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JRi Cortex double adjustable advice needed

so I've been running the boss the first half of the year on your cortex/jri suspension, and I've kept the settings at 6 & 15... mainly out of laziness to get under here and keep adjusting the rears. That will change now since I'm moving her trackside next week to live, so I can wrench a bit!

While super happy with on track performance, I have noticed that she feels very 'jouncy' over low amplitude high frequency road imperfections, undulations, for example where the weather has caused some road surface compression/wrinkling. I get bounced around quite a bit vertically. This happens at high and low speeds, most noticeable at highway speed limits.

I also noticed this was quite apparent at the Glen coming out of the toe of the boot, where the track gets wrinkly. As opposed to me experimenting with the setting permutations, anybody notice similar? What are your preferred adjustments? I'm not sure what difference the low speed compression/rebound and high speed rebound will make...

I'm going to email Filip too, at Cortex, since I haven't really found any good source online. Thanks in advance!
 

Grant 302

basic and well known psychic
What springs? And are you just talking about your front settings? -15/+6? I thought they were shipped with -15/+5?

I thought that the rear took more adjusting for comfort over road imperfections, but I've got 550# fronts and 350# rears.
 
I'm not sure on the springs, but if you also have the street extreme grip suspension, then it's probably the same as yours. I have the fronts and rears set to the middle settings currently, which I believe to be 15/6, but it may be 15/5... thx for the input!
 
Reply from Cortex FYI

The spring rates are 450# front and 225# rear. The rear shocks are valved on the stiffer side so you should try softening up both the low and high speed. Try going 4 click/sweeps at a time. Here are the JRi instructions on which knob is what. Be careful to not exceed the adjustment range going (-) since there is no hard stop.

As a general rule. High speed range is bumps and low speed range is body roll/transitions.

JRi Front Struts Double Adjustable CFS-40-1000-JRI-DA

JRi Rear Shocks Double Adjustable SHK-40-1000-JRI-DA

You can also take a look at the tuning guide.

http://cortexracing.com/vehicle-balance/
 

Grant 302

basic and well known psychic
Sounds like good advice for the street rates. I just noticed that this wasn't in the CorteX forum. I'm not going to move it, but there's also a sticky thread there on the DA adjustments, and I probably should have pointed you there too.

https://trackmustangsonline.com/index.php?topic=8864.0

My settings aren't going to help you much, but I have my shocks set at -22/+8 for the street.

Can you tell if the bouncing is coming more from the front or back?

I also suggest buying one of the JRI pin tools...made my life much easier after I got it.
 
This is why I wanted the single adjustable dampers. ;D

I created a spreadsheet with a table that might help with the adjustments. The number of clicks was not intuitive to me so my table puts the clicks relative to % of firmness. In other words "0" is full stiff and -30 is full soft for the front SA. So -15 if 50% stiff. If anyone wants a copy send me a PM with your email address.
 
Grant 302 said:
Sounds like good advice for the street rates. I just noticed that this wasn't in the CorteX forum. I'm not going to move it, but there's also a sticky thread there on the DA adjustments, and I probably should have pointed you there too.

https://trackmustangsonline.com/index.php?topic=8864.0

My settings aren't going to help you much, but I have my shocks set at -22/+8 for the street.

Can you tell if the bouncing is coming more from the front or back?

I also suggest buying one of the JRI pin tools...made my life much easier after I got it.

Thx. I'm pretty sure the bouncing is more from the rear... I've been using little hex screws for the adjustment works really well:)
 
LTNYC said:
Thx. I'm pretty sure the bouncing is more from the rear... I've been using little hex screws for the adjustment works really well:)

For what ever reason, 225 lbs /in is still a lot of rate especially if you have a large rear stabilizer bar.

I was at 300 lbs /in rear on my Cortex JRi setup, now at 225 lbs /in rear and its very bouncy still even with the 18mm rear stabilizer bar. i'm changing to a 175 rate rear spring shortly.

Also, the 225lbs / in is quite quick and matches the 450 front spring, 500 front 300 rear is matched, 450 front 225 rear is matched, 375 front 175 rear is also matched.. notice its not linear. I found that out the hard way - trial and error.
 
I'm surprised the 225's are too stiff for you in the rear. With my dampers on about 20% stiff my car rode very nice and the only time I noticed the stiffer rear springs was on large sharp bumps. I was using the stock RSB. Granted the roads around here are probably smoother than where you live but I really liked how mine rode on the street. I stiffed them way up for the track especially up front.
 
VooDooBOSS said:
I'm surprised the 225's are too stiff for you in the rear. With my dampers on about 20% stiff my car rode very nice and the only time I noticed the stiffer rear springs was on large sharp bumps. I was using the stock RSB. Granted the roads around here are probably smoother than where you live but I really liked how mine rode on the street. I stiffed them way up for the track especially up front.

They are not too stiff at all @225 lbs/in.. but they are too fast aka ride frequency. I could match the 225 better by increasing my front from 375 to 450 lbs/in, OR, I could match them by making the rear slower and decreasing from 225 to 175. I am going the slow lower rate route because I want the rear soft to help apply power coming out of corners.

I've tried to balance the low and high speed damping, it helps - I can mask the front slowness by lowering the low speed damping a lot, but then its a float master. I've also slowed down the rear a ton via more slow speed damping but then its too stiff a platform in the rear. Guys at Ford performance have been helping me a bit with that frequency matching, its a lot of trial and error.
 

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