free practice days for. This would be the perfect opportunity for testing this..... I know where there's an old k3 sitting so I might try and take some measurements too.

Cheers

[Robert Taylor]

Yeah, interesting...
....I'm keen on trying it out and giving some feedback. I'm pretty sensitive to changes on the bike so I'm sure we'll be able to get some good set up notes.

Yeah, Robert it'll be great if you could get some data on this from Ohlins and instruct on possible changes and I'll hunt out where I can get some shorter dogbones from..... I'll be away racing from Thursday and won't be back until 2nd week in July. I then have a race a week later that I get three free practice days for. This would be the perfect opportunity for testing this..... I know where there's an old k3 sitting so I might try and take some measurements too.

Cheers

I have requested this info so we have to await a reply, it seems that half of Scandinavia is on holiday at present enjoying the one week of summer that they get. Thinking about it there are 2 or 3 likely scenarios;

1) The ''start ratio'' of the link is weak and it blows through its stroke too readily and arrives at the progressive part of the link which may be aggressive. The shock shaft speed accelerates dramatically and so does the damping, this screws tyres.
2) The start ratio is weak and there is little progression in the link also. So it continues to blow through it stroke compressing the spring more and more and accumulating spring force. This scenario would cause understeer off the turns.
3) ( least likely ) The start ratio is strong and the progression is weak.

It will be interesting to know what type of piston design is in that Penske shock? Some of their tuners favour a very agressive low speed damping build up followed by a flat slope. The problem is when you get a damp race with poor grip there is rather less grip with this mentality, and you cannot successfully tune it out externally with clickers. With our own favoured Viking shocks we are having good success with a moderate/ sensible amount of low speed damping followed by a steeper slope to ''catch'' sudden movements. This approach can very often be your friend on bumpy tracks.

As far as different length dogbones are concerned the jury is out on that one, they worked okay for us on earlier model R1s but bear in mind that there are plenty of companies making them as its something to sell and make money out of rather than if it neccessarily works. With all respect to the protectors of the ''free'' world they can get rather economical with the truth when it comes to the hype of marketing products. Having said all that if anyone has had conclusive / very accurately assessed success with varied dogbone lengths on fuel injected SV650s Id love to hear.

Anyway, we shall see what bounces back in due course......

[Robert Taylor]

The start ratio is weak imparting a very slow velocity to the shock ( any shock ) meaning weak damping build up. So the shock has to have quick low speed initial damping build up both internally through the shaft jet and into the reservoir, before there is any hint of lifting the valving stack. The opening point of the valving stack has to also be reasonably firm with a decent slope in the curve to catch sudden movements on bumpy tracks.
The link is designed for compliant road use as the Suzuki factory never had any intention that such a bike would be used for racing.

[JD Racing]

Do you have a choice of compound for the front?
You may be better off with an SC2 front, when switching from Dunlops to Pirelli a lot of riders struggle with the difference in feel. The Dunlop has a stiff sidewall with a triangular profile, the Pirelli is a rounder profile with a softer sidewall hence the wallowy feel, what you are saying about the feel is very common, some riders just can't get their heads round it at all. Although they are the same construction you will most likely find that the SC2 gives more support.

Oil viscosity and ambient air temperature are important tuning factors with SV forks, forks that are stiff in a Canadian spring will be soft and wallowy in summer, choose your oil by it's Centistoke rating not the SAE value.

You shouldn't need to mess about with dog bones a good tuner should be able to sort the shock out, unfortunately it doesn't look like you've found a good tuner. Which Penske shock is it?

[Robert Taylor]

Do you have a choice of compound for the front?
You may be better off with an SC2 front, when switching from Dunlops to Pirelli a lot of riders struggle with the difference in feel. The Dunlop has a stiff sidewall with a triangular profile, the Pirelli is a rounder profile with a softer sidewall hence the wallowy feel, what you are saying about the feel is very common, some riders just can't get their heads round it at all. Although they are the same construction you will most likely find that the SC2 gives more support.

Oil viscosity and ambient air temperature are important tuning factors with SV forks, forks that are stiff in a Canadian spring will be soft and wallowy in summer, choose your oil by it's Centistoke rating not the SAE value.

You shouldn't need to mess about with dog bones a good tuner should be able to sort the shock out, unfortunately it doesn't look like you've found a good tuner. Which Penske shock is it?

I concur exactly, the linkage is what youve got so the tuner should be able to make the shock work. I think there is too much credence paid to ''full external adjustability'' which of course doesnt actually alter the basic character of the shock. You very often have to make internal changes to make it work in harmony with the motion ratio and leverage imparted to it. Just this last weekend I evidenced one of these purported US made ''fully adjustable'' shocks that was rapidly burning up tyres. It clearly needed some work.
I think also that there is a mindset that softer compounds always afford more grip, that is not neccessarily so. Cold track temperatures for very complex reasons often require harder compounds and more spring force / damping force to ''push'' the tyre harder onto the track. Thats an oversimplistic explanation but the reality can often be that.
SV and indeed all damper rod forks are VERY ambient temperature sensitive and I have posted before about this and the need to request both the centistroke ratings and to select a higher quality rather than cheap oils.

[Dom]

Hey John. About the tires. They are totally different to what are avaliable in New Zealand. In New Zealand, most guys run 0, 1 and 2. Where as in the states I was running 1, 2, 3 and 4 and things in between. In the US, I actually preferred the 2 front over the 1 as it has a totally different carcass built into it and felt way firmer. Also, we ran 1 on the rear sometimes and they grip so much better. We could get them to last a 28 lap Superbike race on the right day, right track so maybe thats something else you could try down the track when Robert gets ya soughted with ya bike. Everyone likes grip.

[Shaun]

Hey John. About the tires. They are totally different to what are avaliable in New Zealand. In New Zealand, most guys run 0, 1 and 2. Where as in the states I was running 1, 2, 3 and 4 and things in between. In the US, I actually preferred the 2 front over the 1 as it has a totally different carcass built into it and felt way firmer. Also, we ran 1 on the rear sometimes and they grip so much better. We could get them to last a 28 lap Superbike race on the right day, right track so maybe thats something else you could try down the track when Robert gets ya soughted with ya bike. Everyone likes grip.

Good on ya for sharing your testing thoughts mate