Forks disassembled
05-07-2008, 07:53 PM
#1
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Forks disassembled
Since I was taking pics posted elsewhere on the forum, I thought I'd take an opportunity to show off one of Josh's (JoshuaTest) forks completely torn down. Here ya' go Josh, for your viewing pleasure....
Pic 1: disassembled
Pic 2: compression and rebound stacks
Pic 3: place where suspension magic is performed
Pic 1: disassembled
Pic 2: compression and rebound stacks
Pic 3: place where suspension magic is performed
05-07-2008, 08:56 PM
#3
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He means this voodoo suspension guru **** that guys in Nascar get paid millions of dollars to know.
Good news is - it works - it works real well!
Greg, I resnugged the neck bearings and maybe got two mm's. This is amazing to me how sensitive this suspension is. A little wooble in the front makes the back all fucked up and the damn thing is like driving two motorcycles at once - arrg! This bike is very good after this adjustment. BTW i.m still 139mm and fine where did yours measure out at?
Good news is - it works - it works real well!
Greg, I resnugged the neck bearings and maybe got two mm's. This is amazing to me how sensitive this suspension is. A little wooble in the front makes the back all fucked up and the damn thing is like driving two motorcycles at once - arrg! This bike is very good after this adjustment. BTW i.m still 139mm and fine where did yours measure out at?
05-07-2008, 09:03 PM
#4
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Did you end up putting the zip tie on and riding? How much suspension travel are you using?
I never got out to remeasure. I figured with all the mods and factors between the bikes affecting ride height that it wouldn't be worth it. We'll still troubleshoot you though.
Oh, and you're a rich, single guy with his own business so you should be getting that rear shock soon, if not already, right?
I never got out to remeasure. I figured with all the mods and factors between the bikes affecting ride height that it wouldn't be worth it. We'll still troubleshoot you though.
Oh, and you're a rich, single guy with his own business so you should be getting that rear shock soon, if not already, right?
05-07-2008, 09:17 PM
#6
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Your fancy bench setup looks like one of mine except my comparable 30 year old bench is wood with a poly-coated masonite top but I have a window over it. I have 2 other benches in the shop, a Handy lift and Pitbull stands. A nice place to go hide from the world. wink
Hopefully if I get through this season OK, my forks will be winging their way to you.
BTW Greg, I have not been able to figure out why my left front F4i caliper is causing the pads to drag. The machined clearance is tight but not in bearing, I surfaced the pads to .001 and scrubbed them clean along with the rotor, absolutely no air and if anything its got less travel than before. I checked that the pistons all move though of course the larger ones move first then the inner smaller piston finally the outer small puck. I have a bleeder type banjo bolt on the RC51 MC and may try bleeding from there after down at the caliper (just to try to suck out any muck in the MC). I was hesitant to coat the pistons/seals with a special CRC rubber lube but may try that as a last resort. If it was the MC the right caliper would be doing it too but while it drags a bit I think thats par for the course. The calipers were flushed and pistons cleaned but not disassembled as they are not leaking. Any ideas???
Hopefully if I get through this season OK, my forks will be winging their way to you.
BTW Greg, I have not been able to figure out why my left front F4i caliper is causing the pads to drag. The machined clearance is tight but not in bearing, I surfaced the pads to .001 and scrubbed them clean along with the rotor, absolutely no air and if anything its got less travel than before. I checked that the pistons all move though of course the larger ones move first then the inner smaller piston finally the outer small puck. I have a bleeder type banjo bolt on the RC51 MC and may try bleeding from there after down at the caliper (just to try to suck out any muck in the MC). I was hesitant to coat the pistons/seals with a special CRC rubber lube but may try that as a last resort. If it was the MC the right caliper would be doing it too but while it drags a bit I think thats par for the course. The calipers were flushed and pistons cleaned but not disassembled as they are not leaking. Any ideas???
Last edited by skokievtr; 05-07-2008 at 09:20 PM.
05-08-2008, 11:10 AM
#8
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Here's some information about suspension magic that should help demystify:
http://www.peterverdonedesigns.com/suspension.htm
http://www.suspensionhotline.com/lev...elSuspInfo.php
Lots of really good, helpful information.
http://www.peterverdonedesigns.com/suspension.htm
http://www.suspensionhotline.com/lev...elSuspInfo.php
Lots of really good, helpful information.
05-08-2008, 12:06 PM
#9
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Since I was taking pics posted elsewhere on the forum, I thought I'd take an opportunity to show off one of Josh's (JoshuaTest) forks completely torn down. Here ya' go Josh, for your viewing pleasure....
Pic 1: disassembled
Pic 2: compression and rebound stacks
Pic 3: place where suspension magic is performed
Pic 1: disassembled
Pic 2: compression and rebound stacks
Pic 3: place where suspension magic is performed
Thanks,
RC
05-08-2008, 01:13 PM
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Greg, let me know if I'm on the right track, if you can without revealing your ninja secrets.
Here's how I would appoach it. I will be doing some experimentaation with mine, I have 3 sets of compression and rebound valve assemblies. The RC51 compression valves mount externally, so they can be change very easily.
The VTR forks have no compression damping adjustment. The low-speed compression damping is via a fixed orifice (drilled hole). Fork oil weight is the best way to modify it.
You are putting stiffer springs in, since the stock springs are too soft, so you probably want to decrease the high-speed compression damping a little, since total suspension stiffness is a sum of spring, damping and inertial stiffnesses. My guess is that you are either removing a shim or decreasing a backing shim diameter to decrease the stiffness of the compression stack. Combined with the higher spring rate, you get the same "stiffness", but the softer shim stack eases the transition from orifice damping to shim-controlled damping, providing a more supple, linear feel.
Slow rebound is the only external damping adjustment. It uses a needle and orifice, to control the effective orifice diameter. No internal modifications necessary.
Since the springs are stiffer, you'll want to increase the high-speed damping by increasing the stiffness of the rebound stack. This controls the rate of rebound from the higher spring rate. You can do this by adding a shim to the stack, or increasing the diameter of a shim in the stack.
You'll want to lap the valve faces to improve the seal of the shim stacks. The orifices in the valve bodies are fine. For a serious track effort, you might experiment with different orifice sizes, but not for a basic street setup. Chamfering the holes will improve oil flow (chamfer before lapping).
Finally you are probably reducing the oil height to reduce ramp rate, and disabling, or decreasing the effectiveness of the oil lock piece to increase the range of useful travel.
For a basic street setup, that's all you need.
Alright. Back to work. I have a report to write
Here's how I would appoach it. I will be doing some experimentaation with mine, I have 3 sets of compression and rebound valve assemblies. The RC51 compression valves mount externally, so they can be change very easily.
The VTR forks have no compression damping adjustment. The low-speed compression damping is via a fixed orifice (drilled hole). Fork oil weight is the best way to modify it.
You are putting stiffer springs in, since the stock springs are too soft, so you probably want to decrease the high-speed compression damping a little, since total suspension stiffness is a sum of spring, damping and inertial stiffnesses. My guess is that you are either removing a shim or decreasing a backing shim diameter to decrease the stiffness of the compression stack. Combined with the higher spring rate, you get the same "stiffness", but the softer shim stack eases the transition from orifice damping to shim-controlled damping, providing a more supple, linear feel.
Slow rebound is the only external damping adjustment. It uses a needle and orifice, to control the effective orifice diameter. No internal modifications necessary.
Since the springs are stiffer, you'll want to increase the high-speed damping by increasing the stiffness of the rebound stack. This controls the rate of rebound from the higher spring rate. You can do this by adding a shim to the stack, or increasing the diameter of a shim in the stack.
You'll want to lap the valve faces to improve the seal of the shim stacks. The orifices in the valve bodies are fine. For a serious track effort, you might experiment with different orifice sizes, but not for a basic street setup. Chamfering the holes will improve oil flow (chamfer before lapping).
Finally you are probably reducing the oil height to reduce ramp rate, and disabling, or decreasing the effectiveness of the oil lock piece to increase the range of useful travel.
For a basic street setup, that's all you need.
Alright. Back to work. I have a report to write
05-08-2008, 06:33 PM
#11
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Just let me know on the forks. Give me about a week if you need me to order springs.
Have you checked the retaining pin and the little spring piece for abnormal wear or burrs?
No, it's not. It just takes a lot of practice and trial and error to find out what works and what doesn't.
Here's some information about suspension magic that should help demystify:
http://www.peterverdonedesigns.com/suspension.htm
http://www.peterverdonedesigns.com/suspension.htm
Greg, let me know if I'm on the right track, if you can without revealing your ninja secrets.
Here's how I would appoach it. I will be doing some experimentaation with mine, I have 3 sets of compression and rebound valve assemblies. The RC51 compression valves mount externally, so they can be change very easily.
The VTR forks have no compression damping adjustment. The low-speed compression damping is via a fixed orifice (drilled hole). Fork oil weight is the best way to modify it.
Well, let me first clarify something. The stock VTR compression valve has no bleed hole. It uses a bleed shim instead. It's a smaller (12mm) shim under the "base" shim.
You are putting stiffer springs in, since the stock springs are too soft, so you probably want to decrease the high-speed compression damping a little, since total suspension stiffness is a sum of spring, damping and inertial stiffnesses. My guess is that you are either removing a shim or decreasing a backing shim diameter to decrease the stiffness of the compression stack. Combined with the higher spring rate, you get the same "stiffness", but the softer shim stack eases the transition from orifice damping to shim-controlled damping, providing a more supple, linear feel.
I use a completely new shim stack. It is actually a stiffer stack and is based on the spring stiffness and the road condition that the rider gives me. I also use a lighter oil to move farther away from orifice damping.
Slow rebound is the only external damping adjustment. It uses a needle and orifice, to control the effective orifice diameter. No internal modifications necessary.
Not true. I use a much stiffer rebound stack, also spring stiffness dependent. With my stack, a .90kg/mm spring has optimum rebound damping about 1.5 turns out.
Since the springs are stiffer, you'll want to increase the high-speed damping by increasing the stiffness of the rebound stack. This controls the rate of rebound from the higher spring rate. You can do this by adding a shim to the stack, or increasing the diameter of a shim in the stack.
Honestly, there's only one rebound speed, or rather an maximum amount of rebound "power" which is dependent again on spring stiffness. At deep fork travel rebound there is a lot of force driving the fork back to static position. As the fork nears that position the spring relaxes and thus there is less force extending the fork. You have to account for this in the valving. Only at deep travels does my shim stack actually blow open. After that it's pretty much all bleed.
You'll want to lap the valve faces to improve the seal of the shim stacks. The orifices in the valve bodies are fine. For a serious track effort, you might experiment with different orifice sizes, but not for a basic street setup. Chamfering the holes will improve oil flow (chamfer before lapping).
Some people think that chamfering improves oil flow but all it really does is lessen the turbulence at the stack interface. An orifice flows the same amount of fluid whether it is 1mm in lenth or 10mm in length. Granted, there is also something called "head loss" which is essentially flluid friction that also comes into play, but in an ideal model the orfice length has no effect on flow.
Now, there is another effect that comes into play with chamfering the valves. When you open up the orifice end, it also opens up the face of the shim to which pressure is seen. This will effect, to some degree, how much force is required to blow open the stack. You would think that it has a lot of effect but it doesn't.
Finally you are probably reducing the oil height to reduce ramp rate, and disabling, or decreasing the effectiveness of the oil lock piece to increase the range of useful travel.
Correct. The air spring is the volume of air inside the fork that compresses and is progressive in nature. This is just one more factor to account for when tuning. Modifying the oil locks does increase available travel. It is imperative that the fork be set up properly to prevent hard bottoming though.
For a basic street setup, that's all you need.
Alright. Back to work. I have a report to write
Here's how I would appoach it. I will be doing some experimentaation with mine, I have 3 sets of compression and rebound valve assemblies. The RC51 compression valves mount externally, so they can be change very easily.
The VTR forks have no compression damping adjustment. The low-speed compression damping is via a fixed orifice (drilled hole). Fork oil weight is the best way to modify it.
Well, let me first clarify something. The stock VTR compression valve has no bleed hole. It uses a bleed shim instead. It's a smaller (12mm) shim under the "base" shim.
You are putting stiffer springs in, since the stock springs are too soft, so you probably want to decrease the high-speed compression damping a little, since total suspension stiffness is a sum of spring, damping and inertial stiffnesses. My guess is that you are either removing a shim or decreasing a backing shim diameter to decrease the stiffness of the compression stack. Combined with the higher spring rate, you get the same "stiffness", but the softer shim stack eases the transition from orifice damping to shim-controlled damping, providing a more supple, linear feel.
I use a completely new shim stack. It is actually a stiffer stack and is based on the spring stiffness and the road condition that the rider gives me. I also use a lighter oil to move farther away from orifice damping.
Slow rebound is the only external damping adjustment. It uses a needle and orifice, to control the effective orifice diameter. No internal modifications necessary.
Not true. I use a much stiffer rebound stack, also spring stiffness dependent. With my stack, a .90kg/mm spring has optimum rebound damping about 1.5 turns out.
Since the springs are stiffer, you'll want to increase the high-speed damping by increasing the stiffness of the rebound stack. This controls the rate of rebound from the higher spring rate. You can do this by adding a shim to the stack, or increasing the diameter of a shim in the stack.
Honestly, there's only one rebound speed, or rather an maximum amount of rebound "power" which is dependent again on spring stiffness. At deep fork travel rebound there is a lot of force driving the fork back to static position. As the fork nears that position the spring relaxes and thus there is less force extending the fork. You have to account for this in the valving. Only at deep travels does my shim stack actually blow open. After that it's pretty much all bleed.
You'll want to lap the valve faces to improve the seal of the shim stacks. The orifices in the valve bodies are fine. For a serious track effort, you might experiment with different orifice sizes, but not for a basic street setup. Chamfering the holes will improve oil flow (chamfer before lapping).
Some people think that chamfering improves oil flow but all it really does is lessen the turbulence at the stack interface. An orifice flows the same amount of fluid whether it is 1mm in lenth or 10mm in length. Granted, there is also something called "head loss" which is essentially flluid friction that also comes into play, but in an ideal model the orfice length has no effect on flow.
Now, there is another effect that comes into play with chamfering the valves. When you open up the orifice end, it also opens up the face of the shim to which pressure is seen. This will effect, to some degree, how much force is required to blow open the stack. You would think that it has a lot of effect but it doesn't.
Finally you are probably reducing the oil height to reduce ramp rate, and disabling, or decreasing the effectiveness of the oil lock piece to increase the range of useful travel.
Correct. The air spring is the volume of air inside the fork that compresses and is progressive in nature. This is just one more factor to account for when tuning. Modifying the oil locks does increase available travel. It is imperative that the fork be set up properly to prevent hard bottoming though.
For a basic street setup, that's all you need.
Alright. Back to work. I have a report to write
05-09-2008, 09:25 AM
#12
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Great stuff Greg! Thank you!
I'm trying to gather a knowledge base, to give me some ideas for the approach I need.
In the past, I've had it set up for me and gone out and ridden it.
In the future I want to try some things that are wrong and take note of their effects.
It's endlessly fascinating machinery, because everything is interrelated. It starts with a basic understanding of the mechanics, but there is no substitute for experience.
I'm trying to gather a knowledge base, to give me some ideas for the approach I need.
In the past, I've had it set up for me and gone out and ridden it.
In the future I want to try some things that are wrong and take note of their effects.
It's endlessly fascinating machinery, because everything is interrelated. It starts with a basic understanding of the mechanics, but there is no substitute for experience.
05-09-2008, 10:38 AM
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[QUOTE=Hawkrider;163666]Skokie, the bench was a Birthday present from the wife (or was it Father's Day?..). Anyway, I bought it so I didn't have to freeze my friggin *** off in the unheated garage in the winter. I have it set up in the basement...which is still cold, but not AS cold.
Just let me know on the forks. Give me about a week if you need me to order springs.
Have you checked the retaining pin and the little spring piece for abnormal wear or burrs?/QUOTE]
Greg,
Really not trying to make you jealous but when I designed my detached garage with separate shop, I included heat and AC, a sink, a 5'-6" pocket door with remote operator, 8 twin tube florescent OH fixtures plus task lighting, 110/220v service, wall outlets every few feet plus even in the ceiling, compressed air, carpeting, a frig, tunes, an alarm system and burgler bars, etc. I have a basement shop too with machine tools.
I have RT .95 springs and what I think are proper length PVC pipe spacers.
The pad pins were cleaned, lightly polished and clear coated along with the spring plate. I'm going to flush and bleed again, and maybe lube the seals. I'll let you know, very strange.
Just let me know on the forks. Give me about a week if you need me to order springs.
Have you checked the retaining pin and the little spring piece for abnormal wear or burrs?/QUOTE]
Greg,
Really not trying to make you jealous but when I designed my detached garage with separate shop, I included heat and AC, a sink, a 5'-6" pocket door with remote operator, 8 twin tube florescent OH fixtures plus task lighting, 110/220v service, wall outlets every few feet plus even in the ceiling, compressed air, carpeting, a frig, tunes, an alarm system and burgler bars, etc. I have a basement shop too with machine tools.
I have RT .95 springs and what I think are proper length PVC pipe spacers.
The pad pins were cleaned, lightly polished and clear coated along with the spring plate. I'm going to flush and bleed again, and maybe lube the seals. I'll let you know, very strange.
05-09-2008, 06:05 PM
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Skokie, the clearcoating might be the problem. It's odd that you'd do it and raises my suspicions. Think function over form on this. When you're talking about the pads sliding on these surfaces then a few mils might actually make a difference. Just my thoughts....
05-09-2008, 06:06 PM
#16
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05-09-2008, 08:10 PM
#17
OUCH... MY A$$ HURTS!!!
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Location: Elba, Ny
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Yea, lets take this to email... 3pm, at the flagpole........
ANYWAY.... The forks are back where they belong.. ON MY BIKE...
Had a chance to reinstall forks, adjust sag, take lots of measurements, reinstall my fairings, and even washed it off....
Now tomorrow I FINALLY get to ride again.. lol.... Will ride to work on a drastically changed bike...
-Reworked forks
-micron high mounts
-15/43 combo
-and lots of cosmetic stuff...
I'll report back on my ride experience tomorrow
ANYWAY.... The forks are back where they belong.. ON MY BIKE...
Had a chance to reinstall forks, adjust sag, take lots of measurements, reinstall my fairings, and even washed it off....
Now tomorrow I FINALLY get to ride again.. lol.... Will ride to work on a drastically changed bike...
-Reworked forks
-micron high mounts
-15/43 combo
-and lots of cosmetic stuff...
I'll report back on my ride experience tomorrow
05-10-2008, 06:20 AM
#18
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Here's an example of why I polish the valve faces. This is Josh's valve on the first steps of polishing. Notice the polished vs non-polished areas. How well do you think this valve sealed? All four of his valves were like this.
05-11-2008, 08:15 AM
#19
OUCH... MY A$$ HURTS!!!
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Join Date: Dec 2007
Location: Elba, Ny
Posts: 707
Wouldn't you know it... I ended up getting sick Friday night. Got the bike all put together, came in, and grabbed a chicken bacon ranch sub that was in the fridge, heated it up, and eat dinner.
About an hour later my stomach was killing me, I got all of 2hrs total of sleep all night, had to be at work by 10am. Had made probably 20 trips to the bathroom, but on the last visit, I empty'd myself from both ends (gross huh), and actually seemed to feel better..... But not good enough to ride... So i drove to work, made it all of 2 hours before having to leave. I'm feeling better this morning, but not sure if taking the bike out on Mothers day is the best idea...
I'll report back next week i guess
oh... I LOST 8lbs though.... GREAT DIET
About an hour later my stomach was killing me, I got all of 2hrs total of sleep all night, had to be at work by 10am. Had made probably 20 trips to the bathroom, but on the last visit, I empty'd myself from both ends (gross huh), and actually seemed to feel better..... But not good enough to ride... So i drove to work, made it all of 2 hours before having to leave. I'm feeling better this morning, but not sure if taking the bike out on Mothers day is the best idea...
I'll report back next week i guess
oh... I LOST 8lbs though.... GREAT DIET
05-11-2008, 10:41 AM
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Greg, can you clarify something for me, please?
If you use a new, stiffer shim stack on a valve that has no bleed hole, then how does using lighter oil "move farther away from orifice damping"? How can a valve with no orifice be considered an orifice damper? That doesn't make any sense. Perhaps you're talking about there being less of an impact of resistance from the orifices in the pistons? (not sure what i'm reading in your quote)
Josh - get well soon buddy!
Originally Posted by Hawkrider
I use a completely new shim stack. It is actually a stiffer stack and is based on the spring stiffness and the road condition that the rider gives me. I also use a lighter oil to move farther away from orifice damping.
If you use a new, stiffer shim stack on a valve that has no bleed hole, then how does using lighter oil "move farther away from orifice damping"? How can a valve with no orifice be considered an orifice damper? That doesn't make any sense. Perhaps you're talking about there being less of an impact of resistance from the orifices in the pistons? (not sure what i'm reading in your quote)
Josh - get well soon buddy!
05-11-2008, 01:42 PM
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Ah...I said, "The stock VTR compression valve has no bleed hole." I never said I didn't modify them!
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
05-11-2008, 03:13 PM
#22
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Ah...I said, "The stock VTR compression valve has no bleed hole." I never said I didn't modify them!
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
With the stock valves I run as much as 15 wt but have something less in there now; synthetic of course, along with the .95 RT springs, my PVC spacers and juggled fluid level. It will be intersting to try something new from you.
I possibly figured out why the left caliper pads were dragging. Bleeding (it was firm as it was) did nothing and all was seemingly correct except the pads seemed high down the middle after I had resurfaced them. To be sure the caliper were not cocked I also ground some more clearance and repainted while still attached by the hose; i.e. free of interference withthe side of the lower caliper bracket on the OE fork slider. Now after taking a MSF ERC yesterday (free in IL and 8 hours of simpleton exercises but a $60+ premium discount) the pads appear bedded flat, and while still dragging (which the OE set-up also did), the left is running as cool as the right. I wish I had the shekels for a new set of pads but it is 2-finger now with the RC51 MC and F4i calipers, though some AM pads like EBC or DP may have more initial bite. I run SBS lower-friction rear pads as I like less rear slip in panic stops; they actually have you try to rear slide only in the ERC.
The ERC was attended by practically all Navy RTC related instructer/based types up at GLNSTC; which is 22 miles from where I live. Bush Sr crashed in Lake Michigan while up at GLNSTC and my ex-father also went thru there in WW2. There are a bunch of trainer planes in the water still. They launched and landed off a side paddle wheel converted to a flat top. With all the base closings, besides GLNSTC, how many RTCs are left?
http://en.wikipedia.org/wiki/United_States_Navy
http://travel.webshots.com/album/54222390ZCxoOC http://www.nsgreatlakes.navy.mil/faq.htm
Last edited by skokievtr; 05-11-2008 at 03:19 PM.
05-11-2008, 03:28 PM
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Ah...I said, "The stock VTR compression valve has no bleed hole." I never said I didn't modify them!
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
Look at the valve I posted a pic of. That just happens to be a rebound valve but the compression valve is almost identical. Now the side that I have a pic of is the check valve side. The other side has the shim stack. Notice how the smaller holes go to the other side. Now, imagine a small hole that bypasses the check valve side. That is the "bleed". If you hit a bump large enough the small bypass bleed hole will go to "orifice flow" and the shim stack will blow open. Now imagine a huge bump with very high compression speeds and you're flowing so much oil that the four small holes in the valve (not the bleed) go to orifice flow. Stock forks with 10wt oil can do this, which to the rider feels like the forks have locked up. Moving to a 5wt oil helps a lot here.
Understood with the rest of it.
05-12-2008, 07:53 AM
#24
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Join Date: Dec 2005
Location: South Lake Tahoe, CA, USA
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I didn't get an email - it's probably not listed.
But, without being too long-winded:
I'm having a hard time seeing why you want more compression damping stiffness, when you are adding spring stiffness.
I understand the need for more rebound stiffness. On rebound the spring and damper work in opposite directions.
The rebound velocity is not constant. If it was, the shim stack would not open. A higher spring force, results in higher velocity, damping keeps it in check by varying with velocity.
And no, that check valve was not working. Hard to tune the orifice damping, if the check valve is bypassing.
Thanks for the discussion. Good stuff.
RC
But, without being too long-winded:
I'm having a hard time seeing why you want more compression damping stiffness, when you are adding spring stiffness.
I understand the need for more rebound stiffness. On rebound the spring and damper work in opposite directions.
The rebound velocity is not constant. If it was, the shim stack would not open. A higher spring force, results in higher velocity, damping keeps it in check by varying with velocity.
And no, that check valve was not working. Hard to tune the orifice damping, if the check valve is bypassing.
Thanks for the discussion. Good stuff.
RC
05-12-2008, 08:52 PM
#27
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Location: Fulton, MO
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Ah, regarding the RTCs? I'm pretty sure there is only one now, and that is Great Lakes (or Great Mistakes as some folks like to call it 
). I went to Orlando a loooooong time ago.
Oh, and I'm surprised you don't have problems with the 15wt. Of course, not all 15wts are created equal. Hell, there are 10wts that are spec'd the same as some 5wts!
). I went to Orlando a loooooong time ago. Oh, and I'm surprised you don't have problems with the 15wt. Of course, not all 15wts are created equal. Hell, there are 10wts that are spec'd the same as some 5wts!
05-13-2008, 09:04 AM
#28
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Join Date: Dec 2005
Location: South Lake Tahoe, CA, USA
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I forgot I even had that account! Don't know what it is. I think I tried to access it a long time ago and couldn't get in.
Anyway, I was laying in bed last night, thinking about the compression damping thing. I think I figured out what I was missing.
I had to remember the basic role of the spring, which is to define the attitude of the chassis in steady-state. For a track setup, you want to use all off the travel at the highest load. Basically, the suspension is completely compressed under maximum braking load, where the rear wheel starts to lift.
So the spring defines the suspension position, damping defines how it gets there. By going to a lighter oil, you get faster weight transfer under braking, and a side benefit of more suppleness over small stuff. But the shim stack defines how the suspension reacts over higher speed inputs, providing the level of feedback the rider feels. A stiffer stack gives a more taut feel from the front end.
Am I on the right track? I think I might be close to a passing grade for Suspension 101:Fundamentals. I hope I'm getting close to ready for Suspension 201:Tuning.
I'm going to buy some Mojito fixin's and go to Bob's house with a list of questions.
Anyway, I was laying in bed last night, thinking about the compression damping thing. I think I figured out what I was missing.
I had to remember the basic role of the spring, which is to define the attitude of the chassis in steady-state. For a track setup, you want to use all off the travel at the highest load. Basically, the suspension is completely compressed under maximum braking load, where the rear wheel starts to lift.
So the spring defines the suspension position, damping defines how it gets there. By going to a lighter oil, you get faster weight transfer under braking, and a side benefit of more suppleness over small stuff. But the shim stack defines how the suspension reacts over higher speed inputs, providing the level of feedback the rider feels. A stiffer stack gives a more taut feel from the front end.
Am I on the right track? I think I might be close to a passing grade for Suspension 101:Fundamentals. I hope I'm getting close to ready for Suspension 201:Tuning.
I'm going to buy some Mojito fixin's and go to Bob's house with a list of questions.
Last edited by RCVTR; 05-13-2008 at 11:11 AM.
05-13-2008, 11:10 AM
#29
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One more question:
The low-speed compression orifice has a 12mm shim. Is this just a check valve, to prevent backflow during rebound, or is it a compression flow control.
My RC51 valves have adjustable needle-orifice for LSCD. I haven't looked for a LS check valve.
The low-speed compression orifice has a 12mm shim. Is this just a check valve, to prevent backflow during rebound, or is it a compression flow control.
My RC51 valves have adjustable needle-orifice for LSCD. I haven't looked for a LS check valve.
05-13-2008, 06:44 PM
#30
OUCH... MY A$$ HURTS!!!
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Join Date: Dec 2007
Location: Elba, Ny
Posts: 707
FINALLY got to ride today... Yah...
Bike felt great... Only wish my nerve would catch up... Its like every moment while riding i'm being paranoid that something is not feeling right or something..
Anyway... The bike feels SO much better riding down the horrible roads around here. I no longer feel like the bike is falling apart each time I go over a small bump... Front is very responsive..
Bike felt great... Only wish my nerve would catch up... Its like every moment while riding i'm being paranoid that something is not feeling right or something..
Anyway... The bike feels SO much better riding down the horrible roads around here. I no longer feel like the bike is falling apart each time I go over a small bump... Front is very responsive..
