Ohlins FGK 132 Cartridges...GSX-R 600/750, K6/K7

[Pussy]

So how much internal friction were your original cartridges contributing to the spring rate 0.25n/mm, 0.5n/mm? How did you verify that it was friction that was contributing to the overall spring rate of the fork?

It's VERY noticeable even when statically bouncing on the forks.
With the latest compression valving spec, I've gone from .95 to 1.00 kg/mm springs, and am experiencing a superbly comfortable ride.

[JD Racing]

Unscientifically but effectively. The standard cartridges have a lot of piston ring friction and will not ''drop'' so readily when fully extended, they also dont clock into the forks exactly on centreline. Re-engineerable yes but the 25mm Ohlins system is a total engineering package and we have road settings that are working really well. We modify the pistons and have our own extensively tested valving specs. I am happy to forward these to you in confidence if you have customers with these and wish to try something different.
Pussy has done an enormous amount of road testing with both stock and Ohlins cartridges for me over the years and is VERY fussy. His feedback has been proven to be on the money time and again when we have set other customers bikes up with his road settings. To that end I totally respect his judgement and he is very valuable to me in developing road settings for both stock and aftermarket cartridges.

I've yet to see any standard GSXR600/750 rods that do not drop into the cartridge of their own accord and that's when they've been thoroughly cleaned to remove all lubrication. I've seen aftermarket piston kits whose piston bands stopped the rod dropping but not to the extent of adding 0.5kg spring force. An Ohlins rod will always drop into a cartridge easier because it's a far heavier assembly.

The biggest friction forces in a fork come from the bushes on the outer tubes, the friction associated with 41mm bushes, seals and dust seals is going to far outweigh that created by the cartridge. A fork fitted with an Ohlins cartridge kit should feel very different to a standard fork, as good as Pussy is, if he can push on the two forks and determine that the difference between the two forks is down to cartridge friction then you should have him on the payroll, the guy is a genious.

I'm interested in the fact that you constantly come across forks with off centre cartridges, is there a particular bike that suffers from this, how far out of they? Since I first read you say this I've been measuring for it and not found any.
I've tried threading piece a 10mm ground bar into the bottom of the base valve then rotated the cartridge in V blocks with a dial gauge on the ground bar, I get next to no runout. I've not found a good way yet to measure the concentricity of the centre of the cartridge relative to the outer tube. I tried a bore gauge between the stanchion and spring seat, but the spring seat being pressed tin is not ideal, and is not necessarily concentric to the inside of the cartridge.
I also machined a base valve holder to allow a long 10mm ground bar to be threaded into the top of it when the cartridge body is mounted in the fork. Measuring between the stanchion wall and rod is difficult due to the free play in the cartridge bush being amplified by the length of the rod, how do you measure the concentricity?

[Pussy]

I'm no genius, JD.
But I can pick cartridge friction.... and the FGK cartridges have next to none

[suzuki21]

I'm no genius, JD.
But I can pick cartridge friction.... and the FGK cartridges have next to none

Tried to get hold of you last weekend beatch to visit you and the other half that does more miles on a ike than you lol. You were obviously hammering your forks on some road!

[Robert Taylor]

I've yet to see any standard GSXR600/750 rods that do not drop into the cartridge of their own accord and that's when they've been thoroughly cleaned to remove all lubrication. I've seen aftermarket piston kits whose piston bands stopped the rod dropping but not to the extent of adding 0.5kg spring force. An Ohlins rod will always drop into a cartridge easier because it's a far heavier assembly.

The biggest friction forces in a fork come from the bushes on the outer tubes, the friction associated with 41mm bushes, seals and dust seals is going to far outweigh that created by the cartridge. A fork fitted with an Ohlins cartridge kit should feel very different to a standard fork, as good as Pussy is, if he can push on the two forks and determine that the difference between the two forks is down to cartridge friction then you should have him on the payroll, the guy is a genious.

I'm interested in the fact that you constantly come across forks with off centre cartridges, is there a particular bike that suffers from this, how far out of they? Since I first read you say this I've been measuring for it and not found any.
I've tried threading piece a 10mm ground bar into the bottom of the base valve then rotated the cartridge in V blocks with a dial gauge on the ground bar, I get next to no runout. I've not found a good way yet to measure the concentricity of the centre of the cartridge relative to the outer tube. I tried a bore gauge between the stanchion and spring seat, but the spring seat being pressed tin is not ideal, and is not necessarily concentric to the inside of the cartridge.
I also machined a base valve holder to allow a long 10mm ground bar to be threaded into the top of it when the cartridge body is mounted in the fork. Measuring between the stanchion wall and rod is difficult due to the free play in the cartridge bush being amplified by the length of the rod, how do you measure the concentricity?

Yes I totally agree that main bushing friction and especially main seal friction are the biggest single causes of friction. We are ( unashamedly ) incredibly pedantic about seal friction. We only use genuine seals on sportbikes as frankly all of the aftermarket seals ( that at least are in this market ) are very dissapointing. Some, like those terrible red coloured 3 lip ''All Bollocks" seals increase friction enormously and would likely wear off microscopically thin low friction fork coatings at a massively increased rate. And they have the temerity to market them as low friction seals!!!
We re-lube main and dust seals frequently with seal grease, especially after riding / racing in wet conditions. I dont need to tell you how seal drag increases enormously once they are ''dried out'' We also often put a 5mm long cut in the dust seals to relieve friction and are also very pedantic about fork alignment and front wheel installation. The indicator of stiction is of course measuring the the static sag in two ways, 1) pushing down on the forks and letting them settle back upwards and 2) Pulling up on the forks and letting them settle back downwards. Then seeing what the difference is in readings.
Pussy has a GSXR750 with the said Ohlins cartidges. His other half also has the same model GSXR750 with stock cartridges that we have carefully set up. We have pedantically followed all the processes described so we are not fooling ourselves and its as plain as day that the Ohlins equipped forks are smoother in action, from the standpoint of friction. Both bikes are using very slippery Ohlins fork oil.
When you compare the stock and Ohlins cartridges out of these bikes its also very plain, the stock cartridges feel ''rough'' in comparison. Sure the rod is heavier in the Ohlins cartridge but the tolerancing and concenticity is superb, the polished steel rod is very low friction and there is very little drag on the split ( rather than one piece ) piston ring. The machining in the piston ring groove is also barrelled and backcut to further minimise friction as the fork is deflected, its all in the detail.The very latest production has now gone to an alloy rod with a very very low friction coating.
We see not only many sportbike forks but also lower grade cartridge forks such as in Hornets, Bandits, FZ1 / 6 etc. Its not uncommon to lift the lid and spy non concentricity just with the naked eye. Of course we see this all the time with damper rod forks.
The worst sportbike example is GSXR1000 K1 through to about K5. We have seen up to 0.3mm runout on the cartridge top cap relative to turning the tube in v blocks. You dont need a dti to see that! These are terrible forks ( especially K1, K2 ) and can be improved immensely. Happily we can take away 80 to 90% of that lack of concentricity issue with some careful machining of the seperated components.

[JD Racing]

Yes I totally agree that main bushing friction and especially main seal friction are the biggest single causes of friction. We are ( unashamedly ) incredibly pedantic about seal friction. We only use genuine seals on sportbikes as frankly all of the aftermarket seals ( that at least are in this market ) are very dissapointing. Some, like those terrible red coloured 3 lip ''All Bollocks" seals increase friction enormously and would likely wear off microscopically thin low friction fork coatings at a massively increased rate. And they have the temerity to market them as low friction seals!!!
We re-lube main and dust seals frequently with seal grease, especially after riding / racing in wet conditions. I dont need to tell you how seal drag increases enormously once they are ''dried out'' We also often put a 5mm long cut in the dust seals to relieve friction and are also very pedantic about fork alignment and front wheel installation. The indicator of stiction is of course measuring the the static sag in two ways, 1) pushing down on the forks and letting them settle back upwards and 2) Pulling up on the forks and letting them settle back downwards. Then seeing what the difference is in readings.
Pussy has a GSXR750 with the said Ohlins cartidges. His other half also has the same model GSXR750 with stock cartridges that we have carefully set up. We have pedantically followed all the processes described so we are not fooling ourselves and its as plain as day that the Ohlins equipped forks are smoother in action, from the standpoint of friction. Both bikes are using very slippery Ohlins fork oil.
When you compare the stock and Ohlins cartridges out of these bikes its also very plain, the stock cartridges feel ''rough'' in comparison. Sure the rod is heavier in the Ohlins cartridge but the tolerancing and concenticity is superb, the polished steel rod is very low friction and there is very little drag on the split ( rather than one piece ) piston ring. The machining in the piston ring groove is also barrelled and backcut to further minimise friction as the fork is deflected, its all in the detail.The very latest production has now gone to an alloy rod with a very very low friction coating.
We see not only many sportbike forks but also lower grade cartridge forks such as in Hornets, Bandits, FZ1 / 6 etc. Its not uncommon to lift the lid and spy non concentricity just with the naked eye. Of course we see this all the time with damper rod forks.
The worst sportbike example is GSXR1000 K1 through to about K5. We have seen up to 0.3mm runout on the cartridge top cap relative to turning the tube in v blocks. You dont need a dti to see that! These are terrible forks ( especially K1, K2 ) and can be improved immensely. Happily we can take away 80 to 90% of that lack of concentricity issue with some careful machining of the seperated components.

I'm not for one second disputing that Ohlins cartridges are a superior build quality, what I am disputing is that Ohlins cartriges allow you to run 0.5kg stiffer springs. You seem to be suggesting that when you ride a bike with a 25mm cartridge and a 20mm cartridge you can completely filter out the differences in hydraulic action and determine that the differences between the two is down to the friction.
What I was trying to establish was the concentricity of the centre line of the cartridge bush relative to the centreline on the stanchion, the outside of the top cap could quite easily be 0.3mm out relative to the tube as many are unmachined die cast, it's only function being a spring seat, it doesn't need to be true. On the cartridges I've measured so far the bush centre line is concentric as is the base valve. If the machining of the fork foot is causing the lack of concentricity or angularity of the cartridge then there is nothing much you can do about that.

[Robert Taylor]

I'm not for one second disputing that Ohlins cartridges are a superior build quality, what I am disputing is that Ohlins cartriges allow you to run 0.5kg stiffer springs. You seem to be suggesting that when you ride a bike with a 25mm cartridge and a 20mm cartridge you can completely filter out the differences in hydraulic action and determine that the differences between the two is down to the friction.
What I was trying to establish was the concentricity of the centre line of the cartridge bush relative to the centreline on the stanchion, the outside of the top cap could quite easily be 0.3mm out relative to the tube as many are unmachined die cast, it's only function being a spring seat, it doesn't need to be true. On the cartridges I've measured so far the bush centre line is concentric as is the base valve. If the machining of the fork foot is causing the lack of concentricity or angularity of the cartridge then there is nothing much you can do about that.

Thats Pussys assertion which he seems to be happy with and its probably indeed stretching the point a little but I dont think for one moment there was any attempt on his part to define a hard and fast figure. He is very happy and I like happy customers.
Im not going to read through all this entire thread again in an attempt to split hairs nor am I going to lose a wink of sleep about it. But it would be my reasonable understanding if you reduce friction, all else being equal you could run more preload or an incremental change in spring rate and get away with it. Enough said.
To clarify further on that top cap its 0.3mm runout at the end of the body cap, thats less at the bush but nonetheless there is enough at the bush to significantly magnify friction.
And I totally disagree, spring seats should be as true as possible to end up being perpendicular to the centreline of the fork tube, otherwise you are creating further unwanted side thrust of the springs against the inner walls of the fork tube. Of course the Ohlins internal spring guide system ( also WP, Traxxion, K-Tech and most MX forks ) minimises that issue.

[Pussy]

RT and JD.... you guys have forgotten more than I'll know about the technicalities.
I can tell you both, though, that the present valving spec in my bike has allowed me to run heavier springs to give a characteristic that I like, and am very happy with.

And, JD, I have tried several specs in this machine

[Ascott]

Just a couple of questions, Pussy, are these 25mm cartridges? and what sort of road riding do you do? without giving anything away, do you "push the envelope" you can pm me if you wish. I have got a three week wait, it's like forever! I am fizzing a bit believe me!
Al

[Robert Taylor]

Just a couple of questions, Pussy, are these 25mm cartridges? and what sort of road riding do you do? without giving anything away, do you "push the envelope" you can pm me if you wish. I have got a three week wait, it's like forever! I am fizzing a bit believe me!
Al

Ill answer for Pussy, they are indeed 25mm and they have settings in them that we have spent a LOT of time developing. The bump compliance on the road is superb and when you push the envelope they are very composed / controlled, such as at a track day.
You wont be dissapointed!

[robertydog]

Just a couple of questions, Pussy, are these 25mm cartridges? and what sort of road riding do you do? without giving anything away, do you "push the envelope" you can pm me if you wish. I have got a three week wait, it's like forever! I am fizzing a bit believe me!
Al

Crikey im having enough trouble keeping up with the gixxer

[Pussy]

Ill answer for Pussy, they are indeed 25mm and they have settings in them that we have spent a LOT of time developing. The bump compliance on the road is superb and when you push the envelope they are very composed / controlled, such as at a track day.
You wont be dissapointed!

Answered by PM earlier, RT!

[Ascott]

Thanks R.T. and Pussy, I'm sure I will be thrilled!
Alvin

[Pussy]

Thanks R.T. and Pussy, I'm sure I will be thrilled!
Alvin

No doubt about it!

[Pussy]

Another brief update...

I'm not getting ANYTHING changed as far as internal settings go in these cartridges.
I'm not a fast track rider by any stretch of the imagination, but today was at the Manfeild trackday where we used the entire track.
I tried several different lines on the long left hand sweeper on the extension part of the track. There is a roughish repair on this corner. No matter which part of the repair I rode over, the bike was 100% composed. It just felt awesome!
If you can stretch your budget, I would strongly recommend chucking a set of FGK 132s at your K6 onwards six hundy or sem fiddy....