[choaderboy2]

All the curves I have ever seen from koni's are digressive. It's a matter of degree. Plus, one curve does not tell the tale. Would you rate your first Truechoice setup as better then the AGX's you had before? It was not as digressive but you said it was worlds better then the AGX's and it was the old 8611 style with too much compression dampening. What it boils down to is for nearlly the same amount of money as a set of AGX's you can get a shorter strut. Thats the biggest deal. AND (if you pick the right strut) for $135 a corner you can get a strut that will easily handle 450lb springs and is several inch's shorter then AGX's and has less compression dampending then your original 8611. You may say the AGX's have a better dyno curve. But on the road and the track you can't get a car to handle as well with AGX, not by a long shot. They are simply to long and don't have the ability of the Koni's for rebound control. Plus, AGX's seem to shock the tires too much on the street. B13's in particular like to get bouncy with them. Thats not good handling is it?

The dyno cuve I have for the AGX is more digressive than the one I have seen for the koni red for instance.

Of course the truechoice is better, it has well travel and enough damping for the spring rates. The AGX shock is better for near stock ride height. My Truechoice suspension does not have the STD 8611 compression damping, it has around 120 lbs compression damping on soft and about 200 lbs full stiff.

The AGX's I have seen that are boncy are because the car is too low/no travel, shock is blown because of running to low, etc. The AGX/Hyperco second gen does not seem bouncy to me.

I havent tried your Maxima combo. The shortened Sentra Koni red is underdamped.

 

[98sr20ve]

Back in the day, the B13 front was the only option commonly tired. Now we have Spec V and Maxima inserts. Even back then the standard SE-R fronts are ok up to the 325lb range. Thats the setup Matt (a very good instructor) is using on his SE-R on a roadcourse.
http://www.sr20forum.com/showthread.php?t=47637
But, knowing what I know now, I recommend the SpecV insert. The cost is less then $10 more.
BTW, the Maxima insert ($135 from tirerack) as tested by Koni has nearly the same starting rebound dampening as the 8611 but with out the overly stiff compression portion. It's my favorite setup for the front. The B14 Koni front has about 10% less starting dampening as the 8611 and makes a great rear unit for a B13 GC car. In the end my criteria for a shock are:

1 Shorter then stock
2 Adjustable
3 Easily Revalvable
4 Of a know high Quality
5 Adaptable to a variety of setups
6 Race Proven
7 Will survive a daily driver

Very few shocks make that list. VERY, VERY few.

And all this talk of Digressive dampening curves kinda makes me wonder about all the SE-R Cup cars running Koni's in the past. Take a look at the Advance Design setup.
http://honda-tech.com/zerothread/1104049
It's not even that digressive (I know it's tunable). Like I said in my post a little while back. There is a heck of a lot more in picking a damper then just looking at a dyno curve. I will take "1 inch plus shorter then stock Koni" over the AGX setup any day of the week on a lowered car. If I was to build up any B13/14/15 my first and only choice would be either a set of Spec V or Maxima/B14 setup depending on the springs I was using. I would recommend Progress stuff, but I'm still mad at progress for making my S13 swaybar wrong and not replacing it. I can't imagine buying a $1200 setup of coilovers and getting the same service I have recieved with my simple to make but poorly made swaybar. I will stick with recommending Koni's as they are proven to be a reliable long term performer with great customer service. Just to be clear, it's not "my Maxima" setup in the sense that you have to pay me to get it done. I have posted how to do all this stuff on your own. It's off the shelf simple

 

[choaderboy2]

Back in the day, the B13 front was the only option commonly tired. Now we have Spec V and Maxima inserts. Even back then the standard SE-R fronts are ok up to the 325lb range. Thats the setup Matt (a very good instructor) is using on his SE-R on a roadcourse.
http://www.sr20forum.com/showthread.php?t=47637
But, knowing what I know now, I recommend the SpecV insert. The cost is less then $10 more.
BTW, the Maxima insert ($135 from tirerack) as tested by Koni has nearly the same starting rebound dampening as the 8611 but with out the overly stiff compression portion. It's my favorite setup for the front. The B14 Koni front has about 10% less starting dampening as the 8611 and makes a great rear unit for a B13 GC car. In the end my criteria for a shock are:

1 Shorter then stock
2 Adjustable
3 Easily Revalvable
4 Of a know high Quality
5 Adaptable to a variety of setups
6 Race Proven
7 Will survive a daily driver

Very few shocks make that list. VERY, VERY few.

And all this talk of Digressive dampening curves kinda makes me wonder about all the SE-R Cup cars running Koni's in the past. Take a look at the Advance Design setup.
http://honda-tech.com/zerothread/1104049
It's not even that digressive (I know it's tunable). Like I said in my post a little while back. There is a heck of a lot more in picking a damper then just looking at a dyno curve. I will take "1 inch plus shorter then stock Koni" over the AGX setup any day of the week on a lowered car. If I was to build up any B13/14/15 my first and only choice would be either a set of Spec V or Maxima/B14 setup depending on the springs I was using. I would recommend Progress stuff, but I'm still mad at progress for making my S13 swaybar wrong and not replacing it. I can't imagine buying a $1200 setup of coilovers and getting the same service I have recieved with my simple to make but poorly made swaybar. I will stick with recommending Koni's as they are proven to be a reliable long term performer with great customer service. Just to be clear, it's not "my Maxima" setup in the sense that you have to pay me to get it done. I have posted how to do all this stuff on your own. It's off the shelf simple

The AD chart supplied looks pretty digressive to me. Look how steep the curve is in the 1-2" veloctiy range. In fact it looks slightly more digressive than my front SE-R cup spec and definatly more than my rear spec curves.

But look at Koni reds.

Most modern shocks can be made more digressive, since blow off valves have been added to the circuits.

Results also vary on who is setting up the car to a great deal

Here is a pic of Tom Paules AD equppied car hitting the FIA curbs. Note its bouncing off the ground. The shocks are the old AD valving and Tom is really bad at shock setup. He is such a good driver that minor details like that don't bother him! Following him I could see his car hopping and bounding off of the curbs and bobbing in the rough coners. You can see how much the chassis is upset by the cars attitude and how its heeling over.

As a contrast, Annie Sams old style 8611's in the same turn with the same hit. Its planted. Look how flat the body is at close to max G. This car was the first I tried harmonics tuning on and is set up really well. A lot of attention was paid to the chassis set up on this car. Now its not as good because of changes to the front spring rates. This car works exceddingly well with "old" technology shocks.

Finaly my car with custom spec AD valving. I really clouted the curbs trying to shave every bit off of the track during a time attack. Look how the wheels are all on the ground and the chassis isnt even upset. This is an exccedingly hard hit as well, most other car are launched on two wheels when you do this sort of stuff. Look at the bodys attitude and how flat it is even though the car is at max G here. When my car hits curbs, its a gentile bloop and it goes on, its not a big bounce and slide. Sometimes I even hook my inside tires on the inside of the curbs to try and get more speed. Well set up dampers allow this with little drama.

So how a damper works isnt exatly related to brand. This is what Steve is alluding to. If you are good at tuning what you have, you can make things work.

 

[Shawn B]

So how a damper works isnt exatly related to brand. This is what Steve is alluding to. If you are good at tuning what you have, you can make things work.

Great discussion guys.

Could one of you brainiacs please enlighten me (the forum) on the suspension differences between the three chassis?

I got the B13, McPhereson struts X 4, IRS, blah, blah, blah. I quoted someone.

The B14 has a rear beam instead of IRS with McPherson struts. The beam needs to be bent (already linked a couple of threads on that). The B14 has some issue with less travel (?) in the rear that is different than a B13. Maybe....I think.

And that is the sum total of my knowledge.

Can one of you guys not only explain the differences but what it means from an enthusiasts standpoint? A "Readers Digest" version of what your average forum head needs to know.

Gracias.

 

[choaderboy2]

Great discussion guys.

Could one of you brainiacs please enlighten me (the forum) on the suspension differences between the three chassis?

I got the B13, McPhereson struts X 4, IRS, blah, blah, blah. I quoted someone.

The B14 has a rear beam instead of IRS with McPherson struts. The beam needs to be bent (already linked a couple of threads on that). The B14 has some issue with less travel (?) in the rear that is different than a B13. Maybe....I think.

And that is the sum total of my knowledge.

Can one of you guys not only explain the differences but what it means from an enthusiasts standpoint? A "Readers Digest" version of what your average forum head needs to know.

Gracias.

The B13/B14 front suspension is virturaly identical. The B14 rear suspension works but has some inherit flaws, mostly a super high roll center. B14's require beam bending and a lot of rear roll stiffness to work.

When sused out B14's handle pretty good.

 

[98sr20ve]

So how a damper works isnt exatly related to brand. This is what Steve is alluding to. If you are good at tuning what you have, you can make things work.

Unless you don't have enough shaft travel. Then it's kinda a lost cause. Hence my confusion of you recommending AGX's again all of a sudden.

 

[choaderboy2]

Unless you don't have enough shaft travel. Then it's kinda a lost cause. Hence my confusion of you recommending AGX's again all of a sudden.

I like them for near stock ride height. For sure not lowered.

 

[mpg9999]

Please clarify for me your statements.

1) So...no harness with just a harness bar? You should have a full roll bar and race bucket if you are going to use a harness? Then what is the point of a harness bar? You should only use a harness bar if you have a roll bar and race bucket? :melonscratcher:

2) Uh....yup.

I think I am missing something, I know you are light-years ahead of me mechanically. Please elucidate further sir, keep in mind my high ignorance level.

Sorry for the late reply, I completely forgot about replying to this. Anyways, yes, you should not run a harness without a roll bar. The reasoning is if the car rolls and your strapped in, your body can not move out of the way if the roof caves in. With the stock three point seat belts you can. So basically the only harness bar you should be using is one thats on a roll bar.

 

[mpg9999]

My latest stuff is based on experiances gained working with Motorsports and Nismo suspension engineer, Jeff Lesher who is a hell of a guy.

He taught me about frequency matching of the front and rear suspensions, basicaly the rear suspension needs to have a higher natural frequency than the front so bobing and other chassis exciting, traction reducing effects of bumps and undulations can be reduced. You tune so they will cancel out in 1/2 cycle.

Basicaly in a close to 1:1 motion ratio suspension like ours, this means the rear spring rates must be higher than the fronts. I am starting to do this based on his equations, using roll bars to make up the gradient in roll stiffness that this causes.

The results I have experianced so far are pretty interesting, bobing can be greatly reduced without needing more damping and the tires are getting shocked less with less bobbing and less damping. It seems to work well.

Also a big trend in the motorsports world is to adjust dampers so when you intergrate piston velocity over time the curve has an equal distribution for attack and decay. Need LDPT's to do that which are expensive but I do have the dfata loggers now.

So lately my spring rate recomendations are way different from the status qou. I will have more experiance with this so and will be changing some of the good old standard rule of thumb spring rates soon.

The OEM's are catching on with this lately. Wonder why the Spec V, Maxima, Altima and some other makes of car have such a high rear wheel rate?

Mike

Is this something that can be applied to the street then? What sort of front to rear ratio for the spring rates do your calculations show we need? Has testing showed the calculations are pretty close to what actually works? Werent you working on a large rear sway bar awhile back? With the stiff springs in the rear I'd think you would be going with a larger sway bar in the front now. One last question, whats an LDPT? Some sort of data logging sensor?

 

[choaderboy2]

Is this something that can be applied to the street then? What sort of front to rear ratio for the spring rates do your calculations show we need? Has testing showed the calculations are pretty close to what actually works? Werent you working on a large rear sway bar awhile back? With the stiff springs in the rear I'd think you would be going with a larger sway bar in the front now. One last question, whats an LDPT? Some sort of data logging sensor?

It works for street cars, some Nismo suspesion packages like the Altima and Maxima are tuned like this as is the C6 vette.

You want the bob of the front and rear to cancel out within 1/2 cycle of your target speed. I use 70-80 mph or so for a race car. Street cars use 50-60 mph or so.

A LDPT is a linear varible resistor on a rod used to datalog suspension movement with a very high resolution. I have the data logger but the buggers are expensive. I have some string pots but they don't have the resolution to do what I want to do next, looking at the distribution of shock piston velocity over time.

 

[mpg9999]

It works for street cars, some Nismo suspesion packages like the Altima and Maxima are tuned like this as is the C6 vette.

You want the bob of the front and rear to cancel out within 1/2 cycle of your target speed. I use 70-80 mph or so for a race car. Street cars use 50-60 mph or so.

A LDPT is a linear varible resistor on a rod used to datalog suspension movement with a very high resolution. I have the data logger but the buggers are expensive. I have some string pots but they don't have the resolution to do what I want to do next, looking at the distribution of shock piston velocity over time.

So whats with the big rear sway bar you had been developing? I would think you'd be going with a bigger front, not rear now.

How do I actually calculate this stuff? I started messing around with some equations but I'm not sure if what I've come up with means anything. I figured tune for 60 mph, which is 88 feet/sec. Wheel base is 95.7 inches, so at 60 mph the time difference between the front and rear hitting a bump is .090625 seconds. On a tech paper on optimumg, it said a typical ride frequency is 1.5 to 2.0 hertz on a race car. I used 1.5 hertz for the front, then used the mathematical description of a wave (Acos2pi ((x/lamdba)(t/T)) ) to calculate the time the wave takes to cross the x axis (1/2 cycle). From what I can tell it doesnt matter what you use for wavelength or amplitude (because x is going to be half of the wavelength so you always get .5 for x/wavelength). I came up with 1/3 of a second for t. 1/3 minus the .090625 I found earlier equals .2427 seconds. Thats the time you need the rear to cross the x axis, so multiply that by two gives you the period, and one over that is the frequency, which I get to be 2.06. So, with a 1.5 hertz front ride frequency I get a 2.06 rear. Am I even close to being right on any of this?

 

[brokeser]

...sounds to good to be poo-poo...

L

 

[choaderboy2]

So whats with the big rear sway bar you had been developing? I would think you'd be going with a bigger front, not rear now.

How do I actually calculate this stuff? I started messing around with some equations but I'm not sure if what I've come up with means anything. I figured tune for 60 mph, which is 88 feet/sec. Wheel base is 95.7 inches, so at 60 mph the time difference between the front and rear hitting a bump is .090625 seconds. On a tech paper on optimumg, it said a typical ride frequency is 1.5 to 2.0 hertz on a race car. I used 1.5 hertz for the front, then used the mathematical description of a wave (Acos2pi ((x/lamdba)(t/T)) ) to calculate the time the wave takes to cross the x axis (1/2 cycle). From what I can tell it doesnt matter what you use for wavelength or amplitude (because x is going to be half of the wavelength so you always get .5 for x/wavelength). I came up with 1/3 of a second for t. 1/3 minus the .090625 I found earlier equals .2427 seconds. Thats the time you need the rear to cross the x axis, so multiply that by two gives you the period, and one over that is the frequency, which I get to be 2.06. So, with a 1.5 hertz front ride frequency I get a 2.06 rear. Am I even close to being right on any of this?

I don't want to sound like a dick but I get paid as a consultant to do this stuff and there are a few things that I want to keep to my self.

Since I am the only one in the aftermarket to do this sort of thing to my knowlege and I have gotten a few jobs with this in the motorsports world with very statisfied customers, I am keeping it as my secret for now.

 

[mpg9999]

I don't want to sound like a dick but I get paid as a consultant to do this stuff and there are a few things that I want to keep to my self.

Since I am the only one in the aftermarket to do this sort of thing to my knowlege and I have gotten a few jobs with this in the motorsports world with very statisfied customers, I am keeping it as my secret for now.

Yeah, thats fine, I understand .

 

[jrmnet]

Shawn,

You may want to add a link to tire sizes in the wheel section:

http://www.se-r.net/tire_wheel/tire_sizes.html

 

[Shawn B]

Shawn,

You may want to add a link to tire sizes in the wheel section:

http://www.se-r.net/tire_wheel/tire_sizes.html

Done. And that kicks major ass. :biggthump

To the rest of you gentlemen, Steve (98sr20ve), Mike (mpg9999), and Mike (Choaderboy2). I am going to sort back through your posts and quote you smart folks.

Gracias!

 

[jrmnet]

More suspension info to chew on.

This is one person's progression to the Hyperco/AGX setup:

http://www.geocities.com/g_wellwood/automotive/sentraspringsandstruts.html

Also interesting is his page on sway bars.

 

[Shawn B]

More suspension info to chew on.

This is one person's progression to the Hyperco/AGX setup:

http://www.geocities.com/g_wellwood/automotive/sentraspringsandstruts.html

Also interesting is his page on sway bars.

Great stuff.

I know that guy used to work for Nissan Performance Magazine. I recognize the name.

Integrated in numerous places in the body of the text.

You rock. :biggthump

 

[jerryeads]

Shawn-
The recent, um, unusual discussion circling around structural bracing in the general sr20 section begs the question of where to put informed knowledge about the topic, and given you've already plugged in Dave's "IKEA solution", and given we're really talking about handling when we're talking about structural rigidity, would this be the place for it? I'm not talking about dragging that circus from the last couple days in here, but rather a repository for reasonable knowledge and practice. ?

 

[Shawn B]

Shawn-
The recent, um, unusual discussion circling around structural bracing in the general sr20 section begs the question of where to put informed knowledge about the topic, and given you've already plugged in Dave's "IKEA solution", and given we're really talking about handling when we're talking about structural rigidity, would this be the place for it? I'm not talking about dragging that circus from the last couple days in here, but rather a repository for reasonable knowledge and practice. ?

This is definitely the place for structural bracing, got a whole section on it. As you can tell, pretty much anything having to do with the suspension gets included.

Feel free to PM me or post again on exactly what you would like to see included. I am grateful to anyone that contributes "reasonable knowledge and practice" to this thread.

Since I have no knowledge and am oftentimes unreasonable, I sure can't contribute much myself.