Rojoracing53 front suspension setup for racing - Page 2

rojoracing53 · June 7th, 2015, 07:04 AM

No gear

crazymadbastard · June 7th, 2015, 08:16 AM

where did you get this idea from Jason:

I think ill try 17.5wt(20 in one fork and 15 in the other)

I knew I read it here and it makes sense.

Thanks.

rojoracing53 · June 7th, 2015, 07:53 PM

Quote:

Originally Posted by crazymadbastard

where did you get this idea from Jason:

I think ill try 17.5wt(20 in one fork and 15 in the other)

I knew I read it here and it makes sense.

Thanks.

Someone told me about the method many years ago while I was still racing. Some motorcycle fork legs only have compression adjustment on one leg and rebound on the other leg, so why couldn't you have a slightly different oil weight doing the same thing without issue. You could also mix your 10wt and 20wt before pouring it into the forks that way it's 15wt in both forks. I'd just make sure you stick with one brand of oil when mixing.

pattonme · December 25th, 2015, 10:30 PM

Unless each leg truly lacks damping in one particular direction, the leg with the thicker oil always wins. The one with the lighter oil will indeed try to move faster and it will push/pull on the slower leg by way of the axle and add a twisting moment to the frontend.

An example of a SFF (separate function) fork are the Andreani's where indeed one leg has ~zero compression damping and the other has ~zero rebound damping. It's not uncommon in this situation to run a thicker oil on the rebound and a lighter oil in the comp leg. Indeed to this day the Andreani setup requires this since their comp leg piston and valving can't properly handle real-life street bumps or bumpy tracks. On smooth tracks you likely won't exceed it's limits.

If you want an intermediate rate in a traditional (damper rod or 4-piston cartridge), you need to mix the oils.

Somchai · December 25th, 2015, 11:03 PM

@pattonme, can you confirm the following?
Finetue the fork on thinner fork oil, because: The thicker oil viscosity decreases more and faster with increasing temperature and so the damping during operation weakens more.

pattonme · December 26th, 2015, 04:51 AM

As you can see from the following chart, most fork oil's viscosity index (stability under temperature change) is in the 110-150 range regardless of weight. In forks there is just massive volume vs in a shock so the temperature change and thus changes in damping behavior is relatively minor, comparatively speaking.

If all you have is orifice-based damping (damper rods, GVE) then you do want the oil that best performs it's function and provides the damping characteristics you want at the temperature ranges you generally operate at. So on a 90F ambient day that'll be thicker than if it's 65F even if running at the same pace. There are some guys who really do dump and replace oil based on the day's weather but most just choose to ride around the (general) lack of rebound damping.

The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher.

That said, I build forks using shock oil because it has 3x higher VI value and doesn't cost any extra.

https://www.dropbox.com/s/en31y0wd9u...ghts.html?dl=0

Somchai · December 26th, 2015, 06:06 AM

Thank you Matt.

Note: "The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher." - valid for those who have the chance

tgold · January 4th, 2016, 12:30 PM

Quote:

Originally Posted by Somchai

Thank you Matt.

Note: "The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher." - valid for those who have the chance

A few notes regarding fork oil viscosity: Actual viscosity can vary dramatically above or below what the label says. Make sure whatever brand & line of fork oil that you use, that you consistently use the same stuff so you know relatively which way you are going on viscosity. Otherwise you may actually do the opposite of what you intend.

I agree with pattonme's comments on viscosity index, but I would say that it isn't just changes in ambient temperature that matter, but changes in oil temperature during a race that also matter. That is the main reason that I try to get the oils with the highest viscosity index. I want more consistent damping during a race because it would be tough to change the damping a couple of clicks on the fly.

tgold · January 4th, 2016, 12:39 PM

Quote:

Originally Posted by Somchai

Thank you Matt.

Note: "The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher." - valid for those who have the chance

Everybody has a free choice in the what modifications they make to their bike

toEleven · January 4th, 2016, 02:43 PM

Quote:

Originally Posted by tgold

Everybody has a free choice in the what modifications they make to their bike

Sure, aside from pesky things like budgets.

tgold · January 4th, 2016, 05:21 PM

Quote:

Originally Posted by toEleven

Sure, aside from pesky things like budgets.

How badly do you want to win?

rojoracing53 · January 4th, 2016, 05:23 PM

Hell you can win on stock suspension, you just need to ride very very good.

tgold · January 5th, 2016, 10:00 AM

Quote:

Originally Posted by rojoracing53

Hell you can win on stock suspension, you just need to ride very very good.

That depends on the level of competition. At some level we will find that no matter how hard we try with the equipment (or the skills) we have, we are not going to win. That's when we have to decide if we want to take the next step in order to win or if we are just happy to be in the show.

I passed just being happy to be in the show about 20 years ago

daverdfw · January 27th, 2016, 10:38 AM

I am about to drop some RT springs and preload adjusters in my bike. 1 question

I got PVC with the springs, are you guys adding the PVC on top of the metal spacer (collar) pipe thats already in the stock fork? or cutting a new piece of PVC to replace the stock metal spacer?

pattonme · January 27th, 2016, 11:32 AM

new piece to achieve desired internal preload and and then tweak with external preload adjuster to achieve balance between rider and static sag.

bruce71198 · January 27th, 2016, 12:57 PM

Quote:

Originally Posted by daverdfw

I am about to drop some RT springs and preload adjusters in my bike. 1 question

I got PVC with the springs, are you guys adding the PVC on top of the metal spacer (collar) pipe thats already in the stock fork? or cutting a new piece of PVC to replace the stock metal spacer?

Loose the factory spacer and cut a new on to fit

June 7th, 2015, 08:16 AM	#42
crazymadbastard I'm crazy,your excuse is? Name: Winston Location: Connecticut Join Date: May 2013 Motorcycle(s): 250 2007 ninja Posts: A lot.	where did you get this idea from Jason: I think ill try 17.5wt(20 in one fork and 15 in the other) I knew I read it here and it makes sense. Thanks. __________________________________________________ My Cafe Racer Build My intro post

December 26th, 2015, 04:51 AM	#46
pattonme ninjette.org member Name: Matt Location: Northern VA Join Date: Dec 2015 Motorcycle(s): Lots Posts: 32	As you can see from the following chart, most fork oil's viscosity index (stability under temperature change) is in the 110-150 range regardless of weight. In forks there is just massive volume vs in a shock so the temperature change and thus changes in damping behavior is relatively minor, comparatively speaking. If all you have is orifice-based damping (damper rods, GVE) then you do want the oil that best performs it's function and provides the damping characteristics you want at the temperature ranges you generally operate at. So on a 90F ambient day that'll be thicker than if it's 65F even if running at the same pace. There are some guys who really do dump and replace oil based on the day's weather but most just choose to ride around the (general) lack of rebound damping. The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher. That said, I build forks using shock oil because it has 3x higher VI value and doesn't cost any extra. https://www.dropbox.com/s/en31y0wd9u...ghts.html?dl=0
	1 out of 1 members found this post helpful.

January 4th, 2016, 05:23 PM	#52
rojoracing53 Fast-Guy wannabe Name: Jason Location: Brentwood, Ca Join Date: Oct 2011 Motorcycle(s): 2009 Ninja250, 2011 RM-Z250, 2004 NSR50, Posts: A lot. MOTM - Jan '13	Hell you can win on stock suspension, you just need to ride very very good.
	1 out of 1 members found this post helpful.

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June 7th, 2015, 07:04 AM	#41
rojoracing53 Fast-Guy wannabe Name: Jason Location: Brentwood, Ca Join Date: Oct 2011 Motorcycle(s): 2009 Ninja250, 2011 RM-Z250, 2004 NSR50, Posts: A lot. MOTM - Jan '13	No gear

December 25th, 2015, 10:30 PM	#44
pattonme ninjette.org member Name: Matt Location: Northern VA Join Date: Dec 2015 Motorcycle(s): Lots Posts: 32	Unless each leg truly lacks damping in one particular direction, the leg with the thicker oil always wins. The one with the lighter oil will indeed try to move faster and it will push/pull on the slower leg by way of the axle and add a twisting moment to the frontend. An example of a SFF (separate function) fork are the Andreani's where indeed one leg has ~zero compression damping and the other has ~zero rebound damping. It's not uncommon in this situation to run a thicker oil on the rebound and a lighter oil in the comp leg. Indeed to this day the Andreani setup requires this since their comp leg piston and valving can't properly handle real-life street bumps or bumpy tracks. On smooth tracks you likely won't exceed it's limits. If you want an intermediate rate in a traditional (damper rod or 4-piston cartridge), you need to mix the oils.

December 25th, 2015, 11:03 PM	#45
Somchai Freedom for Germany Location: This World Join Date: May 2011 Motorcycle(s): Ninja 250R-FI Posts: A lot.	@pattonme, can you confirm the following? Finetue the fork on thinner fork oil, because: The thicker oil viscosity decreases more and faster with increasing temperature and so the damping during operation weakens more.

December 26th, 2015, 06:06 AM	#47
Somchai Freedom for Germany Location: This World Join Date: May 2011 Motorcycle(s): Ninja 250R-FI Posts: A lot.	Thank you Matt. Note: "The very nice thing about cartridges is, a couple clicks and you've handily compensated for morning's practice thru mid-afternoon's scorcher." - valid for those who have the chance

January 27th, 2016, 10:38 AM	#54
daverdfw ninjette.org guru Name: David Location: Fort Worth,TX Join Date: Nov 2015 Motorcycle(s): 2009 Ninja 250 Posts: 386	I am about to drop some RT springs and preload adjusters in my bike. 1 question I got PVC with the springs, are you guys adding the PVC on top of the metal spacer (collar) pipe thats already in the stock fork? or cutting a new piece of PVC to replace the stock metal spacer?

January 27th, 2016, 11:32 AM	#55
pattonme ninjette.org member Name: Matt Location: Northern VA Join Date: Dec 2015 Motorcycle(s): Lots Posts: 32	new piece to achieve desired internal preload and and then tweak with external preload adjuster to achieve balance between rider and static sag.