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  #111  
Old 24th March 2015
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Quote:
Okay, but when you do, let me know why the CB700SC rides so wonderful on 1.1 KG/mm linear rate springs. I have oem VTR1000 cartridges and am running 10wt oil. The bike weighs in at about 525 lbs, so its 75 lbs lighter.

Standing by...
Yea, I plan to, but first I have a question, does the Honda have stock damper rod suspension in the forks? and which cartridges are you referring to, forks or shocks?
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Former Ricor test rider for IAS Shocks, Intiminators and Vibranators. Works Dual Rate fork springs, fork brace, Avon Venom X tires, loosen drive belt, and set frame rails level to floor. Read the "7 Pages of Suspension" thread in the Suspension Sticky Index to learn how to fix your suspension.
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  #112  
Old 24th March 2015
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The Honda had stock damper rods, but had an antidive subsystem (TRAC) on the left fork. I upgraded the 39mm stanchions to 41mm ones. That allowed me to use a Honda VTR1100 Superhawk fork lowers with accompanying cartridges. It only has rebound adjustability. I found I did not have to change the stack. Belray 10wt oil. Also, the forks were super long, like 36 or 37" long from top to axle center.

If you get this sorted out, You can tell me about how my 90 Honda PC800 is working with same stiff spring. It came with a damper rod set up too with a TRAC antidive function. I did have a ST1100 front end on for a while, but the stock ST1100 stanchions were too long. So, I got a good deal on a CBR600 F4 front end. A fellow PC rider in Utah machined the stanchions to shorten them up as well as modify the triple tree to accept the 43mm forks. It has some compression damping adjustability; the CBR 600 cartridge is like the VTR cartridges. I never took apart the shim stack to verify if they were set up the same.

Here is a pic of the PC800 test mule I had, I called it Mr Hyde, the other PC was Dr Jekyll. In the pic you can see the wheels I swapped out to (from a VT650V) and the VT1100 engine I was trying to shoehorn in the bike. Once done, all the mods were to go into the other PC. I was never able to get the VT1100 engine to fit right. I only transfered the suspension and braking mods over.


This was a pic of the PC800 with the ST1100 front end/brakes.


Jerry
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  #113  
Old 24th March 2015
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Default More CB700SC Data

XLXR,

I don't have access to all the work done on the CB700SC, but I did download all the pics I posted before the old Nighthawk site went down.

Here is the pic of the springs in the oem forks. I don't know if they were original equipment. I do know they were not properly set up and they soggy.
You can see the rates are close to yours (a bit stiffer on the upper end)


Here is a pic of the racetech springs. I was wrong about them being 1.1 KG/mm, they were 1.2 KG/mm.


Jerry
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  #114  
Old 24th March 2015
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Oops,

You will have caught my error on he progressive spring graph. The dotted line is the test line on the weight equipment. When I adjusted the curve for correct preload, I shifted the curve to the right; they are the solid lines.

My error was shifting them to the right. I should have shifted the lines down till the dotted line meets the red arrow head. That shift would still keep the inflection point at about 165 lbs. The peak load capacity would be about 325 lbs.

BTW, did you notice the preload amount is close to what I need for the sportster; 105lbs for the Nighthawk vs 122lbs for the Sportster? Its because the Nighthawk has about a rake equal to the XL1200T (~31 degrees) and the weights are close with the sportster about 50 lbs or 10% heavier.

This looks like the kind of spring you would use? If I don't get the ordered springs to work, I can ride down to the lake house and pull these springs from the oem Nighthawk forks.

Jerry
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  #115  
Old 24th March 2015
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Quote:
The Honda had stock damper rods, but had an antidive subsystem (TRAC) on the left fork.
Is that an extra hydraulic circuit that kicks in just before the forks bottom out to soften harsh bottoming?
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  #116  
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No, I think it kicks in much earlier so the fork does not dive over. Its sort of is the opposite of the Intiminators. Once it senses the front brakes coming on strong, it changes the compression valving to keep that fork from compressing, it was not on both forks. The Intiminators sense a strong compression force and rechannels the force through a different fluid circuit that has little to no compression damping.

Google Honda TRAC (torque reactive anti-dive control) and you can find more info on this system used in the 80's into the early 90's.

Jerry

Edit: Here is a nice write up from a Goldwing site:
Honda's Torque Reactive Anti-Dive Control (TRAC) system actuates differently than the Suzuki and Yamaha anti-dive front ends. Those setups use front brake hydraulic pressure to control a valve that closes the fork's compression-damping oilways, and they can have two drawbacks. First, additional brake-line plumbing and increased brake-lever ratios can produce a spongy feeling at the brake lever. Second, those systems are either on or off - there's no modulation of antidive effect.

Instead of being triggered by a rise in brake-fluid pressure, Honda's TRAC activates mechanically-independent of brake-system hydraulics-through the torque reaction of the brake caliper. The brake caliper hinges behind the fork leg on a pivoting link. When the pads grip the disc surface, the disc tries to drag the caliper around with it. The caliper pivots, pressing against the anti-dive mechanism's activating valve and closing off the fork's compression-damping oil passage. This valve, in the shape of a piston, is normally held open by a spring. In a very simple non-TRAC system, applying the front brake would cause a valve to close and increase compression damping, which would reduce front-end “dive”.

TRAC is more elaborate. Forward weight transfer during braking compresses the fork, raising fork oil pressure against the underside of the TRAC activating valve and, through the valve, pushing against the caliper's braking torque. These two opposing forces - fork-oil pressure and braking torque - interact through the valve to provide progressive anti-dive. Hitting a bump causes a sharp pressure rise in the fork. This rise can cause the valve to push hard enough against the opposing force of the caliper to open, partially or fully, the normal compression-damping passageway. This opening allows the fork to respond to a bump. Moreover, TRAC's design provides a constant modulation between fork anti-dive and bump response.

Not everyone wants or likes a certain anti-dive setting. A rider can dial in the anti-dive effect with a four-position adjustment on the fork leg. The adjuster controls a small secondary oil passageway parallel to the main compression damping passageway. This secondary passageway provides a way to bleed-off fork-oil pressure from under the anti-dive valve. The rates at which this bleed-off occurs are controlled by orifices, the size of which can be controlled by the external adjuster. Position 1 corresponds to the largest orifice, which offers the least resistance to the passage of fork compression-damping oil; positions 2 and 3 expose progressively smaller, more restrictive orifices, increasing fork damping pressure. Position 4 exposes no hole; all fork-oil pressure comes to bear on the valve's underside and against the braking torque.

Normally, a fork has much lighter compression damping (one-fourth) than rebound damping. In the TRAC system, when the anti-dive seals off the main compression-damping passageway, compression damping becomes two or three times stiffer than normal when the adjuster is set on position one. On successive settings the compression-to-rebound damping ratios become increasingly biased toward compression.

So much for theory, how is it on the road? There is little feeling of anti-dive effect when the adjustable orifice is set on position 1; the fork compresses much like a conventional fork under hard braking, but there's some travel available for bump response. On position 2 the fork resists the front-end braking dive, and the fork's bump response is firmer. The difference is small but obvious. Position 3 gives a noticeably larger increase in anti-dive effect, producing firmer resistance to front-end squat from braking and stiffened reaction to bumps. The fork still dips when the brakes are applied, but slower; it still responds to bumps, but it delivers a firmer jolt. Position 4 produces more substantial effect in the same direction.

Riders who use their front brakes without any particular vigor will find the first two positions useful. These allow the fork to respond nicely to bumps during braking while giving a wonderfully smooth cruising ride. Our staff testers preferred position 3 for rush-about riding. It provides a measure of squat resistance and yet responds nicely to most surface whoops. Those who stand their motorcycles on headlamps during braking will like position 4. It gives generous resistance to front-end dive and responds to hard bumps.
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  #117  
Old 25th March 2015
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First question: In your learning curve about motorcycle suspension, when and how did you make the conclusion / assumption that motorcycle suspension works best when linear?

I learned suspension over about 30 years riding. When I started with dirt bikes, I had to modify all my suspensions because of my weight. My first career was as a diesel and automotive mechanic, so I ended up being an endless tinkerer.

When setting up suspension on my bikes, I go through a lot of the same basic measurements and start with some basic set up. Then I test ride and make changes to tune out the worst characteristic, and I make one change at a time, and repeat and repeat about a million times until I get it the way I want it. See my avatar, all that stuff is related to my Sportster. It all starts with a spring rate, then I try a softer spring rate. I try to get that softer spring rate to work by adjusting preload, oil viscosity, oil height because I consider those aspects fine tuning of suspension. If I cannot get the lighter spring to work for me by with preload, oil viscosity and oil height, then I know that I have to go back to the next heavier spring, and that spring is the lightest possible spring that will work for me. The lightest possible spring provides the most compliant ride. In my opinion, stiff suspension is not good suspension, compliant suspension set to match road conditions, rider weight and technique is way better.

When I had adjustable forks and shocks, I would work through in those aspects as well. I have bought new adjustable shocks and set them back several times to get the dampening curves the way I liked, matching spring rates etc. I have a $1,000 pair of WP (the European company) 3 way adjustable shocks sitting on the shelf because they were never right.

Two points here. At some point suspension tuning has to leave graphs and move towards test riding. Second, everyone has their own definition of what good suspension is. I seriously doubt I would like your suspension set ups. I know I would not like the Sportster, been there, done that. But I do not have any experience with those Honda's so I cannot comment about them. Well, I can. Weight alone does not represent all the factors in determining proper spring rates for different bikes. Stacking of tolerances, lots of little things adding up to make a big difference, is the easiest way to I can think to explain why.

The TRAC system is interesting, but could be dangerous if set up too stiff and the front end starts hopping over braking bumps in the road. But that is also possible with too stiff springs, too high oil viscosity, too high oil level.

Quote:
It gives generous resistance to front-end dive and responds to hard bumps.
This statement is what scares me. Too stiff over big bumps may mean wheel hopping and loss of traction over small bumps. This gets into the difference between high and low speed compression dampening, which one, or both, are affected by TRAC? I don't really care because I will never use it.

Answering some of your questions; I use schedule 80 PVC for preload spacers because every place metal touches metal, such as between washer and a metal spacer, the metal surface gets ground up and puts small metal filings in the oil.

Changing from one viscosity to another, 5 to 10, or 10 to 15, or 15 to 20 w fork oil, in a Sportster, does not make as much difference as changing from one spring rate to the next. Generally, with Sportster dampener rods suspension, a 2.5 change in viscosity is not making enough difference to be able to feel the difference, 5 to 20 is a huge difference, more than changing one spring rate.

I never recommend using less than stock oil levels in the forks. The less oil, the quicker it will get contaminated and/or break down, and less resistance to heat build up, and more likely to have foaming and cavitation problems. I have no ideas what the minimum oil level is that won't start sucking air in to the damper tube.

Probably the most telling comment you have made about suspension is that you are OK with having to ride around bad spots in the road. Not me, I aim for the bad stuff, don't care, I frequently ride on roads so poor only adventure bikes ride on them.

Ricor Intiminators work best with spring rates one lighter than normally recommended without them, 5w oil, preferably Amsoil synthetic. I encourage guys to get some good test riding done, hit the biggest bump they ever hit to see if fork bottoms out or not, measure rider sag and fork oil height before taking their forks apart. I recommend the start with stock oil levels, that means sucking out a bit of oil after adding Intiminators, set rider sag correctly, 1/3 to 1/4 total travel, then test ride and determine what adjustments to make from that point.

With Intiminators, you do not drill out the compression dampening rod holes. Changing to 5w oil reduces rebound dampening.

With Intiminators, a portion of control of the fork compression is taken away from the spring and given to the hydraulic circuits in the Intiminators. The inertia circuit, blows off high speed compression dampening in reaction to vertical wheel movement. The chassis circuit has much higher (slow speed) compression damping than normal cartridge systems. The result is very fast vertical wheel movement that acts like a spike on a otherwise straight line of chassis movement. The wheel moves up, not the chassis.

On a smooth road, no bumps, when you hit the front brakes, the Intiminator chassis hydraulic circuit, which is a shim stack, provides much higher than normal slow speed compression dampening to reduce fork dive. In this example, the inertia valve stays closed because there is not any vertical wheel movement.

With Intiminators in the forks, the inertia valve reduces high speed compression dampening. With Ricor IAS shocks, the inertia valve is on the rebound circuit. In shocks, the inertia valve allows very fast downward wheel movement when the wheel is in the air with the bike. But the slow speed / chassis circuit kicks in when the shocks are compressed, weight of bike and wheel on the ground, and controls chassis movement in the up, shock extending, direction of the chassis.

Bottom line, when properly set up, Ricor Intiminators and their IAS shocks allow for much faster wheel movement in up and down directions, with different dampening characteristics in relation to wheel direction of movement vs chassis movement.

Pics of my (totaled a few years ago) 2005 Ducati Multistrada with factory Ohlins highly modified by one of the best west coast Ohlins tuner. And my Honda XR 650 (sold a few years ago) highly modified suspension for desert racing, 99.9 mph on a dirt road all day long. Rubber mount Sportsters were once thought of as the worst suspended bike ever made. My Ricor suspended Sportster is just as good as those two bikes.

Last edited by XLXR; 25th March 2015 at 08:03..
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  #118  
Old 26th March 2015
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A comment here to all the readers, I'm not posting all this stuff as I sort out my suspension so you will do the same thing I am doing. It is my hope that some of the things I post can help some of you as you sort out your rides. There are several things I will do when I sort out my suspension that is different from what others have done, so I try to document the finer aspects of what I'm doing so you can understand what I'm trying to do and why.

XLXR - I appreciate you taking the time to banter back and forth as it makes keeping the thread up to date with the progress on the effort. So here are my thoughts to your comments.


First question: In your learning curve about motorcycle suspension, when and how did you make the conclusion / assumption that motorcycle suspension works best when linear?
I would NOT say it was the best; I would say it was my preference. As you indicated earlier, this kinds of choices are a riders preference. Riders of all skill levels favor both sides of the fence. I have 2 reasons it is my preference: I don't have to worry about the abrupt suspension transition changes while riding in the twisties but most important, I have 8 motorcycles and keeping track of how each is tuned to ride would be a pain if they were all tuned differently. By keeping them the same, I know how they all ride.

I learned suspension over about 30 years riding. When I started with dirt bikes, I had to modify all my suspensions because of my weight. My first career was as a diesel and automotive mechanic, so I ended up being an endless tinkerer.
We have similar paths; we're not that different in age too.

When setting up suspension on my bikes, I go through a lot of the same basic measurements and start with some basic set up. Then I test ride and make changes to tune out the worst characteristic, and I make one change at a time, and repeat and repeat about a million times until I get it the way I want it. See my avatar, all that stuff is related to my Sportster. It all starts with a spring rate, then I try a softer spring rate. I try to get that softer spring rate to work by adjusting preload, oil viscosity, oil height because I consider those aspects fine tuning of suspension. If I cannot get the lighter spring to work for me by with preload, oil viscosity and oil height, then I know that I have to go back to the next heavier spring, and that spring is the lightest possible spring that will work for me. The lightest possible spring provides the most compliant ride. In my opinion, stiff suspension is not good suspension, compliant suspension set to match road conditions, rider weight and technique is way better.
I do the same thing, but I try NOT to think of the spring not just the steel spring.

When I had adjustable forks and shocks, I would work through in those aspects as well. I have bought new adjustable shocks and set them back several times to get the dampening curves the way I liked, matching spring rates etc. I have a $1,000 pair of WP (the European company) 3 way adjustable shocks sitting on the shelf because they were never right.
What do you want for them... :-)

Two points here. At some point suspension tuning has to leave graphs and move towards test riding. Yes Second, everyone has their own definition of what good suspension is. I would not use the term "good", but "preference"... I seriously doubt I would like your suspension set ups. That is okay as I'm not doing it for you but for me. I'd bet there are lots of riders that might not like mine, but they might not like yours either; I'd guess they all like theirs - for the most part. I suspect there are many that don't know what to do but are unhappy with their current set up. I know I would not like the Sportster, been there, done that. But I do not have any experience with those Honda's so I cannot comment about them. Well, I can. Weight alone does not represent all the factors in determining proper spring rates for different bikes. Stacking of tolerances, lots of little things adding up to make a big difference, is the easiest way to I can think to explain why.
Except for a few odd ball suspensions, most bikes are the same. In looking over the Nighthawk I worked on a few years ago, it appears to have more in common with the Sportster than I would have guessed.

The TRAC system is interesting, but could be dangerous if set up too stiff and the front end starts hopping over braking bumps in the road. But that is also possible with too stiff springs, too high oil viscosity, too high oil level.
The one thing you can count on, Honda engineering is awesome. They would not have put out an unsafe design. With the longer 39mm forks, you could swap out a set on the sportster that you wanted to extend out the forks (about 6" longer than HD oem forks). I would be curious how the Ricor Intiminators work with the TRAC system.

This statement is what scares me. Too stiff over big bumps may mean wheel hopping and loss of traction over small bumps. This gets into the difference between high and low speed compression dampening, which one, or both, are affected by TRAC? I don't really care because I will never use it.

Answering some of your questions; I use schedule 80 PVC for preload spacers because every place metal touches metal, such as between washer and a metal spacer, the metal surface gets ground up and puts small metal filings in the oil.
Given the procedure to fill the fork oil level, how do you account for the volume of the 80 PVC spacers? They take up much more volume within the fork. That is why the factory uses the thin walled steel preload spacers. It might not seem like much, but it doen't take much to increase the rate and make the upper end much stiffer.

Changing from one viscosity to another, 5 to 10, or 10 to 15, or 15 to 20 w fork oil, in a Sportster, does not make as much difference as changing from one spring rate to the next. Generally, with Sportster dampener rods suspension, a 2.5 change in viscosity is not making enough difference to be able to feel the difference, 5 to 20 is a huge difference, more than changing one spring rate.
Do you mean to say "... feel a difference..."?

I never recommend using less than stock oil levels in the forks. The less oil, the quicker it will get contaminated and/or break down, and less resistance to heat build up, and more likely to have foaming and cavitation problems. I have no ideas what the minimum oil level is that won't start sucking air in to the damper tube.
Stay tuned - no pun intended. I think this is worth lerning as you have given guidance to add additional oil. I think it would be good to know what happens on the other end. You might reconsider some things.

Probably the most telling comment you have made about suspension is that you are OK with having to ride around bad spots in the road. Not me, I aim for the bad stuff, don't care, I frequently ride on roads so poor only adventure bikes ride on them.
You must not have bad/big pot holes around where you live. Noone should ride into a pothole if they can help it. Just because you can, does not mean you should.

Ricor Intiminators work best with spring rates one lighter than normally recommended without them, 5w oil, preferably Amsoil synthetic. I encourage guys to get some good test riding done, hit the biggest bump they ever hit to see if fork bottoms out or not, measure rider sag and fork oil height before taking their forks apart. I recommend the start with stock oil levels, that means sucking out a bit of oil after adding Intiminators, set rider sag correctly, 1/3 to 1/4 total travel, then test ride and determine what adjustments to make from that point.

With Intiminators, you do not drill out the compression dampening rod holes. Changing to 5w oil reduces rebound dampening.
I want more rebound damping, not less.

With Intiminators, a portion of control of the fork compression is taken away from the spring and given to the hydraulic circuits in the Intiminators. The inertia circuit, blows off high speed compression dampening in reaction to vertical wheel movement. The chassis circuit has much higher (slow speed) compression damping than normal cartridge systems. The result is very fast vertical wheel movement that acts like a spike on a otherwise straight line of chassis movement. The wheel moves up, not the chassis.

On a smooth road, no bumps, when you hit the front brakes, the Intiminator chassis hydraulic circuit, which is a shim stack, provides much higher than normal slow speed compression dampening to reduce fork dive. In this example, the inertia valve stays closed because there is not any vertical wheel movement.

With Intiminators in the forks, the inertia valve reduces high speed compression dampening. With Ricor IAS shocks, the inertia valve is on the rebound circuit. In shocks, the inertia valve allows very fast downward wheel movement when the wheel is in the air with the bike. But the slow speed / chassis circuit kicks in when the shocks are compressed, weight of bike and wheel on the ground, and controls chassis movement in the up, shock extending, direction of the chassis.
This explanation continues to reinforce this is a compression damping devise. It might be the best compression damping devise out there, but what do you do if you have an interest to meet all the bike's need.

Bottom line, when properly set up, Ricor Intiminators and their IAS shocks allow for much faster wheel movement in up and down directions, with different dampening characteristics in relation to wheel direction of movement vs chassis movement.
But what if you want a different brand of cool-aid?

Pics of my (totaled a few years ago) 2005 Ducati Multistrada with factory Ohlins highly modified by one of the best west coast Ohlins tuner. And my Honda XR 650 (sold a few years ago) highly modified suspension for desert racing, 99.9 mph on a dirt road all day long. Rubber mount Sportsters were once thought of as the worst suspended bike ever made. My Ricor suspended Sportster is just as good as those two bikes.[/QUOTE]
Cool

I hope to make some good progress this weekend if I get my parts in by this Friday.

Jerry
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Old 26th March 2015
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I have a $1,000 pair of WP (the European company) 3 way adjustable shocks sitting on the shelf because they were never right.
What do you want for them... :-)
Make me an offer, they have about 2,000 miles on them, scratched up a bit because they were taken apart so many times for re-valving. You would probably like them, I have two or three different springs to match.


Quote:
I would be curious how the Ricor Intiminators work with the TRAC system.
The complexity of trying to tune each to match the other would not be worth the effort. Intiminators are for damper rod forks only, I assume the TRAC system is on cartridge systems only.

Quote:
This explanation continues to reinforce this is a compression damping devise. It might be the best compression damping devise out there, but what do you do if you have an interest to meet all the bike's need.

But what if you want a different brand of cool-aid?
Well, you are kind of missing the point that setting up the suspension to be the best it can be is considerably different from setting up suspension so you have to ride to miss the bad spots in the road. So, the only thing left for you to do is take a ride to Southern California one day and we can do bike to bike comparison.

Last edited by XLXR; 26th March 2015 at 04:30..
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  #120  
Old 26th March 2015
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Make me an offer, they have about 2,000 miles on them, scratched up a bit because they were taken apart so many times for re-valving.
Let me see how my current XL1200S plans works out. I figured they are not going away in the next 2 months. Is there anything else you can tell me about the shocks; spring rates, damping adjustability?


The complexity of trying to tune each to match the other would not be worth the effort. Intiminators are for damper rod forks only, I assume the TRAC system is on cartridge systems only.
No, the TRAC was on damper rod suspensions only. the TRAC system is connected to the braking system from a mechanical standpoint. An easy way to test them would be to use the Intiminators on Nighthawk bikes. If you never touch the front brakes, the Intiminators behave like you know them. Once you hit the front brakes hard, they invoke a different fork oil path to cause that fork compression path to be different the slows the compression, kind of a reverse of what the Intiminators are trying to do. If you could sort that out, the TRAC might solve the nosedive you might be experiencing(?).

Jerry
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